Alternative fuels for mobility and transport: Harnessing excess electricity from renewable power sources with power-to-gas

Panel: 4. Transport and mobility: How to deliver energy efficiency

This is a peer-reviewed paper.

Authors:
Gerda Gahleitner, Energy Institute at the Johannes Kepler University Linz, Austria
Johannes Lindorfer, Energy Institute at the Johannes Kepler University Linz, Austria

Abstract

This article presents the analysis of economic, technical and ecological aspects of alternative gaseous fuel production from renewable excess electricity. Besides improvements in energy efficiency, renewable fuels will be required for the reduction of overall greenhouse gas emissions in the transport and mobility sector. The ‘power-to-gas’ technology provides hydrogen by splitting water with excess electricity from renewable power sources or further synthesizes methane by using carbon dioxide. Thereby both, the increasing demand for energy storage due to fluctuating renewable power sources and the demand of alternative fuels for mobility, are addressed.

The article provides a short review of realized power-to-gas demonstrations for transport applications and discusses occurring problems as well as topics for further development. In terms of ecological aspects it can be shown that if electricity and carbon dioxide origin from renewable sources, a substantial reduction in greenhouse gas emissions can be reached for synthetic methane compared to conventional diesel.

The presented case study for the supply of an Austrian public bus fleet with synthetic methane indicates that production costs are mainly influenced by the electricity price and the investment costs. They also strongly depend on the amount of full load hours per year of the power-to-gas facility. Currently, the synthetic methane production costs of 0.41 €/kWh are considerably higher than diesel prices. For the future utilization of expected excess electricity from renewable power sources and a possible adaptation of the legal framework in the electricity sector the costs of synthetic methane production can possibly be reduced to approximately 0.13 €/kWh. Future research should focus on improving the efficiency, reliability, costs and lifetime of the components, and optimum system configurations should be determined to improve the integration into the overall energy system.