The idea is to launch giant orbiting solar collectors into space, where there is no night, and beam the power to receivers on the ground, where it is fed as electricity to the grid. Long championed by former President Dr. Abdul Kalam, and the Aerospace Society of India (AeSI), the idea is seen as a long-term solution for energy security and climate change, and the most environmentally benign and scalable renewable energy option, which deserves its own focused development programme.
Such satellites would be the largest, most ambitious space projects ever contemplated. A single solar power satellite would be several kilometres long, with a transmitting antenna about a kilometre across, and generate between one and ten Gigawatts (as much power as 10 nuclear power plants). It might weigh tens of thousands of metric tons and would require a fleet of reusable space vehicles to construct. Follow-on designs might use materials from the Moon.
Existing communications satellites use a similar process, using the power of the Sun on their solar arrays to power a radio transmitter for sending radio and television signals. But the small antenna on communications satellites prevents them from being able to focus a beam for power-beaming. To beam power, the transmitter must be increased to almost a kilometre long, and a special receiver, a rectifying antenna, or rectenna is required. The rectenna would be several kilometres across, about the size of a municipal airport, made of a thin metal mesh, and would be 80 per cent transparent to sunlight, allowing the land underneath it to be used for pastoral, agricultural use or production of algae biodiesel.