Comments on 'Energy intensities, EROIs (energy returned on invested), and energy payback times of electricity generating power plants'-Making clear of quite some confusion

摘要

In a recent paper published in this journal [1], Weibach et al. performed a comprehensive review of the energy performance of a number of relevant electricity production technologies, namely: wind energy, photovoltaics (PV), solar thermal, hydro, natural gas, biogas, coal and nuclear power. Their analysis is quite timely, and could potentially have provided a welcome and thought-provoking contribution to such a complex and often controversial topic [2-5]. Unfortunately, though, the article contains a number of rather seriously inaccurate statements which contribute to perpetrating many widespread misunderstandings and inconsistencies. In the very first paragraph, the authors state: EROI "describes the overall life-cycle efficiency of a power supply technique". This statement is wrong, and quite misleading. Quoting [6], "the EROI metric is not to be interpreted as an overall measure of primary energy demand per unit of energy output, or a sort of 'life cycle energy conversion efficiency". In fact, by way of how the EROI ratio is defined, the two largest direct energy inputs to the system (i.e. the fossil fuel feedstock and the renewable energy input) are not accounted for as part of the denominator, which instead only includes the primary energy previously invested to make them available (i.e. in the supply chain), plus the further investment in terms of the primary energy required for constructing and deconstructing the power plant.