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Biomass is a renewable energy type which uses organic matter (“living things”) to make fuel or generate electricity.

In this article you can learn:

• What biomass is
• Different ways to use energy from biomass
• Different sources of biomass energy
• What the advantage and disadvantages of biomass energy are

This resource is suitable for energy and sustainability topics for primary school learners.

In this video, learn what biomass energy is and how it works.

Biomass uses waste from plants or animals that can be converted to energy. Examples of biomass are plant matter, food waste and human and animal waste. Biomass can be gassy and smelly and when we burn biomass it gives off smoke.

There are three ways we can make use of biomass energy:

• Burning (such as burning wood)
• Rotting (when food and some types of wood rot they release methane gas that can be used as fuel)
• Growing crops as a source of biofuel

All the energy in biomass comes from the same original source: the Sun.

Biomass is made from living things.

All living things grow and gain energy from the Sun. Plants gain energy directly from sunlight. Animals gain energy from eating plants.

They all store this energy as chemical energy. Biomass energy releases this chemical energy so that can be changed into useable heat energy, kinetic energy or electrical energy.

We can burn trees and wood to use the energy given off.

Some people say this is not a good idea because it is destructive and gives off air pollution.

Burning wood only releases as much carbon into the atmosphere as the tree that it comes from absorbed as it grew.

If we plant new trees, they will absorb roughly the same amount of carbon that burning trees will release, but this can take many years.

Balancing out the carbon released and carbon absorbed is known as being carbon neutral. By not burning non-renewable energy sources, such as coal or gas, or trees that are never replanted, we are trying to save on carbon emissions

This is a cycle that we can keep on repeating, meaning that over a long time this process can count as renewable .

We also need to think about what cutting down trees does to their local environment. Trees provide a home for wildlife that is lost if they are removed. Trees that are left to grow longer keep absorbing carbon. And when trees die naturally they rot away and their nutrients help keep the soil healthy so other plants can grow.

We also convert crops into liquid biofuel. For example, biodiesel can be made from sugar cane and used to fuel cars instead of diesel from oil.

A type of alcohol called ethanol can be made from corn and be can also used as biofuel for vehicles.

Most homes and schools have food waste bins to collect leftover food and food waste.

It is collected and taken to a recycling centre where an anaerobic digester processes it.

As the food rots, it produces natural gas. This is captured and used to generate electricity and heat.

We can be responsible citizens and do our bit for Planet Earth by recycling our food waste. Learn more about food waste here: Food waste

Another type of biomass energy is human and animal waste - raw sewage.

Sewage is treated which means the water is separated and cleaned, leaving lots of brown sludge.

This is processed and gets turned into dried pellets which can be burned instead of coal or gas.

By not burning non-renewable energy sources, such as coal or gas, we are saving on carbon emissions.

Biomass energy can be used in several different ways. Some examples are:

• Liquid fuel for vehicles

• Electricity for homes and buildings

• Heating water

• In some developing countries, biomass fuel such as charcoal is used as an important energy source for cooking and heating

Advantages of biomass

• It can create fuel for various uses, not just electricity.

• It is renewable , as crops and plants will continue to grow (but only if we keep replacing them) and humans and animals will continue to produce waste.

• It uses our waste to create energy. This means our waste can be re-used for a positive purpose!

Disadvantages of biomass

• It takes up a lot of land to grow enough trees and crops to generate useful energy. This can reduce space for animal and human habitats.

• In some countries, families have lost their homes because their lands have been taken for crop growing.

• Habitats like ancient forests are destroyed when trees are cut down and made into biomass for burning.

• Burning biofuels is still not good for the environment as it releases carbon dioxide and other harmful gases into the atmosphere.

• Burning any form of wood gives off air pollution (smoke and dust) which is bad for human health (especially if you have asthma or heart disease) and animal health.

• It can be smelly. That’s a downside, especially if you live near a recycling centre or a sewage treatment plant!

Biomass – An important energy source which is converted from materials made from plants and animals.

Organic matter – The waste that comes from living plants and animals that is beginning to breakdown and decay.

Carbon emissions – The release of carbon into the earth’s atmosphere, which contributes to climate change.

Carbon dioxide - About three quarters of carbon emissions are carbon dioxide gas. This can stay in the atmosphere more that one hundred years.

Methane - About one fifth of carbon emissions are methane gas. Methane stays in the atmosphere for about ten years.

Carbon neutral – This is when the amount of carbon that is released into the atmosphere is the same as the amount of carbon that is absorbed from the atmosphere.

Air pollution - Gases and particles (like dust or smoke) in the air that can damage the environment, plants, animals and human health.

Biofuel – Fuel made from biomass that can be used to heat homes and power cars. In some developing countries biofuel is also used for cooking. A biofuel can come in the form of a solid, liquid or gas.

Ethanol – A fuel that is made from crops and can be burned or used as a fuel to power cars and other types of engine.

Anaerobic digester – When we recycle our food waste some of it is taken to a recycling plant and placed in an anaerobic digester. This process allows food waste and other types of waste to rot and be broken down to produce biogas, which can be used generate heat and electricity.

Raw sewage – Human waste is the waste our bodies produce as part of the digestive process. It can be processed and used as a source of energy.

Before recycling your food waste, weigh each bag of food waste that you and your family produce.

• Use scales to find out how many kilograms of food waste you will be sending to the Recycling Centre and add it up over the course of the week.

• Remember to ask for your parents’ permission and their help when using scales and handling the bags of food waste.

Want an extra challenge?

Record this information in a table over 4 weeks.

Are there any weeks where you produce more or less food waste than others?

By recycling our food we are helping the environment in lots of different ways.

It's even better if you use up more food and waste less!

Can you think of how you can reduce your family’s overall food waste?