Environmental Performance Metrics
Compared to 2011, coal and oil consumption decreased and natural gas consumption increased in 2012, mostly because natural gas became a relatively less expensive fuel and we added natural gas generation capacity.
Water withdrawn is the total volume removed from a water source, such as a lake or a river. Due to once-through cooling systems on many of our coal-fired and nuclear plants, about 98 percent of this water is returned to the source and available for other uses. Water consumed is the amount of water removed for use and not returned to the source.
Emission levels and intensities depend on many factors, including generation diversity and efficiency, demand for electricity, weather, fuel availability and prices, and emission controls deployed. Carbon dioxide (CO2), sulfur dioxide (SO2) and nitrogen oxides (NOx) emissions decreased from 2011 to 2012, due to decreased coal generation and increased natural gas generation. Duke Energy and Progress Energy have invested more than $7 billion in SO2 and NOx emission controls since 1999. As a result, we have reduced U.S. SO2 emissions by 83 percent and U.S. NOx emissions by 64 percent since 2005. (There is currently no demonstrated, commercially available technology to control CO2 emissions.) While our total CO2 emissions decreased in 2012, our current forecast indicates an upward trend in our CO2 emissions in the years ahead. This will challenge our ability to meet our 2020 goal of no more than 141 million tons of CO2 emissions. (This goal is based on a 17 percent reduction from our 2005 CO2 emission level.)
Duke Energy's TRI releases for 2012 were down more than 68 percent from 2007, primarily due to the significant investments we've made in environmental controls for our power plants.
We met our goal to reduce nitrogen oxides, volatile organic compounds, particulate matter and carbon monoxide emissions from our on-road and off-road vehicle fleet by 35 percent by 2012, compared to 2006. During that period, we reduced emissions by 41 percent.
In 2000, the Accelerated Main Replacement Program (AMRP) was launched on Duke Energy’s natural gas distribution system in Ohio and Kentucky to prevent leaks requiring repair and to improve safety, performance and reliability. The program accelerates the replacement of approximately 1,400 miles of cast iron and bare steel pipe, some in service since 1873. We exceeded our goal of reducing repaired leaks by 20 percent by 2012 compared to 2007. The AMRP is scheduled to be completed in 2015. Reducing leaks decreases the release of natural gas, which is mostly methane, a greenhouse gas approximately 20 times more potent than CO2.
We exceeded our goal to increase the percentage of U.S. solid waste that is recycled from 52 percent in 2008 to 62 percent by 2012. A new baseline and goal are being developed for the merged company. Our Catawba, McGuire and Oconee nuclear stations also exceeded their goal to reduce by 25 percent the amount of low-level radioactive waste (Class B and C) they generated by 2012, compared to the 2002 through 2006 average of 1,552 cubic feet.
We exceeded our goal to reduce electricity consumption at 13 of our largest commercial buildings by 10 percent by 2012, compared to the 2005 through 2007 average.
Oil spills include releases of lubricating oil from generating stations, leaks from transformers, or damage caused by weather or by third parties (typically due to auto accidents).
No fines were associated with 12 of the 16 citations in 2012.