Turning Biogas into Cash
Until early 2009, the carbon footprint of a wastewater treatment center outside of Cossato, Italy, was partly measured by the flare that burned continuously above the plant. The flame was fed by the biogas that until recently, had been considered a nuisance byproduct of the treatment process. Managers of the plant soon realized there was potential in this flared energy, so they turned to Capstone Turbine Corp. and the flame was put out.
Now, a single Capstone CR200 turbine provides all the electrical power needed at the treatment plant, along with heat to make the plant’s digesters work at optimum efficiency. The combined heat and power (CHP) system can operate efficiently with methane concentrations that range between 50 and 80%. The CR200 is expected to produce 1.7 million kilowatt-hours annually to supply the plant’s electrical power needs by using the 2600 m3 of gas that had been previously burned as waste. An external heat exchanger installed with the microturbine delivers another 2.3 million kilowatt-hours of thermal energy to warm the digesters. This CHP plant is expected to cut carbon dioxide emissions at the plant by 1633 kg per year.
The plant’s Chief Technology Officer, Civil Engineer Fabio Dalla Villa, said Capstone’s CHP package fit the bill perfectly. “I discovered that turbine systems have lower maintenance costs and better performance in hot-water production,” he remarked. “We need hot water in the waste treatment process and are very interested in new systems.” The Cossato plant serves a cluster of small cities with a combined population of 75 000 in the foothills of the Italian Alps in Northwest Italy. Cossato might soon become a destination in its own right for operators of wastewater treatment plants seeking the same financial and environmental benefits that the Cossato Spolina plant discovered.
European biogas applications for Capstone’s technology are still in the early stages, as natural gas-burning turbine installations are far more common. The Cossato Spolina project has attracted attention and may serve as a model for other wastewater treatment plants. “Cossato Spolina is an important reference installation in Italy and also for the rest of Europe,” said Ilario Vigani, a senior sales executive with Integrated Building Technologies, SRL, the Capstone distributor based in Treviso, Italy.
Vigani’s next Capstone customer might as well be Cossato Spolina itself. Dalla Villa and other managers are completing an evaluation of the first CR200 installation that he said likely would lead to another. Plant managers predict that savings realized from the on-site generation of electrical and thermal power, plus the “green” incentives offered by the Italian government, will justify installation of a second CR200 system in 2010.
“I prepared the system for expansion,” said Dalla Villa. “I plan to demonstrate that a second CR200 will be economically useful. In the meantime, I can show the economic evidence of our investment so far.”
Outsmarting Mother Nature
For years, a U.S. laboratory in the Southern United States completely relied on electricity from the local utility to power the building and sensitive laboratory documents. Disaster first struck in 2005, when Hurricane Katrina destroyed its original location. Just two years later, Hurricane Ike battered the center’s new offices. After years of design engineering, the new laboratory opened in April 2009. Needing a power source more reliable than the local utility and realizing an opportunity to gain greater control over energy costs, fficials decided it was time for a change. Capstone Turbines was contracted to provide microturbine-produced on-site power for emergencies and to reduce peak demand from the utility.
In early 2009, Capstone installed its UPSource an independent IT-grade power source that doesn’t rely on the electrical utility and eliminates the need for large banks of DC-storage batteries at the laboratory. The installation features a total of six Capstone C65 natural gas-fueled microturbines. Two units run 24 hours a day, 365 days a year in a redundant configuration. Even with the loss of a single microturbine, the Capstone installation remains a continuously running uptime solution with nearly eight 9’s of reliability for N+1 configurations. Each microturbine has only one moving part and no fluids, meaning fewer breakdowns.
Four other C65 units operate at the laboratory in various modes to ensure the site can support laboratory staff with HVAC system power, lighting and domestic power through an extended outage. These four microturbines operate in parallel and synchronously to the local electric grid. The system can recognize a loss of stable utility power, immediately disconnect from the utility tie, and then step back into a smaller and isolated set of critical loads.
Five of the six Capstone microturbines create a combined UPSource/dual-mode installation that provides on-site electricity and a steady supply of hot water to the labs, as well as building requirements. Each unit produces 74 kW of clean waste heat used to heat the hot water. The ICHP microturbines have eliminated the need for a secondary boiler system. In addition, without the use of any additional energy costs, the system can operate at efficiencies greater than conventional UPS systems and diesel generator backup systems. Capstone also offers IT System Application assistance for all UPSource applications.