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Meet the Experts |
Jim Bell, San Diego: The hydrogen economy sounds so wonderful. We build renewable-energy-capturing devices like windmills and solar cells, then use the electricity we don't use directly to separate water into oxygen and hydrogen. Then we use fuel cells to efficiently convert the H2 and O2 into energy to power our cars, buses and trucks and to produce electricity when the sun isn't shinning and the wind's not blowing. Plus, at the end of the process, we end up with the water we started with. Like I said it sounds wonderful, but the hydrogen economy may be fatally flawed. This flaw is the loss of hydrogen to space that will result when hydrogen is released into the general atmosphere through leaky pipes and storage containers and through incomplete combustion. I've talked with several experts in this field, and they tell me that both hydrogen gas and helium will float out into space if released into the atmosphere because the earth's gravity is not strong enough to hold them. If this is true, any free hydrogen gas that leaks out of storage, distribution pipes, or is not burned completely during combustion, will leave our planet. Because this hydrogen was derived from water, its loss means a loss of planetary water. How much these losses would be per year needs to be calculated, but the loss of natural gas, from wellhead to end user is currently 5 to 10 percent. Presumably, hydrogen losses would be higher since hydrogen is harder to contain than natural gas. But even if the loss of hydrogen and therefore water is small, its use to even out intermittent renewable supplies does not bode well for future generations. Especially considering that there are many other ways to store intermittent renewable energy without losing planetary water. Pump storage, compressed air, flywheels, chemical (battery) storage, and biomass are just some of the options. To tell the truth, I wish that hydrogen was the answer, but unless it can be used in a ways where no hydrogen is lost, other methods for storing renewable energy should be used. Ned Ford, from the Sierra Club's Global Warming Committee,
responds: There are many uncertainties about the economic
feasibility of the hydrogen economy, and the ultimate form it
may take. But the loss of hydrogen to space is not likely to
be one of them, unless we persist in using this technology for
thousands of years. All the world's oil consumption (including
vast quantities that are not used for vehicle fuel) amounts
to a little over 28 billion barrels, while a cubic mile of water
is 24.4 billion barrels. Probably very little of the hydrogen
in the water we use for the hydrogen cycle will be lost to space
- most will be converted back to water as the energy is released,
the rest will react in the atmosphere with oxygen or other chemicals.
But if it were all lost, it would take millennia to affect the
world's water supply significantly.
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