What are biofuels?

Leon and Michael are camping in the forest. - Hey, maybe we can roast some food on sticks over the fire! - The boys can roast their food because the fire produces heat. There’s a lot of chemical energy stored inside the wood. When we burn it, the energy is released as heat. Many years ago, people discovered that they can burn different things, and use that energy to cook, power engines, or produce electricity. Materials we can burn to get energy are called FUELS.

Some examples are coal, natural gas, and oil. They were created by nature over millions of years. These are called FOSSIL FUELS. But we have also learnt how to make fuels from the remains of living organisms - organic matter. These are called BIOFUELS.

They include fast-growing plants such as cereals, corn, sugar cane, and even some kinds of trees like poplar, willow, or eucalyptus. We can even use leftover wood from sawmills, and organic waste such as food scraps, manure, and sewage! Some of these materials can be burned directly, for instance firewood, dried animal droppings, or wood chips and sawdust pressed together into so-called pellets. They burn very well and release a lot of heat. That’s why they are perfect for heating our houses.

Other organic materials need to be processed first, before we can use them as fuels. There are several different processes, and they produce different types of biofuel. If we put organic matter in an air-tight container, so that oxygen can’t get in, bacteria will decompose it. Then the bacteria produce a mixture of gases: mainly carbon dioxide and methane. This mixture can be used as fuel for producing electricity, or for heating.

We call it BIOGAS. Instead of bacteria, we can use other organisms to decompose the organic matter. For example, yeasts use sugars from plants such as corn, wheat, or sugar cane, to produce ETHANOL. Ethanol works very well as a fuel for cars. But some cars have a different type of engine and can’t use ethanol.

For these, we can produce fuel from vegetable oils, for example: rapeseed, soybean, and sunflower. Animal fats such as fish oil can be used too! This type of fuel is called BIODIESEL. [...] Many things that make our lives easier require energy. Without energy we would not have electricity, heating, or cars. With all the people on earth, we need a lot of fuel to produce all the energy we use.

We can grow and harvest plants continuously - year after year. This means that we can produce biofuels and energy from plants at about the same rate as we are using them. This makes them RENEWABLE ENERGY resources. [...] As the wood burns up, the fire dies down. The boys will need more fuel soon! - Oh no! My sausage fell into the fire! - I don’t think that will be enough, Leon.

Let’s collect some wood instead!