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PG&E signs first-of-a-kind space solar power deal. Why?

By Joe Romm  

"PG&E signs first-of-a-kind space solar power deal. Why?"


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Not many people I know think space solar is a low-cost, scalable solution.

Space Solar disk.jpgCertainly it is worth pursuing any genuine low-carbon baseload power source if it can be practical and scalable — and affordable, which I would put at $0.15 a kilowatt hour or less for.  The problem with space solar is that, like hydrogen fuel cell cars, there is little chance it could be affordable until it is massively scaled up — and no guarantee that it would be practical and affordable even then.  That’s one reason major utilities have been unwilling to take the risk on it.

Until now.

Apparently at least one serious utility that has invested in “wind, geothermal, biomass, wave and tidal, and at least a half dozen types of solar thermal and photovoltaic power” is looking in to it.  Jonathan Marshall, Chief, External Communications, Pacific Gas and Electric Co., sends me a link to his posting on NEXT100.com, “a blog supported by PG&E that explores the intersection of the clean energy business and the environment”:

PG&E is seeking approval from state regulators for a power purchase agreement with Solaren Corp., a Southern California company that has contracted to deliver 200 megawatts of clean, renewable power over a 15 year period.

Solaren says it plans to generate the power using solar panels in earth orbit, then convert it to radio frequency energy for transmission to a receiving station in Fresno County. From there, the energy will be converted to electricity and fed into PG&E’s power grid. (See interview with Solaren CEO Gary Spirnak.)

Why would anyone choose so challenging a locale to generate electricity? For one, the solar energy available in space is eight-to-ten times greater than on earth. There’s no atmospheric or cloud interference, no loss of sun at night, and no seasons. That means space solar can be a baseload resource, not an intermittent source of power.  In addition, real estate in space is still free (if hard to reach). Solaren needs to acquire land only for an energy receiving station. It can locate the station near existing transmission lines, greatly reducing delays that face some renewable power projects sited far from existing facilities.

Yeah, well good luck PG&E!

Wikipedia has a good entry on SBSP here.  Scale and cost are probably the biggest problems.  You probably need more than a factor of 10 more drop in launch costs.  The space community has been promising such a drop was just around the corner for decades, now.

It seems all but inconceivable that you could get the cost to drop that sharply without economies of scale and a learning curve driven by a massive number of regular launches.  But who is going to pay for all those incredibly expensive space-based solar systems before the cost drops?

This is a classic chicken and egg problem, compounded by the fact that there is no guarantee you will actually get the cost drops even with large-scale deployment, so all of your money is at grave risk.

The risk is even greater because land-based solar baseload (or load following or dispatchable solar) — aka Concentrated solar thermal power — is practical and scalable now, and certain to be much cheaper.  And land-based PV is poised to drop in cost sharply, and will ultimately have access to tremendous land-based storage through plug-in hybrid and electric cars.

Then we have the life-cycle emissions issue.  It takes a massive amount of rocket fuel to put stuff in orbit.

Solaren CEO Gary Spirnak glosses over this entire issue in his interview with Marshall on the web (here):

Q: Is the renewable energy generated from this project completely carbon-free?

A: Yes. Solaren’s SSP energy conversion process is completely carbon-free.

Q: How will this project impact the environment?

A: The construction and operations of Solaren’s SSP plant will have minimal impacts to the environment.  The construction of the SSP ground receive station will have no more environmental impact than the construction of a similarly sized terrestrial photovoltaic (PV) solar power plant.  Space launch vehicles will place the SSP satellites into their proper orbit. These space launch vehicles primarily use natural fuels (H2, O2) and have an emissions profile similar to a fuel cell. When in operation, the Solaren SSP plant has a zero carbon, mercury or sulfur footprint.  In addition, the high efficiency conversion of RF energy to electricity at the SSP Ground Receive Station does not require water for thermal cooling or power generation, unlike other sources of baseload power (nuclear, coal, hydro).

Uhh, not quite.  The solar energy is carbon free (other then the manufacturing of the cells which is typically recovered in one or two years of operation).

But I’d hardly call H2 — hydrogen– a “natural fuel.”  Today, NASA gets its hydrogen from natural gas in a process that generates large amounts of carbon dioxide.  And then it uses a huge amount more energy to get the hydrogen into the Space Shuttle.   As I discuss in my book, The Hype about Hydrogen:

At atmospheric pressure, hydrogen becomes a liquid only at the ultra-frigid temperature of -253 °C (-423 °F or 20 K), just a few degrees above absolute zero. It can be stored only in a super-insulated tank, known as cryogenic storage.

NASA uses liquid hydrogen as a fuel for the space shuttle, along with liquid oxygen. Some 100 tons or nearly 400,000 gallons of liquid hydrogen are stored in the shuttle’s giant external tank.  To fuel each shuttle launch, 50 tanker trucks drive several hundred miles from New Orleans to Kennedy Space Center in Florida. We have a great deal of experience shipping liquid hydrogen: Since 1965, NASA has trucked more than 100,000 tons of liquid hydrogen to Kennedy and Cape Canaveral….

The process of liquefying hydrogen requires expensive equipment and is very energy-intensive. Refrigeration processes have inherent efficiency limitations, and hydrogen liquefaction requires multiple stages of compression and cooling. Some 40% of the energy of the hydrogen is required to liquefy it for storage….

A major challenge facing liquefied hydrogen is evaporation. Hydrogen stored as a liquid can boil off and escape from the tank over time. NASA faces this in the extreme: The agency loses almost 100,000 pounds of hydrogen each time it fuels up the shuttle, requiring NASA to truck in far more hydrogen than the 227,000 pounds needed by the main tank.

From a global warming perspective, even with large, centralized liquefaction units, the electricity consumed would be quite high. According to Raymond Drnevich of Praxair, a leading supplier of liquefied hydrogen in North America, the typical power consumption is 12.5 to 15 kWh per kg of hydrogen liquefied.  Since that electricity would come from the U.S. electric grid, liquefying 1 kg of hydrogen would by itself release some 17.5 to 21 pounds of carbon dioxide into the atmosphere for the foreseeable future. Burning one gallon of gasoline, which has roughly the same energy content as 1 kg of hydrogen, releases about the same amount–20 pounds of carbon dioxide into the atmosphere. So even allowing for the greater efficiency of hydrogen fuel cell vehicles, if liquefaction is a major part of the hydrogen infrastructure, it would be exceedingly difficult for hydrogen-fueled vehicles to have a net greenhouse gas benefit until the electric grid is far greener than today (that is, has far lower carbon dioxide emissions per kilowatt-hour).

Yes, you could make the hydrogen from renewable sources — and liquefy it with renewable sources.  But there is no prospect that can be done for anything less than an exorbitant cost, which would drive up the price of each launch enormously.

PG&E concludes

From PG&E’s perspective, as a supporter of new renewable energy technology, this project is a first-of-a-kind step worth taking. If Solaren succeeds, the world of clean energy will never be the same.

I don’t think space-based solar should be considered among the plausible climate solutions until and unless someone publishes

  • a realistic cost estimate based on plausible launch costs
  • a full lifecycle analysis of CO2 per kiloWatt-hour using existing launch vehicle emissions.

‹ David Broder is the sultan of the status quo, stenographer of those centrists who are fatally uninformed about global warming

Energy and Global Warming News for April 14 ›

31 Responses to PG&E signs first-of-a-kind space solar power deal. Why?

  1. Harrier says:

    I agree that this seems a little pie-in-the-sky.

    But I’m intrigued by the idea of wireless power transmission. Couldn’t that be the solution to getting energy from, say, offshore wind farms to cities on the mainland? I know there are several ways to do it, including transmission of power through microwaves.

    And of course there’s the system that Tesla was working on…

  2. When you get it wrong, you get it really very wrong, Joe. Things like hydrogen energy technology (straight energy conversion for transporatation) and solar power satellites aren’t designed to be affordable in the near term, they are designed to DRIVE SCIENCE AND TECHNOLOGY FORWARD in all of the areas relevant to energy conversion processes. There is nothing better in that regard than a sustainable space program using hydrogen energy and solar power. Mr. Obama and most of the other ‘status quoists’ like yourself utterly miss the point on this, it’s like some kind of miswiring or mental block.

    [JR: Yes, one thing people say about me is that I am a "status quoist." Good catch!]

  3. Russ says:

    I’d say “we have breakthrough technology which we will deploy over many years starting in 2016″ should be filed in the same category as any other mythical breakthrough. I wonder what sorts of credits they’ll be eligible for a priori for the price of a token investment.

    And although PG&E and Solaren are saying no public money will be used for this, I doubt that’s their real end goal. I imagine the real business plan is something like drumming up hype and capturing the public imagination (just like the overall expensive boondoggle of space travel itself has done) and then turning around and saying they need a bailout or the project will fail.

  4. the overall expensive boondoggle of space travel itself has done

    In your opinion knowledge about our universe and how it works is worthless.

    Here’s one for you. Which is more profitable, beaming that space solar energy back to earth using microwaves, or selling that power to research and tourist operations in orbit, where all they have to do is plug in. Which would drive the technology of energy conversion and space transportation forward?

  5. I agree with Elifritz. Like all other new technologies, we should start using them as soon as they are environmentally viable, and worry about economics later. If PG&E manages to replace a significant amount of fossil fuel production with space solar, then we should not be worrying about where the money will come from. It will come from the technology!

  6. Sasparilla says:

    I sure wouldn’t want to be in an airplane or be a bird that flies through the invisible, massively powerful focused beam of energy coming down through the sky – normally this energy is in the microwave spectrum. (Can’t wait to see the effects this has on, wildlife flying through it, water vapor in clouds and the atmosphere in general – since your microwave heats up the food by heating up the water molecules in it).

    Before things like this really move forward the true long term drawbacks of the technology need to be viewed carefully and a little big picture thinking about this idea would quickly put it in the big drawbacks pile – we’ve got cheaper better solutions right now (solar, wind, geothermal etc. and nuclear if need be). My personal view is that we don’t want these around (and I’m a space buff).

  7. Russ says:

    Thomas, I don’t quite follow your question. I think the technology we have is sufficient, I think space travel has long since passed the point of diminishing returns (and will no longer be viable post-Peak Oil anyway), and I could not possibly care less what is more “profitable”.

    In your opinion knowledge about our universe and how it works is worthless.

    On the contrary, I have great admiration for Thales, Ptolemy, Copernicus, Brahe, Kepler, Halley, Newton and others, not to mention the great philosophers, who amassed great knowledge and were somehow able to do it without the crutch of your monstrous technology.

    I guess even “standing on the shoulders of giants”, the technicians of today are so picayune they can’t function except as vestigial organs of machines.

  8. I think the technology we have is sufficient

    I think you need to entirely rethink that statement.

    the crutch of your monstrous technology.

    I guess you missed those seven billion soon to be nine billion human souls on the surface of this nickel iron cored rocky terrestrial planet.

    How pray tell, do you expect to feed them in the future? Just wondering.

  9. Sustainable_Or_Not says:

    Space weapons program masquerading as green energy.

    Well, there’s a proud tradition of funding nuclear weapons programs through civilian energy applications, why not go for it in The Final Frontier?

    65 pounds of solid rocket propellant per pound of payload to orbit. Unless massive solar power plants are built on earth to produce the propellant, this project will never reach carbon parity.

    Expect major articles in such carefully edited publications as Wired and Scientific American getting everyone excited about this “breakthrough solution”.

    You’d think PG&E would know better.

  10. 65 pounds of solid rocket propellant per pound of payload to orbit.

    May I introduce you to liquid fuels?

    Welcome to the 21st Century as well.

  11. Rick C says:


    I’m just a ham radio operator but when we deal with the emission of radio waves we learned about something called the inverse square law which states that the electromagnetic field strength is inversely proportional to the square of the distance.

    Given that fact, three things have to be established. First, any solar orbiting photovoltaics would have to be placed in low earth orbit around 300 miles up so that the distance is signficanlty reduced because putting them in geosynchronous orbit would, while allowing only one solar array to be built, increases the distance to 22,000 miles in an already crowded Clark Belt. This would decrase the amount of energy available t the earth station due to the inverse square law. Second, because they are in low earth orbit you would have to build a constellation of these orbiting photovoltaics to keep a steady supply of energy beaming down to the earth station because at the typical speeds of 24,000 mph at 300 miles up in space you would have, at best, a window of around 11 to 22 minutes depending on whether you site the earth station on flat terrain or in a hilly or moderately mountainous area. Third, the shear cost to put a pound of anything, even in low earth orbit, is so prohibitively expensive that it would make building an IGCC plant, if a demonstration model was availble, seem like a bargain by comparison.

    Wouldn’t this also put an end to this talk of orbting solar panels?

  12. Lou Grinzo says:

    I think the best thing Joe’s said on this site in a while (and I mean that as a big compliment), is his closing plea for “a realistic cost estimate based on plausible launch costs” and “a full lifecycle analysis of CO2 per kiloWatt-hour using existing launch vehicle emissions”.

    In many ways we’re way out in uncharted waters–the “here be dragons” part of the map–regarding energy and environmental issues. Therefore we all need to approach every issue as a true scientist would: Go exactly where the data leads you and nowhere else. Our ideology shouldn’t be left or right or centrist, but fact-based.

    In the context of SBSP, everything I’ve seen about it feels like I’m reading a marketing brochure for a time share condo. I’m NOT saying SBSP can’t or won’t work or that it’s a bad idea or an inferior solution, merely that we shouldn’t leap to any conclusions about this or any other technology or public policy based on less hard data than we’d demand when buying a major appliance.

    (To be honest, my gut feeling about SBSP very much agrees with Joe’s overall assessment, but I wouldn’t want to completely rule it out based on a hunch and preliminary data.)

  13. Arthur Smith says:

    Actually, the cost of fuel is a relatively small part of the cost of launching into space – only about 1% I believe. Most of the cost of launch is the massive cross-checked human engineering effort that goes into making something go up instead of exploding in all directions.

    If this gave reasonably priced power for 1/10 of current launch costs, fuel would still be only 10% or less of capital investment, so the lifecycle CO2 number shouldn’t be too different, or perhaps even less, than for any other electric generator of comparable capital costs.

    So basically I think Joe’s 2 questions boil down to just the one – realistic cost estimate based on plausible launch costs. I’d love to see that too!

  14. David B. Benson says:

    Did I somehow tune to the SciFi channel by mistake?

  15. James Newberry says:

    This scam is filled with fantasy, falsehood and fraud. It would seem the fossil utility industry is unraveling in this case with a dangerous and economically wasteful diversion.

  16. Sustsinable_Or_Not says:

    OK, let’s try this again.

    Minimum of 30% of energy produced lost in upconversion to RF / antenna losses (even with perfect large-diameter antennas) / rectification / inversion. More energy lost than optical losses through atmosphere. But higher capacity factor; in geostationary orbit experiences Earth shading for portion of the day, but much less than on surface. Call it 2x net power per year.

    Unmaintainable in place so high redundancy in fundamental systems = much higher base system cost. Call it $7/W instead of $4/W.

    You dont like the fuel/CO2 argument? Look at launch cost. Let’s be generous and assume space-based solar weighs 1% as much as earth-based solar (0.3 lbs/Wp) Folks working on getting costs down to $10,000 per pound to geosynchronous orbit. http://www.futron.com/pdf/resource_center/white_papers/FutronLaunchCostWP.pdf

    Given the conversion efficiency issues maybe you get 2x annual electricity in exchange for having done the launch. So instead of $4/W installed on earth you’ve got $307/W in space for 2x annual energy.


    This is a very dangerous space weapons program in a green cloak. The US has more assets to lose from the militarization of space than anyone else.

    As I said, I would have expected PG&E to know better.

  17. Bill Woods says:

    But higher capacity factor; in geostationary orbit experiences Earth shading for portion of the day, but much less than on surface. Call it 2x net power per year.
    Objects in GEO are shaded for ~1 hour/day for a few weeks a year around the equinoxes, so call it 4x net power.

    This is a very dangerous space weapons program in a green cloak.
    This isn’t any kind of weapons program.

    As I said, I would have expected PG&E to know better.
    PG&E doesn’t seem to be putting a penny into the venture; they only have to pay for power delivered.

  18. Greg Robie says:

    Given that the Star Wars missile “defense” system/jobs program is on the chopping block, and this is a California-based company (read aerospace industry dependent state), and there will be a “need” for another “stimulus” package soon, I am in agreement with Sustainable_Or_Not., and see this as a make-work plan.

    In both the short and long term, as a jobs program, it doesn’t have to work as stated, it just needs to create high paying jobs. If your are familiar with the argument made in _Report From Iron Mountain_, such a program would be great for dealing with another growing problem: the inflation that the existing stimulus plans are creating (a problem of immense concern–if we didn’t have all the other immense ones already taxing our limited intelligence. Space is a great place to use up currency you need to get out of the economy.

    In any event, the technology would make one heck of a weapon system. The plane-based version of Star Wars has probably failed, and except for PR/keeping up with the Chinese, the rocket-based system is only good for shooting a sitting duck (tumbling retrograding satellite). Just think, you could go out at night and, due to the reflected light, see the latest iteration of the military’s (or will this too be privatized) string of peals that can help you sleep safe at night. With our current sense of what is just, any country giving shelter to a terrorist could be deemed to no longer be human in our judgment, stripped of such rights, and microwaved for just long enough to cook some of our “good” sense into them . . . as though we have proved ourselves to be a good judge of what is sensible; of what is just; of what love demands!

  19. Pangolin says:

    Today the wind is howling through California’s central valley. The sun is high in the sky and as usual the weather is clear. California bubbles with hot springs that could be tapped for geothermal power and we have vast salt flats ideal for concentrated solar thermal installations. There is a fast tidal current ripping through the golden gate separating San Francisco and Marin counties and PG&E is harvesting almost none of it.

    In California, on 110º F days, we still attempt to air condition buildings with black roofs and 30 year old equipment down to 75º. There are no utility sponsored district thermal loops that could connect dense urban areas to efficient chiller plants. There is no attempt to get people to convert to ground loop thermal systems. I’m not even sure we’ve got a program to paint our roofs white in desert communities.

    Meanwhile my sister in Santa Rosa produces enough power from her rooftop solar system to eliminate her electric bill on her 4,000+ sq. ft. house. My beer is solar powered, my sewage treatment, community college and county jail are solar powered; today. Which solution do we want; the one we can install today or the one we can paint pretty pictures of?

    What we have is PG&E engaging in a massive greenwash by promoting a power source that will never, ever, ever come online ignoring off the shelf equipment that will work. This announcement is nothing but porn to sucker the masses into complacency.

  20. Ronald says:

    Maybe this thing can be put up after they get the space elevator working.


    That would reduce the cost of space travel by enough to change the game. but space solar cells with todays equipment? no.

  21. darth says:

    Everyone knows (I thought) that you build space based solar power systems using materials from the moon. Put a moonbase with a big electric railgun there and fire the refined silicon to GEO earth orbit. Then using an orbiting factory construct your panels in space. Now we’ve reduced launch costs to zero, but first we need that moonbase infrastructure.

    And while on the moon we can extract the Helium 3 for fusion reactors to help defer costs.

    Gerard K O’Neil figured all this out in the 70s – physics hasn’t changed since then so neither has the solution to build this kind of stuff.

    Of course there is massive up front infrastructure costs to getting the moon mining and orbiting factories up and going. May be viable in the 2100′s, but not right now.


  22. Bill Woods –

    Here is a quote from the NSS paper referenced in the PG&E release:

    “For the DoD specifically, beamed energy from space in quantities greater than 5 MWe has the potential to be a disruptive game changer on the battlefield.” http://www.nss.org/settlement/ssp/library/nsso.htm

    Doesn’t sound benign. And what if the aim of the beam is off?

  23. To take some points: yes, you could, theoretically, use microwave beams from space as a weapon. But it’s really, really, really expensive, even by military standards, and not of great military utility. As a means to supply electricity to forward bases, it’s very valuable because it costs a fortune to get diesel past IEDs.

    As a bulk civilian power source, it’s a long, long way away, and I say this as a space enthusiast. While the space elevator requires – at a minimum – carbon nanotube ribbon technology to be perfected, and may still be impractical even if it is, there are a couple of other options for more efficient launch vehicles such as rotorvators and laser launch (aside from nuclear options which would probably work, and could be made to work safely, but I doubt would meet Joe’s approval and are a political impossibility anyway). But both of them are a decade away even assuming an Apollo-style commitment to do so.

  24. Leland Palmer says:

    In order to make this plausible you’d need a few new technologies.

    Ballistic launching of most of the mass of the collectors into LEO using electromagnetic launchers might be feasible – Kolm of MIT and his students studied this years ago and concluded it technically basically sound. Their projectile was something like 20 feet long and six inches in diameter. I believe Sandia has also studied electromagnetic launchers. There is also a gas gun at Livermore Labs that can reach orbital velocity, I think. So it might be possible to launch ingots of aluminum or titanium into space, and process them up there into useful shapes. Electricity cost to lift or shoot something into space is only something like a dollar a pound.

    Needless to say, this would take some development. Trying to use heavy lift launch vehicles would likely be too expensive.

    Solar cells tend to be heavy, solar thermal using lightweight collectors might be more feasible, with Stirling cycle engines. The radiators to get rid of waste heat might be the heaviest components of the system.

    Microwave transmission has unknown heating effects on the ionosphere, last I heard. The HAARP radio antenna array in Alaska has studied this, I think. Also, energy density of the microwave beam presumably used to get the power down to the ground is low, to keep from frying anything that flies into the beam, so the energy density of the microwaves when it hits the rectenna array is roughly the same as sunlight. It’s doubtful that the rectennas can be built at a lower cost than solar cells, last I heard, so just the receiver for the system is more costly and lower in energy density than just building solar cells, I think.

    But really, this seems like a very risky way to spend a lot of vital money that could be spent actually solving what looks like runaway global warming.

    We should remember that this is the same PG&E that played such a big role in the California “energy crisis” during the early Bush administration that bilked the consumers in California of so much money, and that continues to charge inflated prices for electicity even now, due to long term contracts that Gray Davis was forced to sign.

  25. Leland Palmer says:

    Uh, this is so stupid, it does make you wonder what the real purpose of it is.

    I wonder if the idea is to use it against climate refugees heading north?

    Just a stray thought, and not a very likely one, probably.

    On the other hand, any group of people that can look at a potential methane catastrophe and see a really neat opportunity to drill for yet more oil under the current polar icecap could do anything. Here are links to Scott Borgerson’s articles in Foreign Affairs, his Op-ed in the New York Times, and his iprepared testimony to the House Foreign Relations Committee a couple of weeks ago, from the Council on Foreign Relations website. Borgerson actually went to Congress with his hand out, asking for nuclear powered icebreakers, presumably to break the ice for oil tankers transporting arctic crude to the world market:


    We may be approaching a tipping point past which the melting sea ice cannot recover.
    2) This dramatic and unprecedented climatic change is affecting the geopolitics of the region. The Arctic is home to an estimated twenty-two percent of the world’s remaining undiscovered hydrocarbon reserves as well as access to the fabled shipping routes over Eurasia and North America, both of which have led to balance-of-power struggles in the region. The next few years will be critical in determining whether the Arctic’s long-term future will be one of international harmony and the rule of law, or of a Hobbesian free-for-all with dangerous potential for conflict.

    Borgerson claims to be testifying as a private individual, and not an agent of the Council on Foreign Relations.

    For a private individual, he sure is having great success at getting his stuff printed on the CFR website and in the CFR journal Foreign Affairs. He also doesn’t seem to have any trouble getting to testify before Congress or getting his stuff published in the New York Times.

    The CFR, of course, has historically been dominated by the Rockefeller family. The Rockefeller family remain powerful enough within ExxonMobil to recently force the ex-CEO of ExxonMobil, Lee Raymond to resign.

  26. Leland Palmer says:

    Is this an idea to use “pain beam” microwave weapons against climate refugees heading north?

    2009 – Police to Get Pain Beam Weapons


    Starving climate crisis refugees try to head north and get zapped with the “pain beam from the sky?”

    Seriously, we need to remember PG&E’s financially successful role in the California “energy crisis” – a totally manufactured energy shortage, and their subsequent tens of billions of dollars in overcharges against the population of this state.

    What is this corporation up to now? Certainly, they have engaged in massively deceptive behavior before, during our so called energy or electricity crisis right after Bush took office.

    Or is this a plan to ask for public funding for space based solar in the future?

  27. Jim says:

    I’ve come across a number of poorly informed posts here – not surprising considering the complexity and scope of the issue of space solar power.

    I have found the best single source of information on this subject to be the space solar power section of the National Space Society web site at:


    And on that page, don’t overlook the all to easy to miss link to the space solar power library – home to a collection of SSP studies.

    Personally I feel that a space solar power pilot project should be a top energy priority. The data and knowledge gathered from such a test project would allow us to make a better informed decision as to the viability of SSP.

  28. Leland Palmer says:

    At best, space based solar is carbon neutral. In practice, in the short term, it would be highly carbon positive, due to the fact that rockets are hugely inefficient at moving things into space, and all of that wasted energy ends up as heat. So, with a ballistic launcher or something similar, maybe. Without one, nada.

    We need carbon negative forms of energy, in the near term.

    The rectenna arrays themselves intercept energy densities of microwaves lower than those of solar energy, although conversion efficiencies would likely be higher. So the rectennas better be at least as cheap as solar cells, and last I heard, they weren’t.

    The biggest part of the cost, though, is not the rectenna power receiver arrays. The biggest part of the cost are the space based components, especially initially.

    We have a great future in space, if we live, and could easily build space colonies and SBSP stations, in the long run. But we can only do these things if we keep the earth’s climate system from tipping over. The impact of SBSP is too little, too late, and way too expensive in the short term. SBSP is actually counterproductive, IMO, because it soaks up money that could be better used in the short term, by converting the coal plants to biocarbon/CCS.

  29. Leland Palmer says:

    According to Aviation Week:


    Military planners responsible for finding space resources to support troops on the ground think the time may be ripe to advance the 40-year-old space solar power concept to help reduce the logistics train behind forward-deployed forces.

    The concept of collecting solar energy above the atmosphere and beaming it to the ground as microwaves or lasers has long been seen among military freethinkers as a way to get electricity to remote airfields, fire bases or other distant outposts without having to haul fuel for diesel generators.

    But that out-of-the-box concept may be gaining new life as the incoming administration looks for “green-energy” technologies to reduce reliance on foreign oil, and technologists home in on the hardware that would be needed to orbit deployable sunlight collectors measuring kilometers across and get power down from them to troops on the ground. Engineers studying space solar power (SSP) believe a pilot plant could be orbited fairly soon.

    And so on. I’m not sure this makes any sense either – I was under the impression that rectenna arrays are huge, and wouldn’t be very portable, themselves.

    I don’t know. This article in Aviation Week may itself be a cover story.

    Either way, it doesn’t sound like global warming is their main priority.

  30. solar energy says:

    Interesting concept. Sounds exciting. As long as they don’t use it as a weapon like in James Bonds Moonraker haha.

  31. Will says:

    Wouldn’t we be better off focusing on low cost access to space: propulsion breakthroughts, space elevator technology, anti-gravity gum, quantum warp devices, hot female robots that can throw things really far, moon construction facilities, etc. before we spend trillions putting up expensive experiments?