The Renewable Hydrogen–Methane (RHYME) Transportation Fuel: A Practical First Step in the Realization of the Hydrogen Economy

The permanent introduction of green hydrogen into the energy economy would require that a discriminating selection be made of its use in the sectors where its value is optimal in terms of relative cost and life cycle reduction in carbon dioxide emissions. Consequently, hydrogen can be used as an energy storage medium when intermittent wind and solar power exceed certain penetration in the grid, likely above 40%, and in road transportation right away, to begin displacing gasoline and diesel fuels. To this end, the proposed approach is to utilize current technologies represented by PHEV in light-duty and HEV in heavy-duty vehicles, where a high-performance internal combustion engine is used with a fuel comprised of 15–20% green hydrogen and 85–89% green methane depending on vehicle type. This fuel, designated as RHYME, takes advantage of the best attributes of hydrogen and methane, results in lower life cycle carbon dioxide emissions than BEVs or FCEVs and offers a cost-effective and pragmatic approach, both locally as well as globally, in establishing hydrogen as part of the energy economy over the next ten to thirty years.