Space-based solar power can be developed into a source of clean and sustainable energy around the World, on the Moon, or anywhere else humans are likely to go.
Solar power already energizes our satellites and space stations in orbit around Earth. The trick is to harvest solar energy on orbit, convert it into a form of power that can be broadcast safely to Earth, and to do so economically.
The Solar Power Satellite (SPS) Concept
The Solar Power Satellite (SPS) concept would place solar power plants in orbit above Earth, where they would convert sunlight to electricity and beam the power to ground-based receiving stations. The ground-based stations would be connected to today's regular electrical power lines that run to our homes, offices and factories here on Earth.
Why put solar power plants in space? Without the attenuation that results from passing through the atmosphere, sunlight in Earth orbit is about 25% more intense than on the ground. Moreover, in space the sun shines virtually 24 hours a day, 7 days a week. Unlike solar power on the ground, solar power satellites would not be vulnerable to cloudy days or the changes in the seasons. As a result, extra generating capacity and energy storage aren't needed to assure continuous solar energy to meet the needs of society. All told, many of the problems that have limited the use of ground based solar power concepts do not affect space solar power.
Solar power satellites would be placed in so-called "geostationary" or "Earth synchronous" orbit, a 24-hour orbit which is thus synchronized with Earth's rotation, so that satellites placed there remain stationary in the sky when viewed from a point on the Earth. (Likewise, today's communications satellites are put into geostationary orbit, and each TV satellite dish on the ground is pointed towards one satellite "stationary" in orbit.) The receiver is called a "rectifying antenna" (or “rectenna”; pronounced "rektenna").
Geostationary orbit is very high, 36,000 km (22,500 miles) above the surface of the Earth. It is far above the range of the Space Shuttle, which has a maximum range of about 1000 km (600 miles) above Earth's surface.
There are many benefits to using solar power. Many cities around the globe have invested in solar power as an alternative to coal, oil, and nuclear sources due to the following:
- Solar Power is a renewable and infinite resource
- Solar Power is free of any emissions, including carbon dioxide (greenhouse gas)
- Solar Power is a free resource after capital cost of installation (excluding maintenance)
- Maintenance is comparatively low
- Its maximum power output corresponds very well with peak power demand
- Energy production with solar power prevents significant water usage associated with coal, nuclear, and combined cycle sources.