dietz.usc-cse%Rand-Relay@sri-unix.UUCP (10/18/83)
Some additional comments on Gayle's objections to SPS: There are much simpler and "softer" ways to provide space and process heat. I heartily disagree. The alternatives to electricity for industrial process heat are fossil fuels (dirty, expensive and limited), geothermal, ground based solar or biomass. Tests of ground based solar for industrial process heat have failed resoundingly (see a recent issue of Mechanical Engineering for a review). Biomass quickly runs into absurdities when you try to scale it up: because plants are such inefficient energy collectors massive amounts of land are needed, yielding high costs and seriously affecting the biosphere. The economics of ethanol are very dubious because of distillation costs (witness the failure of gasohol). Geothermal is too limited, is more expensive and is somewhat polluting. As for space heating, it has become pretty clear that active solar heaters are uneconomical (unless you can get the government to pay for them through tax loopholes or whatever). The best that can be done is to superinsulate homes and offices; the economics of this approach remain to be seen. Replacing the current stock of buildings will take time (the time to replace 50% of the homes in the US is 50 years) and will reduce total consumption of energy only a little. Electric cars are still waiting for breakthrough in batteries. True. There are alternatives, though. A nifty idea is a car fueled by liquid nitrogen (!) heated by a small heat source (say, a hydrogen flame) to 700 degrees then run though a gas turbine. The result is a car that produces very little pollution and gives a very smooth quite ride. Much less hydrogen (or whatever) is required than in conventional engines, so the hydrogen can be economically stored in metal hydrides. Liquid nitrogen costs about ten cents per gallon today, although this price is so low becuase the LN is a byproduct of LOX production for the steel industry. See the latest High Technology (I think) for a short article on this idea. Significant progress has been made in the field of batteries (see the latest American Scientist for an article on one promising type). Hydrogen is a feedstock for synfuel production, so maybe cars will use methanol (say) made with hydrogen produced with SPS power. Aircraft buring hydrogen have been designed (but not built); aircraft could also burn synthetic hydrocarbons. Hydrogen can very easily substitute for natural gas; indeed, hydrogen is better, because it can be burned more cleanly without flame on a platinum catalyst, even at very low hydrogen flow rates, making it ideal for cooking and warming food. Heat pumps would probably be better for home heating, though. The US wouldn't even need much additional electricity if it built a high speed electrified railroad system... Rail transport is already near it upper speed limits because of track alignment problems. The tracks for bullet trains in Japan, for example, are realigned every night(!), imposing high labor costs. I might agree if you are talking about magnetic flight transportation, at least as far as transportation energy costs are concerned. Providing the U. S. with massive amounts of new energy will only delay for a few generations the inevitable population, resources, and environmental disasters. We'll be better off if we deal with those problems now, while there's still a reasonable amount of land, water, and air left. Who said SPS and ecological concern are mutually exclusive? I'd rather have lots of cheap clean energy AND a clean environment. Building powersats will aid maintaining a clean environment. Cheap energy will make it easier and cheaper to recycle needed elements and destroy dangerous chemicals. SPS will eliminate incentives (such as they are) for building nuclear power plants. SPS will reduce acid rain from coal fired plants. SPS has the least thermal pollution of any energy source, since the rectenna is some 90-95% efficient. Cheap energy will reduce manufacturing costs, raising the relative value of other resources, such as a clean environment. Cheap siderophiles from the asteroids will reduce the cost of pollution controls (catalytic converters, for instance, use platinum, paladium and rhodium). Conversely, I don't see how not developing SPS could possibly help prevent overpopulation, resource depletion and environmental disaster. Cheap energy is necessary to significantly raise standards of living in third world countries, decreasing the birth rate. The shear magnitude of the problem is apparent when one considers the amount of energy needed to supply the world of the year 2000 at (say) half of current US per-capita levels. Conventional energy sources (including biomass and ground based solar) would produce enough waste heat to potentially alter the climate. I get the feeling reading your objections that you have started with the idea that SPS is bad because it is large and are trying to justify that belief. Indeed, I get the idea from your last objection that you would object to ANY cheap source of energy, be it solar, fusion, or whatever, no matter how clean it is, because it would seduce people away from a limits-to-growth philosophy. I recommend you read O'Neill's book "2081" for a lucid analysis of the energy problem.