Ethanol en­ergy

4 x 4 Australia - - Tech Torque -

PETROL may con­tain less en­ergy than diesel but both con­tain a great deal more en­ergy than ethanol, which of­fers a very poor en­ergy re­turn on a vol­ume or weight ba­sis. In fact, ethanol has one third less en­ergy by vol­ume than petrol, or put an­other way, petrol has 50 per cent more en­ergy by vol­ume than ethanol.

Ethanol makes up 10 per cent of E10 fuel, and ethanol’s lower en­ergy con­tent is the rea­son why your car won’t go as far on a litre of E10 as it will on a litre of straight petrol. E10’s lower en­ergy level erodes its lower cost at the pump, some­times mak­ing it more ex­pen­sive in the long run.

What’s not to be con­fused here is that ethanol has a higher oc­tane rat­ing than petrol, which means it’s use­ful for en­gines run­ning high com­pres­sion ra­tios and/or forced in­duc­tion such as tur­bocharg­ing. In other words, it’s a good rac­ing fuel when you’re not con­cerned about fuel econ­omy.

If you’re a diesel driver who thinks none of this is a con­cern, you need to think again. We all pay for ethanol via a fed­eral sub­sidy of around 38 cents per litre, which makes it cheaper for those peo­ple who buy it. Ef­fec­tively we are all pay­ing for ethanol, de­spite the fact that it’s an en­ergy-de­fi­cient fuel of du­bi­ous en­vi­ron­men­tal value. Go fig­ure.

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