Reevaluating Hydrogen Fuel Cells for Land-Based Transportation: The Efficiency Conundrum
Hydrogen fuel cells have long been touted as a promising solution for decarbonizing land-based transportation. However, it is crucial to critically examine the inherent inefficiencies of the hydrogen production and utilization process. In this post, we will delve into the physics behind hydrogen fuel cells and shed light on why they fall short compared to the remarkable efficiency of battery storage.
The round trip losses in converting electricity into hydrogen, then converting it to ammonia for transport, and finally back to hydrogen, followed by its conversion to electricity for propulsion, pose significant efficiency challenges. According to a paper produced by the Commonwealth Scientific and Industrial Research Organization (CSIRO), in Australia, the worst and best round-trip efficiency (RTE) using the best commercially available fuel-cell technology, was 11% and 19% respectively when used in small fuel cells that are appropriate for vehicular transportation. In contrast, battery storage systems boast an impressive >98% RTE, making them a superior option for sustainable transportation.
Fuel cell electric vehicles (FCEVs), which rely on hydrogen fuel cells, represent the worst possible option in terms of RTE. The primary concern lies in the energy-intensive process of hydrogen production and the losses of converting the hydrogen back into electricity. Even if hydrogen is produced on-site at fueling stations from renewable energy, the overall energy requirements can be up to three times higher compared to battery-powered vehicles when viewed from a total energy perspective. If the hydrogen itself must be transported, the additional losses from hydrogen compression, liquification or conversion to ammonia push the ratio up to over five times the total energy as compared to a battery electric vehicle even before including the energy cost of transportation.
Furthermore, hydrogen production by itself demands a massive amount of power generation, and may be derived from conventional sources such as fossil fuels. This results in a paradoxical situation where FCEVs, promoted as zero-emission vehicles, indirectly contribute to carbon emissions during the hydrogen production process. This further undermines the sustainability and environmental benefits claimed by hydrogen fuel cell technology.
In contrast, battery-powered electric vehicles (BEVs) provide a more efficient and environmentally friendly alternative. BEVs leverage the direct conversion of stored electricity into vehicle propulsion, minimizing energy losses and maximizing overall efficiency. With rapid advancements in battery technology, BEVs are becoming increasingly viable, offering longer ranges and shorter charging times.
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When you factor in that BEVs are inherently more energy efficient than internal combustion engines - on average about 3x to 4x more efficient - then even if you use fossil fuel grid power to charge your car, you produce only 25% to 33% of the carbon dioxide pollution as a gas powered vehicle. Conversely, if you were to use grid power to produce the hydrogen for a FCEV, you would be producing effectively the same carbon footprint as your average gas powered vehicle.
Moreover, the charging infrastructure required for BEVs is already well-established, with options for home charging, workplace charging, and an expanding network of public charging stations. This makes BEVs more accessible and convenient for the average consumer, facilitating the transition to a sustainable transportation system.
While hydrogen fuel cells will find niche applications in specific industries such as marine or aviation fuel or as long term energy storage solutions, their limitations for land-based transportation remain clear. The energy-intensive process of hydrogen production, coupled with round trip losses, make FCEVs an inefficient and less sustainable choice compared to their battery-powered counterparts.
In conclusion, as we strive for a cleaner and more sustainable future, it is crucial to prioritize full life cycle energy efficiency over the specific use case impacts of alternative technologies. Battery-powered electric vehicles present a superior option, offering higher efficiency, reduced carbon emissions, and a rapidly expanding charging infrastructure. Let us seize the opportunities provided by battery technology and pave the way for a greener and more efficient transportation sector.