How Clean Are Hydrogen Fuel Cell Electric Vehicles?

, , senior engineer, Clean Vehicles | October 21, 2014, 3:46 pm EDT
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Long planned and anticipated, the first production-version hydrogen fuel cell electric vehicles (FCEV) are rolling out and more are on their way. Mass-market models from Honda, Hyundai and Toyota are in the works. They are an important solution — along with plug-in electric vehicles — for reducing our carbon emissions and achieving our goals of putting more zero-emission vehicles on the road. As I have written before, FCEVs have advantages of greater driving range and faster refueling. Questions arise, however, about just how clean these vehicles are if the early models rely on hydrogen produced from natural gas — a fossil fuel.

Like plug-in cars, FCEVs use clean electric motors and produce no harmful tailpipe emissions. Their total emissions, however, depend on how the hydrogen fuel is made and delivered. As demonstrated in a new Union of Concerned Scientists fact sheet, full lifecycle “well-to-wheels” global warming emissions analyses show that even when using hydrogen from natural gas, today’s early hydrogen-powered FCEVs reduce emissions by over 30 percent compared with conventional gasoline vehicles. And in California, with requirements for renewable hydrogen, FCEVs are cutting emissions even more.

Hydrogen fuel can be made from different sources

Currently, most hydrogen is made by converting natural gas into hydrogen gas and carbon dioxide. However, hydrogen can also be produced from lower-carbon sources of energy such as electricity from solar or wind, which can be used to split water into hydrogen and oxygen through electrolysis. Another low-carbon source of hydrogen is methane gas from landfills and sewage treatment facilities, provided that methane leakage is minimized.

While natural gas is likely to be a significant source of hydrogen fuel in the short term, the first vehicles will also use hydrogen from renewable sources. The initial rollout of FCEVs is happening in California due to the state’s investment in hydrogen refueling stations. California law (SB 1505) requires that at least 33 percent of hydrogen produced at these state-supported stations be generated from low-carbon sources, and the state projects that at least 46 percent of hydrogen will come from renewable sources by the end of 2015. This renewable-hydrogen standard will apply to all stations in the state once production of hydrogen reaches 3,500 metric tons per year (enough for about 15,000 cars).

How does the first production fuel cell vehicle stack up?

The first commercially available hydrogen-powered FCEV, the Hyundai Tucson Fuel Cell SUV, produces substantially lower global warming emissions than the Tucson’s gasoline version. This FCEV produces 286 g CO2eq/mile if fueled by hydrogen produced from natural gas, equal to the emissions from a 38-mpg gasoline vehicle. When using hydrogen that meets California’s 33 percent renewable hydrogen standard, the fuel cell SUV emits 202 g CO2eq/mile—the equivalent of a 54-mpg gasoline vehicle, or less than half the global warming emissions of the SUV’s gasoline version. By the end of 2015, California is projected to produce 46 percent of its hydrogen fuel from renewable sources, which would render the Tucson FCEV’s emissions equal to that of a 63-mpg gasoline car.

FCEV GHG

Future improvements for fuel cell vehicles

Fuel cell vehicles that come to market over the next few years will likely cut emissions relative to gasoline vehicles even more due to advances in fuel cell performance and in automotive technologies such as the electric-drive train, as well as the wider availability of lower-carbon hydrogen. Such evolution has already been the norm among plug-in electric vehicles, including the Nissan Leaf; in just three years on the market, the Leaf lowered its electricity consumption by more than 10 percent, from 0.34 to 0.30 kWh/mile. And because fuel cell vehicles share many components with plug-in electric vehicles, advances such as improved electric motors or more efficient power systems will benefit fuel cell vehicles too. Policies such as those in California, which mandates increases in lower-carbon hydrogen production, will further improve the benefits of switching from gasoline to fuel cell vehicles.

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  • Fuel cell are important, but their use for personal transportation is hard to justify, unless we consider long distance trucks. First, it is a very complicated system that you can’t just build on your own. Second, it is expensive and requires maintenance, something not too many authors talk about. Third, it’s not very efficient when we consider the energy use, conversion, compression, creation of electrons to actually moving the wheels of a car. A pure EV is much more efficient, 90% to 96, depending on design. Lastly, we have the worst draught ever recorded in the history of southern California, which makes it an even more difficult energy system to use, unless we use sea water, which needs to be desalinized.

    It’s not to say it shouldn’t exist, but that there are much better application for fuel cells when it comes to hydrogen. The space exploration, for one. Also, off shore wind farms that can store energy as hydrogen to release it when the wind doesn’t blow. Just to name a few examples.

    If the fear of that once in a while needed range is the only issue, then we have a bigger problem than anticipated in this country. The average US daily commute is 40 miles or less for 80%, something ANY EV on the market today can achieve. Many have second cars, for which a plug-in hybrid PHEV is perfect for those longer trips. I fear we fear fear more than reality, again.

    There are simpler solution than spinning a square fast enough in order to make it act like a wheel.

  • Matt Wandel

    This is a decent article and I say that as a very critical person when people start comparing FCEVs to battery powered electric vehicles. One of the greatest mistakes made when people compare FCEVs to battery vehicles is to ignore where electricity is generated from. FCEVs provide not only a solution to transportation electricity while marching away from fossil fuels, but fuel cells provide a solution to ALL electricity while marching away from fossil fuels.

    Batteries are unsustainable and a dead end. Hydrogen is the fuel source in everything we have ever used: gasoline = hydrogen, coal = hydrogen, methane = hydrogen. The solution is simple: pure hydrogen without hydrocarbons (i.e. water).

    Batteries are not a long term solution for a fundamental energy creation and, in fact, do not generate electricity. Batteries store electricity.

    I know people get very passionate about batteries being a long term solution and have invested in batteries with time and effort. Fear not battery lovers, batteries will play a role and are even necessary on FCEVs and will be very important over the next 100 years as we move toward Hydrogen fuel cells.

    But, please don’t get batteries confused with energy creation or as a long term solution for providing energy in America or world wide. Hydrogen from coal and natural gas for the next 100 years (most likely) as we build infrastructure brick by brick to get hydrogen from water.

    Don’t forget about countries like India & China who have many more people than America does and will be using hydrocarbons for decades to come no matter what. Natural gas and coal can be used to make hydrogen in a much more clean and responsible manner as hydrogen from water tech improves.

    Please pay attention to the IGCC coal gasification projects going on in China to learn more about SynGas and hydrogen from coal with CO2, mercury, and sulfur pollution mitigated to nearly zero and enough hydrogen to power the entire energy needs of cities like Shanhai and Beijing with only water as an emission.

    Hydrogen has always been the fuel we have used. Hydrogen from water is the way to do it for the next million years.

  • Bret Andersen

    It is weird to see on this site a comparison of the MPG/emissions for two vehicles with such different engine power. Hundai’s site says the 2015 Tucson gasoline version is 164HP and in another place that the FCEV version is 134HP. So do we knock 20% off the FCEV estimates here? How about a Honda hybrid accord at 195 HP and 50 MPG? What am I missing?

    • The gasoline version of the Tucson was chosen as the comparison because it’s very similar to the fuel cell version. The exterior and interior are almost identical. I’ve had a brief test drive and I completely agree with this review: “What we mainly like about the Tucson fuel cell is that it looks, feels and drives very much like a conventional Tucson. In fact, it’s probably quieter and smoother.” – USATODAY (http://www.usatoday.com/story/money/columnist/healey/2014/09/20/2015-hyundai-tucson-fuel-cell-a-gem/15850643/)

      The fuel cell does have less maximum horsepower than the gasoline version (134hp@5000 rpm vs.164hp@6200 rpm) but the fuel cell version has higher torque: 221@1000 rpm vs. 151@4000rpm. This pattern isn’t unique to the fuel cell; many EVs have higher torque (available at lower rpms) and lower maximum horsepower. Check out the Honda Fit EV or Toyota RAV4EV vs. the gasoline models to see the same trend.

      Overall,the Tucson fuel cell and gasoline versions are vehicles with almost identical characteristics except for the inherent differences between a gasoline engine and electric motor. I think it would be hard to have a better comparison than the same model with different powertrains.

  • Jean-Bernard Brisset

    People must understand that hydrogen is a means of storing energy and not a fuel as other traditionnal fuels. The arguments against fuel cell cars for the time being are twofold: first, hydrogen as it has been produced so far is not clean, secundly H2 vehicles are too expensive. As regards the first argument, and this is where stands the next revolution: solar an Wind energy very often produce energy which is not needed; this is where hydrogen plays its part; i.e. storing energy that is in excess. As for the price of cars, the new models made in Japan show that within a few years H2 cars could be affordable. My only concern is political. Will countries like France where the State makes a lot of money from taxes on petrol, will join in this hydrogen revolution. I doubt it and I think we are going to drive our good old cars for a long time when Asia will have opted for long for H2 cars.

  • Jim Baird

    Then there is the case of hydrogen production that reverses global warming.

    A Lawrence Livermore group lead by Greg Rau has discovered and demonstrated an ocean water electrolysis technique that removes and stores atmospheric carbon dioxide while generating carbon-negative hydrogen and produces alkalinity that can be used to offset ocean acidification. https://www.llnl.gov/news/newsreleases/2013/May/NR-13-05-07.html

    Rather than just hydrogen and oxygen production, electrolysis of ocean water produces two additional streams. One is alkaline and reacts to neutralize ocean acidity through the production of sodium carbonate and bicarbonate. The other is acidic which can be captured to react with silicate minerals to mimic natural chemical weathering of rock. This insures the carbon dioxide captured by the formation of the carbonates and bicarbonates remains permanently sequestered.

    When the energy required to perform electrolysis is derived from the conversion of ocean heat to electricity this benefit is compounded.

    James Hansen et al. put it in the 2010 paper Earth’s energy imbalance and
    implications – “The rate of ocean heat uptake determines the planetary
    energy imbalance, which is the most fundamental single measure of the
    state of Earth’s climate.”

    The deep oceans, which are a massive cold sink, have difficulty taking up this heat because the natural tendency is for heat to rise. Most of global warming therefore is being trapped near the surface.

    Heat pipes can move heat rapidly into the deep because they utilize phase changes of a working fluid to move heat from the high pressure evaporator end of the pipe to the low pressure condensing end where the latent heat of condensation is dispersed into the cold sink. It takes seconds to move surface heat to an ocean depth of 1000 meters whereas it takes as long as 350 years to diffuse there naturally. By placing a turbine hooked to a generator in the vapor stream mechanical and electrical energy can be produced.

    Estimates are the oceans have the potential to produce between 14 and 25 terawatts of power with ocean thermal energy conversion.

    Due to the low thermal dynamic efficiency of this process, resulting from the small temperature difference between the tropical surface and ocean water at 1000 meters, approximately 20 times more heat has to be moved than power extracted from the system. To produce 14 TW of power therefore 14 TWh would be converted and an additional 280 TWh would be moved to the depths.

    A 2010 NOAA study estimated the oceans are accumulating 330 TWh each
    year so virtually all of this could be moved to the deep where it “would have virtually zero impact” or be converted to productive use.

    Bottom line – fuel cell vehicles can save the planet when hydrogen production is done the right way.

  • BotulismBob

    TYPE XIV Battery

    The weight of the batteries in the early Agena satellites was a concern, and cryogenic fuel cells were still in their very early development. Gaseous fuel cells needed a lot of satellite volume, A fuel cell needs sixteen pounds of oxygen for each pound of hydrogen. The volume of one high pressure oxygen sphere was tolerable since it is reasonably dense, but hydrogen in very light and would require eight high pressure spheres of hydrogen for each sphere of oxygen at the same high pressure. Lockheed was commissioned to see if we could develop a device that was half battery coupled with the oxygen half of a fuel cell. It was named the Type XIV Battery. The Type XIV battery development was a failure and the program was cancelled.

    Any vehicle powered by a fuel cell would have the same problem. If the a car’s gasoline tank was replaced by a high pressure sphere of oxygen, a huge trunk, or a towed trailer is needed for its hydrogen… like the coal cars that were hooked to steam locomotives in the first half of the last century.

    Cryogenic fuel cells are used on today’s satellites and their booster rockets, but cooling their oxygen and hydrogen down to temperatures approaching absolute zero (-460 deg F) is very difficult… and too expensive to ever be practical on highway vehicles!

  • Oil is a diminishing resource with a volatile price and if we want freedom of transport we need another source of energy. http://www.climateoutcome.kiwi.nz/clean-energy-alternatives.html

  • Ben Helton

    Beware; rational articles like this are certain to stir up controversy in the narrow Silicon Valley. Their lust for batteries is second to that of religion. Their extremism should never be under-estimated.

    • Dig Deeper

      Perhaps this is rational but I question the integrity of UCS – a group that outright denies the value of nuclear power as a carbon free energy source.

  • Bride of Yehashuah

    Solar electric vehicles are the future. Hydrogen fuel cells emit catalyst polluted water vapour, which may encourage toxic red algae in wetlands affected by its fallout.

    • Rupert Greenbaum

      Hydrogen fuel cells emit pure H2O, which is distilled water. There’s nothing toxic about them. Please don’t troll or scaremonger.

    • Ben Helton

      Here come the Musk Rats. With all their FUD and anti-hydrogen mongering.

      What’s next? Are we going to try to Hindenburg Boo?

      • The HydroGenie

        “Musk Rats” – Perfect. It’s downhill from here for TSLA- Daimler bailed and Toyota’s FCV rolls out in December. Look Out Below!

    • Odug

      What a troll .. I sure would appreciate a source for that BS

    • T Wicks

      You do know that catalytic converters of conventional gasoline cars lose their catalyst mass by around 60% over its service life and being doing so for at least 35 years around the world.

      If you do some basic reading of H2FC design and performance you’ll know that they retain around 95% of their catalyst mass once they reach end of life.