Researchers in the United Kingdom have proposed the use of rotating solar reflectors to increase the power output of ground-based solar power plants. They argue that this new technique could be particularly useful for improving production at dusk and dawn, when radiant power is lower.
Through their work, the researchers defined a single reference architecture for orbiting solar reflectors, as well as a detailed analysis of integrating orbital dynamics, attitude control and structures. They also evaluated the break-even conditions of these systems in terms of energy prices, startup costs, and discount rates, but noted that the proposed architecture represents current or near-term developments in both the energy and space industries.
They elaborated that orbiting reflectors may be particularly useful for ground-based solar power generation at dawn and dusk, when there is less sunlight and low output.
The reflectors are assumed to be triangular elements, the advantage of which, according to the research team, is that they can be used to build a structure of any size. “Furthermore, if the membrane ruptures, only one triangular module would be damaged instead of the entire structure,” it explained. “The development of a reusable SpaceX Starship launch vehicle is being considered to carry materials and components into space.”
The reflectors would have a hexagonal shape and a diameter of about 1 km. They would also rely on and utilize multiple mirrors in the assemblies control torque gyroscope (CMG) rotors operating at an altitude of 884.59 km and capable of completing 14 orbits in a 24-hour cycle.
“The hexagonal reflector has been considered due to its versatility for on-orbit fabrication and assembly, where it is assumed that the shape would be assembled from equilateral triangular elements with a side length of 50 meters,” the researchers stated. “The combination of shape requirement and actuator limitations ultimately results in a total hexagon of 250 meters.”
The research team considered a variety of planned or operational giant power plants to validate their approach, and said the world’s largest solar project under development — the $20 million Sun Cable project in Australia — can be considered an exemplary solar plant for the proposed technology.
“Inclined orbits are considered in this paper, but the orbit is chosen to be ‘anchored’ to the Sun Cable solar farm,” it also noted. “The reflectors in this orbit can serve nine large solar power plants in one day and produce a total of 283.8 MWh of solar energy.”
Their cost analysis also highlighted that this technology can achieve an average incremental electricity cost of $70/MWh at a 5% discount rate over 20 years. “If a more realistic discount rate of 15 percent is used, the same target price can be achieved by reducing the mass density of the reflector to about 13.2 grams-2”, they concluded. “Although this value is lower than found in this paper, it is expected that future developments in space technology may lead to lower mass density, with the added benefit of allowing smaller actuators for the same reflector size.”
They presented their findings in the journal “A Benchmark Architecture for Orbiting Solar Reflectors to Improve the Power of a Ground-Based Solar Plant,” published recently A step forward in space exploration.