An important new study in the journal Energy (Weißbach et. al. 2013, paywalled) focuses on energy return on investment (EROI, or sometimes ERoEI), which is the ratio of electrical energy produced by a given power source to the amount of energy needed to build, fuel, maintain and decomission that power plant. //

Here's the idea in a nutshell: in the US, a kWh of energy (unweighted) costs about 10 cents but it produces about 70 cents worth of GDP, a ratio of 7 to 1. //

But the big winners in non-fossil energy are run-of-river hydro (Weißbach allows a 100 year plant lifetime, which may be generous) and nuclear (at a 60 year plant lifetime, in line with other studies). And by the way, this is one reason Weißbach's study is better than some earlier works: he includes plant lifetime in his computations, which can make a big difference. Wind turbines, for example, are subjected to large physical stresses which limits their lifetime to about 20 years, both in this study and according to the National Renewable Energy Laboratory. In effect, you have to build a windfarm two or three times over during the lifetime of a nuclear plant, and that adds up.

Two cases were analyzed for coal, one hard coal (EROI 29, EMROI 49) and one brown coal (EROI 31, EMROI 49). These were averaged to an EROI of 30 as shown. In the US we have plenty of hard coal reserves and don't use brown coal. Also, the authors omitted from this study the energy cost needed to transport coal, apparently because that varies by country. Using EIA data, this amounts to 244 KJ per tonne-km for rail transport. So in the US, where a lot of coal is moved from mines in Wyoming to end users far away, a typical 1000 mile trip would lower the EROI of coal from 29 to 28, while EMROI remains unchanged at 49. //

So if you ever wondered why climate scientists like James Hansen are pro-nuclear, this is one reason. Yes, wind is fine if it can be grid-buffered against a non-fossil generating source. And absolutely we need more hydro, especially run-of-river hydro where it's feasible. But there are limits to the amount of river where it is feasible. So if we want to eliminate fossil fuels from electricity production (and we do), and if we want to manage that transition so that it doesn't hurt the economy (and we do), nuclear has to be part of the mix. And in fact, it has to be a much bigger part of the mix than it has been in the past. In the next part of GETTING TO ZERO, I will address the safety issues of nuclear power in detail, but for right now what you need to know is that even after accounting for latent deaths from Chernobyl (and non-deaths from Fukushima), nuclear is still one of the safest forms of energy.

Finally, if you'd like to take a detailed look at the calculations, Weißbach's spreadsheet can be found on Google Docs. I used the spreadsheet to compute some of the numbers above.