Beca led the engineering design and implementation of the Burwood Landfill Gas Utilisation Project. The recently closed Burwood Landfill was generating significant quantities of methane – a greenhouse gas that has an impact 21 times greater than carbon dioxide. Rather than flare the gas to destroy the methane, a complex scheme was designed to harness the gas's energy, which was then used to heat and partially power the city's largest Pool and Sports Complex.
The key innovation on this project was creating a scheme that could transport gas to an alternative site that could convert the gas into both usable electricity AND heat. This consisted of collecting the gas via a network of gas wells, processing and compressing the gas in a treatment plant, then transporting gas via a dedicated 3.5 km 160 mm pipeline to the Sports Complex.
Other innovations included utilising gas absorption chillers instead of cooling the gas for dehydration with conventional electrical refrigeration. These were modified to allow them to be fuelled by the landfill gas itself. Rather than change the boilers to landfill gas, a new burner system was developed and installed, allowing the boilers to be converted back to LPG firing in less than 15 minutes.
Commissioned in May 2007, the scheme's operational reliability has exceeded expectations, and has resulted in $1 million plus savings in electricity and LPG costs. With an expected commercial lifespan of around 15 years, this scheme has become a significant asset to the city of Christchurch.
The project's positive environmental effects have been recognised with over NZ$3 million in Kyoto Protocol carbon credits assigned for its first five years of operation alone.
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