Harnessing Available Resources For Utility Energy Independence
By Jason Wert
Water utilities in search of energy- and cost-saving opportunities can look to the sky — or to Sayreville, NJ — for inspiration.
In the utility sector, one constant is balance — such as balancing the need to invest in technology to maintain operational excellence while simultaneously keeping the overall cost of service within budgetary constraints.
As RETTEW advises utilities throughout the U.S., the topic regularly turns to clients wishing for more control over the types and costs of energy for their utility operations. Typically, energy costs are one of a utility’s largest recurring expenses, only secondary to labor costs and capital obligations.
Working with a diverse group of public and private utility entities, RETTEW has seen a tremendous uptick in innovative energy management. A key theme of successful projects in this movement is using the resources already available to a utility to maximize energy management. While some utilities may have abundant wind or hydropower options, many urban utilities are constrained by available land and the encroachment of neighboring residences and industry, limiting their options. Each utility has approached energy management with an open mind, combining creative ideas with new options to take their operations into the future.
Borough Of Sayreville
One such utility in northern New Jersey found a creative option to enhance its energy management while limiting negative impacts to the surrounding community.
The Borough of Sayreville provides water service to about 42,000 residents through the treatment and distribution of water sourced from the Raritan River.
With a conventional water treatment facility, the borough has managed to provide cost-effective support to its customers with about 7 MGD of potable water service. With rising energy costs in the state, the borough was looking to find energy from a stable and predictable supply.
Solar Market
The solar energy market in New Jersey is one of the most attractive in the nation, with elevated pricing for renewable attributes and third-party partners available for both financing and development. Solar equipment prices have dropped by more than 60 percent since 2009. Major companies are investing in solar energy, such as Target, which has 147 megawatts of solar generating energy panels installed at 300 of its stores. And it’s not only large, national companies. Small and midsize utilities have embraced solar at a rapid pace, providing sustainable energy to drive their operations.
However, the borough still faced challenges with its dense, urban surroundings and limited options for conventional solar field energy generation.
Floating Solar
Partnering with J&J Solar Power, LLC, and RETTEW, the borough decided to embark on a floating solar array at its raw water reservoirs. The borough awarded J&J the execution of a solar photovoltaic (PV) power purchase agreement to reduce both the annual electricity costs to the operation of the borough’s Bordentown Avenue Water Treatment Facility and to increase the borough’s sustainability by reducing carbon emissions. The execution of the agreement allows the borough to enact an energy savings program and reduce a large amount of its operational costs.
The benefits of a floating array in this location included taking advantage of an area otherwise underutilized, a reduction in the amount of environmental disturbance on the site compared with a land-based array, and a significant reduction in the number of trees removed to accommodate the system. A floating solar array also stays cooler, which increases output efficiency and reduces evaporation from the water surface it covers by nearly 90 percent.
System Design
RETTEW designed the solar array at 4.4-megawatts (DC), needing about 10.2 acres of reservoir area. The reservoir surface would be covered with more than 12,000 345-watt PV panels on a proprietary floating solar array produced by Ciel et Terre.
The Ciel et Terre array installs on a floating ballast system specifically designed for waterborne solar installations. Each ballast section is interlocked with the adjacent ballast sections to create a single mat able to withstand wind and other environmental factors. The ballast system is tethered to shore at several points by cables tied to anchor points. With this system, there is no need to disturb the reservoir floor, protected under New Jersey regulations and a key facet of the project permitting.
PV panels at the Bordentown Avenue Water Treatment Facility
The power cables extended from the array to the shoreline at several locations consist of marine-grade cable supported by floating pontoons. Once on the shoreline, the power cables from the array connect to inverter/ transformer pairs and then combine to connect to a single point of interconnection at the borough’s water treatment facility. Access for maintenance and inspection is provided by a series of gangplanks at intervals along the shoreline as needed.
Net Metering
As RETTEW designed the floating solar array to produce approximately the annual electrical load of the water treatment facility, the installation qualifies for net metering under New Jersey regulations. Power produced by the floating solar array is fed directly into the treatment plant’s electrical systems, displacing grid-based energy. This results in an immediate reduction in the usage and load at the borough’s treatment plant.
However, during favorable periods (given the array sizing, this is most periods of production), the solar array will generate more power than the borough treatment plant needs. Through a bidirectional meter installed during the interconnection process, this excess power is credited against the borough’s electric account charges up to the annual generation amount. In effect, the electrical generation costs and electrical distribution costs can be displaced by the power purchase price under the agreement.
Largest In U.S.
Constructed by Solar Renewable Energy, LLC, and Meadow Valley Electric, this floating solar array is the largest in the U.S. Initial construction is underway with a projected operational start-up in October 2018. RETTEW’s team of engineers and scientists led the program, including developing a regulatory permitting pathway with the New Jersey Department of Environmental Protection and designing critical components such as the shore anchoring. Working in collaboration with the borough and the team of professionals needed for an innovative application, the entire Sayreville Floating Solar Array project will deliver long-term power to the borough at a reduction of an estimated 24 percent over current electrical pricing.
While not every community will have the set of conditions that allowed the Borough of Sayreville to capitalize on its resources, the concept of floating solar is another example of a leading utility partnering with industry to manage its energy efficiently and innovatively.
About The Author
A senior technical engineer, Jason Wert is responsible for the development and technical evaluation of traditional and renewable energy projects throughout the U.S. With more than two decades of experience, he brings a practical project knowledge in financing, development, and structuring of public and private energy projects. He is a national expert in the planning, development, design, construction, and operation of membrane treatment, anaerobic digestion, and renewable energy projects.