Wood was once our main fuel. We burned it to heat our homes and cook our food.

Wood still provides a small percentage of the energy we use, but its importance as an energy source is dwindling.

Sugar cane is grown in some areas, and can be fermented to make alcohol, which can be burned to generate power.
Alternatively, the cane can be crushed and the pulp (called "bagasse") can be burned, to make steam to drive turbines.

Other solid wastes, can be burned to provide heat, or used to make steam for a power station.

"Bioconversion" uses plant and animal wastes to produce "biofuels" such as methanol, natural gas, and oil.

We can use rubbish, animal manure, woodchips, seaweed, corn stalks and other wastes.

It is claimed that biofuels will help us to reduce our reliance on fossil-fuel oil, and that this is a good thing.

On the other hand, it is also claimed that it takes a huge amount of land to grow enough crops to make the amount of biofuels we'd need, so much so that it makes a big dent in the amount of land available for growing food.

Who is right? Should we be using more biofuels and less fossil fuels? Think about the carbon dioxide - there are similar CO2 emissions from biofuel-powered vehicles as from petrol-powered ones.

It is claimed that growing plants to make biofuels will take in that carbon dioxide again. But biologists tell us that forests are not 'the lungs of the planet' after all - they give out as much CO2 as they absorb as the plants respire. It seems that it's plant plankton in the oceans that takes in most CO2 and gives out most oxygen.

Don't just take my word for any of this - I'm not an expert. Find out more for yourself!

Advantages

• It makes sense to use waste materials where we can.
  
  
• The fuel tends to be cheap.
  
  
• Less demand on the fossil fuels.

• Collecting or growing the fuel in sufficient quantities can be difficult.
  
  
• We burn the biofuel, so it makes greenhouse gases just like fossil fuels do.
  
  
• Some waste materials are not available all year round.