They recently bumped the tax up on biodeisel so I wouldn't hold your breath. Nice to see they are sticking to their green energy policies.

Avoiding the tax?
How silly. I don't know of anyone who would do that.

Ethanol contains more energy than it takes to make, but less than petrol. Hence the lower mpg. But as oil prices keep getting higher E85 will get comparitively cheaper.

I think that it's better to be paying farmers to crop crops for ethanol than to be subsidizing them to produce food that just goes to waste. However a lot of money could be saved by using organic waste instead of growing crops.

Lastly, they should put one of those pumps near me. I'm planning on building a 3.6 24v Sierra and would like some relitevly green high octane fuel for it.

According to certain EPA numbers, you tend to need 25% to 33% more ethanol by volume to go the same distance, relative to gasoline. But usually not 40% more. It depends on the car model.

http://www.fueleconomy.gov/feg/byfueltype.htm.

Just because ethanol has a lower energy density than gasoline (up to 40%) does not mean that MPG falls in exact proportion, because there are ways to take advantage of ethanol's peculiarities (such as higher octane) to increase miles traveled relative to the energy density of the fuel.

In fact, the Saab model mentioned in this post purportedly suffers very little decrease in overall MPG, and a higher highway MPG, when using ethanol because it has very advanced engine control features, including variable ignition timing and variable turbocharging which, it seems, can effectively boost the compression ratio to take advantage of ethanol's higher octane.

http://www.greencarcongress.com/2004/12/saab_biopower_f.html

On the energy positive-negative issue, I don't think the MPG debate is relevant at the first stage, because energy positive or negative is simply comparing the BTUs in through running tractors, spreading fertilizer and distilling fermented corn mash, with the BTUs out, in terms of gallons of ethanol multiplied by BTUs per gallon.

In fact, engines optimized (or even just partly optimized) for ethanol can have a multiplying effect on the total efficiency of our system. If an optimized engine can get more miles per BTU than a gasoline engine can (say, by getting even 20% fewer miles per gallon while each gallon contains 40% fewer BTUs), than even if ethanol production was energy neutral (that is, consumed one fossil fuel BTU per each ethanol BTU out), we would save energy because we would consume fewer BTUs to drive the same cumulative distance, meaning we'd use less fossil fuels to enable us to drive that distance.

If ethanol production is somewhat energy positive (let's just say 20% for argument's sake; that is, 1.2 BTUs of ethanol are produced from 1 BTU of fossil fuel spent by the farmer-distiller), and ethanol-optimized vehicles used 20% fewer BTUs per mile than gasoline engines (which would mean a somewhat lower MPG number relative to gasoline, but not 40% lower, which is the difference in energy density between the two fuels), then the following would result:

We would immediately need only 80% of the BTUs we formerly needed. Each BTU in the fuel tank (in the form of ethanol) would require require .8 fossil fuel BTUs to produce. We would therefore only need 64% of the fossil fuels we formerly needed to drive the same sized cars the same distances. That's a massive fossil fuel savings already. If non-fossil-fuels are substituded into portions of the ethanol-production process (renewable electricity to run the distilleries and fertilizer factories, biodiesel in the tractors (a partial offset if biodiesel is energy positive like ethanol), plug-ins for the heck of it), then total fossil fuel consumption goes down even more. Highly net-positive technologies like the holy grail of cellulostic ethanol would completely change the game.

Such a scenario depends on ethanol production being moderately energy-positive and ethanol fueled vehicles making a moderate jump in BTU per mile efficiency through optimization over gasoline engines. But I think both of these things are easily within our current technical abilities.

See: http://www.ifp.fr/IFP/fr/IFP02OGS.nsf/0/A035F6E8F33537C880256F94003B7A09/$file/jeuland1_vol59n6.pdf?openelement

The ancillary environmental effects of growing your fuel (such as deforestation in the case of Brazil) are yet another topic for another time.

NBK-Boston, biodiesel is purported (sp?) to have the highest energy balance of the biofuels. I don't have the number infront of me, but I've seen the claims somewhere. I don't know what sort of controversy might surround that claim.

NBK-Boston,

I care little for the energy equations regarding the production of the fuel, I only care about the bottom line fueling costs.

And, sadly, due to the greed and ineptness of the UK government, the fueling costs are currently much, much higher using E85 than petrol.

Yes, the Saab has advanced electronic features to help maximise the economy but it will still cost more than simply slugging in 95 RON petrol.

Plus the E85 engines won't be optimised to run on E85 due to the extremely limited supply, thus meaning they must remain able to run on 95 RON petrol.
Thus they are comprimised.

But I do agree, equal per mile costs could be achived with a car with a 12.5 to 1 compression ratio or similar.

Just in case anyone isn't already aware, we in the UK pay $4.09 per US gallon IN TAX ALONE on gasoline.
We pay around $5.92 per US gallon in total at the moment. (assuming exchange ratio £1=$1.8)

The government have "generously" given us a 36cent per litre tax cut on ethanol.
Its still totally useless though.
It should be tax FREE and thus a very competively priced fuel but, like I said, the UK govenment is inept and greedy.

Andy

Andy,

You make an important point. Dollars per mile is the fundamental unit of importance to most consumers. Energy calculations, though, are an important stepping stone to that final measure for several reasons.

First, they help suggest what the true cost per mile is, assuming you also know what economies of scale are technically possible. That can help a policy maker decide which technologies hold promise to eventually reduce costs / pollution, and which technologies are duds, or more specifically, under which conditions a technology will help, and under what conditions will it flop.

Second, and more important in a high-tax environement such as yours, they provide policy justifications for adjusting tax rates and lowering prices. That is, if it can be shown that ethanol will cut total greenhouse gas output, a carbon credit ought to be given. If it can get English petroleum consumption back within the North Sea production envelope, or push England over to importing fuel from more stable suppliers such as Brazil, the US, France or Argentina, rather than Russia, the Middle East and Nigeria, it could deserve support for geopolitical reasons.

Energy calculations are an important -- I think fundamental -- piece of those puzzles.

People always moan about E85 not doing as many MPG as petrol, but in the same flex-fuel car it won't. Flex-fuel cars are optimized for petrol, but petrol pinks, ethanol doesn't. Actually the only truly flex car would have to have have a turbo. An optimized ethanol engine will have diesel like compression. I'm building a car to be optimized for ethanol it uses a Ford Essex V6 which though old was designed to be either petrol or diesel just by fitting flat top pistons. You would need diesel injector system instead of the distributor too, but the bottom end is strong.