The biogas generated by the digesters can be used in two ways. One is cleaning the gas through the gas clean-up plant and exporting the natural gas (CH4) into the gas grid, the other way is fuelling a CHP.
The CHP (combined heat and power) is an engine that turns a generator using biogas as its fuel. The output is made up of 39% electricity and 61% heat.
The electricty used to power the plant is known as the paracetic load, a proportion is exported to the national grid. The heat is recovered and used to keep the digesters at optimum temperature.
The plant utilises two CHP’s:
It was commissioned in October 2012 producing 499kw of electricity per hour and utilising 230 m3/h of biogas. The CHP has been designed to run in a range between 40-70% methane. If the methane concentration is low (50%) the CHP will require more biogas to run the engine. If the methane concentration is higher the engine will require less biogas. This CHP was bought in a package from Biogas Nord but built by Pro 2.
It was commissioned in March 2015 producing 600kw of electricity per hour using 275 m3/h of biogas. This CHP was purchased from Edina UK Ltd.
Both CHP’s have full maintainace contracts with Edina UK Ltd.