Converting Excess Water Pressure
Into Energy to Generate Electricity
The demand for more energy, specifically, the demand for more electricity, has contributed to the growth of an innovative technology that converts excess water pressure in municipal and other water systems into electricity as a by-product of its role of providing fresh water to the community.
The engineers at Sorensen Systems have designed, built, and installed specialized turbines as replacements for pressure reducing valves in various water systems thus eliminating the dissipating of excess energy in favor of generating usable power in the form of electricity. Known as Conduit Energy Recovery, this process takes advantage of the pre-existing water pressure to convert the potential energy into kinetic energy.
Although the conversion of water power to electricity is common, what is new in these applications is the need to retrofit existing system components with new systems that allow the water, which is on its way to treatment facilities for drinking water, to act as agent in the generation of electricity. Typical sites for this kind of conversion include water treatment plants, reservoir pressure reducing sites, land irrigation sites, and certain industrial process plants.
Water for Boston Creates Electricity
Water flowing under the influence of gravity travels about 85 miles from the Quabbin Reservoir in Western Massachusetts and the Wachusett Reservoir in Central Massachusetts to Boston becoming pressurized as it travels via aqueducts to a treatment plant about 30 miles west of Boston. From there it travels to a network of tanks that depressurize and store the drinkable water before it is distributed to Boston and other communities. The water reaches a high speed as it approaches the treatment area and must be slowed down through the use of specialized reducing valves. They serve to slow the water and allow it to enter at a controlled rate suitable for flow into the system.
According to John Ford, Project Manager at Sorensen Systems, “by by-passing the pressure reducing valves at the Loring Road facility with a 200 kW turbine-generator unit, instead of dissipating the energy with the sleeve valves, it is converted into electricity.” The project was stimulated by a state mandate that called for getting at least 15 percent of its annual electricity requirements from renewable sources. The Executive Director of the Massachusetts Water Resources Authority (MWRA), Frederick Laskey, was quoted in the Boston Globe, “It basically helps get us off the roller coaster of utility bills. The more we can self-generate, the less vulnerable we are to the peaks and valleys of the energy commodities market,” said Laskey.
When working with clients on an integrated system design, our commitment extends from initial concept through commissioning and extended in-the-field follow-up services. For example, when the four pumping skids were planned, they originated as a concept in a computer-aided design. Through fabrication, testing, shipping, installation and start-up, our engineers and technicians worked hand-in-hand with our customer. The final start-up in the deserts of North Africa went smoothly as the oil started flowing from the oil fields to the distribution network facility.
System Design, Build, and Install
The Sorensen Systems team of engineers and technicians were responsible for overall project management to include the turbine generator, the hydraulic power unit, the turbine circuit breaker, the turbine control panel, the Francis turbine unit, the induction motor and the large butterfly valves and piping. John Ford explained that as the water passes through the turbine, the pressure is reduced and the energy is transferred into electric power via the induction generator connected to the turbine water wheel, or runner.
“The electric power generated through this process is used to power the equipment in the vault, with balance exported back to the utility for revenue,” said Ford. The water storage tanks at the Loring Road facility were constructed to protect and store treated water in compliance with the Federal Safe Drinking Water Act. The storage tanks replaced a 100 year old system of open reservoirs. The covered tanks protect drinking water from potential contamination. The two reservoirs that feed into the Loring Road facility supply an average of 200 million gallons per day to consumers.
Among the systems that Sorensen Systems were responsible for included:
- Turbine/Generator Assembly
- James Leffel and Co. horizontal Francis Turbine, base frame, inlet expansion box, draft tube section, Marelli Motori induction generator
- Penstock & Draftube Hydraulic Actuated Butterfly Valves
- 30 inch AWWA C-504 Butterfly Valves by Val-Matic Valve
- Hydraulic Actuator (double acting scotch yoke) by Rotork Fluid System
- Inlet & Outlet Electric Actuated Butterfly Valves
- 30 inch AWWA C-504 Butterfly Valve by Val-Matic Valve
- Electric Actuator by AUMA Actuators Inc
- Hydraulic Power Unit Assembly
- Custom built by Sorensen Systems using Parker Hannifin hose, fittings, filtration and manifolds
- Circuit Breaker Panel
- Custom built by Sorensen Systems using Eaton Magnum DS circuit breaker and Balser GPS-100 multifunction protective relay
- Turbine Control Panel
- Custom built by Sorensen Systems using Allen-Bradley SLC500 PLC and Panelview Plus HMI
- SCADA Panel
- Custom built by Sorensen Systems to provide remote control capability
- UPS Panel
- Custom built by Sorensen Systems using APC-Smart UPS (uninterruptable power system) with extended time battery packs
Sorensen Systems is a provider of motion-control systems for the hydropower generation, water and wastewater markets working in partnership The Hope Group. The company operates from a headquarters, an ISO 9001 certified facility, in Northborough, Mass. through its affiliation with The Hope Group.