27 June, 2011

Space Solar Power redux: now that's what I'm talking about

The Economist Magazine (both web and print versions) recently had an interesting article on the possibility of collecting solar power by a platform in orbit and then beaming it to collection areas or a point of use on earth.

As the article points out, the lure of such an operation is the efficiency gains possible by collecting, concentrating, and converting the solar radiation in space into wavelengths that are not as severely attenuated or scattered by the atmosphere. This idea has been around for decades -- a lot of preliminary design and analysis work had been devoted to a NASA Solar Power Satellite starting in the late 1960's. Significantly, and perhaps not surprisingly, this new work is being pursued not be NASA or a U.S. company but rather by Astrium -- part of EADS.

The current thinking is to use one or more geostationary orbiting platforms to collect the almost 24 hours per day sunlight with a solar array and then beam the converted energy to collector stations on earth. Most prior effort has assumed that power would be transmitted in the form of microwaves. The more recent plan described by The Economist would use advanced LASER devices to beam the power down. The advantage of the latter approach being that the ground collection apparatus could be an order of magnitude smaller in terms of area. An obvious avenue of investigation is the possibility of some sort of direct (or at least more direct) conversion of the incoming solar energy to a laser output, thus avoiding the cost and inefficiencies of using conventional solar arrays (or more likely their descendants).

Just imagine if a U.S. administration were to actually present NASA with a mission to make this, or something like it, work within the next decade or so. NASA would then have a bonafide rationale for developing, fielding, and continuously improving:
  • Routine and frequent access to LEO, HEO, and possibly lunar space
  • Heavy lift and medium lift systems
  • Manned and robotic systems for construction, maintenance, and operations
  • Collaboration with the burgeoning commercial space sector
  • Energy/power collection, storage, conversion, and transmission technologies, most of which would have easily foreseeable applications to ground based applications such as domestic solar array materials and electric vehicles.
The nation, at a cost not appreciably more than is being spent right now just marking time in hopes that someone will finally figure out what we ought to be doing, will achieve:
  • A very badly needed technological renaissance as engineers, scientists, technologists, and educators work to develop solutions to the technical challenges as well as the young minds to maintain our hard-won momentum in the future
  • A relevant and cost-effective jump start to a critical sector of our economy
  • Sensible opportunities for mutually productive international partnerships -- the chance to mend fences with allies and perhaps forge new alliances
  • A productive and significant rationale for a continued presence in space
  • An important step on the path towards U.S. energy independence and feasible reductions in CO2 and other greenhouse gas emissions
  • A great leap into mastering the next frontier that may cause future regional and global conflict: assured readily available fresh water
  • A credible basis for power systems and other logistics and infrastructure needed for persistent lunar and planetary surface operations.
For all of these reasons, a prototype solar power satellite system, first a small scale proof of concept and then a full scale experimental unit, is something I would recommend and endorse. The development of space based solar power would in this way parallel that of fission-based nuclear power about six decades before. And I'd be happy as a clam to see safe and clean fusion power render solar power irrelevant. First, nuclear fusion as a commercial (or any other sort of) prospect seems perennially to be 40 years away. Second, if and when the era of controlled fusion does arise (with electricity being too cheap to meter and all that!), we'll still have the benefits of our experience in space operations and the reduced cost per pound of payload to orbit that must inevitably result.

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