Energy Return on Investment of Major Energy Carriers: Review and Harmonization

Abstract

Net energy, that is, the energy remaining after accounting for the energy “cost” of extraction and processing, is the “profit” energy used to support modern society. Energy Return on Investment (EROI) is a popular metric to assess the profitability of energy extraction processes, with EROI > 1 indicating that more energy is delivered to society than is used in the extraction process. Over the past decade, EROI analysis in particular has grown in popularity, resulting in an increase in publications in recent years. The lack of methodological consistency, however, among these papers has led to a situation where inappropriate comparisons are being made across technologies. In this paper we provide both a literature review and harmonization of EROI values to provide accurate comparisons of EROIs across both thermal fuels and electricity producing technologies. Most importantly, the authors advocate for the use of point-of-use EROIs rather than point-of-extraction EROIs as the energy “cost” of the processes to get most thermal fuels from extraction to point of use drastically lowers their EROI. The main results indicate that PV, wind and hydropower have EROIs at or above ten while the EROIs for thermal fuels vary significantly, with that for petroleum oil notably below ten.

Emerging consensus on net energy paves the way for improved integrated assessment modeling

“…, 8 h) storage‡‡The inclusion of storage devices in the system boundary (rather than at the level of an individual power generation technology), however, is more relevant at the country, regional, or grid level, because each technology, if deployed in isolation, would require some storage capacity to successfully keep up with the pattern of electricity demand. technologies. 29,30 Average EROI values however hide strong regional variability, particularly for solar and wind technologies. 31,32…”

“…or gaseous fuels. 30 8. A rapid large-scale deployment of renewable electricity and associated infrastructure will likely temporarily reduce the dynamic EROI (i.e., PROI) of the energy system as it requires a significant upfront energy investment embodied in infrastructure.…”

Comparing the net-energy balance of standalone photovoltaic-coupled electrolysis and photoelectrochemical hydrogen production

“…This ratio may be converted to consistent electrical units by multiplying the thermal energy denominator by an efficiency ratio of 0.38, as in Raugei et al, 63 which is also within the range of 0.3 to 0.7 investigated by Murphy et al in their review of the ERoEI literature. 64 Calculating ERoEI of the PEC facility over time. The ERoEI for a PEC facility is calculated similarly to the PV-E facility as the total hydrogen energy output divided by the total energy input cost.…”

“…84 The ERoEI of 14.9 is also consistent with the conservative ERoEI range of B19 for PV electricity harmonised with a ratio of 0.3 summarized by Murphy et al in their review that addressed consistent energy units for the ERoEI of fossil-fuel and renewable energy sources. 64 Next, we calculate the ERoEI and EPBT of a coupled PV-E facility. The cumulative output energy of the PV-E facility is shown in Fig.…”

Mobilizing materials to enable a fast energy transition: a conceptual framework

“…Reciprocally, the speed and extent of material mobilization has an influence on the energy demand for 1 https://www.mcc-berlin.net/en/research/co2-budget.html building RE infrastructure. Changing energy investments, measured in Energy Return on Energy Invested (EROI) or Energy PackBack Time (EPBT) (Murphy et al, 2022), influence the dynamics of the transition.…”