One of man’s older pastimes has been making alcoholic drinks from fermented plants. But today, as oil is running out and its price is high, alcohol from plants is being put to another use – providing an alternative fuel for vehicles.
The world’s largest producer of fuel alcohol from plants is Brazil. Two years after the oil crisis of 1973, Brazil launched its alcohol programme, in response to the increasing costs of importing fuel. The Brazilians use a raw material with a low market value and which they grow in abundance – sugar cane.
Initially the process is the same whether the end product is to be an expensive brandy, or fuel alcohol which can drive a car. The raw sugar is mixed with water and yeast and fermented in large tanks, until it turns into an alcoholic liquid, rather like wine or beer.
One hundred per cent (200 proof) alcohol is needed for fuel, so to concentrate the mixture it is distilled. This is done by heating the liquid to vaporize the alcohol, then condensing the vapour to extract the alcohol and leave the water behind. This last stage, to produce anhydrous alcohol, needs a lot of energy, and has led to criticisms that producing fuel in this way can actually consume more energy than it provides.
The US Department of Energy found that when corn is used to produce alcohol, every 100 British Thermal Units (Btus) of fuel require 109Btus to produce them – 44 Btus to grow the corn (in the form of fuel for agricultural machines, and the energy used to create fertilizers and weedkillers), and 65Btus to produce the alcohol from it.
Despite this, alcohol production in Brazil has boomed. More than 80 per cent of the cars sold in Brazil now run on pure alcohol, or a mix of alcohol and petrol, and the bill for imported oil is down by about $2 billion a year. Annual production is over 11 billion litres and will need to increase by another 2 billion litres to keep up with demand.
In the USA, corn-based alcohol is also produced commercially, thanks to generous tax credits. US alcohol is usually mixed with ordinary petrol to improve its performance and replace lead.
Picture Credit : Google
