The concept of space-based solar power (SBSP) has been around for several decades, but has not yet gained significant traction due to cost and technological challenges. However, recent advances suggest that some of these challenges can be overcome, making SBSP a potential player in the transition to green energy.
Utilization of solar energy from space
Solar energy is not a new concept. We are already harvesting energy from the sun through various technologies such as photovoltaics and solar-thermal energy. However, these ways of generating energy have their limitations. They require huge areas and depend on the availability of sunlight and wind. For example, solar power plants cannot produce energy at night and are less efficient in winter and on cloudy days.
But imagine if we could get solar power from space. Satellites in geostationary orbit (GEO), located about 36,000 kilometers above Earth, are exposed to sunlight more than 99% of the year. This means that they can produce green energy around the clock, with no time-of-day restrictions. It is estimated that there is 100 times more solar energy available from GEO than the world’s projected electricity needs by 2050.
Wireless power transmission: Making it possible
The challenge is to transmit energy collected in space to Earth. This requires wireless energy transmission, and microwaves play a key role in this. By using microwaves, energy loss in the atmosphere can be minimized, even in cloudy conditions. Satellites send a focused microwave beam to ground stations, where antennas convert the electromagnetic waves into electricity.
To ensure efficient data transmission, the diameter of ground stations must be at least 5 kilometers, and even more in high latitudes. However, this area is still smaller than the area required for conventional solar or wind power.
Development of SBSP concepts
Over the years, many concepts have been proposed to make SBSP a reality. One of the latest concepts is CASSIOPeiA, which consists of two 2 km wide controllable reflectors. These reflectors redirect sunlight to an array of solar cells. The energy transmitters are about 1700 m in diameter and can be directed to a ground station. It is estimated that the satellite mass for this concept could be about 2,000 tons.
Another architecture, known as SPS-ALPHA, takes a different approach. Instead of large reflectors, a massive structure consisting of small modular reflectors called heliostats is used. These heliostats can be moved independently of each other, and their mass production reduces costs.
The potential of SBSP
If we can overcome the remaining challenges and make SBSP a reality, it could revolutionize the way we generate and distribute energy. Utilizing solar energy from space will eliminate the limitations of using the earth and dependence on sunlight and wind. SBSP has the potential to provide a constant and abundant source of green energy, to help us move away from fossil fuels and combat climate change.
Dr. Paul Jaffe, an engineer at the U.S. Naval Research Laboratory, believes that SBSP is not only feasible, but necessary to meet our future energy needs. He states, “There is no shortage of solar energy in space. We just need to figure out how to bring it back to Earth.”
According to a study published in IEEE Transactions on Power Electronics, SBSP has the potential to supply up to 10% of the world’s energy demand by 2050, significantly reducing greenhouse gas emissions.