We hear about ethanol all the time – particularly when we buy gas. In case you were wondering what it's all about and where it comes from, here is some basic information.
What exactly is ethanol?
Ethanol is an alcohol (the same stuff you get in alcoholic beverages) that is mainly used to blend with gasoline so our cars aren't entirely driven by fossil fuel-derived fuel.
Did you know that some ethanol actually comes from petroleum products? It's true. The ethanol that comes from agricultural stocks is properly called "bio-ethanol" although many now mean bio-ethanol when they mention ethanol, and that's what we mean here.
What is ethanol made from?
Ethanol can be made from various agricultural sources, including sugar cane, various woody shrubs and grasses, sugar beets, sorghum, grain, barley, hemp, potatoes, sweet potatoes, sunflowers, fruit, molasses, wheat, straw, cotton, other biomass as well as many types of cellulose waste and harvestings. It's made by fermenting the sugar and starch in these plant materials by using yeast.
In the US , ethanol is mainly made from corn, which makes corn producers very happy – especially as and when governments begin requiring higher ethanol levels in gas. In Brazil, massive amounts are made from sugar cane and in Australia it's mainly made from sugar cane and waste from starch production and red sorghum.
What's exciting in the ethanol world?
Because we worry about cutting into food crops to "grow fuel", the most exciting developments are in "cellulosic ethanol". That is made from plant waste products – which are simply the by-products of what we are already growing and using for other purposes. Here, the cellulose part of the plant is broken down to sugars and then converted to ethanol. Different means of producing ethanol are also being developed – all in search of getting the biggest bang for our energy buck with the smallest environmental footprint.
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For example, traditionally algae has been grown and then harvested and fermented. With a new process, the algae grow in sunlight and produce ethanol directly. The ethanol is thus removed without killing the algae. How big is that? According to the company pioneering this, the process can produce 6,000 US gallons per acre per year compared to 400 US gallons per acre for corn. |
What's ethanol's energy kick and price compared to gas?
Ethanol doesn't have as much of a kick (embedded energy) as gasoline. It takes about 1.5 gallons of ethanol to produce the same amount of energy as one gallon of gas.
As to how much energy it takes to produce ethanol, that of course, will differ depending on what is used to make the ethanol and how energy efficient the process is. Corn, for example, is a very energy-intensive crop; requiring the use of one unit of fossil-fuel energy to create about 1.3 energy units of ethanol. Cellulose, on the other hand, yields roughly twice as much ethanol (about 2.6 units) as corn per unit of fossil fuel. Clearly, part of the excitement about cellulosic ethanol is that since it's made from stuff already lying around, it doesn't take additional energy to "grow" it – just energy to process it.
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