Alternative fuels

Having written about fossil fuels, it behooves me to also write about alternatives, lest I neglect my environmental duty. Besides, I have all these left-over notes …

We use fossil fuels primarily for power generation and transportation. Huge strides have been made in reducing emissions, but scrubbers and catalytic converters don’t change the fact that fossil fuels are non-renewable, or get rid of carbon dioxide, the main culprit in the projected global warming. This has spurred the search for alternatives.

Fast-flowing rivers can be harnessed to spin turbines and generate electricity. Hydroelectricity doesn’t pollute, but its dams and river diversions can flood habitats.

Nuclear fission splits the large uranium nucleus into two smaller nuclei, releasing huge amounts of energy which can make steam to spin turbines. Nuclear energy is also emissions-free, but reactors are expensive to build and waste disposal remains a concern.

The “ultimate” alternative is fusion, in which two light nuclei are fused to form a heavier one, releasing even more energy than fission, but it won’t be practical for decades.

Fusion powers the sun, whose energy can be tapped either through photovoltaic cells, which turn sunlight directly into electricity, or through mirrors, which focus the sun’s heat. On the plus side, solar energy is inexhaustible and emits no pollutants; on the down side, it requires huge tracts of land covered with solar cells or mirrors.

Wind power is the other major alternative; California, the world leader, has 15,000 wind turbines producing about one percent of its electricity– enough for all the homes in San Francisco. The technology is simple: the wind spins a windmill which drives a turbine. Windmills don’t pollute, but again, they take up huge amounts of land.

When you talk about replacing fossil fuels in automobiles, most people think of electric cars. Changing to electric cars without changing to alternative forms of power generation simply shifts fossil fuel use from automobile to power plant. (Some studies indicate that could actually increase pollution.) But if you could combine alternative power generation with an electric car, you’d have a true emissions-free vehicle.

Electric cars have been around since the early 1900s, when they were as fast as any other car. They were abandoned because existing batteries were heavy and had to be recharged frequently. Things haven’t changed much: although today’s high-tech electric cars look great and can go from zero to 100 kph in eight seconds, they have a range of only a couple of hundred kilometres and then have to be recharged for several hours.

There’s still no miracle battery on the horizon, but there could be a better alternative: a fuel cell. A fuel cell uses an on-going chemical reaction to generate electricity; it’s different from a battery in that it has to be supplied with fuel from an external source. Theoretically, a fuel cell can convert fuel to electricity with nearly 100 percent efficiency. (The internal combustion engine is only 10 to 20 percent efficient.)

Fuel cells work with almost any hydrocarbon fuel, including gasoline, while producing little pollution and maintaining high efficiency, but the best fuel of all, in a fuel cell or straight up, would be hydrogen, because burning hydrogen produces only one by-product: water. Unfortunately, hydrogen is also very expensive to produce and store, which means that for now hydrogen-powered cars aren’t practical.

Today’s solar-powered cars are fragile, expensive and slow. Barring some huge advance in solar cell technology, they’ll stay that way.

The only non-fossil fuel that’s being used on a large scale is ethanol, or grain alcohol, created through fermenting plant material. Its cousin is methanol, or wood alcohol, originally made from wood but now produced from carbon monoxide and hydrogen or processed from natural gas.

Both can be used directly in car engines modified to resist their corrosiveness, and both burn very cleanly. Added to gasoline, they produce gasohol, which can be burned in unmodified engines. Gasohol burns more slowly, coolly and cleanly than gasoline, providing greater octane and fewer pollutants.

The “alternative fuels” most in use today, however, are still fossil fuels. Propane (a component of natural gas) is one; another is natural gas itself. They both burn cleaner than gasoline and produce only about half as much carbon dioxide.

Of course, we’ve got a huge infrastructure built up around our existing use of fossil fuels, and that means any changeover to alternatives will be gradual. But it will happen.

Check back in 50 years: you’ll hardly know the place.

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