Friday, March 18, 2005

What about *net* energy?

The testimony of Jim Wells, GAO's Director of Natural Resources and Environment, before the Subcommittee on Energy and Resources, Committee on Government Reform, House of Representatives a couple of days ago is available from the GAO in pdf form.

That I didn't see any mention of net energy continues to worry me. I am very concerned that we are ignoring net energy in considering future sources for our modern society.

So what? Net energy? What's that?

"Net energy" is something people generally don't think about and only gadflies ever seem to mention. I'm not talking about "net energy metering," which is when your electricity meter runs backwards if your solar cells are delivering energy from your house to the electricity grid because you aren't using it all.

"Net energy" is the ratio of
1) the energy a scheme is capable of delivering in its lifetime
divided by
2) the energy it takes to develop it.

If it takes more energy to develop a particular scheme than it can deliver, the ratio is less than one and the scheme is no good.

If it takes less energy to develop a particular scheme than it can deliver, the ratio is greater than one and the scheme shows promise.

This ratio is also known as EROEI, Energy Return on Energy Investment. Energy in over energy out.

You could also subtract energy in from energy out. If it takes more energy to develop a scheme than you get out, then the answer is negative and the scheme is no good. Generally speaking, that is.

Any number of possible energy sources are bandied about as possible options for the continuation of our modern society, but if these options do not produce substantial positive net energy, then they are not energy sources at all.

All potential sources of energy competing for our attention and dollars should be subjected to net energy analysis. Why isn't this done as a matter of course? My take on it is that 1) it's damned difficult, 2) it's highly political and 3) people just don't think about it, assuming that something from which you get energy is automatically a source of energy.

Why is net energy analysis so difficult? Because you have to take into account every bit of energy, including the heat to make the concrete for the tower or factory, the fuel to mine the raw materials, similar quantities for required connecting infrastructure, and so on. It is difficult and contentious, and it is different in every case.

Why is net energy analysis so political? That one's easy. It's because, if your favorite project is shown not to be likely to yield substantial positive net energy, it'll be axed and you're out of business. Also, it's necessary to tailor the method to the purpose, which means you might or might not count some energy inputs in the analysis, which opens the topic to argument.

Why don't people think about net energy? Beats the hell out of me. Maybe it's because of the difficulty and the politics.

I've only seen what appear to be good EROEI analyses in two cases, for nuclear energy and corn alcohol. In the nuclear case, despite what detractors like Helen Caldicott say, there is substantial positive net energy. In the corn alcohol case, it's positive but not much - basically a bit more than a wash.

People assume that wind will save the day, but when I look for good net energy analysis of wind I wind up looking at marketing materials reflecting the supposed net energy of an individual turbine. I have little reason to think that all the energy inputs required to build that turbine (mining, smelting, transporting the iron for the tower, running the factory building the composite blades, etc., etc., have been considered. Forget about all the energy to build the connecting infrastructure and redundancy required by the intermittent nature of the source. There seems to be a good likelihood that on an infrastructural basis, wind will turn out to be an energy sink not an energy source except maybe in particularly good wind areas (which are probably pretty rare, overall).

What about solar photovoltaics? I think there's a very good likelihood that we're really building batteries charged with today's cheap energy, not energy sources for the future.

Solar thermal concentrators? Maybe. I don't know. The question isn't being studied well that I'm aware of.

Maybe I just have not looked hard enough for this type of study, but it seems to me there should be an "Office of Net Energy" within the DOE and the GAO, whose charge would be to get rigorous with the net energy question so that policymakers could better decide how to allocate scarce research and development assets. The Office of Net Energy should be a scientific organization, not subject to external pressures.

This seems like a pipe dream, though, because money talks louder than morals, but look at how morals obstruct progress in, say, stem cell research.

Oh, well...

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