Syngas, or synthesis gas, is a fuel gas made mainly of carbon monoxide and hydrogen. Gas from air-blown gasifiers also contains nitrogen, carbon dioxide and some methane.

How does gasification differ from combustion?

Combustion supplies enough oxygen to burn the fuel completely, releasing heat directly. Gasification restricts the oxygen, so the fuel's energy is kept in a gas that can be burned later.

Why must the oxygen supply in a gasifier be limited?

Too much oxygen would burn the carbon monoxide and hydrogen to carbon dioxide and water. The gas would then have no fuel value left.

How is syngas used as a fuel?

Syngas can fuel gas engines or turbines that generate electricity, often with the heat recovered as well. The gas can also be burned in boilers and kilns for heat.

CCEA A-Level Environmental Technology 3930

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Energy From Biomass

Gasification and syngas

3 things to know
AS 1

Overview

Gasification and its stages, limited oxygen, the composition and uses of syngas, cleaning syngas, liquid fuels and chemicals, advantages and disadvantages against combustion, solid by-products and suitable feedstocks.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What is gasification?

Key term

What is syngas?

Process

Outline the stages biomass passes through in a gasifier.

Questions from this subtopic

Each one with the model answer underneath.

1
What is gasification?
Model answer
Gasification heats biomass to a high temperature with a limited supply of air, oxygen or steam. The biomass is converted into a combustible gas rather than being burned completely.
2
What is syngas?
Model answer
Syngas, or synthesis gas, is a fuel gas made mainly of carbon monoxide and hydrogen. Gas from air-blown gasifiers also contains nitrogen, carbon dioxide and some methane.
3
Outline the stages biomass passes through in a gasifier.
Model answer
The biomass first dries, then breaks down into vapours and char as it heats. Part of the material burns to supply heat, and the hot char converts the gases to carbon monoxide and hydrogen.
4
How does gasification differ from combustion?
Model answer
Combustion supplies enough oxygen to burn the fuel completely, releasing heat directly. Gasification restricts the oxygen, so the fuel's energy is kept in a gas that can be burned later.
5
Why must the oxygen supply in a gasifier be limited?
Model answer
Too much oxygen would burn the carbon monoxide and hydrogen to carbon dioxide and water. The gas would then have no fuel value left.
6
How is syngas used as a fuel?
Model answer
Syngas can fuel gas engines or turbines that generate electricity, often with the heat recovered as well. The gas can also be burned in boilers and kilns for heat.

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Fossil Fuels

Global Action on Energy Conservation and Climate Change

Macrogeneration

Microgeneration

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