Taking its cue from the Municipal Authority of Westmoreland County, the Pennsylvania American Water Co. has turned a problem into a benefit by going with the flow, literally.
The high pressure of raw water flowing from two reservoirs into the Oneida Valley Water Treatment Plant in Summit Township, Butler County, initially prompted PAWC to install a butterfly valve to crimp the flow into the plant. High water pressure can burst a pipe.
But company officials soon realized that crimping the pipe with a valve was one big waste of renewable energy. A better strategy, they concluded, was to use excess water pressure to turn a turbine generator and produce electricity for the treatment plant.
The plan produces energy and reduces water pressure.
To accomplish that goal, PAWC has partnered with Rentricity Inc., a New York-based company with offices in Pittsburgh, to generate renewable energy with the company's Flow-To-Wire system. The in-pipe generator, in operation since early February, includes a generator wheel inside a casing that water flow spins at 1,200 rpm, enough, officials think, to produce 20 to 25 kilowatts of power for the plant.
The project required a chamber to be built 15 feet below grade with some rerouting of inflow pipes from its Thorn Run and Oneida reservoirs so they enter the plant through a common pipe. The turbine reduces the pressure while producing about 5 percent of the plant's average requirement of 485 kilowatts to treat then distribute water to 18,000 customers in Butler and surrounding municipalities.
PAWC has 2.2 million customers, including 290,000 in Western Pennsylvania.
Daniel J. Hufton, the water plant's senior director of production, said the water-delivery process -- pumping water from reservoirs to the treatment plant, then to storage facilities and finally to customers -- accounts for 97 percent of the Oneida plant's electricity consumption and 90 percent of its greenhouse-gas emissions. The plant processes 6 million to 6.5 million gallons of water each day.
The turbine generator, with a 40-year lifespan, will allow the company to recover project costs of $660,000, including a grant from the Pennsylvania Energy Development Authority, while reducing s greenhouse gas emissions by 113 tons a year.
Frank Bursic, Rentricity regional director, said most systems pay for themselves within five to seven years. The Oneida plant conceivably could pay for itself in 10 years, which means 30 to 40 years of electricity savings for the company.
PAWC got the idea to use Rentricity technology to turn excess flow into electricity from the Municipal Authority of Westmoreland County, which has used the same technology for two years, but in a different way.
That authority is required daily to release 6 million gallons of water from its Beaver Run Reservoir into Beaver Run near Slickville. Through a $330,000 project, 75 percent of it paid with a state grant, water released through a pipe fitted with a turbine generator produces up to 30 kilowatts of electricity -- enough to run the pump station at the reservoir, said John Ashton, the authority's assistant manager.
The authority plans to cover its investment in 3.5 years with annual savings of $20,000 in electricity costs. That has convinced it to consider using turbine generators rather than pressure-reducing valves, similar to PAWC's project, at various locations in its waterlines.
The authority then would generate about 100 kilowatts that would save the authority up to $100,000 a year, Mr. Ashton said.
"We take a good look at the pay-backs and found that this would be advantageous for us on the environmental side and for our customers," he said.environment - neigh_north
David Templeton: email@example.com or 412-263-1578. First Published April 23, 2012 12:00 AM