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Does Renewable Energy Have a Higher EROI Than Fossil Fuels?

There is new momentum behind the idea that renewable energy has a higher energy return on investment (EROI) than fossil fuels.

That contrasts with decades of consensus that the EROI of oil, for example, ranges from 18 to 35 while the range for solar is from 6 to 12.

Nafeez Ahmed wrote in a recent post that

“While the EROI values of wind and solar are “at or above 10”, the average EROI estimate for oil is about 4.2. Murphy et. al’s research concludes that many EROI analyses incorrectly compare fossil fuels with renewables by measuring them at the wrong areas. By consistently measuring them both at their ‘point of use’, they are able to develop a far more consistent approach.”

Similarly, Ugo Bardi wrote a post in January whose title was ” Setting the record straight on the EROI from renewables. It is much better than that of fossil fuels.”

Both Ahmed and Bardi used a 2022 paper, Energy Return on Investment of Major Energy Carriers: Review and Harmonization as their source.

Net Energy and EROI Essentials

Net energy is the difference between the total energy output minus the total energy input over the life cycle of an energy source or technology (Figure 1).

EROI is the ratio of the total energy output divided by the total energy input over the life cycle of an energy source.

That means that the net energy for a 10 megajoule (MJ) energy input and a 20 MJ output is 10 MJ and the EROI is 2 (Figure 1).

Figure 1. Net energy and EROI for a hypothetical energy source or technology. Source: Modified from Hagens (2010).Table 1 shows a range of energy inputs and outputs and their corresponding EROI and net energy values. The important observation is that EROI is non-linear while net energy is linear.

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Olduvai IV: Courage
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Olduvai II: Exodus
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