Discovering the potential of solar energy from satellites

Dear EarthTalk: How feasible is it to create orbiting solar power plants that can beam energy down to Earth? If possible, when can we expect such technology to be implemented?

­– PR, via e-mail

In a story from 1941 Reason, science fiction author Isaac Asimov depicts a space station that generates energy by sending microwave beams to planets. This concept is closer to reality as international space programs and research laboratories test the technology necessary to make it a reality. Traditional solar technologies convert sunlight into usable energy here on Earth. However, their use is limited to daylight hours and is limited by weather and geographical location. The idea of ​​an orbiting solar power plant overcomes these limitations by allowing energy to be collected above the clouds.

There are different designs, but the principles are similar: a large satellite converts solar energy into electricity using photovoltaic cells made of a material that, when exposed to light, generates voltage and electric current. The energy is then transmitted to the ground via microwaves (or lasers) to special receiving stations, which convert it back into electricity, which then feeds into the local grid.

Entities such as the European Space Agency (ESA), Space Solar (a start-up from Great Britain) and the California Institute of Technology are investing in work on launching this type of projects. Apart from the obvious benefit of having full sun at all times, orbiting solar power plants have many other advantages. There are no hazardous by-products produced as with other energy production methods: there is no fly ash from coal or radioactive waste from nuclear energy. Completely renewable – it will not run out in the human age – so it is harmless and could help reduce the effects of climate change if adopted on a global scale.

So why don’t we have these power plants floating around in space anymore? There are still challenges to overcome. The cost is prohibitive; the structure would have to weigh about 2,000 tons, roughly equivalent to the weight of 286 male African elephants, be a mile and a half in diameter, and have a transmitter length of just over half a mile. Another challenge is the engineering, especially of the parts used in these types of drive beam structures. Given the difficulty of accessing satellites for maintenance and repairs, it is suggested that the parts must last at least 15 years in space. Additionally, there is a need to improve the efficiency of current wireless energy transmission to ensure that all energy can be harvested to Earth.

There are also some significant disadvantages. Solar power plants orbiting closer to Earth would transmit energy more easily, but light pollution would be difficult for both humans and wildlife to cope with. Research also suggests that exposure to artificial light at night may increase health problems in humans, including obesity, depression, diabetes and more.

Time will tell whether Asimov’s proposal from almost a hundred years ago will be implemented. ESA has recently been looking for ideas to make this more feasible. “The potential of this concept for long-term sustainable energy is very high,” says ESA engineer Advenit Makaya. For now, you can invest in solar energy on Earth and look to the sky as technology advances and costs drop.

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