WHY HYDROGEN WON'T MAKE IT

Remember the buzzword "The hydrogen economy"? Hydrogen has no wastes other than water! It can be stored as hydride in metals! All we have to overcome is people's prejudices formed with the Hindenburg explosion in their minds. (If history went by prejudices based on accident, there would be no fuel, no water, no dynamite, no passenger vehicles.)

What is most often forgotten is that hydrogen is not a primary energy source. You have to expend energy to produce it by electrolyzing water, or by breaking the water down at high temperatures, or synthesizing it from coal, or by extracting it chemically from the methane in natural gas, which is the way it is produced for industry now. (The amount of pure hydrogen in natural gas is insufficient.)

Like the diluteness of solar energy, this is not something that technology, human inventiveness or an unexpected discovery can overcome; it is a natural law that cannot be broken. If it were pos-sible to produce hydrogen from water using less energy than con-tained in the resulting product, we could run the electrical generator splitting the water on the harvested hydrogen forever as a "perpetuum mobile".

Now loss of energy in itself is nothing prohibitive: we lose 2/3 of the input energy in an electric power plant, 80% of it in a gasoline engine, 95% in a light bulb. The real point is whether the lost energy was invested by man or whether it is not really ours to lose. The energy in coal is solar energy accumulated millions of years ago, and it far exceeds the energy invested by man in mining it; hydropower is solar energy accumulated over vast (drained) areas, again by the sun, and tapped at one point where much more energy is reaped than invested by man; and man had nothing to do with the energy bound inside the atomic nucleus, except to invest a small amount to release it. But to separate hydrogen from water, it is not nature, but the water splitter who has to invest the energy, so it is like throwing rocks into the air and making them do work when they come down again.

Even so, it is possible that a way will be found to let nature produce the hydrogen (e.g. bacteria which will split water using solar energy as input in some large area of biomass). Or the loss of energy might pay off because it is advantageous to lose it here but gain some of it elsewhere (as is done with the production of fer-tilizers and other agricultural inputs to produce beef). However, the negative energy balance is not the only objection.

Safety considerations reveal another drawback. All fuels for an internal combustion engine must be explosive, of course, but hydrogen has exceptionally wide flammability limits. Mixed with air, it can explode in concentrations from 4% to 74% (as com-pared, for example, with methane: from 5% to 15%). This ability to explode at almost any concentration above 4% is not shared by gasoline vapor, and certainly not by gasoline, which in its liquid phase is not explosive at all.

And we haven't even talked cost yet. So barring a breakthrough in hydrogen storage or production, a "hydrogen economy' is not in the cards.