Ethanol: What, When, How...Huh?

This is the background briefing on ethanol in Australia as an automotive fuel


Ethanol, a.k.a. ethyl alcohol, pure alcohol, grain alcohol or drinking alcohol, is the second most common alcohol – a clear, colourless, volatile liquid. It’s the same stuff as in beer, wine and spirits, although the not-for-human-consumption stuff is ‘denatured’ by adding ‘bittering’ agents like denatorium benzoate and/or toxic chemicals like methanol and naptha – making it unpalatable and/or deadly.


Ethanol is two carbon atoms, six hydrogens and an oxygen, all joined at the hip. It’s most commonly produced by fermentation of molasses, waste wheat starch or sorghum – where yeast eats sugary compounds in a balmy climate, excreting ethanol and CO2. Ethanol kills the yeast when the concentration gets to 15 per cent – not coincidentally the upper limit for beer and wine. Beyond that, you need to distill it out (think: moonshine ‘still, only bigger).


Like E10, which is 10 per cent ethanol in 90 per cent petrol, E85 is 85 per cent ethanol in 15 per cent petrol – ie 850ml of ethanol and 150ml of petrol at the bowser.


Engines don’t like to cold start on E100. Here’s why: The so-called ‘flashpoint’ of petrol is minus 40 degrees C. That means petrol is happy to spontaneously evaporate to form an explosive vapour mix, requiring only a spark to set it off, whenever the temperature’s greater than minus 40. Ethanol’s flashpoint is plus 13 degrees C – and a cold engine is often colder than that. (Diesel’s flashpoint is plus 62 degrees C, which is why, although it’s not recommended, you can stub out a lit cigarette in a saucer of diesel – theoretically.)


In practise, the proportion of ethanol will vary seasonally from about 70 per cent in winter to 85 per cent in summer – with the higher petrol proportion in winter acting as a cold-starting incentive for your engine.


Caltex’s partnership with Holden means 32 stations across the country – ACT (2), NSW (10), Qld (6), SA (3) and Vic (11) – will offer E85 (under the Bio E-Flex moniker) by October this year. This will increase to 100 stations by 2011.


Caltex says the price of its Bio E-Flex will be “significantly below” the price of 100 per cent petrol. In practise it will need to be pitched at about 72 per cent of the price of petrol (or lower) – otherwise, you’ll be ripping yourself off by buying it. (See below).


When you buy fuel, you buy energy. One litre of petrol contains 34.8 million joules of energy. Let’s call that 100 per cent for reference. One litre of diesel equals 111 per cent. One litre of E10 is 97 per cent, while E85 is 72 per cent and pure ethanol is 68 per cent.


Because there’s only 72 per cent of the energy in E85, compared with pure petrol, your fuel consumption will suffer. If you get 1000km from a full tank of petrol, you’re likely to get only about 720km from a tank of E85.


Ethanol is a high-octane fuel because it resists auto-ignition better than petrol. (Petrol auto-ignites at 246 degrees C, while ethanol hangs tough until 365 degrees.) So, a modern engine can adapt up by advancing the timing a little more with higher ethanol blends, developing a few more Newton-metres (and therefore kWs) at the crank.


Globally, GM is the big player in flex fuel engines, with 3.5 million of the US’s 7.5 million flex-fuel vehicles sporting the GM badge. It plans to have 50 per cent of its production flex-fuel capable by 2012. The biggest player in ethanol is Brazil and the US, with 70 per cent of the world’s production.


Brazil makes its ethanol from sugar, the US makes its from corn, and, Down Under, we make most of ours with wheat (although sugar waste is used as well). It’s also possible to make ethanol from the byproducts of petroleum manufacturing, or from attacking cellulose – say, hay, old newspapers or wood chips – with special enzymes.


Companies like Coskata in the US are developing ‘feedstock flexible’ ethanol processes where all kinds of carbon-based waste (anything from old tyres to wood chip waste) is broken down in a furnace to synthesis gas (carbon monoxide and hydrogen), which is fed to specially bred microbes that eat the gas and poop ethanol – which is a great concept … yet to be proven viable on a truly industrial scale.


Ethanol is renewable, and it has the capacity to extend the capacity of the world’s dwindling petroleum reserves by something like 400 per cent. We can grow the feedstock here, and refine it here, reducing the national dependency on foreign oil and boosting the country’s energy security. Octane boost delivers slight performance increase in adaptable engines.


Ethanol competes with food production in some markets – undignified when there are starving millions just across the border. Emissions – especially things like the precursors of photochemical smog (formaldehyde, ground-level ozone). Increase in fuel consumption/decrease in cruising range with lower energy content. Some ethanol production processes consume almost as much energy as is created. As-yet unspecified price point for E85 means economic rationality for Aussie motorists is still in doubt, and hi-tech garbage-to-gasohol technology yet to be proven.

fuelJohn CadoganComment