More fuel to the ethanol debate

Interesting piece in the Economist this week entitled, All change, on what the Brazilians are doing with ethanol.

A long time user of ethanol as fuel for motor vehicles (albeit rather uneconomically), engineers have now come up with an innovative new system that gives a consumer a choice as to which type of fuel to put in their car. According the article. Petrol burns best with an air-to-fuel ratio of around 14:1. This means that, for every kilogram of fuel burnt, all of the oxygen in 14 kilograms of air will be consumed. Ethanol, though, requires an air-to-fuel ratio of 9:1. Delphi’s technology works by “sniffing” the amount of oxygen in a car’s exhaust. If too much or too little of the gas is sensed, it indicates that the fuel is burning in a less-than-optimal way, and thus that the air-to-fuel ratio is wrong. A signal is then sent to the engine to tweak the ratio appropriately. This system also makes adjustments to compensate for the outside temperature. Optimal burning requires more fuel in the mixture when the temperature is lower. Sniffing the exhaust means that this happens automatically.’ Sugar 1-0 Oil, I say.