Monday, March 28, 2011
The Ultimate Renewable
Apparently, the Fukushima reactor failures have cause some Americans to rethink their support for nuclear power. Even with the costs of Fukushima, good arguments have been made showing nuclear (fission) remains a very safe power source. That said, there is an upside of this recent (not exactly unfounded) wave of nuclear fear. It should spur public interest (and hopefully funding) in developing alternatives, primarily solar power. Other renewable sources work decently on a small scale, but tend to have serious, often unintended, impacts on the surrounding environment and population. Minimally, there are well reasoned arguments against large scale deployment of geothermal, hydroelectric and wind power. Furthermore, long term, I don't see how hydroelectric or wind power will ever produce enough power. I strongly doubt human society will decrease our energy appetite without a horrific population crash. Terrestrial solar power has its own problems, of course. It takes up a lot of space, it works best in sunny, low latitude environments, it doesn't generate power at night, efficient cells tend to cost a lot, etc. Still, it's the most direct of the sun driven renewables and the gives the ability to decentralize the grid (an advantage not all would agree with). Solar power is definitely worth investing time, thought and money in and I doubt many would disagree. But solar power doesn't have to be terrestrial. We can place solar power stations outside the atmosphere, in orbit where there are no clouds and there need not be night. There's no latitude affect in orbit, either. And there's a lot more, well, space. So space solar power solves all of the basic problems of terrestrial solar power and replaces them with different set: how do you build, locate and maintain a solar power satellite and how do you get the power back to earth? These are non trivial problems, but the basic answers are in place. The ISS proves we can build and maintain large scale structures in space, albeit expensively, but it's definitely possible. Power transmission can be done with low intensity microwaves* beamed down to rectennas on the ground. *Unfortunately, "microwave" tends to evoke thoughts of cooking and the ever frightening "radiation" so there is a small PR problem, maybe. Long term, space solar power is our best renewable energy source. Without it and with a still growing population, we are damned as a world to live in energy poverty. That poverty will eventually lead to a Malthusian disaster. It will, however, be a massive undertaking requiring Apollo program levels of investment. In brief, here's how I think we should proceed, as fast as possible. 1a) Develop a heavy launch capability (100 Mg to LEO) while also reducing launch costs, using different vehicles if necessary. We'll also need a manned launcher or very, very good robotic capability, but we have Soyuz now. 1b) Design and prototype a small scale solar power sat and rectenna. Demo these. An ISS experiment might be the fastest way to do this. 1c) Design and prototype an orbital broom. A working solar power sat would likely greatly ease the design and deployment of an orbital broom. This needs to be done ASAP, lest we hit the Kessler Syndrome. 1d) Continue to improve photovoltaics. This should be ongoing no matter what. 1e) Develop and improve effective high impulse thrusters like VASIMR. Like the orbital broom, these will benefit greatly from having large solar panels in space and enable us to efficiently mine near earth asteroids for resources. 2) Develop in-situ solar panel production if at all possible. The moon is a good candidate, but I suspect that some of the near earth asteroids might be better choices. The heavy launch capability is both the fall back if this doesn't work and the enabling mechanism -- we'll be able to launch factories into orbit to build the panels. 2a) Continue to refine power sat prototypes and rectenna systems. Demonstrate these and show that they're not dangerous. 3) Build and deploy the solar power sats. We could pull all of this off in 30 years, right? 3a) Develop a true "bridge to space" like a space elevator to really make this permanent and low cost. The good news is that NASA could be on this course with the Space Launch System and the ccDev space iniatives and the ISS provides a ready made platform to at least test LEO power sats. The bad news is that this requires a massive investment in resources, probably on an international level and there's almost no low hanging fruit to get the ball rolling. If at all possible, we* should leverage the current public awareness about power generation to drive the development of space solar power. *"We", I guess, is anyone who reads this, particularly those in charge of major media and awareness groups.