A Greener World?

A GREENER WORLD?

VEHICLE MAKERS ALLOcate R&D funds to contingencies like hydrogen fuel cells because it’s good business to be ready. They do it also because it earns them “green points” in public relations. Honda currently is showing a scooter powered by its new “FC Stack” fuel cell, calling it an R&D project. Renault showed at the Paris Auto Show last year a fuel-cell-powered “quad,” and Peugeot revealed its “Quark urban/inter-urban 4WD vehicle.” Fun for all.

A fuel cell is an electrochemical means of reacting a fuel with an oxidizer to produce electricity instead of heat. This shouldn’t seem too strange since the bond energy in chemical compounds consists of electric fields. This electric power then drives the vehicle via electric motors. While a gasoline engine converts 15-25 percent of its fuel’s energy into useful power, and a diesel pushes to 33 percent or so, a fuel cell running on pure hydrogen can reach 50-60 percent conversion efficiency.

This is an attractive number, and especially attractive in urban areas is the fact that a fuel cell’s “exhaust” consists of pure water.

The problem is that there is no hydrogen for the taking. The sun is mostly hydrogen, but it’s 93 million miles away. On Earth, all the hydrogen is chemically combined-either as water or in hydrocarbon compounds in petroleum or coal. Liberating hydrogen from water costs at least as much energy as will be released when that hydrogen reacts in a fuel cell. Stripping hydrogen from petroleum molecules consumes energy and produces carbon dioxide. Once isolated, hydrogen must be stored as a compressed gas or absorbed into a storage medium such as titanium chips. The liquid hydrogen that fuels the Space Shuttle’s main engines requires even more energy to liquefy.

Other fuel-cell schemes bypass the problems of isolating and storing hydrogen by starting with a conventional fuel such as an alcohol or methane gas. An in-vehicle fuel reformer strips the conventional fuel of its hydrogen and the leftovers are burned to supply heat for the ^process. The I resulting hydrogen Athen drives the fuel jpjL Overall system Pficiency is comparable that of a small turbodiesel engine.

So, what’s the point of concept scooters and impractical quads? It’s practice for a possible future world in which all íof hydrogen’s problems have been solved.

Kevin Cameron