Micro Turbines Begin Generating Power

A Conservation Improvement Program (CIP) project co-sponsored by the Minnesota Department of Commerce (DOC) and Alliant Energy is now capturing methane biogas...

At Minnesota Wastewater Treatment Facility

A Conservation Improvement Program (CIP) project co-sponsored by the Minnesota Department of Commerce (DOC) and Alliant Energy is now capturing methane biogas produced by the wastewater treatment process at the City of Albert Lea, MN, Wastewater Treatment Facility and burning the gas to generate electricity and heat.

The heat that is generated from the gas is used to help maintain the proper temperature in the waste digester and the electricity is used to power the wastewater treatment facility's equipment. The facility has four 30 kW Capstone MicroTurbines™ that can produce 2,500 kWh of electricity per day at peak gas production and 28 million BTUs of heat per day.

"We are pleased to be the first wastewater treatment facility in the state of Minnesota to use Capstone MicroTurbines to supply a portion of our own heat and electricity needs," said Rick Ashling, plant superintendent, City of Albert Lea wastewater treatment facility. "This has been an exciting and interesting project for us, and the results couldn't have been more positive."

Capstone MicroTurbines are ideally suited for wastewater treatment facilities because they convert methane biogas into electricity without the noise, vibration, and maintenance issues of reciprocating engines. The City of Albert Lea and the Minnesota DOC each purchased two Capstone MicroTurbine units, which were installed in summer 2003 by Unison Solutions, of Dubuque, IA.

The Albert Lea wastewater treatment facility project met the requirements to be a CIP project because it saves electricity and/or natural gas by using distributed generation and cost effectively uses renewable fuels.

"We're impressed with the effectiveness of this technology, and hope to encourage other Minnesota cities to consider capturing methane biogas to not only protect Minnesota's environment, but to save energy," said Lois Mack, manager, Conservation Improvement Program and Special Projects, Minnesota DOC.

"Protecting the environment and conserving energy are also important goals at Alliant Energy," said Diane Ramsey, managing director, Sales and Strategic Accounts. "As we plan for our customers' future energy needs, we recognize the important role that distributed generation will play in our planning."

According to Ashling, the Albert Lea wastewater treatment facility is currently undergoing a significant renovation. The final phase of the methane gas system project was to start in May with the replacement of a digester holder cover, which will provide more gas storage for the microturbines.

As a result, the amount of available biogas varies considerably, while its current waste volume is 4.5 millions gallons per day. The Capstone MicroTurbine system, specifically designed to allow for the operation of any combination of the four micro turbines, promotes optimal use of the available biogas.

Alliant Energy is an energy-services provider that serves more than three million customers worldwide. Providing its regulated customers in the Midwest with electricity and natural gas service remains the company's primary focus. Other key business platforms include the international energy market and non-regulated domestic generation.

Capstone Turbine Corporation is a producer of very-low-emission microturbine systems used for onsite power production. In 1998, Capstone was the first to offer commercial power products using microturbine technology, the result of more than 10 years of focused research.

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