Japan is currently the only country with a focused solar power satellite plan. In fact, space power is one of the nine official goals of the Japanese space programme. The country’s space agency is planning to construct a solar power station in space and use it to beam energy down to earth using lasers by 2030.
SSPS consists of a space-based power generation/transmission facility that gathers sunlight, converts it into microwaves or laser beams, and transmits those to the ground; and a power receiving facility on the ground. There are differences in characteristics and capability between microwaves, which are used in microwave ovens and cellular phones, and laser beams, which you commonly see in computer printers and presentation pointers. We have not yet decided which of the two to use with SSPS, or whether we will somehow combine them. We are currently conducting ground-based experiments to find the most efficient way to transmit energy.
Laser beam-type SSPS
What is the progress status of SSPS in Japan?
There are many technological challenges to solve before SSPS can be implemented. However, in principle, we are getting close to the stage where it is feasible, and we have just moved from the study phase to the technology demonstration phase. Researchers have started preparation for the world’s first demonstration of 1kW-class wireless power transmission technology, and are aiming for practical use in the 2030s. At this point, you could say that Japan is leading the world in SSPS research. I think that this is all thanks to JAXA’s long-term commitment to this research.
the advantages of Japan’s SSPS technology
When transmitting power by microwaves, a significant technological challenge is how to control the direction, and transmit it with pinpoint accuracy from a geostationary orbit to a receiving site on the ground. Transmitting microwaves from an altitude of 36,000 kilometers to a flat surface 3 km in diameter is like threading a needle. In my opinion, Japan currently has the most advanced technology to do this.
With laser beams, as with microwaves, large reflectors will be used to collect sunlight. But uniquely, the energy of the sunlight itself will be used at the collection point as excitation energy for the laser beams. This would allow us to keep the structure simple, and therefore reduce the size and weight of the orbiting power plant.
Other Space Based Solar Work
Other organisations around the world, however, are exploring space solar power concepts, including Astrium, a subsidiary of the European Aeronautic Defence and Space Company.
This firm is vowing to put its own solar demonstration satellite into orbit by the decade’s end (2020), according to announcements made in 2010.
Meanwhile, the US and India are making pledges to collaborate on a space-based solar programme, an idea initiated by the Institute of Defense Studies and Analyses. A report prepared by Peter Garretson, a US Air Force lieutenant colonel, called for the governments of India and the US to initiate this project and make the space-based solar energy a commercially viable business venture by 2025.
The Chinese have also committed to the development of SSP this year. Speaking at the China Energy Environment Summit in August, Wang Xiji, a space technology pioneer for the China Academy of Sciences, described a study on space solar power completed a month earlier by the academy.
Solaren and other small companies that have made big Space Solar promises
Solaren, Inc. is a Southern California startup corporation created to utilize solar energy for terrestrial electricity usage. The company has a contract under negotiation with Pacific Gas and Electric Company of California to deliver 200 megawatts of power for at least 15 years starting in 2016. The cost of the contracted activities has been reported as “slightly more” than California’s projected energy cost in 2016 of 12.9 cents per kilowatt hour.
Solaren plans to provide this electrical power to PG&E’s customers from solar panels mounted on satellites placed in Earth’s orbit.The satellite would convert this energy into radio waves and send it to a receiving station in Fresno County, California. The plan is to provide 200 megawatts of continuous power, estimated as the average usage of 150,000 homes.
Solaren expects its power plant to convert about 50 percent of the sunlight into electricity, and about 80 percent of that into radio waves. Its receiver station should be able to convert 85 percent to 90 percent of the radio waves back to electricity.
But radio waves can scatter, and the water and aerosol in the atmosphere would absorb some of the radio waves before they hit the ground. So the efficiency from sunlight to electricity on the ground would likely to be 25 percent, Spirnak said.
That means Solaren would need to build a power plant with 800 megawatts in generation capacity in order to deliver the promised amount of electricity to PG&E.
Engineers at Solaren will be busy with working on various energy conversion and transmission technologies in a lab. It plans to demonstrate its designs outside of the lab and then in space in 2011 and 2012, before construction begins.
In May 2010, Solaren had Eight to 10 employees in March 2010. They expected 100 by December 2010. People and talent here in Southern California are in such abundance that we can’t believe it. In 5 years we expect to have hired between 800 and 1000 people.
We’ll raise a billion dollars over the next 12 months, and a lot more after that, but we can’t reveal investor information without permission.
System requirements will be completed in next couple of years, and we’re looking at the first launch (test launching) in late 2013.
If we have an IPO in 2016, we’ll need to project profits over the following 20 years and work backwards to get the stock price. 2016 IPO would be based on cumulative earnings by 2030-40, profits over the next 20-30 years.
Space Island Group Missed Oct 2010 target
Orbital Power Corp
The space segment of the OPC system is comprised of a collection of Independent Solar Energy Satellites (ISES) working together to form a single microwave power beam. The number and size of the satellites is dependent upon scaling decisions for the individual satellites, and the total amount of power to be delivered. The baseline design calls for 10 tonne satellites, with cloud sizes ranging 12 to 300 satellites depending on power required in a particular beam.
Each satellite is comprised of a core, a photovoltaic array and a microwave transmission array. The core of the spacecraft comprises propellant tanking, attitude control; de-spin fittings and power management and control systems. The photovoltaic array is composed of thin-film solar cells, supported by a UV-cured inflatable composite frame. The microwave transmission array is composed of small, independently controlled transmitter/processor elements.
The power beam is a large 5.9 GHz microwave radio signal that is tightly focused to arrive at a relatively small ‘footprint’ on the surface of the earth. The energy of the beam is managed to never exceed a certain energy density. The precise number is yet to be determined, but will likely be on the close order of 1,000 W / sq Meter.
National Space Society