Comparing World Economic and Net Energy Metrics, Part 2: Total Economy Expenditure Perspective

Assessing Global Long-Term EROI of Gas: A Net-Energy Perspective on the Energy Transition

Natural gas is expected to play an important role in the coming low-carbon energy transition. However, conventional gas resources are gradually being replaced by unconventional ones and a question remains: to what extent is net-energy production impacted by the use of lower-quality energy sources? This aspect of the energy transition was only partially explored in previous discussions. To fill this gap, this paper incorporates standard energy-return-on-investment (EROI) estimates and dynamic functions into the GlobalShift bottom-up model at a global level. We find that the energy necessary to produce gas (including direct and indirect energy and material costs) corresponds to 6.7% of the gross energy produced at present, and is growing at an exponential rate: by 2050, it will reach 23.7%. Our results highlight the necessity of viewing the energy transition through the net-energy prism and call for a greater number of EROI studies.

Well-to-wake analysis of switchgrass to jet fuel via a novel co-fermentation of sugars and CO2

Lignocellulosic biomass such as switchgrass can be converted to n-butanol using fermentation, which can be further processed into jet fuel. Traditional acetone-butanol-ethanol (ABE) fermentation only converts sugars derived from switchgrass to ABE. Novel co-fermentation processes convert sugars and gas (CO₂/H₂) produced during fermentation into butanol, thus increasing ABE yields by 15.5% compared to traditional ABE fermentation. Herein, the environmental impact of a Switchgrass to Jet Fuel (STJ) pathway was assessed using life cycle assessment (LCA) from well-to-wake. LCAs were performed for greenhouse gas (GHG) emissions from jet fuel production via co-fermentation of sugars and gas for ideal and practical cases of ABE fermentation and seven other jet fuel pathways. The ideal case assumes 100% sugar recovery and 95% ABE yield. The practical case assumes 90% sugar recovery and an 80% ABE yield. Results are presented based on 100-year global warming potential (GWP) per MJ of jet fuel. Co-products were allocated using various methods. The increase in butanol yield via the co-fermentation technology reduced GWP-100 for the STJ pathway by 6.5% compared to traditional ABE fermentation. Similarly, the STJ pathway for the practical case with co-fermentation had 14.2%, 47.5%, 73.8%, and 44.4% less GWP-100 compared to HRJ, Fischer-Tropsch jet fuel from switchgrass, Fischer-Tropsch jet fuel from coal, and conventional petroleum jet fuel. The results demonstrate that the STJ pathway via co-fermentation has the potential to increase product yield while reducing GHG emissions compared to other jet fuel production pathways.

Creating an Energy Analysis Concept for Oil and Gas Companies: The Case of the Yakutiya Company in Russia

Recently, energy analysis has been added to Russian gas companies’ annual reporting system. This new practice indicates that corporate reports are improving their analyses by addressing energy issue and the financial efficiency of energy production. However, the use of summary energy indicators is limited in these annual reports. In this paper we review the history of energy analysis in Russia from the early USSR period to today. Under the guidance of energy return on investment (EROI), we compare energy efficiency indicators with financial efficiency coefficients. The results show that the value of the return on cost of sales (ROCS) is negative in certain instances, while the value of the energy return on cost of sales (EROCS) is extremely high under the example of the Russian energy company JSC “YATEC.” Money-based indicator values (ROCS and return on fix assets (ROFA)) fluctuate with internal company financial management goals, and from the outside depending on market prices. Meanwhile energy-based values (EROCS) remain stable. Added financial analysis and energy analysis in companies’ annual statements will supplement each other in practice and will present the full picture for company efficiency analysis.

Analysis of Point-of-Use Energy Return on Investment and Net Energy Yields from China’s Conventional Fossil Fuels

There is a strong correlation between net energy yield (NEY) and energy return on investment (EROI). Although a few studies have researched the EROI at the extraction level in China, none have calculated the EROI at the point of use (EROIPOU). EROIPOU includes the entire energy conversion chain from extraction to point of use. To more comprehensively measure changes in the EROIPOU for China’s conventional fossil fuels, a “bottom-up” model to calculate EROIPOU was improved by extending the conventional calculation boundary from the wellhead to the point of use. To predict trends in the EROIPOU of fossil fuels in China, a dynamic function of the EROI was then used to projections future EROIPOU in this study. Results of this paper show that the EROIPOU of both coal (range of value: 14:1–9.2:1), oil (range of value: 8:1–3.5:1) and natural gas (range of value: 6.5:1–3.5:1) display downward trends during the next 15 years. Based on the results, the trends in the EROIPOU of China’s conventional fossil fuels will rapidly decrease in the future indicating that it is more difficult to obtain NEY from China’s conventional fossil fuels.