Atlantic City is known for gambling, but the City Island Wastewater Treatment Plant’s energy and environmental initiatives are far from a roll of the dice. Instead, this 40-mgd activated sludge plant finds success by combining strategic energy conservation practices with some of the largest wind and solar initiatives in the wastewater sector.
It’s all about rate stabilization and environmentalism, says Tom Lauletta, P.E., vice president for the Wastewater Division of the Atlantic County Utilities Authority (ACUA), which oversees the plant and the regional wastewater collection system.
“We were looking at 15 percent annual increases in combined energy costs every year at one time,” Lauletta says. “Everything we do is designed to keep our rates affordable and efficiently treat the wastewater.”
The strategy has paid off. The plant saves more than $1.6 million per year in energy costs. Additionally, energy represents 20 percent of the plant’s overall budget, down from 30 percent only a few years ago. The efforts have even turned the plant into a tourist attraction, and its operation has received numerous awards from the National Association for Clean Water Agencies.
Starting from within
The City Island plant realized that the first step toward energy savings was to reduce consumption of electricity and natural gas. As such, it targeted improvements in aeration and biosolids processes.
At one point, roughly half the plant’s total 2.3-MW demand was for aeration, largely to drive four aerator impellers in each of the plant’s six aeration tanks. The plant switched out the old-style impellers with more efficient screw-type mixers manufactured by Philadelphia Mixing Solutions.
It also tied the new mixers into a SCADA system for automated and continuous control based on varying dissolved oxygen requirements. The project was completed in 2006. The result is an 8 percent reduction in energy use, saving $96,000 year.
“Before, we were running our mixers on high speed, possibly exceeding the need for oxygen, or at low speeds, and not meeting the oxygen needs,” Lauletta says. “The new aeration process lets us match the oxygen demand throughout the day and all year. We only have to monitor the system as opposed to manually operating it.”
At the same time it tackled aeration, the plant staff set out to feed its incinerator with dryer biosolids to reduce natural gas consumption. They replaced two 20-year-old centrifuges with newer ALDEC 706-G2 centrifuges (Alfa Laval). The new units increased solids content from 25 percent to 32 percent. That, in turn, has reduced natural gas consumption by 23 percent, for annual savings of $429,000.
Riding the wind
While working on energy savings, ACUA began discussions with Jersey-Atlantic Wind LLC, about using wind power to supply part of the plant’s electrical needs as part of a long-term lease/power purchase agreement (L/PPA).
“We happen to be in a very windy location and the wind developer thought our site would be ideal for wind turbines,” says Lauletta. “They wanted to put the turbines in and we said, ‘Okay, as long as it doesn’t cost us anything.’”
In addition to its location on the windy Atlantic Coast, the treatment plant had the land and electrical infrastructure in place to accommodate the proposed wind farm. Funded fully by private investors and a variety of government grants, ACUA moved forward with the $12.5 million wind farm in 2005. Considered the first coastal wind farm in the northeastern United States, it includes five 1.5-MW wind turbines (GE). It began operation in 2006 and meets nearly 60 percent of the plant’s power needs.
Under the 20-year L/PPA, ACUA will purchase power for 7.95 cents per kWh for 20 years. That compares with approximately 13.5 cents per kWh for utility power. The agreement saved $664,146 in 2008, including $15,000 ACUA collects as the wind farm’s landlord. To date, the plant and its ratepayers have benefited to the tune of $1.7 million.
City Island plant operators assist with wind farm maintenance on occasion, although GE is primarily responsible for maintenance. “When the GE person needs help, we provide some labor to assist,” says Lauletta, “but we didn’t have to staff up for it, plus we actually get a little revenue from it.”
An added benefit of the wind farm is publicity for renewable energy sources: The 380-foot-tall towers attract a lot of positive attention. Each year, the treatment plant plays host to thousands of visitors. “I think it was last year when we were giving a tour and a family wanted to know where the gift shop was,” says Lauletta.
Solar pays dividends
The notion of cost-effective wind power drove ACUA to consider solar power, as well. “The benefits of wind power were much more than we anticipated, but solar is much, much better than we anticipated,” says Lauletta.
ACUA teamed with WorldWater & Power Corp. (now Entech Solar) and SunDurance Energy LLC to install a 500-kW photovoltaic system at the treatment plant in 2005. The system includes 2,800 Sharp solar panels in five arrays, which include four separate ground- and rooftop-mounted units. The fifth unit is a canopy array over the employee parking lot.
Through 12 months ending in May 2008, the system generated 665,737 kWh to meet about 3 percent of the plant’s power needs. That year, the plant saved just over $90,000 by not having to purchase power. In addition, ACUA can sell Renewable Energy Credits (RECs) to others in the state.
One REC is equivalent to 1,000 kWh. Initially, each REC was worth $150, but that has increased to $640. In 2008, ACUA generated $338,416 by selling the credits. When it’s all said and done, the agency expects a five-year payback on the solar system.
Lauletta says solar power is easy to own and operate. “We thought there would be more maintenance, but solar has been wonderful as far as that’s concerned,” he says. “It just sits there and makes power.”
Doing even more
ACUA also takes advantage of an energy curtailment program through North American Power Partners (NAPP), an electric utility demand service provider. The program helps industrial users lower energy costs and reduce demand on the grid.
Under the program, NAPP is allowed to ask the treatment plant to reduce power consumption for 15 minutes once a month during the utility’s peak demand period. At those times, the plant shuts down its aeration system and effluent pumps. The arrangement generates $50,000 in revenue without adversely affecting processes. The plant receives the savings even when not asked to curtail power consumption. “It has very, very little effect on the system and we’re paid to be sitting there ready to do it,” Lauletta says.
The City Island plant is looking into more ways to save energy and help protect the environment. The staff is studying the feasibility of capturing waste heat from the plant’s incinerator and using it to generate electricity. A fats, oils and grease program is also on the drawing board.
All in all, the plant has made significant strides in reducing its dependence on fossil fuels. Says Lauletta: “We definitely take a lot of pride in our energy program.”
