The Bolivar Wastewater Treatment Plant (BWTP) is the largest wastewater treatment plant in the Adelaide region, processing almost 70 per cent of Adelaide’s metropolitan wastewater. The South Australian Government has approved a $25.8 million project for SA Water to optimise the energy utilisation on the site, which will provide a major upgrade to the BWTP power supply via the installation of on-site electricity generation, fuelled with the digester gas produced during the treatment plant process.

In May 2012, Clarke Energy Australia was awarded the contract to design and construct a fully operational turnkey gas-to-power cogeneration plant using GE Jenbacher gas engines, and to fully integrate the electricity generated into the existing electrical infrastructure.

No wastage at the wastewater plant

Clarke Energy’s cogeneration power plant design provides three GE Jenbacher highly electrically efficient dual-fuel gas engines installed inside of the existing power house, each 2.4 megawatts in capacity. The gas engines will operate either solely on digester gas or a blended mix with natural gas during times of low digester gas production.

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Once completed, the plant will generate up to 85 per cent of the plant’s annual electricity demand. This means annual electricity savings of $1.3 million with a capital payback period estimated at eight years.

A clean and efficient source of power

Clarke Energy Sales Manager Martin Smith says there are a number of benefits for adopting cogeneration technology.

“Cogeneration provides a clean and efficient source of heat and power, in this case from a renewable fuel source,” he says. “Cogeneration from biogas means that the by-product of the sewerage treatment process is used to generate heat and power which would have otherwise been provided by the grid.

“In addition, cogeneration systems lessen the reliance on centralised power stations, and can negate the need for expensive network augmentation.”

The project is due to be commissioned in July 2013, when it will be handed over to the facility’s operations and maintenance alliance contractor, Allwater.