The UK disposes of its waste primarily by landfill. Landfill
sites generate landfill gases that are emitted to atmosphere.
Landfill gas (LFG) is 50% methane,
which is not only a potent greenhouse gas (21 times more so
than Carbon Dioxide) but is also a combustible fuel.
As part of the Government’s
greenhouse gas reduction plan, a target has been set to meet
10% of the UK’s electricity demand from renewable sources
by 2020.
Crown House Engineering has been
able to assist the government in meeting this target by undertaking
the innovative design and build of ten Landfill Gas Fuelled
Power Generation Plants in the UK. The plants utilise the
landfill gases generated and convert the gases to electricity
that is then sold onto the National Grid. As the table below
indicates, to date over 30MW has been generated and transferred
to the National Grid.
Non
Fossil Fuel Agreement (NFFO)
Location
MW
Power produced
Year
Commissioned.
NFFO2
Burnstump
– Notts
3.0MW
1989
NFFO3
Offham
– Kent
1.2MW
1996
Stangate
– Kent
5.0 MW
1996
Judkins
– Nuneaton
2.0 MW
1996
NFFO4
Ongar
– Essex
2.0 MW
1998
Bradgate
– Leicester
2.0 MW
1998
Sutton
Courtenay
6.0 MW
1999
Llanddulas
– Wales
3.0 MW
1999
Burnstump
– Notts
2.0 MW
1999
Aveley
4.0 MW
2000
Allerton
Park
3.0 MW
To be
built 2002
Edmond
Richards
3.0 MW
To be
built 2002
Kaimes
3.0 MW
To be
built 2002
Modern landfill sites are subject
to strict controls to minimise their environmental impact.
Modern landfilling is a major civil engineering exercise involving
impermeable basal liners and side walls; internal drainage;
leachate control; impermeable capping; and in-situ refuse
compaction. All these features are to prevent pollution of
groundwater and aquifer minimise the effects of settlement,
but such encapsulation of the waste promotes the generation
of landfill gas.
The landfill gas is collected,
filtered and combusted to produce energy. Spark-ignited gas
engines are the most popular means of generating electricity
from landfill gas in the UK as they offer the best compromise
in terms of capital cost, efficiency, performance and maintenance.
Waste to Energy Plant at Stangate,
Kent
A landfill site taking around
300 tonnes of degradable waste per day for 10 years could
theoretically generate as much as 4.5 billion cubic meters
of landfill gas over a period of 40 years. This can be captured
and used to create sustainable energy rather than released
to atmosphere as a harmful greenhouse gas.
Landfill gas fuelled power generation
provides convenient sized, embedded generation units (as shown
below), which not only supply power but also help mitigate
the greenhouse effect of refuse disposal sites.
These projects have been carried
out under the Government’s NFFO program, and the UK has
become the world leader in this technology.
