(258b) Transportation Fuels from Renewable Hydrogen and Green Carbon Dioxide – a Technical, Economic, and Environmental Evaluation

The desire to reduce greenhouse gas emissions from the transportation sector along with the increasing penetration of fluctuating renewable power sources in several countries have led to an growing interest in the production of synthetic fuels from electricity [1]. Most of the corresponding processes employ water electrolysis in order to produce hydrogen. Apart from direct use in fuel cell electric vehicles, hydrogen can also be reacted with CO₂ to form various gaseous or liquid organic fuels that are more compatible with existing infrastructure and engines. Several pathways are being suggested in literature that use CO₂ from different sources [2] and lead to different fuels [3]. However, comprehensive comparisons to assess the benefits and drawbacks of these options including both fuel production and use in transportation are still scarce.

In this contribution, we present a detailed technical, environmental, and economic evaluation of several pathways that are considered promising. This includes direct application of hydrogen in a fuel cell vehicle, as well as conversion of hydrogen and CO₂ to combustion engine fuels like methane, methanol, and different methyl ethers, some of which can also be used as blend components with conventional fuels [4]. The CO₂ used is assumed to be obtained from biogas upgrading, where it occurs as a currently unused byproduct in high concentrations. Biogas upgrading is already being conducted at a number of operating biogas plants in order to obtain biomethane of higher purity [3]. The pathways are evaluated with respect to their well-to-wheel efficiency, greenhouse gas emissions, and fuel cost. A technical analysis is conducted based on detailed process simulations in order to highlight what causes the differences in the performance of the different pathways, and an outlook is given on the potential for improved production processes.

References:

[1] M. Bailera, P. Lisbona, L.M. Romeo, S. Espatolero. Renew. Sust. Energ. Rev. 69: 292–312, 2017.

[2] G. Reiter, J. Lindorfer. J. CO₂ Util. 10: 40–49, 2015.

[3] W. Wang, S. Wang, X. Ma, J. Gong. Chem. Soc. Rev. 40: 3703–3727, 2011.

[4] L. Lautenschütz, D. Oestreich, P. Seidenspinner, U. Arnold, E. Dinjus, J. Sauer. Fuel 173: 129–137, 2016.