Saturday, February 14, 2009

Hydrogen Argues for A Role In Future Energy

Hydrogen is the simplest and most prevalent element in the universe. The chemical combination of hydrogen with oxygen yields energy and water. But on Earth, free hydrogen is rare and must be manufactured, which costs energy, time, and money.

A country such as Iceland, with abundant hydroelectric and geothermal energy resources, might devote a portion of its electrical power to the electrolytic production of hydrogen from water. The hydrogen can then be used as gaseous fuel for fishing boats and long-haul ground vehicles. Such an approach may work for Iceland, since Iceland has abundant natural potential to generate electricity.

Other nations may have less natural electrical generation potential, but more biomass. The generation of hydrogen from biomass recently received a boost by a team from Virginia Tech, U. Georgia, and Oak Ridge.
Researchers at Virginia Tech, Oak Ridge National Laboratory (ORNL), and the University of Georgia have produced hydrogen gas pure enough to power a fuel cell by mixing 14 enzymes, one coenzyme, cellulosic materials from nonfood sources, and water heated to about 90 degrees (32 C).

The group announced three advances from their "one pot" process: 1) a novel combination of enzymes, 2) an increased hydrogen generation rate--to as fast as natural hydrogen fermentation, and 3) a chemical energy output greater than the chemical energy stored in sugars--the highest hydrogen yield reported from cellulosic materials. _SB
Hydrogen can also be produced from biomass by the production of syngas via biomass gasification. Gasification requires large amounts of energy, however. If the catalytic process above is a more energy-efficient way of producing hydrogen, it is worth pursuing.

Efficiency is at the heart of the decision. There is always an efficiency loss whenever energy is converted from one form to another. Using electricity to produce hydrogen which is later used to produce electricity involves inevitable energy losses with each conversion. Even the most efficient method of converting biomass to electricity will involve energy losses as well. Is hydrogen worth the trouble?

Hydrogen advocates point to the clean effluent of hydrogen fuel cells or hydrogen combustion: steam. What could be cleaner? But if you burn coal to produce the hydrogen in the first place, you are leaving out a big part of the picture.

Al Fin has advocated the use of solar energy to produce hydrogen to power fuel cells for when the sun is not shining, for off-the-grid 24 hour loads. But then, if electricity is what you want, better battery storage makes more sense. Another thing: it takes a lot of energy to produce photovoltaic cells, batteries, fuel cells, and other solar to electricity conversion equipment. Much of that energy will come from fossil fuels. So nothing is completely clean.

Nuclear energy could produce abundant hydrogen. But hydrogen is not the easiest material to store and transport safely. Rather than using hydrogen as the fuel, it might be smarter to use the hydrogen as a chemical reactant for manufacturing other fuels that store and travel more safely, and contain better energy densities than hydrogen. Which is what will probably happen long-term, once the giddy "hydrogen euphoria" wears off and the realities of safety, economics, and energy efficiencies begin to dawn on policy makers.



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