Harvard Business Review and Yale e360 hype space solar. Why?

Harvard Business Review touts space solar in its September piece, “On the Horizon: Six Sources of Limitless Energy?” (subs. req’d) Of course, they also tout nuclear fusion as one of the six (see HBR figure above), so perhaps that tells you their time horizon is … 50 years from now (or maybe never), long after the climate is destroyed.

More puzzling is Yale e360, which has a long piece on space solar, with the hype “Now, a host of technological advances, coupled with interest from the U.S. military, may be bringing that vision close to reality.” Aside from discussing the military’s interest, which may not be totally benign and in any case is largely irrelevant to the question of commercial viability, the piece discusses the deal Solaren Corporation has with Pacific Gas & Electric (PG&E) “to provide 200 megawatts of power “” about half the output of an average coal-fired power plant “” by 2016 by launching solar arrays into space.”

As I blogged here, the physicist Marty Hoffert sent an email to the media in the spring on this (which I reprint in full below) that begins:

The PG&E deal is a scam. Pure and simple. We don’t need to study it in detail any more than one needed to study Bernie Madoff’s investment scams.

Since space solar is getting hyped again, let me start with my original discussion (here).

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

Certainly 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, “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.

On the even more skeptical side, here is the full email from Hoffert:

The PG&E deal is a scam. Pure and simple. We don’t need to study it in detail any more than one needed to study Bernie Madoff’s investment scams. There’s no way to do this any more than there is a way to get 12% return on investment consistently regardless of the economy. Didn’t stop investment in Madoff and it may not stop investment in this harebrained scheme.

There’s no way to get 200 Megawatts from orbit with microwave beaming by 2016 from private sector investment. The infrastructure to do it efficiently with microwaves requires huge structures in orbit and in-space assembly by robots. This is very far from existing technology. Microwaves are the wrong way to start a space solar power business. What we can do in a few hundred kilowatts with laser beaming to PV modules on Earth in a five year time frame because there’s no in-space assembly needed and single-launch vehicles could likely do it. This could realistically lead to a buildup of a viable orbital and power industry. Even so, we will need major up-front money to test the idea from the feds. The promoters of the PG&E deal idea say they’ll provide a thousand times more power and do it all from the private sector. Might as well say we’re ready to go to the Moon or Mars with private sector financing. The physics of this is very well understood by the research-active SBSP community.

Too bad, because when it all unravels it will be a major setback for space solar power. Ken [Caldeira], this is very much like your experience with the company that wants to get rid of CO2 in seawater by a proprietary process that violates basic chemistry. Their CEO says he has special insider knowledge to do this, and so does the company pushing this space solar power deal. His defense it that he took many companies public. These ideas get as far as they do most because people making business decisions about alternate energy are often scientific illiterates. There are real technological and scientific hurdles, showstoppers, that is; and there are often potential effective technical and scientific approaches around them.

The problem is not knowing the difference. It’s a much a disaster to overestimate the prospects for near-term profit based on flawed physics as to underestimate the longer-term potential of a new technology based on the opportunities that physics does provide. As Richard Feynman sagaciously observed, “You can’t fool Mother Nature.” If only we didn’t have to deal with those idiotic Homo sapiens primates inhabiting this planet. All very depressing because I’m a strong advocate space solar power technology.

Marty HoffertProfessor Emeritus of PhysicsNew York University

And then there’s this amazing story in Wired, “Hurricane-Killing, Space-Based Power Plant” based on Solaren’s 2006 patent for “altering weather using space-born energy” (see inset figure from patent below, click to enlarge).


Many readers of the original post were concerned the device could be used as a weapon. Not so far-fetched an idea now “” at least no more far-fetched than Solaren’s plan to weaken or alter hurricanes from space.

This is a self-inflicted wound by Solaren on its own credibility.

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.

Yet consider the email response I got from the company in response to my question “Does somebody have a lifecycle CO2 or GHG emissions calculation per kWh given the fuel needed to launch this stuff?” Cal Boerman, Director Energy Services for Solaren, replied:

Solaren plans to use launch vehicles (Atlas V/Delta IV Heavy Class) that primarily use liquid hydrogen and liquid oxygen for fuels. The resulting emissions are water. These fuels are formed via electrolysis. The Wikipedia definition is: Electrolysis of water is the decomposition of water (H2O) into oxygen (O2) and hydrogen gas (H2) due to an electric current being passed through the water. Solaren assumes the electricity used for this process was generated from clean resources.

Therefore the lifecycle environmental impact per kW-hr is negligible. Also, we do not use solid rocket motors so there is no added pollution from them.

Hope this Helps

Well, It helps me understand how little Solaren has thought about this important issue. Electrolysis is good for generating pure hydrogen, but it is incredibly electricity intensive (duh) as is making liquid hydrogen for transport. Presumably a lot of this is done at night when electricity is cheap “” if someone can find information on who exactly makes hydrogen for NASA, I’d love to see it. All I could find is this 2002 article that says it is done near New Orleans using “ technology that releases large amounts of carbon dioxide into the atmosphere.” Plus they lose a lot of hydrogen through evaporation from the trucking. And of course the trucking uses a lot of fossil fuels.

Making hydrogen from renewable-based electrolysis would probably triple the cost of the fuel. And if Solaren really thinks it can cut launch costs by the factor of 10 or more needed to make this entire effort viable, then it can’t be tripling the cost of the fuel.

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.