November 14, 2008

DAYTON AND KNIGHT LTD.

The micro turbines at the Prince George wastewater treatment plant convert gas from the plant’s digester into energy and back up power.

Micro turbines improve efficiency of Prince George wastewater treatment plant

Jim Stirling

correspondent

A recent upgrade to the City of Prince George’s wastewater treatment plant is reaching its objectives of function and energy efficiency.

Five new high-speed micro turbines have been installed, which convert gas from the plant’s digester into energy and back-up power for the operation.

“The turbines are small, identical, modular units which are like little jet engines,” described Marko Fornari, manager of the utilities division for the City of Prince George.

The new equipment is manufactured by Capstone in the United States and typically operates at around 98,000 rpm, he said.

Fornari estimated that the new system will lower greenhouse gas emissions by 2,800 tonnes annually and contribute a three to four per cent natural gas cost offset.

The plant’s former system, a diesel engine linked to methane emanating from the digester, was in need of replacement.

“We looked at different technologies, including fuel cell, but that was very expensive,” Fornari said.

During its research, the city discovered a similar system was working well at an application in Portland, Oregon.

And, at $75,000 per unit, the system was affordable.

“We’re looking at about an eight year pay back,” he explained.

Fornari said the new system was still going through its start-up curve and it was too early to get a handle on regular maintenance costs.

The wastewater treatment plant is staffed by instrumentation and control systems personnel.

The team quickly became familiar with the new equipment and the transition has been relatively easy.

The energy efficient turbines represents a continuing trend for the Prince George plant, which is designed to meet the needs of a population of about 110,000 people.

“Our treatment centre is well designed and very energy efficient,” Fornari said.

“We know that from the interest shown in it by our benchmarking group of cities and regional districts across Canada.”

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