Water Online

SEP 2016

Water Innovations gives Water and Wastewater Engineers and end-users a venue to find project solutions and source valuable product information. We aim to educate the engineering and operations community on important issues and trends.

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By Erin Bonney Casey F rom an installed base of 72 zero liquid discharge (ZLD) systems and 67 power plants utilizing reclaimed water across the U.S., Bluefield Research is seeing an increasing trend toward reuse in the U.S. power sector as companies look for new water management strategies. ZLD, a water treatment process in which all wastewater is purified and recycled, helps conserve water supplies and manage wastewater flows. The power sector is increasingly looking to ZLD systems to meet regulatory challenges and reduce water use in water-stressed areas. On the other hand, reuse of municipal reclaimed water can provide a drought-proof and cost-effective water supply source for water- hungry power plants. Use of ZLD systems, installed to expand on-site water reuse and eliminate concerns about wastewater discharge, is expanding, although they are still somewhat of a niche play. Currently, the 72 U.S. power plants employing ZLD systems have a total combined capacity of 22,000 GPM (119,000 m 3 /day). New thermal power plant additions from 2016 through 2025 are expected to total 38 gigawatts (GW), mostly through the addition of natural gas-fired plants. The U.S. power sector is evolving toward greater adoption of combined-cycle gas plants — a substitute for decommissioned coal plants — and sparking growth opportunities for water solution providers. The Mid-Atlantic and Midwest, regions that historically have relied on coal, are shifting to gas-fired plants, with large-scale capacity additions planned to compensate for the scheduled retirement of coal plants. New gas-fired plants are also increasingly looking at ZLD technology for reuse as a means of reducing their water footprint and complying with regulatory shifts. In Texas, California, and Arizona, which are water scarce, planned thermal power capacity additions total 16 GW, 42 percent of the total. Companies will be looking at new water management strategies for new thermal plants to secure the necessary cooling water and boiler feed supplies for plant operation. For example, the largest ZLD installation at a power plant in the U.S. is at the Duke Energy natural gas- fired combined-cycle (NGCC) plant in Arlington Valley, AZ. Installed in 2009, the system has a flow rate of 3,600 GPM (19,620 m3/day). The ZLD system allows the plant to reuse water in this extremely water-stressed region. Additionally, the new Steam Electric Power Generating Effluent Guidelines passed by the U.S. EPA in 2015 will force wastewater treatment retrofits at coal-fired plants not slated for retirement. This follows a series of regulations aimed at reducing air pollution and prompting the installation of flue-gas desulphurization (FGD) units, which moved some of the removed toxins into the wastewater stream. ZLD systems can provide a solution for operators looking to clean effluent from FGD units. 30 wateronline.com n Water Innovations U.S. Power Profile Shift Sparks Water Opportunity The power sector looks to zero liquid discharge and taps municipal reclaimed water as a water reuse strategy. Most power capacity additions are planned for the Mid-Atlantic and Midwest states, reflecting the ongoing shift from coal to natural gas. Planned Thermal Power Additions By State

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