By Art Haddaway, WaterWold Editor
When it comes to generating electricity, power plants require a substantial amount of freshwater for a variety of manufacturing processes and operations, including extracting fuel, generating steam, controlling polluted emissions, and especially cooling their facilities. Sometimes this water is withdrawn from a local source and returned for potential reuse; sometimes it is consumed, meaning it is removed from the environment, primarily through evaporation.
Considered a water-intensive industry, the electric power sector relies heavily on water resources to efficiently produce and maintain energy. According to the Union of Concerned Scientists (UCS), electric power generation is "responsible for more than 40 percent of freshwater withdrawals in the United States -- on the order of 100 billion gallons per day in 2008 -- primarily for cooling."
To support the development of new methods for reducing the amount of water used in power plants, Georgia Power recently launched its new Water Research Center at Plant Bowen near the city of Cartersville, Ga. The facility will feature a state-of-the-art workshop focused on researching ways to conserve water, as well as improving the quality of water returned to the environment from energy utilities. Further, the $12-million facility serves to discover and promote new and forthcoming technologies that will improve the overall water footprint of power plants across the nation.
"The Center will yield industry-wide insights that will help Georgia Power and other utility companies minimize the use of water in power plants and increase conservation of one of our most valuable natural resources," said Jeff Wilson, project manager for the Water Research Center. "It is an innovative collaboration between public and private entities focusing on developing revolutionary technologies with real-world applications that will be deployed to improve the management of water use across the entire energy industry."
The first facility of its kind, the Water Research Center was established through a partnership between Electric Power Research Institute (EPRI) and the Southern Research Institute, along with 14 other power-related companies. The Center opened its doors in November 2013 and serves as an extension of a pilot conservation project that originated in May 2010 at Plant Bowen to study water balances and identify opportunities for improved water preservation. Wilson noted that the Center focuses on combining conservancy with regulatory compliance and aims to enable power plants to address challenges relating to both.
With regard to these challenges, a recent UCS report indicated that water withdrawals can possibly threaten aquatic wildlife such as plants and fish by trapping them in utilities' water intake systems. The returned water can also be harmful to these species and the environment, as it is potentially discharged in excess at a higher temperature. Further, groundwater extractions can possibly deplete local aquifers essential to surrounding areas. As for consumption, the amount of water available for other uses, including sustaining ecosystems, can potentially be reduced.
Accordingly, the power industry continues to face increasing water use and quality regulations imposed by the Environmental Protection Agency (EPA) that limit the amount of effluent generated and discharged from these sites. These guidelines include various steam ejections and other emissions control measures, as well as some pollution control statutes, such as the Clean Water Act (CWA) and the National Pollutant Discharge Elimination System (NPDES). Power plants, therefore, are required to implement efficient water quality and conservation strategies in order to meet these demanding standards.
"Over the last five to 10 years, we've seen a real shift in the importance of water, and now we're seeing a shift from the EPA as well on some of the regulations they're putting out toward water," said Wilson. "We are seeing that seasonally, geographically and situationally, water is stressed, and water availability is absolutely crucial to us; we must be able to optimize our water use and minimize that footprint," he said. "Finding new ways to protect water resources and use them more efficiently is a priority for Georgia Power."
In order to better tackle these challenges and meet and maintain increasing water quality regulations, Georgia Power's Water Research Center has dedicated much of its research and operations to seven distinct focus areas pertaining to safeguarding water quantity and quality: moisture recovery; cooling tower and advanced cooling systems; flue gas desulfurization (FGD) and process wastewater treatment; zero-liquid discharge (ZLD); solid landfill water management; carbon technology water issues; and water modeling, monitoring and best management practices. These areas encompass everything from improving the way water cools power plants to increasing moisture recovery during operations to enhancing how water and wastewater are treated throughout the process.
The cooling process consumes the most water used at power plants, with 80 to 90 percent of it devoted to the process, according to Wilson. The Water Research Center is studying how to better reduce this water -- whether it's used for closed-cycle or once-through cooling -- through new techniques such as increasing cooling tower cycles of concentration, diverting/reducing cooling tower heat loads, assessing the feasibility and applicability of hybrid wet/dry cooling systems, and much more, according to a recent Georgia Power press release.
Jay Wos, water research manager for Southern Research Institute, said the Center's cooling research seeks to address a few key questions: How much water are we using for cooling? What are we doing with it after we cool with it? Are we reusing it or discharging it? Are we taking water from another process and using that water instead? "The concept of what works and what doesn't work is the premise behind this Center," he said. "It was to establish a place -- a proving ground -- to conduct research and development to answer these types of questions."
The Center also focuses on exploring and developing solutions relating to reclaiming moisture that would otherwise be lost or consumed through cooling tower plumes as well as through flue gas or emissions scrubbing, according to the release. Likewise, process wastewater such as cooling tower blowdown, in addition to FGD discharges, floor drains and stormwater runoff, require advanced reuse and treatment technologies, which Georgia Power's new workshop is devoting many of its efforts toward researching.
With regard to solids management, the Water Research Center is examining technologies that concentrate on advancements in the field of zero liquid discharge (ZLD). For example, efforts are being made to develop the capability to separate polluted water into a solid material that can be used or landfilled, as well as a high-quality distillate that can be reused, as noted in the release. Georgia Power's new site is also considering the addition of new solids such as ZLD salts and sludges to better manage these on-site landfills. "We want to make sure that as we get these constituents out of the water and air, we keep them in a solid form and keep them at a landfill on site, and that's how they stay forever," said Wilson.
Modeling and monitoring is also an important key to improving water quality and conservation in the power industry. As such, the Center is conducting research dedicated to reducing the impact of carbon dioxide capture on water use within plants by creating models that help better determine the influence of various post-combustion and carbon-capture technologies. The release further indicated that, holistically, the new facility is striving to "model strategies for managing water use/reuse and to explore tools for evaluating overall water use (baseline and real-time)" from the results of the research conducted for each of these focus areas.
"The seven focus areas are key because there is a strong correlation amongst them," said Wilson. "For example, it would be short-sighted to install a wastewater treatment or ZLD technology without a solids solution for those technologies. We want to use water more efficiently, and to do so, we must focus on all seven of these areas at once."
The research focus areas were specifically chosen as a result of extensive consultation with industry experts from across the globe. Wos explained, "Trying to determine what a suitable testing model was, what technologies are out there, which ones are worth testing, and how to design infrastructure to accommodate those should they be brought to the center was quite a bit of an effort."
"I feel much better about the future because of the research we're doing here," Wilson added. "This is something that we all like to do in our industry -- to have folks that have a great idea or technology come to our site and demonstrate it in our world." Wilson said he believes the Center is going to bring technologies to this industry that will allow energy utilities to make better decisions, use water more efficiently, and ultimately benefit customers by keeping down costs.