MediaWiki API result
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{
"compare": {
"fromid": 1,
"fromrevid": 1,
"fromns": 0,
"fromtitle": "Home",
"toid": 2,
"torevid": 2,
"tons": 0,
"totitle": "Space Based Solar Power",
"*": "<tr><td colspan=\"2\" class=\"diff-lineno\" id=\"mw-diff-left-l1\" >Line 1:</td>\n<td colspan=\"2\" class=\"diff-lineno\">Line 1:</td></tr>\n<tr><td class='diff-marker'>\u2212</td><td class='diff-deletedline'><div><del class=\"diffchange diffchange-inline\"><strong>MediaWiki has been installed</del>.<del class=\"diffchange diffchange-inline\"><</del>/<del class=\"diffchange diffchange-inline\">strong></del></div></td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The Wikipedia's take on the topic is here https://en.wikipedia</ins>.<ins class=\"diffchange diffchange-inline\">org/wiki</ins>/<ins class=\"diffchange diffchange-inline\">Space-based_solar_power</ins></div></td></tr>\n<tr><td class='diff-marker'>\u00a0</td><td class='diff-context'></td><td class='diff-marker'>\u00a0</td><td class='diff-context'></td></tr>\n<tr><td class='diff-marker'>\u2212</td><td class='diff-deletedline'><div><del class=\"diffchange diffchange-inline\">Consult the [https://www.mediawiki.org/wiki/Special:MyLanguage/Help:Contents User's Guide] for information on using the wiki software.</del></div></td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">= What are Power Satellites? =</ins></div></td></tr>\n<tr><td class='diff-marker'>\u00a0</td><td class='diff-context'></td><td class='diff-marker'>\u00a0</td><td class='diff-context'></td></tr>\n<tr><td class='diff-marker'>\u2212</td><td class='diff-deletedline'><div>== <del class=\"diffchange diffchange-inline\">Getting started </del>==</div></td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The history is covered in the Wikipedia article above.\u00a0 The 1968 work by Peter Glaser is briefly mentioned in the video here: https://www.youtube.com/watch?v=VEkZkINrJaA</ins></div></td></tr>\n<tr><td class='diff-marker'>\u2212</td><td class='diff-deletedline'><div><del class=\"diffchange diffchange-inline\">* </del>[https://<del class=\"diffchange diffchange-inline\">www</del>.<del class=\"diffchange diffchange-inline\">mediawiki</del>.org/wiki/<del class=\"diffchange diffchange-inline\">Special</del>:<del class=\"diffchange diffchange-inline\">MyLanguage</del>/<del class=\"diffchange diffchange-inline\">Manual</del>:<del class=\"diffchange diffchange-inline\">Configuration_settings Configuration settings list]</del></div></td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td class='diff-marker'>\u2212</td><td class='diff-deletedline'><div>* [https://<del class=\"diffchange diffchange-inline\">www</del>.<del class=\"diffchange diffchange-inline\">mediawiki</del>.org/wiki/<del class=\"diffchange diffchange-inline\">Special:MyLanguage</del>/<del class=\"diffchange diffchange-inline\">Manual</del>:<del class=\"diffchange diffchange-inline\">FAQ MediaWiki FAQ]</del></div></td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">They are a way to collect solar power out in space, usually GEO where the sun shines 99% of the time.\u00a0 Solar power on the ground has the problems of intermittency from clouds, night and the sun being low in the sky. Typically, ground solar in good locations averages about 20% of its peak rating. Power satellites are subject to short eclipses (up to 70 minutes) near the equinoxes around midnight.\u00a0 Because demand is low, the interruptions can be tolerated.\u00a0 With deep market penetration, the microwave beams can be crossed if the demand exceeds the capacity of the surface grid to redistribute power east to west or west to east.</ins></div></td></tr>\n<tr><td class='diff-marker'>\u2212</td><td class='diff-deletedline'><div><del class=\"diffchange diffchange-inline\">* [https:</del>//<del class=\"diffchange diffchange-inline\">lists</del>.<del class=\"diffchange diffchange-inline\">wikimedia</del>.<del class=\"diffchange diffchange-inline\">org</del>/<del class=\"diffchange diffchange-inline\">mailman</del>/<del class=\"diffchange diffchange-inline\">listinfo</del>/<del class=\"diffchange diffchange-inline\">mediawiki</del>-<del class=\"diffchange diffchange-inline\">announce MediaWiki release mailing </del>list<del class=\"diffchange diffchange-inline\">]</del></div></td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td class='diff-marker'>\u2212</td><td class='diff-deletedline'><div><del class=\"diffchange diffchange-inline\">* [</del>https://<del class=\"diffchange diffchange-inline\">www</del>.<del class=\"diffchange diffchange-inline\">mediawiki</del>.org/wiki/<del class=\"diffchange diffchange-inline\">Special</del>:<del class=\"diffchange diffchange-inline\">MyLanguage</del>/<del class=\"diffchange diffchange-inline\">Localisation#Translation_resources Localise MediaWiki </del>for <del class=\"diffchange diffchange-inline\">your language</del>]</div></td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">They potentially scale to more than ten times the current energy needs of the human race.\u00a0 Started soon and pushed hard, they could end the build up of CO2 in the atmosphere and even reverse it.</ins></div></td></tr>\n<tr><td class='diff-marker'>\u2212</td><td class='diff-deletedline'><div><del class=\"diffchange diffchange-inline\">* [https</del>://www.<del class=\"diffchange diffchange-inline\">mediawiki</del>.<del class=\"diffchange diffchange-inline\">org</del>/<del class=\"diffchange diffchange-inline\">wiki</del>/<del class=\"diffchange diffchange-inline\">Special</del>:<del class=\"diffchange diffchange-inline\">MyLanguage</del>/<del class=\"diffchange diffchange-inline\">Manual:Combating_spam Learn </del>how to <del class=\"diffchange diffchange-inline\">combat spam </del>on <del class=\"diffchange diffchange-inline\">your wiki]</del></div></td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">If power satellites reach a high market penetration at times the power demand will go below their output.\u00a0 Power in excess of current demand can be fed to synthetic fuel plants solving the liquid transport fuel problem as well.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Methodology of This Work ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The specifics in this study are less important than the analysis methodology.\u00a0 Important concepts include levelized cost of power, specific mass in terms of kg/kW, lift cost, ERoEI, and payback times.\u00a0 The attempt here will be to analyze specific examples but the details of choices such as PV vs thermal are less important than the analysis procedure.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">= Power Satellites and Energy Economics =</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">In the absence of other forces (such as legal requirements to buy renewable energy) power satellites compete in the energy market.\u00a0 Of all energy forms, electrical energy is the ultimate standard commodity.\u00a0 When a customer plugs in a toaster, there is no way to tell what source the energy came from.\u00a0 At the end of the month, they pay the bill at the rate set by the power company under the oversight of a utility commission.\u00a0 One level up, the power companies are hemmed in by regulations that they buy (or make) the lowest cost electricity, with exceptions in some places that they have to purchase certain amounts of renewable energy.\u00a0 Wind and (ground) solar are both intermittent, requiring other sources or expensive storage to provide reliable power.\u00a0 The capital cost of intermittently run backup power either bankrupts the utilities or results in very high electrical rates.\u00a0 This is the current situation: the higher the fraction of renewable, the higher the consumer cost of electricity.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">[[File:Mearns.jpg]]</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The reason for the higher cost for systems that includes a lot of renewable power is not hard to understand.\u00a0 Wind and solar are intermittent.\u00a0 If steady, reliable power is desired then alternate sources of power are required.\u00a0 The capital cost of these backup sources must be included in the systemwide average cost of power in addition to the capital and maintenance cost of the wind or solar.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Space based solar power is renewable but not intermittent.\u00a0 That should make it easier to sell power from space at a premium.\u00a0 However, governmental energy policy changes unpredictably over time.\u00a0 An alternative would be a "design to cost" effort where the target cost of power is low enough to get a large market share without government intervention.\u00a0 Competing on cost is the way discount suppliers of many commodities obtained a substantial market share.\u00a0 (Examples, Southwest Airlines, GEICO, Charles Schwab.)</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>== <ins class=\"diffchange diffchange-inline\">Levelized cost of power </ins>==</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The formula for the levelized cost to generate electricity is here:\u00a0 </ins>[https://<ins class=\"diffchange diffchange-inline\">en</ins>.<ins class=\"diffchange diffchange-inline\">wikipedia</ins>.org/wiki/<ins class=\"diffchange diffchange-inline\">Cost_of_electricity_by_source]</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">This spreadsheet [https</ins>:/<ins class=\"diffchange diffchange-inline\">/docs.google.com/spreadsheets/d/1wDvn369EudkYGsPK3jNt4FmBFpNFtt0ZwDZl_lt_SNM/edit#gid=1481425448] assumes $1,600,000 per MW ($1600/kW) as the initial cost and 10% per year of the parts cost for maintenance.\u00a0 Power satellites supply base load.\u00a0 In the spreadsheet, it is assumed to be ~91% of the time.\u00a0 It may be higher.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The discount rate used in the spreadsheet is 6.8%, same as the US government uses for other sources.\u00a0 The accounting period is 20 years, and no salvage value is assumed.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The ratio between the $1600/kW cost and the cost that comes out of the formula (~2 cents per kWh) is approximately 80,000 to one.\u00a0 Electric power cost is proportional to the cost of a power satellite (or any power source that has no fuel cost and low maintenance) in this ratio for this discount rate and years of service.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The UK government has determined that 3.5% discount is proper for projects of this kind.\u00a0 Using 3.5%, the electric cost comes out at just over 1.5 cents per kWh and ~100,000 to one.\u00a0 Extending the accounting period to 30 years at 3.5% brings the cost of power down to 1.24 cents per kWh and a cost of power to cost of investment ratio to ~130,000 to one.\u00a0 It is a live spreadsheet; try your own numbers.\u00a0 A ratio of 80,000 to one is conservative.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">To take market share from coal will require the cost to be less than 4 cents per kWh for electricity from coal.\u00a0 Three cents per kWh allows a capital cost of $2400/kW.\u00a0 That, or less, is the "design to cost" target.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Cost allocations ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The current model has the $2400 target cost (from levelized cost above) split out as follows</ins>:</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">*$200/kW for the rectanna ($1 B for 5 GW), </ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">*$900/kW for the cost of parts and minor labor in space and </ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>*<ins class=\"diffchange diffchange-inline\">$1300/kW (6.5 kg/kW[</ins>[https://<ins class=\"diffchange diffchange-inline\">spacejournal.ohio.edu/issue18/thermalpower.html]] and $200/kg) for the cost of transport to GEO.\u00a0 (add pointer to sustech 2014 paper)</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">These numbers are targets which future work will firm up.\u00a0 If they go too high, something (like the cost charged for the electric power) will have to be adjusted.\u00a0 Of course, if they go too high, the entire idea needs to be reconsidered.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== ERoEI (Energy Returned on Energy Invested) and Energy Payback time==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">One of the metrics used to evaluate energy projects is energy</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">return on energy invested.\u00a0 This is expressed as a ratio, and for</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">shallow oil wells decades ago was typically 100 to one or higher.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">I.e., number of barrels of oil needed to drill an oil well divided</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">into the number of barrels it produced.\u00a0 An alternate way more applicable to</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">renewable sources is the energy payback time.\u00a0 It's typically about</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">two years for PV or wind.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">High ERoEI and short payback times usually accompany low cost.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Most of the energy embedded in a power satellite comes from the transport fuel.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">===Transport energy===</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Combustion of hydrogen is 143 MJ/kg or 39.4 kWh/kg plus the energy needed to liquefy the hydrogen.\u00a0 Google for "A Future Energy Chain Based on Liquefied Hydrogen" (you may need to add Berstad)</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">and go down to page 20.\u00a0 There they cite a number of ~6.5 kWh/kg to liquefy hydorgen.\u00a0 A large industrial plant might</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">do a little better by warming the LNG before steam reforming with hydrogen to start the cooling.\u00a0 Ignoring that possible small improvement, the energy cost of LH2 is about 46 kWh/kg.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">It's hard to say exactly where you should measure the input energy,</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">but the process to make hydrogen from natural gas is efficient, and (if we ship it as LNG) it</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">only uses about 1.7% of the energy in a kg of natural gas to liquefy it.\u00a0 I.e.,</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">measuring at the well head will not make a great deal of difference.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The CO2 released by steam reforming of natural gas is about 2.5 times the hydrogen produced.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The current LEO to GEO hydrogen consumption (using electric</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">propulsion) is 4000 tons to get 15,000 tons to high orbit.\u00a0 On</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">average, that makes a 15 ton Skylon payload 11.84 tons cargo and 3.16</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">tons of hydrogen reaction mass.\u00a0 I.e., 73% of the payload in LEO gets to GEO.\u00a0 At launch the average Skylon has 59</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">plus 3 or 62 tons of LH2.\u00a0 That makes the hydrogen per ton of payload</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">62 tons/11.84 tons or 5.25 kg/kg of payload.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The solar energy used to power the LEO to GEO transport is not</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">included since it is outside the Earth system.\u00a0 (The capital cost of the</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">propulsion power satellite is included in the financial models.)</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">For a power satellite specific mass of 6.5 kg/kW, a kW of power satellite (i.e., 6.5 kg) would use a little over 34 kg of LH2 to put it in GEO.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Using 46 kWh/kg for the energy content of LH2, that's around 1566 kWh of energy per kW of power satellite.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">===Parts energy===</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Without a detailed list of the parts, materials and mass in a power</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">satellite, it's not easy to say how much energy goes into making the parts.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Aluminum has the most embedded energy at 15 kWh/kg.\u00a0 But not very much</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">will be aluminum.\u00a0 If we estimate 10 kWh/kg, the energy in the parts</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">would be ~650 kWh, for a\u00a0 total of 2216 kWh per kW of capacity.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">When the power satellite is turned on, it takes 92 days (at 100% on</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">time) to repay the energy used to build it and move it to GEO.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">That's a three-month energy repayment time.\u00a0 There are no other renewable</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">proposals that are even close.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">If the power satellites last 30 years, you get an ERoEI of 120 to one, as good as early shallow oil wells.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">This is subject to adjustment as we settle on more accurate numbers in</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">the design phase, but it is good enough to justify investigation in detail.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">In his book on power satellites, John Mankins gives a payback time of 8 weeks.\u00a0 John uses the energy from physics, about 12 kWh/kg from the surface to GEO) (IIRC, it's actually 14.75 kW/kg)and doubles it twice for his estimate.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">= Power Satellite Types =</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Photovoltaic (PV) and Concentrated PV==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Most designs for power satellites since the 1970s have been PV.\u00a0 PV has advantages, long experience powering communication satellites being important.\u00a0 However, PV suffers from relatively low efficiency (20%) and degradation from radiation.\u00a0 There are proposals by Robert Forward and Robert Holt on draining the van Allen belt [http://en</ins>.<ins class=\"diffchange diffchange-inline\">wikipedia</ins>.org/wiki/<ins class=\"diffchange diffchange-inline\">HiVolt]; however, just the presence of a substantial number of power satellites in GEO is expected to greatly mitigate the radiation from particles trapped in the Earth's magnetic field.\u00a0 (The particles are stopped by running into a power satellite.\u00a0 There are only about 3 kg of protons trapped in the belts.)\u00a0 </ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">There are PV cells that range up to 40% efficient, but they require concentrated light and cooling.\u00a0 The work on thermal power satellites makes CPV possibly attractive, though there are problems with the limited supply of gallium which is used to fabricated the multi-junction cells.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Thermal ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Thermal (heat engines) power satellites are expected to eventually range up to 60% efficient, similar to combined cycle plants on earth. This means they need about 1</ins>/<ins class=\"diffchange diffchange-inline\">3 of the light interception area of ordinary PV, which reduces station keeping from light pressure.\u00a0 However, they also need radiator area that is about twice the sunlight interception area, (Bejan, 1997, pg 495, ref Bejan, A. Advanced Engineering Thermodynamics, 2nd ed. New York</ins>: <ins class=\"diffchange diffchange-inline\">Wiley, 1997.) Counting both sides of the radiator makes the exposed area for thermal and photovoltaic power satellites about the same.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">= Common considerations =</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">==Light pressure and Mass==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Light pressure is about 9 N</ins>/<ins class=\"diffchange diffchange-inline\">km^2</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The original studies done in the late 1970s came up with a mass of ~10 kg</ins>/<ins class=\"diffchange diffchange-inline\">kW</ins>. <ins class=\"diffchange diffchange-inline\"> More recent realistic studies have averaged around 7 kg/kW</ins>. <ins class=\"diffchange diffchange-inline\"> A few studies have proposed designs under one tenth of a kg</ins>/<ins class=\"diffchange diffchange-inline\">kW.\u00a0 Very light designs require a lot of station keeping against light pressure where designs in excess of 5 kg</ins>/<ins class=\"diffchange diffchange-inline\">kW can average the light pressure over a year.\u00a0 Because a substantial fraction of the construction cost is for transport to GEO, the mass of a power satellite is as important a number as the lift cost to GEO.\u00a0 This analysis will use 6.5 kg</ins>/<ins class=\"diffchange diffchange-inline\">kW.\u00a0 The number can be adjusted in the spreadsheets.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">==Energy transmission loss==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">How efficient is the transmission of the energy with the microwave beam?</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">For economic analysis, 50%.\u00a0 The loss chain might be a little better with technical improvements, but not much.\u00a0 It means you generate two kW in space for one kW on the rectenna bus.\u00a0 That's been assumed in all the analysis here.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Transport Methods Surface to LEO ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">====Falcon Heavy====</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Consider the projected Falcon Heavy, 53,000 kg to LEO, 121,400kg of</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">RP-1.\u00a0 That's about 2.3 kg of fuel for every kg lifted to LEO (here I assume that the entire mass in LEO is either reaction mass for the trip up or can be converted to power satellite parts--this may not be reasonable).\u00a0 RP</ins>-<ins class=\"diffchange diffchange-inline\">1</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">is 42 MJ/kg, so the energy expended to LEO is about 96.2 MJ/kg or 26.7</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">kWh/kg.\u00a0 You also have to lift the reaction mass for the LEO to GEO</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">leg so the fuel cost needs to be increased by around 20% giving 33.4</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">kWh/kg.\u00a0 If the reaction mass is hydrogen, it's energy content is not</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">zero, hydrogen is close to 50 kWh/kg to make it and another 20 kWh/kg</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">to make it into a liquid.\u00a0 So to move a kg from LEO to GEO would take</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">1/4 kg of LH2 at 70 kWh/kg or 17.5 kW/kg, for a total of ~51 kWh/kg.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">At 10 kg/kWe (on the ground) 510 kWh will be required to move a kW of power sat to GEO.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">At 100% on time, that's about 23 days to repay the energy.\u00a0 Unless I made an error, John's number is close enough.\u00a0 If only half of a Falcon Heavy payload becomes power satellite parts, John's estimate is very close.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">====Skylon====</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Much of the analysis been done using 50 kWh/kg as a ballpark number for hydrogen.\u00a0 It's good enough for rough calculations and it what it takes to make hydrogen if you are making it with electric power.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Combustion of hydrogen is 286 kJ/mol.\u00a0 Mole is 2.016 gm, so 496 moles in a kg, 143 MJ/kg or 39.4 kWh/kg.\u00a0 That's quite a bit less.\u00a0 The rough analysis have also been using 20 kWh/kg to liquify the hydrogen.\u00a0 That's way off.\u00a0 If you Google for "A Future Energy Chain Based on Liquefied Hydrogen" Berstad and go down to page 20, they cite a number of ~6.5 kWh/kg.\u00a0 We might do a little better because we can use warming the LNG to cool the hydrogen.\u00a0 That makes the energy content of the LH2 about 46 kWh/kg.\u00a0 It's hard to say exactly where you should measure the input energy, but the process to make hydrogen from natural gas is efficient, and it only uses about 1.7% of the energy in a kg of NG to liquify it.\u00a0 I.e., measuring at the well head will not make a great deal of difference.\u00a0 Still, this Wiki article needs to go into the thermodynamics of steam reforming.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Transport Methods LEO to GEO ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The current LEO to GEO hydrogen consumption (using electric propulsion) is 4000 tons to get 15,000 tons to high orbit.\u00a0 On average, that makes a 15 ton Skylon payload 11.84 tons cargo and 3.16 tons of hydrogen reaction mass.\u00a0 At launch the average Skylon has 59 plus 3 or 62 tons of LH2.\u00a0 That makes the hydrogen per ton of payload 62/11.84 or 5.25 kg/kg of payload.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">(Why hydrogen and not an inert gas?\u00a0 For a given amount of energy you can get considerably more exhaust velocity out of hydrogen.)</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The solar energy used to power the LEO to GEO transport is not included since it is outside the system.\u00a0 (The capital cost of the propulsion power satellite is included in the financial models.)</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Using my supported but perhaps optimistic number of 6.5 kg/kW, an installed kW would use a little over 34 kg of LH2 to get it in place.\u00a0 Using 46 kWh/kg for the LH2, that's around 1566 kWh per installed kW.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Without a detailed </ins>list <ins class=\"diffchange diffchange-inline\">of the parts materials and mass in a power satellite, it's not easy to say how much energy goes into the parts.\u00a0 Aluminum has the most embedded energy at 15 kWh/kg.\u00a0 But not very much will be aluminum.\u00a0 If we estimate 10 kWh/kg, the energy in the parts would be ~650 kWh, for a\u00a0 total of 2216 kWh per kW of capacity.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">When the power satellite is turned on, it takes 92 days (at 100% on time) to repay the energy used to build it and move it to GEO.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">That's a three month energy repayment time.\u00a0 I don't know of any other proposal that is even close.\u00a0 And the energy from a power satellite not intermittent.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">If the power satellites last 30 years, you get an ERoEI of 120 to one.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">This is subject to adjustment as we settle on more accurate numbers in the design phase, but it should be reasonably close.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">ERoEI is an interesting metric, but the more important figure is the cost.\u00a0 Target cost is 3 cents a kWh falling to 2 cents within a few years.\u00a0 This just barely meets Gail's requirements. For a first approximation, the embedded energy in the parts and the energy required to make LOX are so small in comparison to RP1 or LH2 that they can be ignored.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">It's surprising that even with a lower kg/kW number the energy payback time is longer for the Skylon.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">==Energy payback time, EROEI and Maximum Growth Rate==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">I recently ran an energy payback time for power satellites constructed using Falcon Heavy. It came in at around 8 weeks.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The current computation of LEO to GEO hydrogen consumption (using electric propulsion) is 4000 tons to get 15,000 tons to high orbit. On average, that makes a 15 ton Skylon payload 11.84 tons cargo and 3.16 tons of hydrogen reaction mass. At launch the average Skylon has 59 plus 3 or 62 tons of LH2. That makes the hydrogen per ton of payload 62/11.84 or 5.25 kg of hydrogen per kg of payload.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The solar energy used to power the LEO to GEO transport is not included since it is outside the system. (The capital cost of the propulsion power satellite is included in the financial models.)</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Combustion of hydrogen is 286 kJ/mol. Mole is 2.016 gm, so 496 moles in a kg, 143 MJ/kg or 39.4 kWh/kg. If you Google for \u201cA Future Energy Chain Based on Liquefied Hydrogen\u201d Berstad and go down to page 20, they cite a number of ~6.5 kWh/kg. We might do a little better because we can use warming the LNG to partly cool the hydrogen. That makes the energy content of the LH2 about 46 kWh/kg. It\u2019s hard to say exactly where you should measure the input energy, but the process to make hydrogen from natural gas is efficient, and it only uses about 1.7% of the energy in a kg of NG to liquify it. I.e., measuring at the well head will not make a great deal of difference. Still, we need to dig into the thermodynamics of steam reforming.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Using s perhaps optimistic number of 6.5 kg/kW, an installed kW would use a little over 34 kg of LH2 to get it in place. Using 46 kWh/kg for the LH2, that\u2019s around 1566 kWh per installed kW.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Without a detailed list of the parts materials and mass in a power satellite, it\u2019s not easy to say how exactly much energy goes into the parts. Aluminum has the most embedded energy at 15 kWh/kg. But not very much will be aluminum. If we estimate 10 kWh/kg, the energy in the parts would be ~650 kWh, for a total of 2216 kWh per kW of capacity.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">When the power satellite is turned on, it takes 92 days (at 100% on time) to repay the energy used to build it and move it to GEO.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">That\u2019s a three month energy repayment time. We know of no other energy proposal that is even close. And the energy from a power satellite not intermittent.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">If the power satellites last 30 years, you get an ERoEI of 120 to one.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">This is subject to adjustment as we settle on more accurate numbers in the design phase, but it should be reasonably close.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">ERoEI is an interesting metric, but the more important figure is the cost. Target cost is 3 cents a kWh falling to 2 cents within a few years. This just barely meets Gail\u2019s requirements.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">By the criteria given here </ins>https://<ins class=\"diffchange diffchange-inline\">en</ins>.<ins class=\"diffchange diffchange-inline\">wikipedia</ins>.org/wiki/<ins class=\"diffchange diffchange-inline\">Energy_cannibalism and here https://web.archive.org/web/20090817071517/http</ins>:/<ins class=\"diffchange diffchange-inline\">/www.climate2008.net/?a1=pap&cat=1&e=61 a power satellite growth rate of lower than 360% per year would result in lowering GHG emissions.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">==Reliability==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Electric power needs to be reliable.\u00a0 First, the</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">power satellite size is only 5 GW.\u00a0 The target number is 3000 for 15</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">TW.\u00a0 There would be spares sending power to low priority loads that</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">could be switched in less than a second to replace a higher priority failed one.\u00a0 Plus</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">we would still have the grid to distribute electricity from the</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">remaining powered rectennas, and for a long time, there would be other generation in the mix.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">None the less, there are ways we could lose the whole fleet of them in</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">an instant if they were not designed to deal with it.\u00a0 In the year 774 or 775</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">the Earth seems to have been hit with either a unprecedented solar flare or a fairly close gamma ray burst.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The latter are typically a few seconds, the former might take a few hours.\u00a0 In any case, it put a serious kink in the carbon</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">14 for the next growing season.\u00a0 Such an event would take out the</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">controls for any power satellite that did not have enough shielding</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">around the control computers.\u00a0 The shielding needed against these 1000</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">year events is considerably more than the worst solar flares observed to date.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Unlikely as they are, GRB or intense high energy solar flares are a concern that requires mitigation and recovery strategies</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">such as watch dog timers and hardened reboot memory.\u00a0 Radiation</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">resistance is an argument in favor of rotating machines rather than PV.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">A solar flare can be seen coming and outside workers would probably have time to reach shelter.\u00a0 A GRB would be over before the workers had a chance to move.\u00a0 Neither are serious problems for people behind shielding good enough to stop cosmic rays.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">= Transport Earth to LEO =</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== SpaceX ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">SpaceX may not get the transport cost down low enough.\u00a0 It has to be to</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">be SSTO or possibly TSTO runway operations.\u00a0 </ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">SpaceX _will_ eventually get the cost to GEO down by a full order of</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">magnitude, a remarkable achievement.\u00a0 Unfortunately this won't do it</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">for power from space, it takes _two_ orders of magnitude reduction.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Elon Musk knows this.\u00a0 It might be why he is so down on power satellites.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Note Oct 15,2016.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Musk was recently talking about a rocket with a cost of putting cargo into a Mars trajectory for $143/kg.\u00a0 That's remarkable and is low enough </ins>for <ins class=\"diffchange diffchange-inline\">power satellites to make economic sense.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Skylon ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Until Reaction Engines demonstrated their high performance precooler, there were no realistic SSTO proposals out there.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">[[www.reactionengines.co.uk/space_skylon.html]</ins>]</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Skylon Doesn't Cause Much Ozone damage (NOx) ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">NOAA worked out that up to a million Skylon flights per year there is little damage to the ozone.\u00a0 There is no point in solving the carbon and energy problem with power satellites if the cost is a billion cases of skin cancer.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The NOAA people put a lot of effort into modeling the problem, hundreds of hours of supercomputer time on the models, writing a paper and getting it through peer review.\u00a0 Highly appreciated.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The paper is available online at</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">http://onlinelibrary.wiley.com/doi/10.1002/2016EF000399/full</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Click on the PDF symbol next to the journal title.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">= LEO to GEO =</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Space Junk ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Back in the late 70s, Boeing proposed building power satellite in LEO and then self powering to GEO (using ion engines or arcjets).\u00a0 They even did some nice artwork.\u00a0 But even in those days there was enough space to make this a very risky move and it was abandoned.\u00a0 HKH redid the math in recent years using the density of space junk given in the Wikipedia article.\u00a0 The result was that a power satellite would be hit almost 40 times while self powering to GEO.\u00a0 Almost all the hits are below 2000 km altitude.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Building power satellites in LEO would work, it's just they could not be moved to where they are useful unless the plan includes cleaning up the space junk first.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Engines ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Arcjet ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== VSMIR ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Power ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Tug Rectenna ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Increasing the frequency to 25 GHz and reducing the distance to half allows reducing the tug rectenna to 500 m.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">This has not been optimized, nor have the tracking details worked out.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Worker Transport ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Getting workers out to 12,000 km takes either a fast transport to keep the radiation exposure from the inner van Allen belt down or sending them up inside cargo containers.\u00a0 If they go up with power satellite parts around them for shielding, the trip is about 25 days.\u00a0 The return trip is shorter, around 5 days, but unless a lot of shielding is taken</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Propulsion power satellite ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Reaction Mass ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Construction Orbit ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">= CONSTRUCTION SITE =</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Tentatively we have selected 10,400 km, less than one third of the way to GEO.\u00a0 This is in a six hour orbit orbit.\u00a0 The choice is based on this altitude being the low radiation zone between the inner and outer van Allen belts.\u00a0 The orbit is subject to tradeoff/optimization studies which have not been done yet.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Platform (JIG) ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Even more tentative, we have envisioned a kind of "dry dock" for power satellites.\u00a0 Big frame of beams to move cargo from the stacks to the work sites where the power satellites are constructed.\u00a0 We also project a rotating habitat with the spin axis pointing solar north/south and a concentrating reflector to bring light inside through a window.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Habitat--Company Town? ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">On the roughest of analogies dating back to Liberty ship construction in WW II, it might take 400 construction workers for the 10 per year pilot construction plant.\u00a0 This includes families.\u00a0 The shielding on the habitat will need to be ~six tons per square meter to reduce the cosmic radiation to the level seen on Earth.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The consequence for a 50 m habitat is 60,000 tons of shielding, about $9 B in lift cost at $150/kg.\u00a0 </ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">It has to be a spinning habitat.\u00a0 One thing learned from the ISS is that neat as zero g is, human do not do well health wise in long term zero g.\u00a0 The spin rate for one g at the equator is 6 RPM.\u00a0 Do we spin the shielding or just the habitat?\u00a0 In either case, there is a considerable amount of rotational kinetic energy in the habitat.\u00a0 Whatever is used for a bearing must be proof against lockup.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">There is a reason for families.\u00a0 We can't expect construction workers to live like monks or nuns.\u00a0 Taking them to and from 10,400 km (6 hour orbit) is either slow or very expensive in reaction mass and power.\u00a0 It is relatively easy to ship the workers and families up.\u00a0 They are shielded by containers of parts for the 25 days it takes to transit up.\u00a0 But there are no parts coming back down so shielding for returning workers would have to be carried at great cost.\u00a0 Alternately, they could go up in the habitat if it was constructed in LEO.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">About the interaction of radiation, workers and transport . . . we might be able to build power satellites entirely using</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">robots directed from the ground or by AIs.\u00a0 We don't have such robots/AIs yet, but if the development time is short and the cost less than $9 B, that may be the way to go.\u00a0 (Teleoperated robots are closer and a 6 hour orbit does not induce as much speed of light delay as GEO.)\u00a0 I would be OK with that, though saddened by the loss of human</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">experience.\u00a0 Assuming we don't have robots building power satellites,</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">or at least they need help from people, then we have to have people in</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">space.\u00a0 For social and economy of scale reasons</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">fewer than about 200 may not make sense.\u00a0 If the ISS is any indicator,</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">one quarter of them will be working on maintenance to keep the habitat</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">liveable.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">A power satellite project makes a lot of money but can it afford 200</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">workers in space?\u00a0 Perhaps the least complicated analysis is to take</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">the income stream from 10-12 power satellites per year.\u00a0 That seems to</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">be the minimum were transport economies of scale kick in.\u00a0 11 power</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">satellites at $11 billion each is $121 B.\u00a0 A thousand people would be</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">building $121 M per person, 500 would be building $242 M each.\u00a0 A pay</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">rate of a million per person per year would make the labor charges on</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">the product under half a percent.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">We get the wages back at the company store where we charge them</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">$200/kg for steak.\u00a0 Just kidding!</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">After feeding the workers, the "used" food becomes part of a power</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">satellite so the effective cost to feed them is zero.\u00a0 If there is</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">nothing else to use it for, each power satellite needs a substantial</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">"space anchor."\u00a0 A "space anchor" is just a multi ton mass (anything</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">will do) on the end of a long string.\u00a0 It is connected to the</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">transmitter disk edges by a bridal and winches.\u00a0 It eliminates using</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">reaction mass for pointing the power satellite.\u00a0 (Gravity gradient</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">stabilization.)</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">So we can pay the workers and feed them.\u00a0 Next problem is getting them</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">out to the construction site.\u00a0 If we use 10,400 km (in the radiation</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">minimum between the van Allen belts) then the time for the reference</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">beamed energy transportation system is about 25 days up and about 5</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">days back.\u00a0 In the Apollo program,</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">http</ins>://www.<ins class=\"diffchange diffchange-inline\">braeunig</ins>.<ins class=\"diffchange diffchange-inline\">us/apollo</ins>/<ins class=\"diffchange diffchange-inline\">VABraddose.htm, the astronauts skirted</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">around the belts and went fast so they didn't spend time in them.\u00a0 For</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">power satellites we have to bull right through the hottest part of the</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Van Allen belt and slowly too due to the orbital mechanics of spiral</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">orbits.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">However, we have something on the trip up the Apollo astronauts didn't</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">have, tens of thousands of tons of power satellite parts which can be</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">used for shielding.\u00a0 The scale of the cargo stacks is more or less set</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">by beamed energy microwave optics used to power the stack out to the</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">construction site.\u00a0 If made of Skylon sized containers, a cargo stack</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">has 11 layers of 91 containers per layer.\u00a0 If the modules for human</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">transport are buried a few layers down and in the center of the stack,</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">it's hard to imagine the relatively low radiation of the worst part of</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">the belt giving them much exposure (though it should be calculated).</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">An alternative would be to build the habitat in LEO and send it up with the workers inside.\u00a0 Depending on the propulsion power available, this could take a couple of months.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The exposure on the way down is 1</ins>/<ins class=\"diffchange diffchange-inline\">5th the time, but with no cargo to</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">shield them, the radiation exposure would be much larger, perhaps</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">lethal.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">My solution to this problem is to send workers up one way.\u00a0 I.e., they</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">would be expected to stay at least ten years.\u00a0 That means that (unless</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">you plan on using monks) we have to send up families.\u00a0 That means</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">children, and that means controlling the radiation in the construction</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">habitat to no worse than the level at Denver and spinning the habitat</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">to one g. </ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">=== Limited Recycling ===</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Most food for the workers can be shipped up.\u00a0 It is essentially free since after people eat it, it can all be recycled into parts of a power satellite.\u00a0 Not so with fresh food that cannot survive a month shipping.\u00a0 Salad greens need to be grown in the habitat.\u00a0 This does not look like a hard problem and may eliminate some of the atmosphere contaminate problems that require burners in submarines.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== Self Power (Out to GEO) ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">In terms of reaction matter consumption, it makes no difference if the power satellite self powers part of the way out or not.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">[[Category</ins>:<ins class=\"diffchange diffchange-inline\">Earth Orbit]]</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">== stuff to move ==</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">>> We get the wages back at the company store where we charge them $200</ins>/<ins class=\"diffchange diffchange-inline\">kg</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">>> for steak.\u00a0 Just kidding!</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">></ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">> Not really kidding, though. The burdened cost of labor in orbit is indeed</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">> exorbitant, however you do the accounts. You should see the rent on a 30 m^2</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">> studio per month! Orbital habitat is indeed the epitome of the company town.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">> The 19th c. mining barons would salivate over the opportunities to exploit</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">> labor in this environment. I doubt modern financiers are all that much</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">> different.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">I don't know </ins>how to <ins class=\"diffchange diffchange-inline\">solve this problem.\u00a0 I would think the</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">organization that was running the power satellite construction project</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">would want to keep their workers happy.\u00a0 However, don't assume the</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">workers are western.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">>> My solution to this problem is to send workers up one way.\u00a0 I.e., they</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">>> would be expected to stay at least ten years.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">></ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">> This isn't medically viable unless you have an artificial gravity</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">> environment.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Agree.\u00a0 And radiation shielding to Earth surface exposure as well, at</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">least for the inside.\u00a0 The problem comes from the interaction of</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">orbital mechanics, the slow trip up (needed to keep the reaction mass</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">cost down) and the lack of shielding during the trip back down to LEO.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">The radiation exposure for the trip back may be reduced by draining</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">the Van Allen belt, but there does not seem to be a low cost way of</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">moving people to the construction site outside the cargo stacks.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">> The marginal cost tradeoff is between transportation expense</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">> and habitat capital and operating expense.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">That's sort of true.\u00a0 But when it takes 25 days to get up and 5 to get</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">back, the working come would be cut by 1/3 if you had the workers on a</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">2 month schedule.\u00a0 Plus coming back they would probably accumulate a</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">lifetime radiation limit, if it didn't kill them.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">> In terms of cost estimating, the easy was to deal with all this is to assume</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">> a fractional cost burden </ins>on <ins class=\"diffchange diffchange-inline\">powersat maintenance and then design habitat to</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">> that cost. It's not going to be possible to know a whole lot more at the</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">> current stage of maturity.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">I don't understand maintenance.\u00a0 This is only about construction.\u00a0 I</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">have not yet considered where we base the human maintenance workers.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Any thoughts?\u00a0 In any case, shielding is a big problem no matter where</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">you base people in space.</ins></div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div>\u00a0</div></td></tr>\n<tr><td colspan=\"2\">\u00a0</td><td class='diff-marker'>+</td><td class='diff-addedline'><div><ins class=\"diffchange diffchange-inline\">Keith</ins></div></td></tr>\n\n<!-- diff cache key spacepedia_prod:diff::1.12:old-1:rev-2 -->\n"
}
}