Water utilities are increasingly turning to on-site power systems to help reduce energy costs. Three recent projects include use of a waste heat turbine generator, an in-pipe turbine system that generates power from water flow in pipelines, and a floating island solar system.
Water utilities are increasingly turning to on-site power systems to help reduce energy costs. Three recent projects include use of a waste heat turbine generator, an in-pipe turbine system that generates power from water flow in pipelines, and a floating island solar system.
The Massachusetts Water Resources Authority (MWRA) recently completed a project to improve the efficiency and overall performance of the Deer Island Wastewater Treatment Plant. Energy-efficient infrastructure upgrades included:
- A waste-to-energy boiler plant that uses methane from the wastewater treatment process to generate steam for space heating and treatment process requirements.
- One 18,000 kW back pressure steam turbine generator (BPSTG).
- Two 600 kW and one 100 kW wind turbine generators.
- Two 1,000 kW hydro turbine generators.
- 700+ kW photovoltaic paneling on facility rooftops.
In addition to its existing upgrades, MWRA identified an opportunity to improve efficiency by modifying the existing back pressure steam turbine generator to a condensing unit, yielding more power for each pound of steam generated. However, this solution required delivery of steam to the plant for its use and to supply a heat loop.
SourceOne, energy management and consulting services subsidiary of Veolia Energy North America, worked with the MWRA to install a new 1.1 MW BPSTG that would exhaust at 15 psig and serve the plant and the heat loop, while generating additional power.
SourceOne focused on developing a conceptual design to integrate this additional power source and select a Design Build firm to complete the design, install the additional equipment, and commission the equipment for MWRA's use. The installation of this new generator will enable the MWRA to take advantage of excess heat produced in the summer, as well as enabling other process efficiency improvements. In addition to making the larger generating unit more efficient, it will generate additional power from the waste heat that can be used productively as "free" energy for the facility.
In-Pipe Hydropower System
In a separate project, the Portland Development Commission (PDC) and the City of Portland, OR, have agreed to partner with Lucid Energy on the development of a hydropower system within the city.
The partners plan to collaborate with the Portland Water Bureau on a project that will use Lucid Energy's patented LucidPipe™ Power System, an in-pipe turbine that captures energy from fast-moving water inside of gravity-fed water pipelines to produce electricity. The partners also will identify innovative applications for the technology, such as providing power to eco-districts, car charging stations, desalination plants, purification systems and off-grid water agency tasks.
"We are very motivated to find ways to reduce the costs of delivering water to our customers," said David Shaff, Portland Water Bureau administrator. "We are looking forward to working with Lucid Energy to achieve this important objective."
Lucid Energy's in-pipe hydropower systems are targeted at large water users such as municipal water and wastewater systems. Because of the systems use a unique lift-based, vertical axis spherical turbine, which spins as water passes it, they can operate across a wide range of flow conditions, volumes and velocities without any significant reduction in pressure.
LucidPipe extracts very little head pressure per turbine, often 1-5 psi. This feature allows the modular system to be placed in series, while allowing for uninterrupted water flow. It does not need to be placed in a pressure transient zone or where extreme differential pressures are needed.
Many in-conduit hydropower systems are designed to replace pressure reduction valves (PRVs) in small-diameter pipelines ≤16 inches. LucidPipe works in conjunction with valves in large-diameter pipelines ranging from 24 – 96 inches. It can be configured to efficiently generate electricity within a wide range of pipe diameters, head pressures and water velocities.
For more information, visit www.lucidenergy.com.
Floating Solar Power Energizes New Jersey Treatment Plant
Floating on a reservoir near New Jersey American Water's Canoe Brook Water Treatment Plant in Millburn is the East Coast's first solar array on a body of water designed to withstand a freeze/thaw environment.
The 538 solar modules will generate 135 kilowatts of DC power, which will then be converted to 115 kilowatts of AC power, generating approximately two percent of the water treatment plant's power. Annually, the solar field will produce 135,000 kilowatt hours per year. New Jersey American Water estimates a savings of approximately $16,000 per year in energy costs.
"New Jersey American Water is exploring new ways to use green energy to enable us to operate more efficiently," said Suzanne Chiavari, vice president of engineering at New Jersey American Water. "Using innovative solutions to control costs and reduce our carbon footprint provides benefits to our customers and furthers our goal of becoming a more environmentally friendly business."
The $1.35 million project is a pilot for New Jersey American Water as the company monitors the effectiveness of the solar station during changes in weather, and also considers adding more solar panels on the 735-million gallon reservoir. The Canoe Brook Water Treatment Plant sits on more than 500 acres of protected land and only a small portion of the property can be used for construction and/or operational purposes. With such little space available, the spacious reservoir is the most viable place to install solar power.
"The support structure of the anchored array features a unique mooring system that allows it to rise and fall with the water level of the reservoir," said Bob Biehler, senior project manager at New Jersey American Water. "The solar panels are fixed at a 14-degree angle and specially made to endure the severe weather conditions – such as heavy wind, rain, snow, and ice – that are not uncommon during northern New Jersey winters."
New Jersey American Water chose ENERActive Solutions of Asbury Park to design and build the solar station. To the benefit of the company's ratepayers, some of the cost of the project may be offset through solar tax rebates obtained through the American Recovery and Reinvestment Act.
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