2007 Environmental Performance Update
TVA environmental performance reporting for 2007 is focused on cleaner energy and general environmental stewardship. The Environmental Impact Index illustrates the combined impact of TVA activities on the environment. Graphics and data for contributing elements are available by clicking on the links at right.
The Environmental Impact Index (EII) is a composite of 23 elements in 5 categories air quality, energy consumption, water quality, land, and waste production. This gives a snapshot of TVA’s overall environmental performance as measured against a 2002 baseline score of 100. Beginning in FY 2008, the EII will be replaced by a new set of Environmental Metrics based on TVA's new Environmental Policy, and new projections for out year performance will be developed for these new metrics and reported in next year's update.
Air Quality Indicators
Air quality expenditures
The Tennessee Valley enjoys cleaner air today than it has in many decades, thanks in part to TVA’s continued commitment to reduce its emissions and their impact on the environment. TVA has spent $4.8 billion to date on clean air modifications at its coal-fired power plants. In 2007, ozone-season nitrogen oxide (NOx) emissions were at 81 percent below peak 1995 levels, and sulfur dioxide (SO2) emissions were 82 percent below peak 1977 levels despite the fact that total generation had increased 52 percent since 1975.
Sulfur dioxide emissions
SO2 emissions per GWh of total TVA generation is an indicator of air quality in the TVA region and a measure of TVA's diverse generation mix (fossil, nuclear, hydro, solar, wind, and natural gas). It is also a measure of TVA's success in achieving its planned SO2 reductions through fuel switching and the addition of new scrubbers.
Nitrogen oxide ozone season emissions
NOx emissions per GWh of total TVA generation during the ozone season is an indicator of air quality in the TVA region and a measure of TVA's diverse generation mix (fossil, nuclear, hydro, solar, wind, and natural gas). It is also a measure of TVA's success in achieving its planned NOx reductions through the addition of new selective catalytic reduction systems (SCRs) and NOx Star technology. The ozone season is the five-month period beginning May 1 and running through September 30.
Carbon dioxide emissions
CO2 emissions per GWh of total TVA generation is an indicator of TVA greenhouse gas emissions and is a measure of TVA's diverse generation mix (fossil, nuclear, hydro, solar, wind, and natural gas).
Energy Efficiency Indicators
TVA buildings’ energy consumption
This element measures the amount of energy consumed in TVA's standard buildings including office, shop, restroom & warehouse buildings.
Green Power Switch® blocks sold
Green Power Switch (GPS) is a program that allows Valley consumers to purchase electricity from renewable sources, including solar, wind, and methane gas. Commercial and industrial customers buy blocks in 150-kilowatt-hour increments, based on the amount of energy they use. Each block adds $4 to their monthly power bill.
Reduction of peak energy demand
TVA promotes the use of energy-efficient water heaters, heat pumps, and other measures in new and existing homes to help reduce the demand for electricity. It also provides energy-management information and analysis to consumers and industries to assist them in their energy consumption planning.
Energy-efficient new homes
This measure reflects the specific impact of TVA's effort to influence Demand Side Management through the installation of energy-efficient new homes. This is a measure of the cumulative number of energy efficient new homes, defined as site-built homes in the energy right® Program with Home Energy Rating System (HERS) ratings >= 83 or a HERS Index <= 93 and ENERGY STAR® rated manufactured homes.
This measure represents the cumulative energy savings attributable to energy right® Heat Pump installations.
Impacts to Land Indicators
Accidental releases to land
Spills to land are accidental releases of petroleum products (oil, gasoline, diesel, lubricating oil, transformer oil, or fuel oil) or other hazardous substances at a TVA facility, or related TVA operations. These are single releases beyond secondary containment that are immediately cleaned up and do not, result in remediation projects.
Alternative right-of-way management
Alternative right-of-way management refers to transmission line rights-of-way (ROWs) that are managed through public partnerships and enhanced resource management to establish areas maintained with low-growing native plant species which provide wildlife habitat and to control exotic invasive plants. TVA tracks the acres of ROW managed using this approach.
Fly ash, bottom ash, and gypsum utilized
This is a measure of the amount of coal combustion by-products (fly ash, bottom ash, and scrubber gypsum) from fossil plant sites that are recycled, rather than disposed of.
Hazardous waste disposed
Hazardous waste is a material that meets certain characteristics such as flammability, corrosivity, reactivity, or toxicity or is specifically designated by environmental regulations.
Low-level radioactive waste generated
Low level radioactive waste includes ion-exchange resins, compactable and non-compactable trash, mechanical filters, tank residue, and irradiated reactor components. This measure reflects the total volume generated expressed in cubic meters, from operational and maintenance activities.
This element tracks the amount of recyclable materials coming from office-type environments. These include paper, glass, aluminum, cardboard, plastic, and steel from cans.
This element tracks the amount of scrap metal picked up by vendors
The water permit violations figure is a combination of performance in five areas related to water temperature or to discharges of certain substances such as chemicals and storm water beyond permit limits.
Certified marinas in Clean Marina Initiative
There are 235 marinas on the Tennessee River system. This indicator measures the number of marinas certified each year, including both new certifications and periodic recertification of previously certified marinas. This effort promotes sound, environmentally responsible marina and boating practices.
Dissolved oxygen target attainment
For each of the 15 dams with aeration systems installed, a planned operating schedule is determined. If a system is operable on days it is scheduled for use, it is counted as being available. If it is not available due to an aeration system forced outage and the dissolved oxygen falls below the established target, it is counted as "DO deficit due to force outage." Data are reported monthly and accumulated throughout the year to determine the annual performance.
TVA maintains minimum water flows at 29 locations to improve water quality, reduce negative environmental effects on aquatic life, and support healthy drinking water for Valley citizens. The chart percentages represent the sum of days at all locations when flow targets are met divided by the total number of days possible.
Tailwater quality gap
This is an indicator of biological conditions downstream of selected TVA dams, and represents the difference between the sum of all tailwater ratings (good, fair, or poor) and an ideal situation where all sites are rated “Good”.
Reservoir water quality gap
This is an indicator of overall water quality conditions and health of major reservoirs operated by TVA. It represents the difference between the sum of all reservoir site ratings (good, fair, or poor) and an ideal situation where all sites are rated “Good”.
Stream water quality gap
This is an indicator of overall water quality conditions and health of streams draining into the Tennessee River system. It represents the difference between the sum of all stream ratings (good, fair, or poor) and an ideal situation where all sites are rated Good.
Spills to water
Spills to water are spills of petroleum products or hazardous substances beyond established reportable quantities to Waters of the United States.