The volume and quality of biogas available at the site have changed over time – especially as the landfill has been closed for several years. This means the existing configuration of the old power generators struggled to provide reliable, efficient power as they did when the landfill was open and regularly refilled with waste.
Mike Curry, environmental systems manager for Durham County Council, recognised that a change in equipment was needed, and turned to Finning for expert support on the best approach.
“Making use of the methane produced by sites like Coxhoe is a great way to generate renewable power and prevent what is a potent greenhouse gas from entering the atmosphere,” said Curry. “Finning has played a crucial role in this and has supported our biogas generators for over 20 years, supplying a comprehensive maintenance and repair programme.
“So, they were our go-to experts for advice when we identified that we no longer had the right equipment for the methane the site is now producing.”
Clint Noble, senior sales manager at Finning UK & Ireland, explained: “It’s critical that the equipment used for biogas generation is right for the nature of the fuel available, as this can vary widely and dramatically impact the power generated.
“This was the case at Coxhoe where it had changed significantly over time, so we needed to find a way to help Durham County Council make the most efficient use of the methane available. Having worked with the team there for many years, we were in an ideal position to recommend the most effective solution.”
Analysis of the volume and quality of gas produced at the site confirmed that the current configuration of four 1MW generators was no longer suitable. Continued use of the generators would not only have meant unreliable production, but a potential shortened lifespan of the generators and increased servicing and repair costs, which could lead to generator downtime. This downtime can cause biogas to divert to the site Flare, combusting the wasted gas and creating unwanted carbon dioxide (CO2) emissions.
Finning instead specified two smaller units, a Cat 400kWe and Cat 600kWe, reciprocating power generators (CG132B-08 & CG132B-12) to replace two of the 1000kWe power generators. These would be able to cope better with the lower volume and more unpredictable quality of methane. This was backed with the same Finning maintenance and support package to troubleshoot issues before they cause unplanned downtime.
Durham County Council can now benefit from more consistent running times and outputs in their work to reach net zero.
Curry concluded: “We were very happy with the solution Finning provided, and the assurance that the maintenance and support package maximises uptime from the generators. We are now considering whether to add a further 600kWe unit given how well our current generator has coped with the methane produced at Coxhoe.”