EROEI Calculations for Solar PV Are Misleading

The Energy Returned on Energy Invested (EROEI) concept is very frequently used in energy studies. In fact, many readers seem to think, “Of course, EROEI is what we should be looking at when comparing different types of energy. What else is important?” Unfortunately, the closer to the discussions of researchers a person gets, the more problems a person discovers. People who work with EROEI regularly say, “EROEI is a tool, but it is a blunt tool. An EROEI of 100 is good compared to an EROEI of 10. For small differences, it is not so clear.”

Because of the idiosyncrasies of how EROEI works, different researchers using EROEI analyses come to very different conclusions. This issue has recently come up in two different solar PV analyses. One author used EROEI analysis to justify scaling up of solar PV. Another author published an article in Nature Communications that claims, “A break-even between the cumulative disadvantages and benefits of photovoltaics, for both energy use and greenhouse gas emissions, occurs between 1997 and 2018, depending on photovoltaic performance and model uncertainties.”

Other EROEI researchers with whom I correspond don’t agree with these conclusions. They recognize that in complex situations, EROEI analyses cannot cover everything. Somehow, the user needs to be informed enough to realize that these omissions result in biases. Researchers need to work around these biases when coming to conclusions. They themselves do it (or try to); why can’t everyone else?

The underlying problem with EROEI calculations is that EROEI is based on a very simple model. The model works passably well in simple situations, but it was not designed to handle the complexities of intermittent renewables, such as wind and solar PV. Indirect costs, and costs that are hard to measure, tend to get left out. The result is a serious bias that tends to make the EROEIs of solar PV (as well as other intermittent energy sources, such as wind) appear far more favorable than they would be, if a level playing field were used. In fact, published EROEIs for solar PV (and wind) might be called misleading. This issue also exists for other similar calculations, such as Life Cycle Analyses and Energy Payback Periods.

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Intermittent Renewables Can’t Favorably Transform Grid Electricity

Many people are hoping for wind and solar PV to transform grid electricity in a favorable way. Is this really possible? Is it really feasible for intermittent renewables to generate a large share of grid electricity? The answer increasingly looks as if it is, “No, the costs are too great, and the return on investment would be way too low.” We are already encountering major grid problems, even with low penetrations of intermittent renewable electricity: US, 5.4% of 2015 electricity consumption; China, 3.9%; Germany, 19.5%; Australia, 6.6%.

In fact, I have come to the rather astounding conclusion that even if wind turbines and solar PV could be built at zero cost, it would not make sense to continue to add them to the electric grid in the absence of very much better and cheaper electricity storage than we have today. There are too many costs outside building the devices themselves. It is these secondary costs that are problematic. Also, the presence of intermittent electricity disrupts competitive prices, leading to electricity prices that are far too low for other electricity providers, including those providing electricity using nuclear or natural gas. The tiny contribution of wind and solar to grid electricity cannot make up for the loss of more traditional electricity sources due to low prices.

Leaders around the world have demanded that their countries switch to renewable energy, without ever taking a very close look at what the costs and benefits were likely to be. A few simple calculations were made, such as “Life Cycle Assessment” and “Energy Returned on Energy Invested.” These calculations miss the fact that the intermittent energy being returned is of very much lower quality than is needed to operate the electric grid. They also miss the point that timing and the cost of capital are very important, as is the impact on the pricing of other energy products. This is basically another example of a problem I wrote about earlier, Overly Simple Energy-Economy Models Give Misleading Answers.

Let’s look at some of the issues that we are encountering, as we attempt to add intermittent renewable energy to the electric grid.

Issue 1. Grid issues become a problem at low levels of intermittent electricity penetration. Continue reading