Water is a shared natural resource that is vital to the production of electricity at many power plants. Power plant water use varies significantly with the type of generation. Typically, power plants that use a steam turbine to produce electricity (also known as steam-electric plants) are the largest water users on a per megawatt-hour basis. However, it should be noted that use does not mean consumption, as many plants use water for cooling but then return it to the source.
Historically, heated water from the steam-condensing process was discharged back into the source water body, such as a river or lake, from which it was withdrawn. Typically, more than 95 percent of the cooling water was returned for these once-through cooling systems. However, to minimize potential impacts on fish and to reduce thermal discharges, a few older plants and all new plants built since 1977 use closed-cycle cooling systems. Examples of closed-cycle cooling systems include cooling towers or off-stream cooling ponds. As compared to once-through cooling systems, closed-cycle cooling systems withdraw significantly less water from rivers or lakes, but consume (through evaporation) significantly more water.
Additional operational uses of water include:
We are committed to being good stewards of natural resources and are focused on innovative, responsible, community-based solutions to protect the water resources critical to our operations. For example:
The flue gas desulfurization systems, or scrubbers, on coal-fired boilers at several plants use water as part of the process to remove contaminants from the air. This resulting effluent must be treated before the water can be reintroduced into the environment. Through collaboration and extensive research, we identified two innovative technologies to provide treatment in an environmentally responsible manner: constructed wetlands and a bioreactor system.
Both Progress Energy Carolinas and Progress Energy Florida maintain a groundwater monitoring program to ensure the protection of public health and safety. In the Carolinas, monitoring wells have been installed around all of our active coal ash storage facilities and data are collected and analyzed on a regular schedule throughout the year. In Florida, we maintain a series of monitoring wells at several generation sites and test them regularly. All of our data are shared with the appropriate state regulatory agencies.
The Carolinas and much of the Southeast have experienced several droughts in recent years. After the most recent, Progress Energy took action to drastically improve water conservation at its seven Raleigh facilities. These actions resulted in saving more than 2 million gallons of water in 2008. The company has continued its conservation efforts through 2011.
In addition, our Florida headquarters building, Progress Energy Place, was built with a number of water- and energy-conservation technologies. The building, which opened in 2006, uses low-flow toilets and sinks as well as automated on/off controls for the sinks. The building also has 100 percent solar hot water heating, which provides up to 1,200 gallons of hot water each day. The building continued to perform well in 2011.
Progress Energy has embarked on a green building program for future facilities. In Florida, Progress opened the first Leadership in Energy & Environmental Design (LEED) Silver project at our Wildwood transmission facility. We also are building a new facility at the Crystal River Energy Complex that will be LEED Silver when certified. In the Carolinas, Progress Energy opened up a new Raleigh operations center, which will be a LEED Silver facility when certified. In addition, the renovation of the downtown Raleigh headquarters building will achieve a LEED Silver certification for commercial interiors when the project is completed in early 2013.
One area of focus during LEED construction activities is the recycling or reuse of construction debris. In preparation for the new Raleigh operations center (located on U.S. Highway 1), two old buildings were demolished onsite; the majority of materials were recycled, and the concrete foundation and driveways were crushed to establish the construction entrances and lay down yard base of the new building. As part of the renovation of the Progress Energy Building in downtown Raleigh, more than 80 percent of the demolition debris is being recycled, including all carpeting, sheetrock and ceiling tile. Additionally, the old furniture from the building will be repurposed in Progress facilities across the Carolinas.
The University of Florida Water Institute was created through a partnership with Progress Energy to develop sound, science-based solutions to global water problems. The institute hosted its third symposium in February 2012, and brought more than 450 experts from a variety of institutional affiliations, disciplines and personal interests together to discuss challenges to sustainable water resources in Florida and beyond.