The letter by Donald Anthrop on hydrogen and fuel cells (OGJ, Oct. 13, 2003, p. 10) commented on my letter on the topic (OGJ, Aug. 25, 2003, 10). I would like to respond to that letter.
I emphasized in my original letter that one needs to go beyond energy efficiency calculations for the purpose of comparing different energy conversion and usage technologies. In his letter, Anthrop indeed did that to show resource constraints of electrolysis hydrogen and potential CO2 emissions increases of electrolysis hydrogen with coal-based electricity. This certainly confirmed my point that energy efficiency calculations are not particularly useful if done in isolation. On a technical note, energy efficiency calculations treat btus in all energy sources equally. In practical terms, all btus are not created equal. We know that btus in petroleum have higher usage value than btus in coal. Energy efficiency calculations fail to take that into account.
Anthrop went through calculations to show how much electricity would be required if the entire US motor vehicle fleet is to be replaced with fuel-cell vehicles powered by hydrogen produced from electricity. This unrealistic assumption naturally concluded that a huge amount of electricity would be required, given the enormous size of the US motor vehicle fleet. Furthermore, with another unrealistic assumption that all the required electricity would be generated in coal-fired power plants, Anthrop concluded that huge increases in CO2 emissions could occur. To date, I am not aware of anyone else, except Anthrop, having made these assumptions for large-scale hydrogen production.
Anthrop criticizes the idea of using natural gas as a resource for hydrogen production. I am aware that North American natural gas supply is limited. That is why I included non-North American supplies in my evaluation of potential production of transportation fuels from natural gas. Anthrop questioned whether the US would benefit at all if imported oil is replaced with imported natural gas, a subject that has been strongly debated in the energy field. I would defer this debate to experts on energy security.
Scientific evaluation of energy and environmental effects of advanced vehicle technologies and new transportation fuels requires thorough analyses of energy feedstock production, fuel production, fuel transportation, and distribution on a consistent, systematic basis. A spreadsheet-based model that we developed at Argonne, available at http://greet.anl.gov, has been serving that purpose.
Michael Wang
Center for Transportation Research
Argonne National Laboratory
Argonne, Ill.