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Japan plans to launch a solar power plant in low Earth orbit to transmit energy to Earth by 2025. The first demonstration prototype will weigh about 180 kg and transmit about 1 kilowatt of energy power, enough to power a device home appliance. This is a first step towards larger-scale production aimed at significantly reducing dependence on fossil fuels.
Although solar power has been used since the 1970s, its widespread adoption remains limited due to technical and logistical challenges. Difficulties include, for example, the lack of suitable location for the installation of photovoltaic panels, the degradation of the installations over time and the dependence on weather conditions and the day-night cycle. In order to make up for production deficits, users are still forced to turn to fossil fuels.
First proposed by Peter Glaser, a former Apollo mission engineer, space-based solar power generation could help overcome these limitations. Unlike most terrestrial green energy technologies, space solar power plants could produce energy continuously, because they would not depend on weather conditions and would be less enslaved to the day/night cycle (depending on the type of orbital placement).
An invitation to dream, ready to be worn.
However, generating solar power from space is generally considered impractical and far too expensive. Indeed, it requires the installation of enormous infrastructures in orbit, which would require dozens of rockets to transport them. However, researchers at Japan Space Systems believe that recent advances in space engineering and solar technologies could be a game-changer, not to mention the urgent need to decarbonize the global energy industry.
A cost/profitability ratio that is debated
Designed as part of the Ohisama project, the Japan Space Systems device consists of a small 180-kilogram satellite which will orbit at an altitude of 400 kilometers. It will be equipped with a 2 square meter photovoltaic panel which will charge an integrated battery. The accumulated energy will then be converted into microwaves and then sent to a receiving antenna on Earth. Since the satellite will move at high speed (28,000 km/h), the receiving antenna elements will be distributed over a distance of 40 kilometers and spaced 5 kilometers apart.
However, it is important to note that this is only a demonstration prototype, which will only send one kilowatt of energy power, enough to power a small dishwasher or kettle for a period of time. hour. In addition, “the transmission will only take a few minutes, but once the battery is empty, it will take several days to recharge it,” said Koichi Ijichi, advisor to Japan Space Systems, during the presentation of the project roadmap. at the International Space Energy Conference in London.
Furthermore, researchers have already carried out a first demonstration of the wireless transmission of solar energy from a stationary Source placed on the ground. And in December this year, they plan to carry out the transmission from an airplane, installing on it a solar panel identical to the one that will equip the satellite. The aircraft will transmit energy over a distance of 5 to 7 kilometers, relative to the receiving antenna on the ground.
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Furthermore, according to the directors, advances in photovoltaic cells (such as flexible solar cells) would make it possible to extend this type of technology to commercially viable scales. Under this vision, a related government project plans to launch satellites equipped with giant 2-square-kilometer solar panels that could generate up to 10 times more power than ground-based panels. Each satellite could thus produce monthly the equivalent of the daily production of a nuclear power plant. The future availability of SpaceX’s Starship rocket could also facilitate installations.
However, the true potential of space solar energy is debated. According to a recent NASA report, the investments required for the construction and launch of space plants would be too high in relation to the quantity of energy produced, which calls into question their profitability. In view of the capital involved, the energy produced could cost around $0.61 per kilowatt hour, compared to $0.5 for terrestrial solar energy. On the other hand, the carbon emissions generated by rockets required to launch them make them much less environmentally friendly than one might think. Indeed, 68 ships would be needed to put into orbit a power plant capable of producing one gigawatt hour of electricity.
Nevertheless, other research centers and space agencies such as the European Space Agency (ESA) and the US Air Force are currently working on different strategies for the feasibility of space solar power plants.
