Power Afloat

Solar photovoltaic panels on a New Jersey reservoir provide a test for a concept that could expand opportunities for renewable energy for water agencies
Power Afloat
The 400 solar panels have a combined 112 kW capacity.

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The forest-encircled Canoe Brook reservoir in New Jersey is home to many bird and native plant species — and now 400 floating solar panels that help power the nearby Canoe Brook Water Treatment Plant. With a capacity of 112 kW DC power, the solar array contributes 1.3 percent of the treatment plant’s power (135,000 kWh annually) and has potential to expand.

Located 14 miles west of Newark in Millburn, N.J., the reservoir and treatment plant are owned and operated by New Jersey American Water. As part of its goal to reducing fossil fuel usage and its carbon footprint, the company chose solar energy to address growing power needs.

The company has installed or planned nine ground-mounted and roof-mounted solar energy projects totaling nearly 3 MW since 2005. The Canoe Brook is the East Coast’s first floating solar array designed to withstand a freeze/thaw environment.

 

Testing a floating array

Installed in October 2011, the Canoe Brook project will test the maintenance and operational constraints of a floating solar energy system exposed to freezing temperatures and contact with wildlife.

“With ground-mounted solar systems, there is very little maintenance, and we expect that to be the case for this floating solar array as well,” says Bob Biehler, senior project manager at New Jersey American Water. “But there is no bubbler system to stop the entire dock system from being encapsulated by ice. Will it twist the frame and result in deformed members or affect the flotation of the dock system? Will flexing damage a solar module? We want to learn whether there will be maintenance risks for this system.”

If the test proves successful, the solar array, now 100 feet by 110 feet, could theoretically be expanded to up to 25 acres to handle 100 percent of the water treatment plant’s power needs. In addition, floating solar arrays could be installed at other New Jersey water plants that experience less severe temperature changes.

Another concern is the potential for animal interference. The reservoir is in a lushly forested area with abundant wildlife. The company is monitoring the system to see whether birds will interfere with the system, and in turn whether the array affects wildlife.

One expected benefit of the array is improved water quality through reduction in algae. The floating structure provides shade, which discourages algae growth. “The array is near the intake structure, so by shading that area, we may get a benefit in water quality,” says Suzanne Chiavari, vice president of engineering.

Algae is the main component removed at the Canoe Brook plant, so less algae in the source water may reduce chemical usage during treatment. The company is monitoring algae levels during the testing period.

 

Solar feasibility

The secluded nature of the Canoe Brook site is part of what made it attractive for the solar array. Beginning in 2009, New Jersey American Water worked with ENERActive Solutions of Asbury Park, N.J., to evaluate 15 to 20 sites in a one-year feasibility study. Canoe Brook emerged as a top site because it is exposed to sun throughout the year, is close to a water treatment plant, and has nearby access to overhead electric power lines.

Although the property is more than 500 acres, only seven acres are buildable, and that space is already occupied by the treatment plant. With a 200-acre surface area, the reservoir is an ideal location for the floating solar panels.

Once four sites were chosen for different solar energy projects, New Jersey American Water developed a capital budget plan, obtained approval from the local planning boards, received permits from the state Department of Environmental Protection, and began planning. Design and construction of the Canoe Brook project took only a few months.

 

Unique design

To engineer the floating array’s docking system, ENERActive Solutions turned to Poralu Marine of St. Eustache, Quebec. The flotation components are HDPE-covered foam blocks robust enough to handle harsh weather and freezing.

On the aluminum dock, the array, developed by ENERActive Solutions is designed just like a ground-mounted system. A racking system holds each 77- by 39-inch solar panel at a 14 degree angle for sun exposure. Each panel, made by Suntech Power Holdings Co. in Wuxi, China, can be easily removed or replaced as needed. Deflector shields on the back sides of the panels protect against wind damage.

Under the dock, the mooring design is more complex. The reservoir, built in the 1920s, holds up to 735 million gallons pumped from the Canoe Brook and the Passaic River. Depending on demand and time of year, water levels can fluctuate by up to eight feet.

To accommodate water level changes and avoid perforating the bottom of the aging reservoir, the dock is connected to concrete block anchors with a Seaflex elastic mooring system (Seaflex AB, Umeå, Sweden) that involves numerous crisscrossing rubberized hawsers. The flexible mooring provides the right level of tension to hold the array at a proper orientation for maximum solar benefit throughout the year.

 

Potential savings

For many communities, the water treatment plant is the greatest electrical power draw, so that is often where utilities seek alternate energy sources. “Most people don’t realize how much energy it takes to purify and pump water to homes and businesses,” Chiavari says. “We are using power every day, 24 hours a day, 365 days a year. Solar power is well worth the investment.”

For the Canoe Brook project, New Jersey American Water expects a savings of $16,000 annually from energy no longer bought off the grid. In addition, the New Jersey Board of Public Utilities offers clean-energy incentives in the form of solar renewable energy certificates (SRECs). When a utility does not meet its target clean energy generation goal by certain deadlines, it can buy SRECs from businesses and households that generate solar energy.

SREC values fluctuate depending on the demand on the energy grid. New Jersey American Water is working to get its power needs off the grid, but as its solar power program expands, the company hopes to sell SRECs in the future.

The Canoe Brook project has applied for a rebate from the American Recovery and Reinvestment Act of 2009 (ARRA) for 30 percent of design and construction costs. “The ARRA helped to generate more clean-energy projects and drive the environmental benefit while creating a lot of jobs in New Jersey,” Chiavari says. “There are many solar projects being installed across New Jersey, creating a substantial number of jobs.”

As a result of the rebate, reduced electric costs and potential SRECs, New Jersey American Water expects the Canoe Brook project to see a return on investment of less than 10 years. Payback for a standard ground-mounted solar project is usually less than five years, but research, development, engineering and other costs for this unique floating array were higher.

 

Plant updates

The Canoe Brook treatment plant is undergoing an upgrade to meet new surface water treatment regulations that take effect in 2012. The plant, built in 1929 and expanded in the 1940s and 1950s, uses conventional clarification and sand filters to produce an average of 10 mgd, although the design capacity for the new plant includes 5 mgd from groundwater and 14 mgd from surface water. Once renovations are complete in 2012, the plant will have a maximum daily capacity of 22 mgd.

The updated treatment plant will clarify surface water using a pre-ozone system and a dissolved air flotation process, followed by granular activated carbon filters that minimize disinfection byproducts (the primary update needed for the new regulations). The water then will be disinfected in the storage tank before delivery to customers. Groundwater circumvents the earlier steps of the process and goes directly to the storage tank for disinfection. The Canoe Brook facility serves a population of 126,000 people in 10 communities, representing about 25 percent of the drinking water within the Passaic River basin system.

 

Improved sustainability

New Jersey American Water will pursue Leadership in Energy and Environmental Design (LEED) certification for the renovated Canoe Brook treatment building, which is separate from the pumping system. Biehler is confident the facility will receive certification.

“The facility will use natural light where possible and energy-efficient/low-use fixtures,” Biehler says. “The plant will be laid out so we can recycle the majority of our sampling stream to go back to the head of the plant instead of going down the drain and burdening the sewer system. During renovation, we will recycle demolition materials from the older buildings.”

Sustainability and solar power will continue to be an emphasis for New Jersey American Water as the company looks for ways to control costs and be a good environmental steward. “I would love to say all our facilities are powered by the sun, but we’re not there yet,” Chiavari says. “It’s not as inexpensive as it probably will be 10 years from now, but it would be a great goal to have water delivered to your tap through the power of the sun.”



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