Gas has faults, but it will reign supreme

http://www.nationalpost.com/opinion/columnists/story.html?id=9ec14946-955d-4547-a8bd-2c005b1e6bc8
David Booth, National Post Published: Friday, July 25, 2008
My engineering degree is so old that I actually used a slide rule in my first year of university. For those of you who don't remember what a slide rule is -- and that's pretty much anyone under 50 -- you might try Googling caveman mathematics or, better yet, ways we are so much better off than our parents.Despite my ancient degree, I feel some confidence in noting that the problem in finding an alternative to that nasty gasoline stuff we pump into our cars is not in the engines that power our automobiles but in their gas tanks. OK, I should be more technically correct and call them energy storage devices since a) they store fuel other than gasoline and b) they may indeed not be tanks at all but a bank of batteries. Nonetheless, the stumbling block in terms of safety, cost and mass production seems to be the storage method and not the propulsion mechanism.Take the electric car as an example. The electric motor is a well-known quantity. No doubt there will be advances in its design, but it is not the electric motor that is preventing the mass adoption of electric cars.That stumbling block would be the batteries that would power said electric motors. First and foremost, there's the amount of energy they can store. We are seeing some phantasmagorical claims for battery-powered cars these days with extended range their most adamant boasts. But, let's be absolutely clear about this: In all its current guises, the purely electrically powered automobile will remain a boutique item. Claims of 200-kilometre ranges may seem dramatically greater than the 100 or so the Saturn EV1 managed, but those are under ideal circumstances (i. e. no cold weather requiring an electric heater, a moderate cruising speed, etc.) and, after that, they require a relatively long refuelling process. Compare that with the 600-to 900-kilometre range and the two-minute fill-up of a gasoline-powered car and you have a serious inconvenience. Recent ultracapacitor technology, such as that being pursued by Montreal's Zenn Motor Company, promises to eliminate these compromises, but it is a long way off. Until then, any electric car looking for widespread adoption will require a gasoline engine (and its easily stored fuel) as a backup as in the Chevrolet Volt.Hydrogen-fuelled vehicles suffer similar problems. The BMW Hydrogen 7, for instance, uses a very familiar V12 engine. Yes, the injection system is different, but it is the hydrogen storage that remains the BMW's stumbling block.Unlike most other auto-makers experimenting with hydrogen-powered automobiles, BMW stores the onboard hydrogen as a liquid. This requires that the lighter-than-air gas be chilled to a martini-frosting -250C. As you might imagine, that requires more than just some room service-delivered ice cubes. BMW's solution is a high-tech, multilayer canister with a near-perfect vacuum insulation layer. BMW claims that the storage tank is so efficient that, if it contained frozen water, it would take 13 years for the ice block to melt completely. Nonetheless, after 17 hours of non-use, the Hydrogen 7 must start "boiling" off hydrogen in the tank to maintain its temperature. After a few weeks of sitting, the tank would be completely empty of liquid hydrogen with just a minuscule amount of gaseous H2 left to get you to a refuelling station.Even though fuel cell vehicles sound futuristic, the fuel cell itself is nothing but a hydrogen-powered battery that produces electricity that powers the automobile's electric motors. And while fuel cell technology is still in its infancy, engineers can already see the mass production solutions that will lead to economies of scale. Their typical storage solutions still face some hurdles. Most store gaseous hydrogen under high pressure -- 5,000 psi or more. A storage tank strong enough to withstand that amount of pressure is not without its limitations, some requiring expensive carbon fibre/Kevlar construction. This will get more complicated as mass production starts and they must be shaped to fit the specific automotive applications. And, though these tanks have been tested to rigorous standards, the concept of 5,000 psi of hydrogen in a crash situation still gives pause.Compare all of this with gasoline that can be stored at room temperature under ambient pressure and can be pumped into an automobile in a matter of seconds. The gas tank can be molded to fit any automotive application and it has proved to be remarkably safe. In emergencies, it can be transported in a plastic tank that costs about $8. In other words, it's convenient. That's the reason why, despite its many acknowledged faults, gasoline is, for the foreseeable future, going to be powering the majority of cars.dbooth@nationalpost.com

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