Much has been made about the benefits of using ethanol as a bio-fuel so today were going to talk about Alcohol being used as a replacement fuel in internal combustion engines. For simplicity we’ll leave the politics of putting food in our cars for another day.
Alcohol, or more accurately Ethanol was used widely used during the Second World War to help ease the restrictions on daily life caused by petrol rationing. Its use met with mixed results depending on the individual engine it was run on, however modern engines are made to be more durable and flexible in the fuel they use.
So, on with the comparison of ethanol and petrol.
Ethanol’s vapour pressure is lower than that of petrol and so engines using it as fuel are more difficult to start.
Ethanol takes longer to burn to explosion than petrol and so it needs a higher compression and stroke than a petrol engine.
Mixtures of Ethanol and air have a wider explosive range which allows for greater variation in the air supply.
Ethanol requires less air to burn than petrol and so we get a more complete burn due to the improved air/fuel mix.
Ethanol burns at a lower temperature than petrol. However this is largely offset by its more complete combustion.
And so we have a mixed bag really. Ethanol burns better but at a lower temperature with fewer exhaust gases. However it can be difficult to start an Ethanol engine on a cold day. And your engine may need to be adjusted to use Ethanol. Usually this just means the injectors need to be open for a few micro-seconds longer. But it still adds to the cost of the project over all.
However as this is a blog about self reliance we think ethanol has the edge for certain applications. Due to the relative ease of manufacture it lends itself to home production. The relatively small amounts of fuel produced makes running a car day to day impractical but it can be used to supplement the existing fuel supply and therefore cutting the fuel bill.
Ethanol really come into its own when used as a the fuel for backup generators, especially for those long duration but lower draw situations I.e. night time when the TVs are off and all that’s running are the fridge/freezer’s and central heating.
Also there are other applications such as chainsaws, shredder’s, mopeds and quad bikes. Basically any small scale but regular power need.
So keep an eye out for the OTF article where we will go in-depth into the fermentation process, distillation techniques and a few hints and tricks to keep your costs down to well….. Practically nothing!!