In a paper appearing in the July 18 issue of Science magazine, Alex Farrell, assistant professor of energy and resources at UC Berkeley, and David Keith, associate professor of engineering and public policy at Carnegie Mellon University, present various short- and long-term strategies that they say would achieve the same results as switching from gasoline-powered vehicles to hydrogen cars.
"Hydrogen cars are a poor short-term strategy, and it's not even clear that they are a good idea in the long term," said Farrell. "Because the prospects for hydrogen cars are so uncertain, we need to think carefully before we invest all this money and all this public effort in one area."
Farrell and Keith compared the costs of developing fuel cell vehicles to the costs of other strategies for achieving the same environmental and economic goals.
"There are three reasons you might think hydrogen would be a good thing to use as a transportation fuel - it can reduce air pollution, slow global climate change and reduce dependence on oil imports - but for each one there is something else you could do that would probably work better, work faster and be cheaper," Farrell said.
The biggest problem with hydrogen as a means to reduce pollution is that it has to be produced from another energy source. But the most cost competitive energy sources are all forms of fossil fuels. The production of the hydrogen is not 100% efficient and producing it from fossil fuels produces pollution. The transportation and storage of the hydrogen also use substantial amounts of energy.
Hydrogen is also more difficult to store and transport and takes up much more space than liquid hydrocarbon fuels. It is not the only conceivable approach to pursue for reducing net pollution from vehicles for the purpose of reducing green house gasses. Another approach to reduce the net production of green house gasses would be to develop a light-driven chemical process that would fix carbon out of atmospheric carbon dioxide to make hydrocarbon fuels. Or if cheap photovoltaic solar cells could be developed then another approach would be to use electricity from solar cells to drive the chemical process to fix carbon from carbon dioxide. Effectively gasoline would be generated from solar power. Then the gasoline could be burned in cars. This artificial carbon cycle would eliminate the net addition of carbon dioxide gas to the atmosphere.
Back in 2000 the MIT Sloan Automotive Laboratory report On The Road: A life-cycle analysis of new automobile technologies by Malcolm A. Weiss, John B. Heywood, Elisabeth M. Drake, Andreas Schafer, and Felix F. AuYeung registered reservations about the future of hydrogen fuel. (PDF Format)
Continued evolution of the traditional gasoline car technology could result in 2020 vehicles that reduce energy consumption and GHG emissions by about one third from comparable current vehicles and at a roughly 5% increase in car cost. This evolved “baseline” vehicle system is the one against which new 2020 technologies should be compared.
More advanced technologies for propulsion systems and other vehicle components could yield additional reductions in life cycle GHG emissions (up to about 50% lower than the evolved baseline vehicle) at increased vehicle purchase and use costs (up to about 20% greater than the evolved baseline vehicle).
If automobile systems with drastically lower GHG emissions are required in the very long run future (perhaps in 30 to 50 years or more), hydrogen and electrical energy are the only identified options for “fuels”, but only if both are produced from non-fossil sources of primary energy (such as nuclear or solar) or from fossil primary energy with carbon sequestration.
A more recent MIT study released in March 2003 voices even greater doubts about the viability and desireability of hydrogen as a fuel source in the next couple of decades.
Published in MIT Tech Talk, March 5, 2003.
Even with aggressive research, the hydrogen fuel-cell vehicle will not be better than the diesel hybrid (a vehicle powered by a conventional engine supplemented by an electric motor) in terms of total energy use and greenhouse gas emissions by 2020, says a study recently released by the Laboratory for Energy and the Environment (LFEE).
And while hybrid vehicles are already appearing on the roads, adoption of the hydrogen-based vehicle will require major infrastructure changes to make compressed hydrogen available. If we need to curb greenhouse gases within the next 20 years, improving mainstream gasoline and diesel engines and transmissions and expanding the use of hybrids is the way to go.
These results come from a systematic and comprehensive assessment of a variety of engine and fuel technologies as they are likely to be in 2020 with intense research but no real "breakthroughs." The assessment was led by Malcolm A. Weiss, LFEE senior research staff member, and John B. Heywood, the Sun Jae Professor of Mechanical Engineering and director of MIT's Laboratory for 21st-Century Energy.
However, the researchers do not recommend stopping work on the hydrogen fuel cell. "If auto systems with significantly lower greenhouse gas emissions are required in, say, 30 to 50 years, hydrogen is the only major fuel option identified to date," said Heywood. The hydrogen must, of course, be produced without making greenhouse gas emissions, hence from a non-carbon source such as solar energy or from conventional fuels while sequestering the carbon emissions.
The full text of the March 2003 MIT study Comparative Assessment Of Fuel Cells is available as a PDF document.
Curiously, in spite of the drawbacks of hydrogen as a way to store and transport energy hydrogen produced in cars for immediate burning may be a way to increase the efficiency of internal combustion engines.
But the researchers want to take the concept a big step further, using plasma technology to turn cars into small-scale hydrogen- producing plants - and sharply boosting the spark-ignition engine's efficiency along the way.
"Spark-ignition engines are roughly 30 percent efficient and diesels are about 40 percent efficient," notes Cohn. "We want to approach a diesel level of efficiency while avoiding diesel's pollution problems."
The plasmatron - about the size of a half-gallon milk carton - would convert about a third of a vehicle's gasoline stream into hydrogen. In doing so, it would boost efficiency in varied ways.
I think the hydrogen fuel hype is vastly overblown. The US government spending on hydrogen development is money that would be better spent developing photovoltaic materials that can be made much more cheaply than current photovoltaics. The goal of US government-funded energy research ought to be to obsolesce fossil fuels by developing cheaper competitors.
Update: A big step forward in battery tech would lower the cost and weight of batteries far enough to make hybrid vehicles competitive would allow reductions in emissions and in fossil fuel use in a way that would use all the existing infrastructure. Donald Sadoway of MIT says that a big step forward in battery tech is achieveable. On the subject of whether much better batteries could be developed for use in hybrid vehicles see my Energy Tech archives and in particular see my post Is Hydrogen The Energy Of The Future? for the bottom part of the post where I link to Sadoway's views.
On the question of whether photovoltaics would have to take up too much space, first of all, it will eventually be possible to achieve fairly high solar photovoltaic cell efficiency. See my post Material Discovered For Full Spectrum Photovoltaic Cell about some LBNL researchers who found a material that is 50% efficient. Surely nanotubes will be able to achieve a still higher effiency.
Also, I've done rough calculations on surface area needed for photovoltaics and the energy needed looks like it is achieveable with a fairly small portion of the Earth's surface. On my Parapundit.com blog in the Grand Strategy archive see the comment section of my post Energy Policy, Islamic Terrorism, And Grand Strategy where I introduce some rough calculations on the area needed for photovoltaics. I'd appreciate it if anyone could point to more accurate calculations of how much energy the United States currently uses and how much space in southern parts of the US would be needed to be used to collect enough energy for current consumption rates.
|Share |||Randall Parker, 2003 July 20 10:14 PM Energy Tech|