Hydrogen internal combustion engines to 2030

Here we review the latest advances in power density and efficiency of H-2 internal combustion engines (ICEs). Dual fuel direct injection (DI) diesel-H-2 compression ignition (CI), and H-2-only positive ignition (PI), DI and jet ignition (JI), ICEs, have the potential to deliver peak efficiency about 50%, peak power efficiency above 46%, and driving cycle average efficiency above 35% when fitted to hybrid powertrains. These achievements need modest expenditure in research and development (R&D) most for the H-2 injection system and storage. Dual fuel DI diesel- H-2 CI ICEs may deliver extremely low emissions of the regulated pollutants, NOx, unburned hydrocarbons (HC), CO and particulate matter (PM), and CO2 emission. H-2 PI ICEs with DI and JI may deliver even lower emissions of the regulated pollutant NOx, and practically zero emissions of PM, and CO2. PI ICEs allow much higher power densities than CI ICEs being the combustion event controlled by the turbulent mixing rather than vaporization, mixing and diffusion, thus permitting an about constant combustion duration in terms of crank angle degrees, and thus the ability to run extremely high rpm. LiquidH(2) and LNG have many similarities for infrastructure and engine and vehicle technology. Long-haul HDT dual-fuel LNG-diesel CI ICEs are now spreading across the world because of their economic and environmental advantages. Replacement of LNG with liquid H-2 in these vehicles is the best avenue for the substantial introduction of H-2 use within this decade. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.