Original URL: http://www.theregister.co.uk/2008/01/16/greener_than_thou_toyota_chevy_prius_volt_hot_air/

Motor titans crowd aboard 'green' bandwagon

Hot air now figuring prominently in debate

By Lewis Page

Posted in Science, 16th January 2008 14:12 GMT

The struggle among motor-industry biggies regarding who can seem the greenest (while simultaneously not actually doing very much about carbon emissions) continues. Toyota and GM are vying for supremacy in the plug-in hybrid stakes, Ferrari has dipped a toe in biofuel, and out of left field come French and Indian contenders with a car powered by compressed air.

As regular Reg readers will be aware, a hybrid car is one with both a conventional engine and a battery. Electric motor-generators permit the battery to drive the wheels, to charge itself up by braking, and to be charged by the ordinary engine while stationary or coasting. All this means that the petrol/diesel (or fuel-cell) engine can be smaller than would otherwise be required for decent performance, and can be run in a more fuel-efficient, less polluting manner.

The Chevrolet Volt

The Chevy Volt. Nuclear powered in France; runs on coal in America.

A plug-in hybrid is one in which the battery is large enough that it can drive the vehicle a useful distance without help from the engine; very few such cars are presently on the road. The plug-in, as its name implies, can thus take power from the electrical grid while stationary and use it for short trips. In the case of a short commute where the car could plug in at home and at work, it might not burn any fossil fuel at all on most days, emitting no carbon.

Toyota, maker of the famous Prius - the world's first mass-market hybrid - has previously pooh-poohed plug-in, saying that in the US (where grid electricity comes largely from burning coal) a plug-in car is effectively a very inefficient and dirty coal-powered one.

However, many green motorists aren't terribly concerned about ultimate sources of energy, and there has long been vocal lobbying for a plug-in Prius. Some green-tech fanciers - for instance Google - also contend that plugged-in car batteries could help the grid deal with demand surges, so preventing fossil fuel burn in standby generation plants.

Reports from the Detroit Motor Show indicate that the firm may be yielding to the pressure. Another factor in the firm's deliberations may be US motor behemoth GM, which has stated it will have its planned Chevy Volt plug-in hybrid on the market in 2010.

Electric-drive cars can deliver very nippy acceleration (though less so when they must haul a fossil engine about too). However, even battery supercars like the troubled Tesla Roadster don't offer the same kind of top speed as similarly-priced petrol machines. Roadster drivers, when they receive their beta-test cars, won't be able to keep up with a slightly cheaper Porsche 911 Carrera S.

Unsurprisingly, then, Ferrari has avoided electric and instead made a foray into biofuels. The new F430 Spider Biofuel model can run on either petrol or E85, a mix of 85 per cent ethanol and 15 per cent petrol.

The Ferrari F430

The F430 Spider Biofuel. Designed to fit aboard a bandwagon.

Ethanol as it now stands - made from corn in fossil-burning conversion plants - isn't any greener than grid electricity. However, it does have powerful US political lobbies behind it, and it ought to be feasible to make ethanol out of greener feedstocks using greener energy to do so one day.

What's nice about ethanol is that you don't have to sacrifice performance and you don't really have to do very much to a normal car to make it run on E85. So one might doubt the seriousness of Ferrari's green commitment here.

Biofuel and electric cars are fairly old hat on the alternative motoring beat, but there are other ideas. Developers in France, for instance, are partnering with Indian motor colossus Tata to try and get cars powered by compressed air onto the road.

This approach has obvious disadvantages, not least the fact that air inevitably heats up as it is compressed - and thus a lot of energy gets wasted. Indeed, the (hot) Air Car has been around for a long time without <cough> gaining any traction, but designer MDI still reckons it could go at 100mph and cover 125 miles on a single charge.

Like electric or hydrogen vehicles, compressed-air cars would be no more than a way of storing energy from somewhere else. In France, MDI's cars could use compressors powered from the country's mostly nuclear grid, and be truly low-CO2, but in most other countries this would lead to more hydrocarbons being burnt overall. A lot more, actually, as the electric powerplants turn fuel into 'leccy inefficiently, then the grid moves it to the cars inefficiently and finally the cars mostly use it inefficiently. Compared to burning the hydrocarbons on board, anyway.

Orthodox greens don't like nuclear, anyway; nor do they much care for ethanol vehicles, saying biomass power should be used in other ways; nor do they think a big expansion in electricity use is OK.

(There's no pleasing those chaps on this front, really, except perhaps by getting rid of your car.)

Despite all the headlines out of Detroit just now, green motoring even in the sense of low-carbon would seem a long way off. Green motoring in the Greenpeace sense of green may not even exist. ®