Space-based Solar Power Comes to Light

By | March 1, 2009 | Feature, Telecom

The use solar energy is forecasted to soar in the next eight years as the world’s population looks for alternatives to fossil fuels. It is estimated the sun can provide 219 thousand billion kilowatt hours of energy a year for 6.5 billion people, but converting the sun’s energy into a usable form in a cost-effective manner has proven difficult. Can the satellite industry use its experience with solar arrays to forge a new energy market direction?

In 1941, Isaac Asimov published a science fiction short story of a space solar power system orbiting on geostationary orbit that would beam down from space usable electrical energy. While the vision has taken a few practical steps since that time, the satellite industry should play a key role in making this dream of large-scale solar power production a reality. "The solar industry was born out of the space industry," says Ron Pernick, co-founder of the research firm, Clean Edge, a research and consulting firm focusing on clean technology, "It came out of Bell Labs of the very early implementation of solar for the space industry because they had a very definite requirement for space and satellites. In many ways the terrestrial solar industry has the space applications [industry] to thank for really helping solar gestation for up to two and three decades before it was ready for prime time terrestrially…. They feed on each other. It is a virtuous loop. It is important to pay homage to the fact that today’s modern terrestrial solar energy has very much the space industry to thank," Pernick adds.

John Mankins, president of Space Power Association, a private, international organization that promotes space solar power, estimates with today’s technology the project would cost $10 billion and be in place by 2025. "Energy from a solar power satellite would be transmitted in a coherent beam of low-intensity radio or light energy. An individual receiver on the ground might receive anywhere from 200 to 400 megawatts of power, up to 2,000 to 4,000 megawatts of power," he says. According to Mankins, "the development of space solar power must be an international undertaking and the U.S. should definitely play the leadership role in pulling together that effort."

Several U.S. federal agencies — Department of Energy, NASA, Department of Commerce — have reviewed the concept and concluded that it had no flaws and could be built. The U.S. Department of Defense’s National Security Office has been reviewing the concept as a way of providing energy for global troop deployment. The U.S. Energy Policy Act of 2005 saw the largest budget increase for solar research in U.S. history (to $148 million), but that pales in comparison with two other efforts — the California Solar Initiative, a $3.4 billion project signed into law in August 2006, and Google’s plans to install solar systems in what would be the largest solar electricity corporate campus ever built in California. Internationally, Japan’s Mitsubishi Electric is taking a leading technology role in Asia, and Canada and India have expressed interested in such an electrical grid from space. Chinese, Japanese and European space agencies also are funding research-related space solar power energy projects.

Satellite Industry Can Help, But Has Work to Do

The satellite industry, using its long history of solar power development, can play a major part in the development of space solar power efforts. The main technologies can be categorized as concentrating solar thermal (CST) or concentrating photovoltaic (CPV). The former concentrates the sun’s energy on a thermal conductor and then uses the heat to move an engine or turbine. The latter concentrates the sun’s energy directly onto high efficiency photovoltaic material to directly create electricity; however, the current technology of harnessing and the storage of the electricity limits CPV’s ability to be dispatchable. CST is dispatchable but the heat increases the cost of operations. CPV has a concentrated system which can be either a reflector or what is called a Fresnel lens. In a CST system, a Stirling or Brayton engine which utilizes a parabolic reflector to reflect solar energy back into the engine uses the heat (up to 1,500 degrees) in creating alternating current electricity. Photovoltaic cells with a tracking system can increase energy output by as much as 35 percent. Pernick says, "Concentrating solar as far as CPV may have more of a technology challenge. There have not been many CPV technology market places. Many companies are still working on proving the concept."

Solar energy satellite antennas make a lot of sense for manufacturers of antenna systems. One of the U.S. leaders in the convergence of the satellite industry and the solar industry is Patriot Antenna Systems, a division of Cobham, which produces more than two million antennas per year. In 2005 Patriot Solar Group began to focus on compatible opportunities for the company’s satellite antenna design and manufacturing core competencies. "Having the two markets; namely, solar and satellite antennas, is very beneficial. I do not know if this is a huge market in terms of the satellite market, but certainly it is for equipment manufacturers," says Jeff Mathie, president of Patriot Solar Group. "It is especially strong for parabolic, tracking and control manufacturers. Frankly, the solar market needs all the technology and capability that satellite industry integrators have. You have to know the same types of things, such as understanding foundations, appreciating tracking, making sure that the wind loads are calculated, and knowing controller systems."

“The solar industry can now give all of those satellite submarkets categories such as antennas, controllers, integrators and installers a new revenue source that is 10 or 20 times higher than the satellite business ever was.”

— Mathie, Patriot Solar Group

"In my opinion, the same type of companies that were doing business in the satellite industry back in the heydays of satellites in the 80s and 90s can now see opportunities in the solar industry," says Mathie. "The solar industry can now give all of those satellite submarkets categories such as antennas, controllers, integrators and installers a new revenue source that is 10 or 20 times higher than the satellite business ever was. Where we think that most of the technology advances are for our existing satellite technology is in CPV and Stirling engines."

If the answer to space solar power depends on hardware in orbit, there are still numerous — but not impossible — challenges that must be solved, says Mike Ryschkewitsch, NASA’s chief engineer. "There are many engineering challenges, but you are not violating any of the laws of physics. So far at least, no one has identified any show stopper that says that it is impossible," he says. "Everything that I looked at says that it ought to be technically feasible to do it, but no one has taken a hard look at the public policy or political issues, and the economics are just not there….You have to solve the problem of a solar array you build and launch in space is always going to cost significantly more than what you would put on the ground because you have to put it on a rocket and it has to last for a very long time having someone service it. Servicing it would have a high overhead."

Another major issue is that the geostationary orbit already is very crowded with communications satellites, Ryschkewitsch says. "Now you have to put these very large structures [and ensure] that you have no possibility of collisions; that you don’t have any interference from the microwave beams with your communication channels. So there are many other challenges that make it exceedingly unlikely that you are ever going to make a solar array and come out ahead. I am not arguing that solar power in space is not a good idea; however, the key is to do an end-to-end analysis to validate solar arrays in space."

Efforts on the ground also are being developed. In Israel, energy startup Zenith Solar is pioneering a "concentrated solar power" method that is up to five times more efficient than standard technology. A joint Israeli-German research team has designed a working prototype, which consists of a 10-square meter dish lined with curved mirrors made from composite materials. The mirrors focus the sun’s radiation onto a 100-square centimeter "generator" that converts light to electricity. "The first generation of our technology should be capable of harnessing about 70 percent of the solar energy that hits the dish to produce electricity and thermal heat," says David Faiman, chief engineer at Zenith Solar. With that type of efficiency, Zenith Solar says the cost of producing energy with its technology is close to that of conventional fuels.

Other sectors also are working on efforts. Within the global telecoms sectors, Ericsson and Nokia Siemens Networks have installed hundreds of base-stations powered by solar power antennas in developing countries and in rural areas within the developed world. Ground-based satellite solar antennas could be easily networked into an electrical grid to provide "free energy from the sun" and result in reducing the dependency on foreign energy sources.

While large-scale solar energy use is still some time off, other uses for solar power based on satellite industry efforts are making their way into the market. In November, Global Satellite USA launched the Voltaic Solar Backpack, a 4-watt solar-powered storage bag that uses high-efficiency solar cells, to generate power in a limited space. It includes a battery pack designed to store and convert the electricity it generated in order to charge PDAs, cameras, cell phones, satellite phones and iPods. One hour of sunlight will power over 3 hours of iPod playtime or 1.5 hours of cell phone talk.

Converting Solar Hope into Energy

The satellite industry’s efforts in the space solar power arena could play a key role in turning around the U.S. economy. The technologies could converge into a durable business model and lead the U.S. economic recovery from a commercial space business potential, generating investment, innovation and sustainable jobs. A "global smart solar power grid" consisting of space-based and terrestrial solar energy systems would encourage countries to start working together instead of in isolation. Solar energy has the edge on all the other renewable energy sources due to the abundance of the sun’s energy and will lead the energy revolution. The key question is: Can the governments fund and coordinate the necessary research to meet the growing demand of clean and inexhaustible solar energy from Space? "Space solar power is possible, but it will take a long time," says Mankins. "If a thoughtful and [adequately funded] space solar power program were started in 2009, then it’s possible that a 100-megawatt pilot plant demonstrator could be operational in geostationary Earth orbit as early as 2017. Five power satellites could supply 2 percent of the energy needs for the United States," he says.

"Our satellite industry already has the knowledge and capabilities to merge into the solar industry," says Mathie. "The big issue is understanding how to integrate the various elements in a solar system. The key concern in the market is: How are you going to integrate a solar system into the world markets? The satellite industry has a large network of integrators."

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