The 60,000 water and 15,000 wastewater systems in the United States account for as much as 35% of municipal energy usage and 3% of the of the nation’s electric load. As populations grow and environmental requirements become more stringent, the demand for energy in water and wastewater is expected to grow by approximately 20% during the next 15 years.
Studies estimate a savings potential of 15% to 30% (31 billion kWh) for water and wastewater, according to the U.S. Environmental Protection Agency (EPA). Water quality utilities that participate in energy efficiency programs have reduced energy consumption by between 20% and 40%, according to Ted Jones, industrial programs coordinator of the Consortium for Energy Efficiency (CEE; Boston), a nonprofit organization comprising electric and gas utilities and state energy programs.
On the facility level, energy costs are nearly 30% of operations and maintenance. Because the industry is consistently faced with increasing costs from aging infrastructure, new public health regulations, and growth, becoming more energy efficient and controlling energy costs is truly the current of the future. Some utilities are taking advantage of the resources available now and are savings millions of dollars each year.
Streamlining Energy Efficiency
CEE, which is partially funded by EPA’s Energy Star Program, launched its National Municipal Water and Wastewater Facility Initiative in December 2004 to enable its members to assist the industry in harnessing energy efficiency opportunities, including reducing peak load demand and upgrading equipment, Jones said. The initiative’s goal is to help shape energy efficiency — in design, as well as facility, systems, and component (motors) performance.
States and electric utilities invest in energy efficiency because it enables them to reduce the need to buy more power and to avoid building additional power generation facilities, Jones said. “There is a unique opportunity in water [and] wastewater because in many areas of the country, infrastructure is crumbling,” he noted. “As new facilities are built, there is the opportunity to address future energy supply.”
Several states also have programs that assist the water quality sector with streamlining energy consumption and costs. Wisconsin’s Focus on Energy works with government and industrial facilities and provides technical support. “We try to identify the opportunities, provide insight, and present payback,” said Joseph Cantwell, program manager for water and wastewater.
The program conducts energy surveys, develops energy management plans, recommends equipment and technologies, locates contractors and evaluates their proposals, and provides information, education, and training resources. Wisconsin has 1900 wastewater, industrial waste treatment, and water utilities, and to date Focus on Energy has about 200 members, mostly small and medium-size utilities that are beginning to track energy usage. “The program helps them reduce their energy consumption and makes them more aware of the energy they’re consuming,” Cantwell said.
Savings and Consumption
“The biggest thing we focus on is consumption,” Cantwell said. “In saving their energy, they are reducing their bill.” Although rates are continuing to increase, participating water quality utilities are saving about 20% on their energy bills, he said.
According to Caterina Hatcher, Energy Star national manager for Public Sector Partnerships, which will roll out tools and guidance this fall as part of its Water and Wastewater Focus initiative, the bottom line is “the cost to run systems [is] a significant portion of the public energy bill. From a fiscally responsible perspective, looking into energy savings in the water and wastewater sector saves money.”
Energy’s Heavy Hitters
According to Shahid Chaudhry, program manager of California’s Water-Energy Efficiency Program, energy consumption accounts for one-third of operations and maintenance costs at water and wastewater utilities. Optimization for both water and wastewater pumping systems means looking at efficient motors, pumps, drives, and monitoring and control technologies — supervisory control and data acquisition (SCADA) systems, dissolved-oxygen (DO) monitors, and other systems.
For wastewater, 60% to 75% of energy consumed is for aeration, and pumping and solids management each account for about 12% of energy use. “If we use efficient pumps and motors and fine-bubble diffusers [and flexible membranes], there is a lot more potential for energy efficiency,” Chaudhry said.
Treatment, including ultraviolet (UV) disinfection, and collection account for 28%, Chaudhry said.
However, when combined with secondary wastewater treatment, total energy consumption for treatment and collection could be as high as 60%. (The New York State Energy Research and Development Authority [NYSERDA] is completing a UV cost analysis tool, UVCAT, which will be available online this fall.)
Improving the design of UV reactors to reduce energy needs is an important area of research and development. Researchers are working on improving reactor hydraulic efficiency and lamp efficiency. “In wastewater, UV is really becoming the method of choice,” said Karl Scheible, principal of HydroQual (Mahwah, N.J.). “It obviously is an energy user, so the more efficient you can be with it, the better you are.”
Research in dyed microsphere actinometry with Purdue University (West Lafayette, Ind.) is helping to pave the way to more energy-efficient design of UV reactors, Scheible said. This method directly measures reactor dose distribution — a key parameter in sizing reactors.
Water and wastewater energy efficiency opportunities include upgrading with DO controllers, fine-bubble aeration, automation, and SCADA, as well as running processes at off-peak times when energy rates are cheaper (also known as peak shaving), using renewable energy, making use of storage, and managing pump systems more efficiently, Chaudhry said. The California Energy Commission’s Web site has information on adjustable-speed drives, premium efficiency motors, and electronic controls at www.energy.ca.gov/process/water/eff_water.html.
DO probes and analytical equipment, “which are always improving,” and automatic controls help to better modify blowers to maintain DO concentration, Cantwell said. However, if a facility is running old blowers, it still could be consuming more energy than is necessary, he said.
Also, while fine-bubble aeration is not new, flexible membranes offer finer control, Cantwell noted. Information about Focus on Energy’s PowerPoint and classroom presentations and Water and Wastewater Industry Energy Best Practice Guidebook is available at www.focusonenergy.com/page.jsp?pageId=370.
Fuel cells powered by natural gas cost about four to five times more than diesel-powered counterparts, said Rob Taylor, energy manager at the Washington Suburban Sanitary Commission (WSSC), which supplies water and wastewater services to Prince Georges and Montgomery counties in Maryland. Fuel cells “are not yet cost-effective,” he said, noting that unless rebates are available, the payback is not worth the expense.
However, fuel cells may be more cost-effective for facilities that have anaerobic digesters, especially when they receive large amounts of industrial waste with high levels of biochemical oxygen demand (particularly food and dairy waste), said Greg Lampman, NYSERDA’s project manager in the Energy Efficiency Services Group. For example, a wastewater facility in dairy-rich upstate Oneida, N.Y., is developing a facility plan that would enable the plant to operate primarily by cogeneration. Such utilities would be eligible to receive monetary and other incentives for each kWh generated through New York State’s Renewable Portfolio Standard.
Taylor also noted that “microturbines have had spotty success.” Instead, WSSC is putting in next-generation low-emission diesel motors as backup generation. The new engines will reduce loads and energy needs.
Because equipment is fairly consistent, CEE is developing detailed guidance for energy efficiency programs on pumps due out at the end of 2007, and blowers, due out in 2008, Jones said. For more information, see “Motors Matter” at www.motorsmatter.org.
Balancing Supply and Demand
The standard across the country, Taylor said, is that most pumping systems, variable-speed drives, efficient motors, aeration systems, blower technologies, and cogeneration are being looked at. “The technologies are in place,” he said. “It’s a matter of having the will and the resources to put it all together. Equipment is the easiest part.”
According to Taylor, the first thing a facility should do is create a tracking system to monitor “what areas use what form of energy at what cost. … If you can’t measure it, you can’t manage it.”
Second, Taylor said, audit all facilities for equipment and systems upgrades. Third, look at how you purchase fuel, and look at different ways to buy it, such as shifting load or buying it more efficiently. And fourth, provide staff with proper training. WSSC has instituted energy-management training that is approved by the state of Maryland and to date has brought 100 operators through the program.
For wastewater and water managers, tying together demand (how energy is used) and supply (how energy is procured) is an important balance to maintain. “If you neglect one for the benefit of the other, you could be saving energy but spending more money,” Taylor said.
Shifting and Procurement
Kathleen O’Connor, NYSERDA’s project manager for Environmental Research and Development, recommends monitoring times of use and not testing equipment during peak hours to help streamline energy costs. Since facilities operate 24 hours a day, the potential to reduce peak demand is a significant factor.
During wet weather, pumping may increase, but aeration doesn’t have to, Cantwell noted. “You want to control your peak demand when you can,” he added. In Wisconsin, it may cost $10 to $12 per kW during peak periods, compared to $1.50 during off-peak times.
WSSC’s Taylor buys energy to optimize loads and sheds loads so equipment is not running until rates are low. “You don’t save kilowatt-hours, and you have to look at saving energy dollars,” he noted.
State Support and Funding
NYSERDA spends about $175 million annually for energy efficiency in all business sectors and in residential, providing funding on a cost-sharing basis through System Benefit Charge Funds — a surcharge tax on the transmission and distribution of electricity.
On average, there is a 20% energy savings with a 5-year payback for facilities that have not done any energy work, Lampman said.
If a suggested project qualifies, NYSERDA will also cost-share demonstration projects. See www.nyserda.org/Programs/Environment/muniwaterwwtImplementation.asp for information about funding programs.
In California, 19% of electricity consumption is water-related, Chaudhry said. The state, which set target dates for energy efficiency in 2010 and 2017, provides energy efficiency programs with $45 million per year.
“California has the most R&D [research and development] funding for developing energy-efficient, environmentally friendly technologies,” Chaudhry said. It offers cash incentives in the form of rebates and low-interest loans (currently 3.9% with a 14-year payback) and will partner or fund research, development, and demonstration projects. The program also offers water utilities up to $20,000 per year for technical assistance and provides energy audits.
Wisconsin’s Focus on Energy offers reimbursement grants once new equipment is paid for — approximately 10% of project cost.
Several states are supporting the industry to streamline energy consumption. (See www.cee1.org/ind/mot-sys/ww/cr.php3 for links to organizations providing resources for water and wastewater.)
“You can save a lot of money,” Taylor said. WSSC will have spent more than $20 million on equipment upgrades from 2001 to 2009. Upgrades, supply agreements, buying energy in real time, and incorporating automatic pump-control systems that monitor energy rates have all helped the commission save about $3.5 million per year in energy costs. In 2 years, it will save another $2 million annually with renewable wind energy.
WSSC made a wholesale deal with nearby Edison Mission, a 30-million-MW wind farm currently under construction in Forward, Pa. Eighty-five percent of the farm’s output will provide 70,000 MWh annually to more than 85 of WSSC’s facilities, including dams, pumping stations, and water and wastewater treatment facilities. With this commitment, WSSC is hedging a third of its power generation costs at a fixed price for 10 years.
“Sometimes it takes years to build onsite,” Taylor said. “It’s a lot bigger bang for the buck if we buy renewable energy from a third party.”
California is also a big proponent of wind energy and solar power. Two windmill installations produce 2 MW, and four fuel cell installations produce another 2.5 MW. There are also more than 30 solar applications at California water and wastewater facilities that together account for 8.5 MW.
In 2002, the state set a goal to be using 20% renewable energy by 2017 and started the California Solar Initiative Program, which is targeting production of 3000 MW annually by that time. The first application of solar energy at a wastewater facility was in Northern California at the Oroville, Calif., plant. The largest solar photovoltaic installation, producing 3.1 MW, is owned by Nevada’s Las Vegas Valley Water District.
According to Taylor, photovoltaic cells require subsidies to make them cost-effective. Without the subsidy, “it would be putting a lot of money in for very little benefit,” he said.
Fuel cells for cogeneration and wave energy are still in research and development, Chaudhry said. NYSERDA is researching hydropower — microhydroturbines — at outfall locations and in process where water channels have potential. The units are costly, Lampman said.
In Los Angeles and other urban areas, green infrastructure — rain gardens and other vegetation to retain stormwater — is minimizing air-conditioning needs, according to Valerie Nelson, founder of the Coalition for Alternative Wastewater Treatment (Gloucester, Mass.). The coalition advocates more sustainable, decentralized water, wastewater, and stormwater systems.
“It is well documented that greening cities reduces the heat island effect and more than makes up the cost of what you would pay for costly stormwater conveyance,” Nelson said.
Energy Star Labeling
Energy Star’s Water and Wastewater Focus is a short-term effort to determine what tools and resources a particular sector needs to streamline energy usage. The program has more than 20 organizations participating.
“The goals are to help municipal drinking water and wastewater utilities to improve efficiency,” save money, and reduce greenhouse gas emissions, Hatcher said.
In its Portfolio Manager software, the Focus program is developing best practices handbooks for water and wastewater and benchmarking tools that enable users to input information, then the program tracks progress and compares this to other utilities. The water benchmarking tool will be available by the end of the year. Energy guidelines for water were in near final form at press time, and the guidelines for wastewater were under peer review.
Eventually, some facilities “may be able to earn the Energy Star label,” Hatcher said.
No Silver Bullet
Water-related electricity demand will continue to grow quickly because of population increases, transportation of water over great distances, and the development of innovative technologies that treat emerging contaminants, Chaudhry said.
Using less electricity to pump, treat, and distribute water; addressing conveyance system leaks; and using more new local water supply sources, such as water reuse and brackish water desalination, will help save money and energy in transporting water great distances.
“If we can incorporate good energy management … we can hopefully improve infrastructure,” O’Connor said. “But there is no silver bullet for this sector.”
— Andrea S. Bistany, WE&T