The Field’s Point Wastewater Treatment Plant expects to save more than $1 million per year through a solar energy project funded by low-interest loans.
Three large wind turbines are helping to power the Field’s Point Wastewater Treatment Facility, saving money and reducing carbon dioxide emissions. The $14 million project will save more than $1 million per year out of the plant’s $2.5 million electric bill.
Owned by the Narragansett Bay Commission (NBC), the team at Field’s Point in Providence, R.I., began studying the feasibility of wind power in 2006 with a $35,000 grant from the U.S. EPA and $25,000 from the state Office of Energy Resources.
A quick payoff
The three 1.5 MW turbines went online in October 2012 at reduced capacity while some issues with connecting to the electrical utility grid were solved. Even with several months operating at 40 to 80 percent capacity, the turbines met NBC’s minimum goal. “Over the first year they provided about 42 percent of our electrical needs,” says Jamie Samons, public affairs manager. “We had determined it would be a win if we hit 40 percent.”
The turbines achieved full capacity in February 2014. In the first five months they produced 54 percent of the plant’s energy. Winds do drop in summer, so the annual production is expected to be about 45 percent, or some 7 million kWh per year.
While saving money, the turbines will reduce carbon dioxide emissions by 3,000 tons per year by displacing fossil fuels to the power plant, the state’s fifth largest electricity user. The plant provides secondary treatment for up to 77 mgd (average 55 mgd).
“It was about six years from the time we started the wind studies until the turbines were operational,” says Samons. “It does take a while.” The initial 18-month study looked at wind data, environmental impacts and economics. It determined that the site had enough wind resources to support three 1.5 MW turbines.
The original plan called for turbines 400 feet tall to the edge of the blades. However, the Federal Aviation Administration objected because the plant sits along the edge of the glide path to the T.F. Green Airport, the state’s largest. The FAA originally set a height limit of 265 feet.
At that level there was not enough wind to make the project economically feasible, so NBC sought help from the airport in analyzing the height restrictions. After further study and with significant involvement from U.S. Sen. Sheldon Whitehouse, the FAA agreed to 365-foot-tall turbines. “It took 18 months of going back and forth with the FAA,” says Samons. All told, it took three years from the start of feasibility studies to receive the go-ahead to pursue wind energy.
NBC received a loan for the project from the Rhode Island Clean Water State Revolving Fund at 1.7 percent interest, well below market rates. The state says its low-interest loans reduce project costs by 17 percent. “We had some venture capitalists and others look at it,” notes Samons. “It seems the turbines are efficient enough to be a good deal for us, but I don’t know that they would be commercially viable.”
Public reaction to the project has been positive. “We are located in the Port of Providence,” says Samons. “Our neighbors are a scrap metal company and some liquefied natural gas tanks. But we’ve had pretty great response to the turbines, even from people across the river on the West Bay of Rhode Island.”
Still, there was some controversy that can serve as a lesson for others considering wind projects. NBC built the turbines first, then did all the wiring and underground work. “So the turbines were up and not spinning for several months,” says Samons. “I was the one who got all the angry phone calls — ‘What’s the problem? Why aren’t they working? Is this a big boondoggle?’”
While people understood once it was explained, a change in the construction schedule would have helped avoid some of the perception problems.
Mix of providers
The Gilbane Building Company of Rhode Island developed the project with consulting assistance from Barnhart Crane & Rigging of Tennessee. General Electric offered technical assistance and advice even though it generally is involved in much larger wind farm projects.
Gilbane chose a multisynchronistic turbine design from Goldwind USA for its efficiency and ease of maintenance. Goldwind is a subsidiary of Goldwind Science and Technology of China, so 15 percent of the turbine was made in China. That made the project ineligible for stimulus grant funding from the U.S. government.
The 1.5 MW permanent-magnet direct-drive turbines have just one moving part. The design uses no gears, bearings or couplings and no slip rings or carbon brushes in the generator. That reduces maintenance and increases life expectancy. The turbines kick in at just 6 mph wind speed and can operate in winds up to 50 mph.
The 150-foot turbine blades were manufactured by LM Wind Power of Grand Forks, N.D. The 210-foot towers are from SIAG Aerisyn in Chattanooga, Tenn. The treatment plant staff operates the wind farm and Goldwind maintains the turbines.
Power from the wind farm goes directly to the treatment plant first. Any excess is purchased by National Grid, the local utility, through a net metering agreement. “There are days when we generate everything we need and provide some electricity onto the grid,” says Samons. “Hopefully we’ll be able to substantially reduce our energy costs and our reliance on fossil fuels.”
Samons says alternative energy is part of NBC’s strategic plan: “It not only saves money for ratepayers, but as an environmental agency it is one of our responsibilities.”