Stone Pit Landfill Site, Dartford, UK
Stone Pit 1 is a large historic landfill site located near the Dartford Crossing in Kent. Site owner, UK land specialist, Land Logical, began the first stage of a site restoration project in May 2015. Land Logical inherited a large and complex buried landfill gas management system which had grown ‘organically’ over many years with little being available in the way of installed plans or schematics. The system had a number of separate gas flows with different methane levels and a legacy landfill gas flare which was not operational.
Landfill Systems supplied Land Logical with a conventional elevated hire flare for pumping trial purposes. The poor condition of the legacy gas management system meant that uninterrupted flaring was difficult to achieve because of low methane levels. The main sustainable gas flow was estimated to be around 600m3/hr at 20% methane. Landfill Systems designed and constructed an LC1250 Low Calorie flare which was installed in April 2017. The flare was installed and commissioned in one working day. A sustainable gas flow of 455m3/hr at 14% methane was quickly established.
Now with sustainable flaring on the site, Land Logical were better able to understand the complexities of their inherited gas management system. Many improvements and replacements were made resulting in the establishment of two distinct gas flows; one with relatively high methane content suitable for power generation and one with lower methane content which needed to be flared to maintain environmental control.
Renewable energy company, NewEnCo, were brought in to supply and install a Capstone micro turbine which is operated under the UK Government’s micro generation scheme, exporting 50kWe and attracting 1.8 ROC’s per MWh. Because of the separated nature of the gas flows on the site, Landfill Systems designed and constructed a stand-alone booster package to supply higher calorie gas to the Capstone engine. The package automatically diverts the gas flow to the flare when the micro-turbine is stopped.
Land Logical invested further in their gas management system, resulting in a significant increase in the higher calorie gas flow. It became apparent that more gas was available than the micro turbine could use and so NewEnCo supplied and installed a Scania spark ignition engine to use the excess gas flow. Landfill Systems designed and converted a standard ISO container to package the Scania engine. Another, larger booster package was also supplied to pump gas to the new engine.
By embracing the many years of landfill gas experience and know how provided by Landfill Systems and NewEnCo, Land Logical have achieved:
• Full control of their gas management system.
• World class site emissions levels.
• Maximum financial benefit from the production of renewable energy from their landfill gas resource.
Landfill Systems and NewEnCo continue to support the installations at Stone Pit with regular maintenance regimes and full remote access and monitoring services.