(This is Part 27 of a series. Go back to Part 26.)
Biomass. Biomass is the term for any fuel that derives from growing plant material. The primary idea currently is to produce ethanol, similar to gasoline, from corn. Other ideas involve using biodiesal or vegetable oil from plants as fuel.
The main problem with biomass is that it has a very low —and perhaps negative—energy return. So much energy is required in the growing, harvesting and extraction of the fuel that it's difficult to obtain a net energy "profit".
The EROEI of ethanol, for example, is calculated by various sources to be between 1.34 and 0.59. Anything below a ratio of 1.0, of course, represents a net energy loss. Even 1.34, the most optimistic number, represents a very small energy yield.
In addition, biomass produces lots of pollution and in this respect is similar to coal, oil shale, etc. Thus, for both net energy and pollution reasons, biomass seems unlikely to provide any significant help to the future world economy.
Hydroelectric. Hydroelectric energy is clean and has a relatively high EROEI. So what's not to like?
The problem with hydro is that it's basically been done. Hydroelectric dams were built at a furious pace on most major rivers throughout the world during the 20th century. Aside from a few countries, there's just not a lot of room for major new dams.
One possibility is microhydro, where small hydroelectric dams are built on streams, particularly in the developing world. Along with major hydro, however, this has a huge downside: It means an economy relying on a resource even more endangered than fossil fuels—water. Probably not a great idea.
Nuclear. The thing about nuclear energy is that it creates enormous amounts of radioactive waste. For instance, an average nuclear plant produces annually a thousand tons of radioactive waste. That's not counting 100,000 tons of radioactive uranium mill tailings.
Moreover, this is waste that must be dealt with for tens of thousands of years. It is a fact that no country in the world has to date been able to construct a permanent high-level nuclear waste repository. Hmm, I wonder if that tells us something. And there are other major problems, such as safety and huge cost.
Fusion reactors may make a difference down the road, but a successful fusion reactor would have to somehow hold temperatures of 360 million degrees F. and no material or process known can do that. Even its proponents admit that commercial fusion is at least 50 years away.
(This is the end of Part 27. Go to Part 28.)
—jim sloman, 10.22.04 for Dec 24
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