Consumer Reports hypes hydrogen cars
Consumer Reports has a fluff piece on hydrogen fuel cell cars in its latest issue (subs. req’d).
I spend way too much time debunking this most consumer unfriendly of alternative fuel vehicles — I even wrote a book on the subject, The Hype About Hydrogen. So I was happy to get an email from Tom Gage, President and CEO of AC Propulsion, containing a letter he sent to the magazine. I asked him if I could run it, and he not only said yes, he expanded it:
The second sentence in your fuel cell article (Consumer Reports, Oct. 2007) tells me you haven’t thought very carefully about hydrogen fuel.
You say hydrogen is the most abundant element in the universe as if to imply that, unlike oil, it’s undepletable. But it’s not the hydrogen atoms that have value as a fuel, it’s the energy potential of hydrogen atoms bonding with oxygen to form water. Most of the hydrogen on earth is spent of this potential, it’s already in water. It’s useless as fuel.
Elsewhere in the universe, such as within our sun, uncombined hydrogen abounds, but even among hydrogen enthusiasts, a notably credulous group, a 93,000,000-mile pipeline might seem unrealistic.
On a more down to earth level, you’ve been misled by the Argonne/GM study that makes hydrogen derived from natural gas seem like a good idea. They compare a fuel cell car to a conventional car fueled with gasoline. If you are going to use natural gas to make the hydrogen you should compare a fuel cell car to an advanced conventional car, such as a Prius, fueled with natural gas.
When you do that you find that for the same amount of natural gas, you travel farther, produce less pollution, and save money if you burn the natural gas directly in a conventional engine instead of converting it to hydrogen for use in a fuel cell. It doesn’t make sense to convert natural gas to hydrogen.
The other choice is to use electricity to convert water into oxygen and hydrogen — to reverse the action of the fuel cell. This is hugely inefficient. Three fourths of the electricity use to electrolyze water,compress it for storage on a fuel cell vehicle, and convert it back to water to generate electricity to drive the wheels is wasted. If you are going to use electricity to make hydrogen you should compare a fuel cell car to a plug-in electric car. The same amount of electricity will take the battery-powered plug-in car four times as far as the hydrogen-powered fuel cell car.
The hydrogen lobby shrugs off this 4-fold energy penalty saying “we’ll use renewable energy so it doesn’t matter how much we use.” Of course nothing could be further from the truth. The renewable energy resource (e.g. solar, wind, or geothermal) may be unlimited, but the capital investment and other resource commitments necessary to recover it are not. Energy should always be used wisely and efficiently. It takes one megawatt-hour (MWh) of electricity to drive a fuel cell car 833 miles. A plug in car needs only 25% of that MWh to go 833 miles. That leaves the remaining 75% to be used for other purposes such as reducing the amount of coal burned in conventional generation plants. It doesn’t make sense to convert electricity to hydrogen.
Please reconsider your over-optimistic assessment of hydrogen fuel. Hydrogen does not exist in usable form on Earth, it has to be produced by converting either natural gas or electricity. The overriding thermodynamic fact is that unavoidable conversion losses will always waste a significant portion of the primary energy. Since energy consumption is the crux global warming, not to mention energy security and air pollution, the energy losses from hydrogen production are unlikely ever to be acceptable.
Let me close with one of my own calculations:
In order to replace half of the U.S. ground transport fuels (gasoline and diesel) with hydrogen from wind power by 2050, for example, might require 1400 gigawatts of advanced wind turbines or more. However, replacing those fuels with electricity (for plug-in hybrids) might require less than 400 gigawatts of wind. That 1000 GW difference is an insurmountable obstacle for hydrogen fuel especially because the U.S. will need hundreds of gigawatts of wind and other zero-carbon power sources just to sharply reduce greenhouse gas emissions in the electricity sector.