Monday, May 22, 2006

Hybrid Cars are not so Green?

To set us all a good example, would be Prime Minister David Cameron, and actual governmental ministers Gordon Brown (more likely to become the next P.M. after Tony Blair) and John Prescott have all got hybrid cars. A "hybrid", in this context at least, is a car with a self-charging electric motor that runs alongside a petrol engine. The hybrid is generally perceived as a "green" conscience smoother for those who can't or won't give up their cars, and are prepared to pay around 10 - 20% more for that priviledge, although the edge is taken off that by a very low road tax of anly £40 a year, to encourage the adoption of these vehicles more widely. Significantly, hybrids are also exempted from the £8 a day congestion charge in London - which Ken Livingstone looks set to raise for other kinds of vehicle.
The realities of hybrid efficiencies have been called into question as a result of a new study commisioned by "Which?" magazine, that has investigated three different makes of car. As one example, the recently promoted Honda Civic was found to achieve a mere 28 - 34 mile per gallon fuel-to-road output, which is by far lower than the most efficient petrol or diesel powered cars, and around only half the 54 mpg value claimed in Honda's advertising brochures. David Cameron drives a Toyota Lexus RX400, but this only provided 25 - 34 mpg during the Which? experiment, and is around twice the fuel consumption of the most efficient diesel-run car. The U.K.'s best selling hybrid, the Prius, did manage 45 - 50 mpg, but again this is rather shy of the 66 mpg figure claimed for it. Nonetheless, since it is shown that the car produces 44% less CO2 than a standard "non-hybrid" equivalent, it is still a promising machine.
A senior researcher at Which?, George Marshall-Thornhill said he was "surprised" by these results, and offered a possible explanation for them. In essence, rather than doing an in-house, "wheel on rollers" type of determination of the cars' efficiencies, under controlled laboratory conditions, the cars were just driven around as they would normally be in practice, on a variety of roads and at a range of speeds, which surely is a more reliable measure of a car's performance in reality. A spokesman from Toyota said the "claimed" figures were produced by the vehicle certification agency rather than the manufacturer, and that "all cars are tested in the same way - and the published figures come from those tests. Which?'s figures would have been greatly influenced by the road conditions at the time". Well, of course they would, as indeed will be the case when anyone buys a car and drives the kids to school in it, goes off to work, or for any other purpose for that matter. Real life is not conducted under clinical conditions.
On another tack, Which? have looked into bio-diesel, aiming at motorists who want to "go green" without stumping up the extra cash to buy a hybrid car. It is the old argument being trotted out agin, that because growing the crops to produce bio-diesel consumes CO2, then 70% of CO2 emissions can be eliminated overall, from that pumped into the atmosphere by burning the stuff in cars. I applaud this more realistic estimate of 70%, as opposed to the innumerate "bio-diesel is 'carbon neutral'" claims often made for it. However, to grow "bio-diesel" crops on sufficient scale to replace the 54 million tonnes of petroleum fuel that is currently burned in the U.K. alone, every year, is simply impractical. I have done the sums before (please see my previous posting for the details if you are interested: "Biofuels - How Practical are They?"), and concluded that we would need about 5 times the total area of arable land in the U.K. for this purpose. In other words, even if we were to stop growing food entirely and turn all our fertile land over to bio-diesel production, we could still only provide 20% of current fuel use. Makes you think, doesn't it?
In Sweden apparently, 13% of new cars are now sold that run on bio-ethanol, mixed with 15% petrol. Sounds good, but Sweden is a fairly small country, and is all their bio-ethanol home-grown? I doubt it, since Sweden has a very short growing season. A lovely country, where people traditionally eat a lot of meat, got from animals that can graze the moss under the snow during the rest of the year, i.e. Rudolph and his friends, many of which are still radioactive (though healthy) as a legacy of Chernobyl. I shall look into the energy economics of bio-ethanol, but my gut instinct is that it is not much better than bio-diesel as a truthfully effective substitution for petrol (gasoline). Ethanol has poor thermodynamics as a fuel, and can only deliver around 60% as much energy as petrol, pound for pound. It is also extremely acre- (hectare) intensive as a crop.
Assuming that we wished to run the U.K.'s transportation requirements on bio-ethanol, and presuming further that an equivalent quantity of fuel could be derived per unit area as bio-diesel, the"bio-fuel" sum becomes worse since we could only provide 20% x 60 % = 12% of our massive 54 million tonnes annual fuel budget by its means.
Apparently Ford and Saab now sell cars in the U.K. that will run on the 85% bio-ethanol:15% petrol mix, but vide supra, this is merely hype and a conscience tax imposed upon the gullible. I deliberately don't run a car, and remain firm in my conviction that cutting the number of cars by about 90% (possible by localising communities) and cutting unnecessary plane flights, which consume about a quarter of all fuel in the U.K., is the key to solving the problems threatening humankind by "Peak Oil". 10% of our current petrol equivalent might be provided by alternative means, e.g. from gas or coal liquifaction, and even a relatively small contribution from bio-fuels, but not the equivalent of 54 million tonnes of it. I think we should forget about hybrids and focus more directly on limiting our fuel use in the first place.


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