An idle dream for decades, the idea is now gradually inching towards reality. It has been known for some time that it is possible to put up a very large solar power plant — say, all of 10 sq km — up in space, where it will make electricity from the plentiful and 24-hour supply of sunlight and beam it back to Earth in the form of microwaves; a device here can convert the microwaves back into electricity. This way you have a perennial supply of clean energy.

Clean, yes, but cheap? So far, the cost of taking several tonnes of material up there has killed the idea at birth. But the advent of better rockets, lighter materials and 3D printing promises to stir awake the dormant thinking. You can launch tens of thousands of ‘solar satellites’ into space and assemble them into a giant solar farm at site. The best illustration of the thought coming alive is the UK government’s commission of Fraser-Nash Consultancy, in November 2020, to study the proposal afresh. China has said it aims to build a space-based solar station by 2050.

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