In a growing number of regions, power plants are competing with many other users for scarce freshwater supplies, and the situation is likely to get worse. The International Energy Agency (IEA) recently predicted that “Water scarcity is likely to become an increasingly important consideration in planning thermal power plants.”
China is one such place, according to a December 2015 IEA presentation. In China, water will join coal transportation and power transmission costs as a siting consideration and, under a “New Policies Scenario,” could increase capital costs 85% by 2040. Consequently, the IEA’s 2015 World Energy Outlook anticipates that China will add hundreds of gigawatts of new coal-fired capacity that will increasingly use once-through saline water sources for cooling, as well as dry cooling, while the share of once-through freshwater and wet-tower cooling capacity drops.
Concentrating solar power and coal-fired facilities with carbon capture and sequestration require the highest amounts of water, according to a 2011 report from the U.S. National Renewable Energy Laboratory (NREL) and other studies. Wind, solar photovoltaic (PV), combustion turbine, and natural gas combined cycle plants using dry cooling require little to no water for operation and maintenance, which can give those technologies an edge in water-stressed regions.
But in the U.S., at least in the near term, additional low-water-use renewables are unlikely to substantially affect water use and consumption. A September 2015 NREL report, “Water Impacts of High Solar PV Electricity Penetration,” found that water withdrawals for power generation are trending downward, yet the authors expect solar cost and water restriction scenarios to have “very little impact on national levels of water withdrawals, largely due to existing thermal facilities that continue to operate through 2050.”
Don’t Take Water for Granted
March 22 of each year is United Nations World Water Day, which was established to remind us all about the significance of freshwater and to promote sustainable freshwater resource management. Coincidentally, water is also the focus of our March issue.
Though North Americans are used to taking resource abundance for granted, even here some have learned how quickly apparent abundance can become scarcity. You may have heard that the governor of California declared a drought state of emergency last January and instituted conservation measures that took effect in June, requiring the state’s local water supply agencies to reduce consumption by 25%. Brown lawns were the most visible result, but there were many others.
For example, in October, a Los Angeles Times story noted that the Northern California city of Fort Bragg had declared a Stage 3 water emergency, which included requiring restaurants to use “disposable plates, cups and flatware to cut back on water used to wash dishes.” The article continued, “For restaurant owners and fine-dining connoisseurs, that pain has come in the form of plastic knives that some say can’t even cut through a New York strip steak.” One could dismiss this example as a trivial “First World problem,” but it’s indicative of the unusual measures that were required, on short notice, for all water users.
Fort Bragg’s situation was exacerbated because in fall the city gets about 40% of its supply from the Noyo River, which had reached historic lows and, “in late September, high tides sent salt water from the ocean toward the pumps that draw from the river,” the Times reported. Now imagine if a thermal power plant had been reliant upon that river.
Know Your Options
What can you do to ensure that power plants have sufficient water in the future? Start by reading this issue of POWER, which includes articles on technologies related to both freshwater and wastewater management. Around the world, industry groups like the Electric Power Research Institute, government research laboratories, and individual generating companies are researching technologies and operating practices that use water more efficiently. Here are just two examples.
A January article at miningweekly.com reported that the research arm of South African utility Eskom has invested in a pilot “eutectic freeze crystallisation plant” to test whether freezing liquid discharge from power plants (and, potentially, the nation’s mine wastewater streams) might provide an alternative water treatment for its power plants. As the article explains, “when water freezes, salts and impurities are excluded from the water matrix,” allowing their removal as a dry solid before the water is brought back to ambient temperature.
A July 2015 NREL report, “Water Constraints in an Electric Sector Capacity Expansion Model,” offers details on the first model to “incorporate water resource availability and costs as a constraint for the future development of the electricity sector.” Among its findings: “[A]t current prices of water and energy technologies, it can be economically advantageous to build water-intensive power plants in certain locations where there is water rather than build power plants with lower water intensities in locations with water scarcity.” One wonders when those dynamics might shift.
Nominate Award-Worthy Water Projects
While you’re giving extra consideration to water use and wastewater handling this month, consider nominating an industry-leading project for the 2016 POWER Water Award. Project owners, developers, or vendors can submit nominations. Our Water Award goes to a water-related project at a power plant anywhere in the world that demonstrates leadership in the management of water and/or wastewater streams.
Winning projects will have successfully implemented innovative, leading-edge approaches to water stewardship, water quality, water availability, or wastewater-handling issues. Although technology may be involved, the award is not specifically for a new commercially available technology. Rather, the award recognizes creative problem-solving that results in water management strategies that may serve as models for other plants. The submission deadline is April 29; you’ll find more information and nomination forms at powermag.com/power-awards. ■
— Gail Reitenbach, PhD is POWER’s editor.