The concept of SBSP was theorized over 40 years ago by renowned scientist Dr. Peter Glaser. Since then, in response to periodic energy crises, the idea has been re-evaluated from time to time by the U.S. Department of Energy, NASA, major aerospace companies and countries such as Japan and India. Their studies generally concluded that there is no technical barrier to implementing SBSP; rather, the principal impediment has been economics -- the ability to provide SBSP at a cost that is competitive with other energy sources.
Solar power satellites are large arrays of photovoltaic panels assembled in orbit, which use very low power radio waves to transmit solar power to large receiving antennas on Earth. The resulting power can either supplement, or be a substitute for, conventional electricity sources. Several of the technologies required to build a working SBSP satellite have, in principle, already been developed---and some of the component technology is already in use across a variety of sectors.
The advantage of placing solar collectors in geosynchronous Earth orbit (GEO), about 36,000 kilometers above Earth, is that it uses the constant and unobstructed output of the Sun, unaffected by the Earth's day/night cycle.
By contrast, ground-based solar power provides a vital and valuable addition to the Earth's energy needs, but is limited by these factors:
Because none of these factors applies to SBSP, an SBSP cell can provide an estimated 6-8 times more power than a comparable solar cell on the Earth's surface.
- Variable seasons
- Atmospheric blocking of sunlight
- Poor direct sunlight at higher and lower latitudes
- Expensive and limited storage capacity
A long-range wireless power transmission test was conducted in mid-2008, successfully transmitting a microwave beam (similar to the kind that would be used to transmit energy from space to Earth) between two Hawaiian Islands across 148 kilometers---more than the distance from the surface of the Earth to the boundary of space. This test demonstrated the technical feasibility of transmitting SBSP to Earth.
The frequency of radio waves sent down from an SBSP satellite would be comparable to cell phone, wireless Internet, or cordless phone signals. Based on several studies done by NASA, this transmission is safe to human, animal, and plant life near the receiving antennas---large structures designed to convert the radio waves into usable electricity.
These antennas would be placed in areas with limited access to mainline grid power, giving rural and developing areas a much-needed power alternative. They might also be placed close to main power grids to provide a substantial amount of grid power.
Recently, as efficiencies of solar cells and other core systems have increased, and the price of (and demand for) energy has risen, SBSP has become more commercially viable. Factors that have contributed to this development include:
With these new efficiencies and price points, the cost of a viable SBSP solution is substantially lower than just a few years ago.
- Efficiency and mass of photovoltaic cells (becoming more efficient and lighter, as well as cheaper)
- Wholesale electricity cost increases
- Demand for electricity (increasing rapidly)
- The availability and cost of commercial space lift transportation (becoming cheaper, faster, and more reliable, with billions of development dollars now being invested)
- The identification of additional, easily accessible revenue streams for SBSP