Fifty pathways for transportation fuels are evaluated for their lifecycle greenhouse gas emissions. Forty-five of those involve hydrogen. Thirty-six pathways have been investigated for their energy use and thirty-one of those involve hydrogen. The hydrogen pathways that are studied include the following components:
- Feedstocks. The following feedstocks can be converted to hydrogen: coal, crude oil, natural gas, biomass, nuclear energy, and hydropower (can also be used as a proxy for wind and solar).
- Intermediate Products. In addition to the direct production of hydrogen, some of the feedstocks mentioned above can produce various intermediate energy carriers that can be used for the eventual production of hydrogen; these include methanol, electricity, ethanol, LPG, FT Distillate, and gasoline.
- Distribution. Hydrogen can be produced on site or it can be produced at a central facility. The distribution from a central facility can be as a liquid or a compressed gas. The compressed gas can be distributed by pipeline or by truck. Liquid hydrogen can be distributed by truck or rail. Some of the pathways will only be feasible with large central facilities that require hydrogen distribution while others could be small decentralized systems or large central systems. The impacts of the distribution system on the results are discussed and the most likely option for each pathway can be modeled.
- Utilization. The hydrogen could be used in an internal combustion engine or in a fuel cell. The data in GHGenius for the hydrogen ICE has been reviewed with a literature search to ensure that it is consistent with the latest developments in this area.