����tv

Biomass is organic material from plants and animals. This can be used as a source of energy.

By-products from forestry, plants and animal waste from farms, even sewage and some waste from landfill can be burned as fuel or used to generate electricity.

Just like fossil fuels, such as coal or gas, biomass contains lots of chemical energy. Biomass can be processed into different fuel sources:

• Liquid biofuels such as bioethanol can be used for cars and other transport, just like petrol and diesel.
• Solid biofuels such as wood pellets can be burned to heat homes and other buildings or to generate electricity.
• Biogas, often a mix of methane and carbon dioxide can burned for heating or to generate electricity.

Biomass power stations works in exactly the same way as fossil fuel power stations:

1. Biomass is burned, giving off heat - chemical energy is transferred into heat energy.
2. The heat is used to boil water to create steam.
3. The steam expands and builds up enough pressure to turn turbines - heat energy is transferred to kinetic energy.
4. The turbines turn generators which contain electromagnets. This creates a flow of electricity - kinetic energy is transferred into electrical energy
5. Electricity is supplied to the grid for use at home, work or school.

Like fossil fuels, biomass fuels are very portable.

Solid, liquid and gas biofuels can all be transported by road, rail or boat. In some placers biogas is transported through pipelines to where it is needed.

Sites for processing and burning biofuels are often located near where the source of fuel is grown, for example near timber forests or sugar cane plantations. This reduces the need for transport.

Steven's Croft power station near Lockerbie, Dumfries and Galloway is the largest biomass power station in the UK. The majority of the fuel it burns is waste product from the local timber industry.

Steven's Croft power station provides both electricity and heat energy for local homes and industry and also contributes electricity to the National Grid.

Combined heat and power stations that produce electricity and heat from burning waste tend to be located near the towns or cities where the waste is produced. They need to be near good transport links. Where there is nearby housing, the heat produced can be piped directly to them as part of a district heating system.

Sugars from plants can be converted into ethanol and carbon dioxide by a process called fermentation using enzymes in yeast. Ethanol is highly flammable; it is a store of chemical energy which is converted to different types of energy (including heat) when burned.

When ethanol comes from a plant it can be classed as a biofuel.

In some countries, such as Brazil, the source of sugar is sugar cane, which yeast can directly ferment into ethanol. Brazil have been using bioethanol as a fuel in cars since the 1970s. Brazil is a major producer of sugar cane so there is always plenty available to be turned into ethanol.

Bioethanol can be burnt in a car engine but some engine modification is needed. Modern petrol engines can use petrol containing up to 10% ethanol without needing any modifications, and most petrol sold in the UK contains ethanol.

In Brazil, they commonly use fuel that is 25% ethanol and 75% petrol although there are some cars that run on 100% ethanol.

This is one way of removing fossil fuels from modes of transport. This works successfully in Brazil because the climate is suitable for growing sugar cane and petrol is expensive and must be imported.

To develop a sustainable future you need to think about meeting today's needs and protecting the environment�����Ի���resources for the future.

Biomass fuel can be used in very similar ways to fossil fuels, so it could help cut down on the amount of fossil fuels we extract and burn.

Turning waste products into energy by using biomass is great because we can recycle waste and live more sustainably.

Processing waste into biofuel can reduce landfill which is a source of the greenhouse gas methane.

Biomass fuel is renewable since more plants can be grown to replace those used to make it. If the source is human or animal waste, then these are also being replaced on an ongoing basis.

However biomass fuel may not be sustainable because growing crops for biofuel can use up land that would otherwise be used for food production, or which would be left wild. Many people would argue that food supply is more important and that crops for fuel should be grown in places where other crops can't grow. For example plants like marram grass or agave can be grown for fuel in areas that are too dry for many plants.

Even when biofuel crops are replaced, they do still remove nutrients from the soil, and use of fertilisers and pesticides to grow them can contribute to global heating and damage local environments.

Advantages

• Biomass is renewable since we always produce waste. Crops can be grown specifically for biofuels rather than using fossil fuels
• Biomass is cheap and readily available
• Although biomass fuels release carbon dioxide when burned, the plants they are made from absorb the same mass of carbon dioxide when grown

Disadvantages

• Biomass is burned releasing carbon dioxide into the atmosphere which contributes to climate change
• Growing crops for biofuels takes up land that could otherwise be used for crops of wildlife. Producing biofuels can decrease biodiversity and remove nutrients from the soil that could be used to grow food
• Some people morally object to using food crops to produce fuels. For example, it could cause food shortages or increases in food prices