Monitoring Gas
What is landfill gas?
As bio-degradable waste decomposes it gives off methane
gas. This potent greenhouse gas has to be carefully disposed
of as it is potentially flammable or explosive.
How do we get rid of it?
There are six closed landfill
sites in Cheshire East that the Council are responsible
for, some of which require landfill gas to be pumped out and burnt
by a process called 'flaring'. Flaring takes place in specially
built Flaring Units which break down the main part of the gas
(methane) into carbon dioxide and water. Methane is a greenhouse
gas and burning it in this way reduces the impact on Global
Warming.
When burnt as fuel the gas has a calorific value of about half
of that of natural gas. If the landfill gas produced by all 12
closed landfill sites across Cheshire wasn't burnt it would be
released into the atmosphere and the effect on global warming could
be equivalent to driving 432 million miles by car every year.
There is a programme to replace all closed landfill site open
flares with state of the art, smaller capacity and low-emission,
high-temperature enclosed flares. We are leading the way in
reducing the impact on the environment and helping the Environment
Agency with its national programme on mitigating effects of
landfill gas.
The remaining closed landfill sites produce an insufficient amount
of gas to sustain active gas extraction. However, these sites are
still regularly monitored for sub-surface landfill gas using
high-tech portable infra-red equipment.
Operational landfill sites
Many of the operational landfill sites (those which are still
being filled up with waste) have been designed so that the landfill
gas can be burnt within purpose-built engines. These engines use
the gas to produce electricity and this is sold to the National
Grid. Such a scheme is generally not possible at the older sites as
they have already passed their gas-producing peak. Although with
the recent introduction of improved efficiency small scale engines,
coupled with subsidies from the Government’s renewable obligations,
it may be possible to exploit the gas on some closed sites.