Efficient operations help us save energy, conserve water and reduce our use of raw materials. In addition to the environmental benefits we achieve, these efforts frequently result in cost savings for the company as well.
All thermal power plants use water to generate electricity. In the boiler, water is heated to generate steam, which in turn runs the turbine to generate electricity. Most of this water is condensed and then reused back in to the process. At some of our plants, we also generate steam for export to communities and local businesses. This is a very efficient use of the waste resource, but can increase water consumption, since we may not receive the condensate back to reuse in our process.
The largest water demand at our facilities is typically for cooling the steam after it has exited the turbine. All of our facilities use air or water-cooled condensers to cool the steam. These are both recognized as a best-practice for electricity generation, because they significantly reduce water consumption relative to “once-through” cooling plants, they don’t introduce a thermal load to a receiving water body like a lake or a river, and the significantly lower water consumption means much less chance for damaging aquatic organisms.
We are increasingly using non-potable water and sources of reclaimed wastewater in our operations. Reclaimed wastewater now makes up 24% of our water consumption, up from 11% in 2007. Total alternative water sources, including reclaimed wastewater, stormwater, saline water, and once-through cooling discharge water, made up 35% of our 2015 water consumption.
Example alternative water source projects:
- The Babylon facility on Long Island treats leachate collected from underneath the neighboring landfill, helping to control local groundwater impacts.
- The Lancaster, PA facility and three facilities in Florida (Lee County, Hillsborough County and Pasco County) use treated wastewater from local wastewater treatment plants.
- The Montgomery County facility in Maryland uses the once-through cooling water discharge from a neighboring power plant.
- We’ve partnered with Global Cycle, Inc. to reuse certain non-hazardous industrial wastewaters after treatment in our air pollution control equipment at our Southeastern Massachusetts facility.
|Reclaimed wastewater use (%)||15%||19%||24%|
|Other Alternative water use (%)||9%||11%||11%|
|Total water use (Mgal.)||8,440||9,040||9,180|
Total water consumption increased from 2013 to 2015 as a result of greater steam output at one of our combined heat and power plants, resulting in greater condensate loss, a slightly greater overall water demand associated with the use of reclaimed wastewater at our Delaware Valley facility, an apparent increase as a result of better monitoring of the use of saline water, and the addition of the Pinellas facility to our fleet.
“It is important to measure, monitor and reduce, where possible, water use in waste management processes, including EfW. The use of water is of great concern in some geographic locations and should be always taken into consideration.”
Anders Damgaard, Ph.D.
Senior Researcher, Department of Environmental Engineering,
Technical University of Denmark
In addition to making strides to optimize our water consumption, we also work to minimize our wastewater discharge, using water internally to the extent possible. A total of 15 of our facilities are zero process water discharge, meaning that only sanitary wastewater is discharged to the local wastewater treatment plant.