THE REALITIES OF A HYDROGEN ECONOMY
September 1, 2004
Some policymakers see the eventual switch to hydrogen-powered cars as inevitable, and the Bush administration has allocated $1.7 billion to the development of automotive hydrogen fuel cells for commercial use by 2020. But the road to hydrogen dependence is a bumpy one, according to Science Magazine.
- Steam reformers, which are used to break down natural gas into hydrogen and CO2 molecules, are only about 85 percent efficient; 15 percent of energy in natural gas is lost during the process.
- It costs about $5 to produce enough hydrogen equivalent to the energy potential of one gallon of gasoline.
- Hydrogen's low density would require 21 tanker trucks to haul the amount of energy delivered by a single gasoline truck today, and a hydrogen tanker traveling 500 kilometers would use an amount of hydrogen equaling 40 percent of its cargo.
- At room temperature, hydrogen takes up 3,000 times more space as an energy-equivalent of amount gasoline, therefore, compressed or liquefied gas must be used in vehicle tanks; but tanks on today's hydrogen vehicles take up to eight times as much space as a normal gas tank to store an equivalent amount of fuel.
Furthermore, to create the necessary infrastructure to fuel about 40 percent of American car would cost about $500 billion.
Hydrogen-powered vehicles will not reduce greenhouse gas emissions if the hydrogen is produced through electric power plants that burn fossil fuels. But using solar or wind power to generate hydrogen is expensive; indeed, solar power still costs 10 times more than coal, in spite of its cost declining substantially over 20 years.
Source: Robert F. Service, "The Hydrogen Backlash," Science, August 13, 2004.
For text (subscription required): http://www.sciencemag.org/cgi/content/short/305/5686/958
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