Chemistry

Green Fuels in the 21st Century



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Green fuels are of particular interest to us in the early part of the 21st century for two reasons - the traditional fossil fuels such as petrol (gasoline) and gas that we have used are running out and becoming far too expensive - also the carbon dioxide emissions from these fuels is now widely believed by scientists to be causing an increase in the greenhouse effect, and therefore global warming and climate change.

Clearly, as this century unfolds the emphasis is going to be increasingly upon different, 'green' fuels that are renewable and that do not contribute to further climate change. Obviously, this change is not going to happen overnight, but it would be helpful if we all understood what might be happening in the near future.

The main type of fuels to talk about are the so called 'biofuels'. These fuels might be termed 'green' fuels because they are renewable and they are carbon neutral i.e they do not, overall, add extra carbon dioxide to the atmosphere. The reason for both of these things is that biofuels are made from plant material. Obviously plants are renewable - they are not going to run out! Also since they make all of their own molecules from carbon dioxide absorbed from the atmosphere by photosynthesis - when these molecules are burned to release this carbon dioxide back into the atmosphere it has not added overall to the level of atmospheric carbon dioxide.

These biofuels take the form of ethanol and biodiesel. Ethanol is made from sugar, produced from plants through the process of fermentation. Ethanol is an excellent fuel - it gives rise to no acidic gases on combustion and does not have to be compressed as it is already in a liquid form. Ethanol has been used as a fuel in Brazil for many years and is starting to be mixed in with petrol (gasoline) in Europe - up to about 5%. Biodiesel is made from similar plant oils to those used to make margarine and cooking oil.

The disadvantage of using these types of green fuels made from sugar, grain and seeds is that this usage inevitably pushes up the price of the foodstuffs traditionally made from them. This has certainly happened in Europe as biodiesel and ethanol have become more commonly used.

However, this disadvantage could be got around by using waste plant material to make ethanol. In fact a few places in Canada have just started producing ethanol from wheat stalks - which are usually just burnt after the crop is taken in.

So, we are sure to see more of these green fuels in the near future - maybe higher food costs are a price worth paying if these fuels will help us avoid the perils of climate change.

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