(This is Part 29 of a series. Go back to Part 28.)
Hydrogen. As noted earlier, hydrogen is not an energy source but rather an energy carrier, because it takes more energy to produce hydrogen than hydrogen can provide. Yet hydrogen could become an ideal energy carrier since it contains no carbon atoms—its combustion produces only energy, water and heat.
When produced from clean and renewable sources, hydrogen represents the end-stage of a process that energy historians call decarbonization.
Fuel wood, which humankind used for most of its history, contains 10 atoms of carbon for each atom of hydrogen. With the switch to coal, humankind began using a fuel that has 1 or 2 carbon atoms for each atom of hydrogen.
With the rise of industrialism and the use of modern fossil fuels, decarbonization evolved further—oil has two atoms of hydrogen for each carbon atom, while natural gas has four hydrogen atoms for each atom of carbon. Hydrogen, of course, completes this process because it has no carbon atoms at all.
As humanity has used progressively lighter fuels, it has gradually dematerialized its energy sources, from solids (wood and coal) to liquids (oil and gasoline) to gases such as natural gas and (ultimately) hydrogen.
Along with this dematerialization in fuel energy has come a progressive dematerialization of industry itself—from heavy and massive steam-powered technology to today's light and virtual information technologies.
What makes hydrogen so promising is the development of the fuel cell. In a fuel cell, hydrogen does not burn; rather, it combines with oxygen to produce water and electricity. Really, it's more like a battery than a combustion engine —but a battery that in theory could be tremendously more lightweight and efficient.
This opens up the possibility of fuel-cell-powered trucks, autos, trains, buses and aircraft. It opens up the possibility of self-powered homes and businesses using renewable wind and solar energy sources—and then storing excess energy as hydrogen to power fuel cells for transportation, portable devices, etc.
Sounds pretty good, doesn't it? But what's missing from the picture is that the net energy equation doesn't add up in getting to this new hydrogen economy. That doesn't mean we won't get there. It just means that we won't get there in the style to which we have become accustomed.
Promoters of hydrogen are counting on the "transition fuel" of natural gas. In this transitional picture, we use natural gas to make hydrogen and then use hydrogen to power everything else.
Except that, as we've seen, natural gas is on a slippery slope. Unlike oil, production could collapse quickly once the peak is passed. In North America the industry is on a treadmill; it's drilling more holes and finding less gas. And gas from the Middle East is tied up by shipping contracts to Asia.
The thing is this: As incredibly valuable and crucial as renewables are, their EROEIs aren't nearly as high as the lavish EROEIs which oil bestowed on the Industrial Age in its advancing phase.
What this means is that renewables don't contain enough net energy to get world society from here to the Hydrogen Age in the time available. A gap appears, because fossil fuels are needed to make the transition but fossil fuels are near their production peak and are about to go down the backside of the bell curve.
Building an economy based on wind, solar and hydrogen is going to take gargantuan amounts of energy in itself. There simply isn't enough net energy available to both maintain the global economy in its present form and also construct the renewable one. A sizable gap will almost certainly appear.
What this means in turn is that humankind will have to go through a period of time where its net energy is declining.
(This is the end of Part 29. Go to Part 30.)
—jim sloman, 10.23.04 for Feb 19
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