How green is my Bentley
The electric-powered Mini E is a con, says Bentley chairman Franz-Josef Paefgen. Far from being a zero-emissions vehicle, he says, it pumps 133 grams of CO2 into the atmosphere every kilometer. That's because the Mini E's electricity is generated by burning fossil fuels. (By contrast, a 1.6-liter diesel-powered Mini Cooper D has a CO2 emissions rating of just 104g/km; a Bentley Continental GT is rated at 396g/km.)
"We are measuring the wrong thing," says Paefgen of the emphasis on tailpipe emissions, which governments are beginning to use to tax heavy CO2 emitters. A far more meaningful measure, he says, is well to wheel -- the total CO2 emitted during the extraction or production, and burning of fuel.
Because bio-fuels recycle carbon dioxide, they deliver lower overall CO2 emissions on a well-to-wheel basis. Bentley figures show corn ethanol delivers a 20-percent CO2 reduction compared with traditional fossil fuels, using sugar beets saves 40-percent, and sugar cane 80-percent. Cellulosic ethanol could deliver a 90-percent or more reduction.
The downsides? Ethanol has a lower energy content than gasoline, which means you need to burn 25 to 30 percent more to travel the same distance. Also, corn and cane crops require vast quantities of water, effectively limiting supply until cellulosic ethanol can be produced on an industrial scale.
Bio-fuels will make it possible to build a traditional Bentley for a few years yet. But Paefgen's biggest challenge will be making the notion of well-to-wheel environmental impact a widely understood metric. "It might be confusing," he adds, "but it is what the truth is all about. You have to give people the true story."