2011-07-07 Source: www.economist.com
Harvesting solar power in space, for use on Earth, comes a step closer to reality
THE idea of collecting solar energy in space and beaming it to Earth has been around for at least 70 years. In “Reason”, a short story by Isaac Asimov that was published in 1941, a space station transmits energy collected from the sun to various planets using microwave beams.
The advantage of intercepting sunlight in space, instead of letting it find its own way through the atmosphere, is that so much gets absorbed by the air. By converting it to the right frequency first (one of the so-called windows in the atmosphere, in which little energy is absorbed) a space-based collector could, enthusiasts claim, yield on average five times as much power as one located on the ground.
The disadvantage is cost. Launching and maintaining suitable satellites would be ludicrously expensive. But perhaps not, if the satellites were small and the customers specialised. Military expeditions, rescuers in disaster zones, remote desalination plants and scientific-research bases might be willing to pay for such power from the sky. And a research group based at the
This summer, Stephen Sweeney and his colleagues will test a laser that would do the job which Asimov assigned to microwaves. Certainly, microwaves would work: a test carried out in 2008 transmitted useful amounts of microwave energy between two
Dr Sweeney’s team, working in collaboration with Astrium, a satellite-and-space company that is part of EADS, a European aerospace group, will test the system in a large aircraft hangar in
In the case of Dr Sweeney’s fibre laser, the beam will have a wavelength of 1.5 microns, making it part of the infra-red spectrum. This wavelength corresponds to one of the best windows in the atmosphere. The beam will be aimed at a collector on the other side of the hangar, rather than several kilometres away. The idea is to test the effects on the atmospheric window of various pollutants, and also of water vapour, by releasing them into the building.
Assuming all goes well, the next step will be to test the system in space. That could happen about five years from now, perhaps using a laser on the International Space Station to transmit solar power collected by its panels to Earth. Such an experimental system would deliver but a kilowatt of power, as a test. In 10-15 years Astrium hopes it will be possible to deploy a complete, small-scale orbiting power station producing significantly more than that from its own solar cells.
Other researchers, in
Whether the Astrium system will remain a specialised novelty or will be the forerunner of something more like the cosmic power stations of Asimov’s imagination is anybody’s guess. But if it comes to pass at all, it will be an intriguing example, like the geostationary communications satellites dreamed up by Asimov’s contemporary, Arthur C. Clarke, of the musings of a science-fiction author becoming science fact.
- CBCSD and Members Participated and Suggested on the Project for Technical Regulation on Low-carbon Pilot Community
- CBCSD and Members Participated in the APEC Cooperation Network Construction Forum of Green Supply Chain
- Calculation Method of CO2 Emissions in Petroleum and Natural Gas Exploitation Enterprises & Calculation Method of CO2 Emissions in Water Network of Chemical Enterprises
- CBCSD Attended the Workshop for Environmental Protection and Sustainable Development and Delivered Introductions
- WBCSD: Tackling the Challenge, How to Make Informed Choices on Forest Product?
- The National New-Type Urbanization Plan Released, Board Members of CBCSD Help the Sustainable Development of Cities
- Board members of CBCSD Actively Participated in the Carbon Trading and International Climate Change Process
- Two industrial Standards Compiled by CBCSD Passed Examination
- Widespread Use of the Achievements Businesses Energy Saving and Greenhouse Gas Management
- CBCSD held Chemical industry enterprise value chain (range 3) greenhouse gas emissions, accounting and reporting guidelines