Energy Return on Energy Invested (ERoEI) for photovoltaic solar systems in regions of moderate insolation: A comprehensive response

The researchers above created a reponse to.

A recent paper by Ferroni and Hopkirk (2016) asserts that the ERoEI (also referred to as EROI) of photovoltaic (PV) systems is so low that they actually act as net energy sinks, rather than delivering energy to society. Such claim, if accurate, would call into question many energy investment decisions. In the same paper, a comparison is also drawn between PV and nuclear electricity. We have carefully analysed this paper, and found methodological inconsistencies and calculation errors that, in combination, render its conclusions not scientifically sound. Ferroni and Hopkirk adopt ‘extended’ boundaries for their analysis of PV without acknowledging that such choice of boundaries makes their results incompatible with those for all other technologies that have been analysed using more conventional boundaries, including nuclear energy with which the authors engage in multiple inconsistent comparisons. In addition, they use out-dated information, make invalid assumptions on PV specifications and other key parameters, and conduct calculation errors, including double counting. We herein provide revised EROI calculations for PV electricity in Switzerland, adopting both conventional and ‘extended’ system boundaries, to contrast with their results, which points to an order-of-magnitude underestimate of the EROI of PV in Switzerland by Ferroni and Hopkirk.

Michel Gélinas on linkedin said

Thank you for linking. Reminescent of the Raugei et al vs Weißbach et al disagreement of a few years ago. Whether the EROI of solar in CH is 0.8 or one order of magnitude larger, its power density is low. The low power density of RE is a matter of larger sociaol and economic consequence.


I thought should we be investing in systems that probably wont provide enough power or in researching ideas that will…

Also I guess energy storage is not important

Even so, Ferroni and Hopkirk’s choice of 25% is unsupported. Firstly, such a high storage requirement fails to take into account the potential synergy of combining PV with wind (Nikolakakis and Fthenakis, 2011), the drastic smoothening of PV fluctuations by considering geographical diversity (Perez and Fthenakis, 2015), and the optimization/minimization of storage requirements for load-following and ramp-rate control duties (van Haaren et al., 2015). Secondly, energy storage would be more fittingly addressed as part of an analysis of a country’s whole energy system. Palzer and Henning, 2014a and Palzer and Henning, 2014b showed that, for the case of Germany, about 8% of the generated electricity would have to be stored for an 87% renewable energy system, and a similarly low percentage was estimated for the UK (Gross et al., 2006). Also, the National Renewable Energy Laboratory estimated that high penetration (>80%) of renewables would be possible in the USA with only ~5 times current storage capacity, which is currently at a comparatively low ~20 GW (Hand et al., 2012). Bogdanov and Breyer (2016) indicate an electricity storage demand of less than 15% for Northeast Asia for a 100% renewable energy system with a limited level of integration in other energy sectors. More specifically, given the high share of reservoir hydropower in the Swiss grid mix – producing 31.7% of total electricity (Swiss Federal Office of Energy, 2015b) – it seems plausible that the already-available hydro dams could often be used for flexible generation on demand, thereby significantly reducing the need for additional energy storage.

Also the response did not address the problems associated with building solar panels in China. From my quick review.

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