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Biomass

18 April 2023

Objectives

Be able to understand what biomass is, how it can be used to produce electricity, and be able to evaluate

its advantages and disadvantages.HSW: AF2: Make balanced judgments about scientific developments by

evaluating the economic, moral, social or cultural implications. Used before in: Will use again in:

PLTS: Independent enquirers: support conclusions, using reasoned arguments and evidence.

Used before in: Will use again in:

KeywordsBiomass, biofuel, chemical energy, carbon neutral.

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Outcomes

• All students should be able to: • Give examples of biofuels.• Most students should be able to:• Explain the process by which electricity

is produced and why biomass power stations are carbon neutral.

• Some students should be able to:• Evaluate the advantages and

disadvantages of using biomass fuels.

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Biomass, also known as biofuels or bioenergy, is material from living sources. The simplest biomass energy sources are plants, which can be burned to produce steam to turn a turbine.

The carbon dioxide released during burning biomass is absorbed by the replacement plants. Biomass is said to be

‘carbon neutral’ and does not add to global warming.

What is biomass? Examples…

Traditionally, wood is burned to give heat but trees grow slowly and require a lot of land. Other materials, such as poultry farm waste, can also be burned.

Biomass fuels are renewable as more plants can be grown, producing yet more biomass.

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Methane is a biogas, which can be used a replacement for natural gas. This biofuel can be produced by making use of the natural decomposition of organic waste material.

How can waste create biofuel?

Methane can be produced from concentrations of rotting sewage or manure stored in containers called anaerobic digesters. These can be readily used in remote places, such as this digester on a pig farm.

Another source of methane is the rotting organic waste buried underground in landfill sites. The gas can be drawnup through pipes to generate electricity or provide heat.

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Some sources of biomass energy can be processed to produce biofuels that are even more useful.

How else can biofuel be made?

Certain plants can be fermented to form ethanol, a biofuel, which can be used instead of petrol or even aviation fuel, as in this plane!

Sugar cane and beet are the most efficient sources of this ‘bioethanol’ but potatoes, corn, wheat and barley can also be used.

Another biofuel is ‘biodiesel’ which can be made fromvegetable oils, animal fats or recycled cooking oils.

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Using non-renewable fuels in power stations

1) A fuel is burned in the boiler

2) Water turns to steam and the steam drives a turbine

3) The turbine turns a generator

4) The output of the generator is connected to a transformer

5) The steam is cooled down in a cooling tower and reused

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Energy Chain

Sun

Plants

fuel

burnt

steam

turbine

Use the energy chain to explain how electricity is

produced by biofuels.

generator

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What are the pros and cons of biofuels?

Some advantages of using biofuels are:

Some disadvantages of using biofuels are:

energy used in transportation must also be considered.

Biofuels are made from plant materials which makes them completely renewable.

They are biodegradable, so do not cause as much pollution if spilled.

They produce less pollution, when burnt, than fossil fuels.

Vehicles need to be adapted to run on pure biofuel. Large areas of land are needed to grow crops, which

could lead to loss of habitats. Biomass is ‘carbon neutral’ but the environmental impact of

using fertilizers to grow sources of bioenergy and the

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Using biofuels – true or false?

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TASK

Scenario• You work for an electricity company, “El

Power”, who uses Fossil Fuels to produce most of your power. You want to become greener and are planning to produce 10% of your power using Biofuels to become greener and attract new customers.

Task• Write a speech to the board of directors of

your company outlining (ALL) what biofuels are, (MOST) how they make electricity and are carbon neutral and (SOME) explain their advantages and disadvantages.

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Plenary

• Students deliver their speeches.• Video.• Peer assess: • Tell them what went well and even better

if• Did they: • ALL: Give examples of biofuels?• MOST: Explain the process by which

electricity is produced and why biomass power stations are carbon neutral?

• SOME: Evaluate the advantages and disadvantages of using biomass fuels?

C

B

A