MendoCoastCurrent, April 17, 2009
San Francisco — PG&E has begun exploring renewable energy from space as it seeks approval from California state regulators, the CPUC, to purchase power from Solaren Corporation offering 200 megawatts over 15 years.
Solaren’s technology uses solar panels in Earth orbit, converting the energy to radio frequency for transmission to an Earth-based receiving station. The received radio frequency is converted into electricity and fed into the power grid.
Solaren envisions deploying a solar array into space to beam an average of 850 gigawatt hours the first year of the term and 1,700 gigawatts per year over the remaining term according to their filing to the CPUC.
A clear advantage of solar in space is efficiency. From space, solar energy is converted into radio frequency waves, which are then beamed to Earth. The conversion rate of the RF waves to electricity is in the area of 90%, said Solaren CEO Gary Spirnak, citing U.S. government research. The conversion rate for a typical Earth-bound nuclear or coal-fired plant, meanwhile, is in the area of 33%. And space solar arrays are also 8-10 times more efficient than terrestrial solar arrays as there’s no atmospheric or cloud interference, no loss of sun at night and no seasons.
So space solar energy is a baseload resource, as opposed to Earth-based intermittent sources of solar power. Spirnak claims that space real estate is still free although hard to reach. Solaren seeks only land only for an Earth-based energy receiving station and may locate the station near existing transmission lines, greatly reducing costs.
While the concept of space solar power makes sense on white boards, making it all work affordably is a major challenge. Solar energy from space have a long history of research to draw upon. The U.S. Department of Energy and NASA began seriously studying the concept of solar power satellites in the 1970s, followed by a major “fresh look” in the Clinton administration.
The closest comparison to the proposed Fresno, California deployment is DirecTV, the satellite TV provider, Spirnak explained. DirecTV sends TV signals down to earth on solar-powered RF waves. However, when they reach the Earth, the solar energy is wasted, he said, as all the receivers pick up is the TV programming.
Solaren claims they’ll be working with citizen groups and government agencies to support the project’s development. Solaren is required to get all necessary permits and approvals from federal, state and local agencies.
At onset, in exploring space solar energy as in exploring all nascent technologies, explorers shall have to show and prove their renewable technology safe.