2015 Hyundai Tucson Fuel Cell, 2016 Toyota Mirai at hydrogen fueling station, Fountain Valley, CAEnlarge Photo
It's now clear that the zero-emission vehicles of the future will be powered by electric motors.
The electricity to power those motors, however, will come from one of two competing technologies: high-capacity batteries or hydrogen fuel cells.
The debate over which technology is superior, which has the lowest wells-to-wheels carbon footprint, and which is likely to appeal more to mass-market buyers has become ... epic.
DON'T MISS: 10 Questions On Hydrogen Fuel-Cell Cars To Ask Toyota, Honda & Hyundai (Oct 2014)
As long as the costs, efficiency, practicality, and consumer appeal of the two technology are publicly debated, Green Car Reports will publish a variety of articles exploring different ways to analyze those issues.
Our reader Victor A. Ettel, an electrochemical engineer and retired R&D executive, has had a life-long interest in advanced transportation technologies, including hydrogen fuel-cell vehicles.
He submitted an analysis comparing the energy usage of the two approaches that we felt was worthy of publication. What follows are his words, lightly edited by Green Car Reports for clarity and style.
2017 Honda Clarity Fuel Cell, Santa Barbara, CA, March 2017Enlarge Photo
Fuel-cell vehicles are, without a doubt, a brilliant technical accomplishment.
But with the technology rapidly maturing and approaching its limits, it is becoming clear that they cannot offer viable, cleaner and more sustainable transportation than other showroom-available, new vehicle technologies.
Emerging hard data leaves no room for any other conclusion, meaning that the life support for the fuel-cell dream increasingly depends on discredited assumptions, deceptive comparisons, and unconvincing distant future prognostications.
The two most energy-efficient vehicles among the three fuel-cell cars now offered in California are the Honda Clarity Fuel Cell and the Toyota Mirai, rated at 68 and 67 MPGe respectively.
Miles Per Gallon Equivalent (MPGe) is the distance a car can travel electrically on the same amount of energy as contained in 1 gallon of gasoline.
But MPGe ratings should not be directly compared to the ratings of gasoline cars since, unlike gasoline, producing hydrogen requires twice the energy that the resulting hydrogen contains.
Hydrogenics hydrogen fueling stationEnlarge Photo
Hydrogen wastes energy resources, whether fossil or renewable
This proves to be true whether the gas is produced by electrolyzing water or through steam reformation of natural gas.
This estimate, based on multi-year monitoring of existing hydrogen refueling stations, is consistent with design energy requirements published by a manufacturer of hydrogen refueling stations and other credible sources.
As both technologies have been practiced on an industrial scale for nearly a century, and their efficiency is limited by the laws of physics, these numbers cannot be expected to change dramatically.
Moreover, as real fuel cells operate at around 50-percent efficiency, only a quarter of the initial energy (fossil or renewable) is available to power the fuel cell vehicle—compared to more than 80 percent of the initial electrical energy that remains available to power an electric vehicle.
As a result, the Honda Clarity Fuel Cell consumes more than three times more electricity per mile than an electric vehicle (e.g. the 2017 Chevrolet Bolt EV).
It also consumes almost the same amount of natural gas as the now-discontinued 2012 Honda Civic Natural Gas—which, unlike a hydrogen fuel-cell vehicle, did not use energy-conserving hybrid technology.
The idea that future transportation will be based on hydrogen produced from renewable electricity proves completely unrealistic, as it would require doubling total electricity generation in the U.S.