Offering solar farms an extra two hours of generation each day, the concept was developed by space engineers working at the University of Glasgow.
Designed to boost the output of future large-scale solar farms, the system would use kilometre-wide orbiting reflectors to reflect additional sunlight to the Earth’s surface at both dawn and dusk.
The researchers used computer simulations to determine the most effective method of using orbiting solar reflectors. Their models showed that putting 20 ‘gossamer-thin’ reflectors into 1,000km orbit could reflect sunlight to solar farms for an extra two hours each day on average.
The additional sunlight could boost the output of the world’s future solar farms, particularly after sunset when electricity demand is high. The output could be scaled up further by adding more reflectors or increasing their size.
The reflectors would maintain an orbit close to the Earth’s terminator line – the boundary where daylight transitions into night – in an arrangement known as a Walker constellation. Such arrangements are widely used in satellite communication systems, where groups of equally spaced satellites form rings around the planet to ensure consistent communication with the Earth’s surface.
The team developed an algorithm to determine how the reflectors could be arranged in the constellation and angled to catch the Sun’s rays most effectively, maximising the additional sunlight reflected to solar farms in the early morning and late evening.
They found that 20 reflectors could generate an extra 728 megawatt-hours (MWh) of electricity per day – the equivalent of adding an additional large-scale solar power farm to Earth without the associated cost of construction.
“Solar power has the potential to be one of the key accelerators in our race to reach net zero, helping us to mitigate the global impacts of climate change by reducing our reliance on fossil fuels,” said Dr Onur Çelik, corresponding author of the paper.
“The price of solar panels has dropped quickly in recent years, increasing the pace of their adoption and paving the way for the creation of large-scale solar power farms around the world.
“One of the major limitations of solar power, of course, is that it can only be generated during daylight hours. Putting orbiting solar reflectors in place around the Earth would help to maximise the effectiveness of solar farms in the years to come. Strategically placing new solar farms in locations which receive the most additional sunlight from the reflectors could make them even more effective.”
According to a recent article by Dr Çelik on The Conversation, the reflectors would illuminate areas approximately 10km across on the Earth’s surface. The orbital installations would angle themselves to illuminate solar farms as they passed over them before rotating back to be edge-on to the Sun, minimising their effect on astronomical observations.
Dawn and dusk have the highest electricity demand, Dr Çelik added, so the system could prevent coal and gas power plants being used to compensate.
The idea is similar but separate from the concept of space-based solar power (SBSP), which would use giant solar panel satellites to absorb energy from sunlight while in orbit. That energy could then be converted to low power density microwaves and beamed to receivers on Earth to enable constant solar power generation.
The new paper is one of the outputs from Solspace, a University of Glasgow-led research project supported by €2.5m funding from the European Research Council.
“The idea of orbiting solar reflectors isn’t new – in fact, it predates even the space age, as the idea of illuminating cities with light from space was first discussed in the late 1920s,” said co-author Professor Colin McInnes.
“However, space reflectors have only been demonstrated once back in the early ‘90s, when a 20-metre aluminium-foil reflector was released from the Russian Mir space station to reflect sunlight back to Earth.
“The Solspace project is working to devise, develop and demonstrate ideas for orbital reflector technology that could work on a much more ambitious scale to deliver global clean energy services.
“Tackling the challenges of climate change requires big ideas. While this is undoubtedly a big idea, it builds on technologies that are already well-understood and computer models like ours show how they could be scaled up. In addition, the falling cost of launching payloads to space opens up entirely new possibilities for the future.”
The work was published in Acta Astronautica.
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