By Mark Miner
I am taking a course in renewable energy, which is a fascinating topic. The world keeps draining the oil reserves, coal will be around longer, but has a number of other issues, nuclear fission plants are politically touchy and run on another finite fuel supply, fusion is a nascent technology, and greenhouse gases and global temperatures are slowly, but undeniably correlatively, on the rise.
Also, Mars is not yet a viable escape route.
I do not mean to be alarmist. The world will be around tomorrow. On the other hand, I do not want my grandchildren to have a mess to clean up.
Nothing is clean cut in this question. No single avenue can take us clear of non-renewable energy, and it seems that there will always be some role for non-renewables in the world economy, but I do think that a change is in order.
How? That is the $64,000 question, and one that I am quite curious about. Solar energy is very diffuse, and any diffuse energy source is capital-intensive to collect. That capital has to be created, and those processes can (and often do) more than offset the benefits.
Hydrogen can be produced with less capital (an electrolyzer can run for a good long time), but how do you seal and store nature's smallest molecule? Simply stated, you can't. Hydrogen escapes from any tank. To fuel the space shuttle's main engines, NASA plans around the loss of ~30% of the hydrogen between the production plant and the launch pad. Also, at a reasonable electrolyzer efficiency of 70% (electric energy in / hydrogen energy out), 3112 trillion kilojoules of energy are required to equal the gas that gets burned in autos (based on USDOE data for American gasoline consumption in 2000). This more than doubles total American electricity production for 2003, which was 1400 trillion kilojoules (data from CIA.gov). Arnold Schwarzenegger's much-vaunted hydrogen economy begins to look a bit more dubious, especially when one considers how that electricity is generated.
Ethanol cannot be produced from corn in sufficient quantities to make a difference in the world's transportation fleet. Corn requires large amounts of nitrogen fertilizer, which is created using the "Haber-Bosch" process that reacts steam and natural gas to get hydrogen, then combines that with nitrogen to get the ammonia fertilizer that feeds agriculture. This is not at all a renewable process, and requires substantial energy inputs to achieve the high temperatures and pressures required for the process. Cellulosic ethanol is not yet a proven technology, although certain promising enzymes have been isolated in termite digestive tracts. If ethanol could be produced from cellulose, the 1.5:1 ethanol:gasoline energy ratio (by volume) would seem less intimidating.
For now, we can all expect more of the same; for tomorrow, we should be working and thinking how to best manage the world that God has given us.
