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┬áthat 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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What has gone wrong with oil prices, debt, and GDP growth?

Our economy is a mystery to almost everyone, including economists. Let me explain the way I see the situation:

(1) The big thing that pulls the economy forward is the time-shifting nature of debt and debt-like instruments.

If we want any kind of specialization, we need some sort of long-term obligation that will make that specialization worthwhile. If one hunter-gatherer specializes in finding flints that will start fires, that hunter-gatherer needs some sort of guarantee that others, who are finding food, will share some of their food with him, so that the group, as a whole, can prosper. Others, who specialize in gathering firewood, or in childcare, also need some kind of guarantee that their efforts will be rewarded.

At first, these obligations were enforced by social norms such as, “If you don’t follow the rules of the group, we will throw you out.” Gradually, reciprocal obligations became more formalized, and included more time shifting, “If you will work for me, I will pay you at the end of the month.” Or, “If you will pay my transportation costs to a land of more opportunity, I will repay you with 10% of my wages for the first five years.” Or, “I will sell you this piece of land, if you will pay me x amount per month for y years.”

In some cases, the loan (or loan-like agreements) takes the form of stock ownership of an enterprise. In this case, the promise is for future dividends, and the possibility of growth in the value of the stock, in return for the use of funds. Even though we generally refer to one type of loan-like agreement as “equity ownership” and the other as “debt,” they have a great deal of similarity. Funds are being provided to the enterprise, with the expectation of greater return in the future.

As another example, governments make promises for future benefits, such as Social Security, healthcare, and payments to the unemployed. These payments are not guaranteed, so are not considered debt. Even without a guarantee, they act in many ways like debt. Citizens plan their lives around these payments, even though they may be reduced or eliminated.

Surprisingly, even “cash” is debt. It is similar to a bond that pays zero interest and has no redemption date; this type of bond can also be easily transferred from person to person. Since cash can be hidden under mattresses, it too can be used as a device for time-shifting.

(2) The big thing that goes wrong in this time-shifting approach to operating the economy is the loss of what I would call an “opportunity gradient.”

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