Alternative FuelsCase HistoryViridor Waste Management Landfill, London, UK

Where: South Ockendon landfill near Dartford, London, UK

Supply:Three 1750 LBTU 1.75 MWe generator sets

Application:To recover methane from landfill and generate low-cost electricity

Ockendon landfill site generates electricity into the future thanks to Cummins turnkey solution

Viridor is one of the UK’s leading recycling, renewable energy and waste management companies. It operates 22 landfill sites around the country, generating electricity from the gasses that accumulate in the buried waste. At Viridor’s landfill site near Dartford on the eastern edge of London, the time had come for a power generation upgrade, and Cummins Power Generation Energy Solutions Business (ESB) was the vendor of choice for a turnkey solution.

Peter Hall, Viridor Regional Landfill Gas Operations Manager South East, takes up the story. “We had four Crossleys installed. They were 1 MWe with non-turbocharged engines, and we had been using them since the early 1990s. We wanted bigger engines to generate more electricity. So in 2008 we decommissioned the Crossley units and installed Cummins generator sets. They are 1.75 MWe each, so we generate 5.25 MWe.”

“The Crossley generator sets were coming to the end of their life,” comments Dick Turner, Director of Waste Energy, Viridor. “We went to Cummins ESB as they had the best proposal to fit into the building. The four previous generator sets were in one big hall. There were health and safety implications and it was a very noisy environment. One of the things Cummins ESB did was to build cells to accommodate the three new generator sets.”

Another important contribution from Cummins ESB was bringing in containerised generator sets to cover for the change-over period. These temporary units – known as ‘swing sets’ because they swing into operation and out again – minimised the loss of electricity generation while the changeover to new equipment was underway.

Viridor took the opportunity to have extensive work done at the site. “Everything was stripped out, the building was gutted,” Hall recalls. “When Cummins ESB built cells into the large engine hall, they also reconfigured the air inlets and outlets, and put a corridor in. The control room was stripped too.” All of this work was done on a turnkey basis, as Viridor required.

“Cummins ESB offered the most bangs per buck. They came out ahead in cost per kilowatt, and also in the operations and maintenance cost,” Turner observes. “Other solutions were just offering straight replacements, four for four. This way we reduced it to three generator sets, and we got a higher installed capacity. Also, the way the containerised units could swing in and swing out was a definite advantage. And Cummins ESB fitted out the buildings very well.”

Electricity at the South Ockendon landfill site is generated at 415 V and transformed to 11,000 V for export over two connections. Cummins ESB upgraded the switchgear as part of the turnkey solution. Gas from the landfill is fed through gas filters into the generator sets and two high temperature gas flares burn off excess gas and maintain environmental control. The only glitch that occurred in the whole operation was a cooling issue – the system was running a little too hot. Cummins ESB responded swiftly, and provided the solution by upgrading radiators.

The site is set to carry on as it is now for the foreseeable future. It is capable of taking more landfill, but tipping operations were discontinued around 1990. Environmental conditions are stable, and gas continues to be produced from waste that is in the ground already. Even without further tipping, the site could continue to generate electricity for 15 years or more. “It’s a good installation,” says Turner. “It certainly does the job.”

For more information about alternative fuel power systems or other energy solutions, contact your local Cummins Power Generation distributor or visit www.cumminspower.com/energysolutions.

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Environmental conditions are stable, and gas continues to be produced from waste that is in the ground already. Even without further tipping, the site could continue to generate electricity for 15 years or more.

A QSV91 generator set housed in its completed generator set cell Containerised generator sets provided power during construction