As discussed earlier in the Key Issues section, Dominion continues to take steps to voluntarily reduce greenhouse gas emissions by using a variety of less carbon-intensive generating technologies and improving the overall efficiency of our generation mix.
The graphs provide data for our generation fleet owned and operated during the time period.
Note: The annual CO2 Emissions chart represents CO2 emissions from all Dominion operated electrical generating sources at their ownership percentage. The annual CO2 Emissions/MW-hr Generation chart represents CO2 emissions from Dominion operated electrical generation units normalized by the electrical generation at their ownership percentage. (For instance, if Dominion owns 50% of a unit, 50% of the emissions are included.) Beginning in 2009, the data is reported as CO2 equivalent emissions, which includes methane and nitrous oxide emissions.
The emission changes in the graph reflect the changing fuel mix for our fleet. At our Possum Point Power Station, the coal-fired units were converted to natural gas, resulting in decreases in carbon intensity. Three fossil fuel-fired units (Brayton Point, Manchester Street Station and Salem Harbor) were acquired in 2005. In addition, some fossil fuel-fired units have been retired or divested. Two units at Salem Harbor were retired in 2011 and the station was sold in 2012.
More than 2,900 MW of new gas-fired generation has been added since 2000, plus more than 2,500 MW of non-greenhouse gas emitting nuclear generation and 225 MW of renewable generation (biomass, biomass co-firing with coal, and wind).
In 2012, 600 MW of coal fired generation was added at the Virginia City Hybrid Energy Center.
Lower natural gas prices and the economy led to less operation of some of our coal fired generation in 2012. Additional changes to our fuel mix are being implemented in 2013 which will result in further reductions in carbon intensity.
Dominion has expanded its greenhouse gas inventory process to include CO2 equivalent emissions from gas operations.
CO2 equivalent is a quantity that describes, for a given mixture and amount of greenhouse gas, the amount of CO2 that would have the same global warming potential, when measured over a specified timescale.
The graph shows the greenhouse gas emissions from Dominion’s Transmission (DT) and East Ohio Gas (EOG) Delivery business units since 2005, Dominion Cove Point LNG (CP-LNG) since 2006, and Dominion Hope since 2009.
Prior to 2008 for Dominion Transmission, the protocol used to calculate the non-combustion related emissions was the Greenhouse Gas Emission Estimation Guidelines for Natural Gas Transmission and Storage, Volume 1 – GHG Estimation Methodologies and Procedures. Revision 2, September 28, 2005 developed by the Interstate Natural Gas Association of America.
For Dominion East Ohio, the protocol used to calculate the non-combustion related emissions was the American Gas Association’s Draft Greenhouse Emissions Estimation Methodologies and Procedures for Natural Gas Distribution Operations.
For Dominion Cove Point LNG emissions, the protocol used was the American Petroleum Institute February 2004 Compendium of Greenhouse Gas Emissions Methodologies for the Oil and Gas Industry. For direct combustion emissions, AP-42 emission factors were used from 2005 to 2007. From 2008 going forward, EPA's mandatory Greenhouse Gas Reporting Rule emission factors were used. Greenhouse gases included were CO2, methane and nitrous oxide.