MW or 750 MW net per unit, the rated power output leaving the plant through the transmission lines. The gross capacity was 2409.3 (MW) or 803.1 MW per unit, the rated power output at the generator that includes power used internally in the operation of the plant. Annual net energy generation in 2011 was 16.9 terawatt-hours (TWh), with a net capacity factor of 86%. Annual gross generation was 18.3 TWh. Fuel consumed (primary energy) in 2011 provided of heat input, resulting in a net heat rate of 34% or . In 2014, generation fell to 72% of capacity, and to 61% in 2016. In the first 11 months of 2016, the plant consumed and produced 10.7 TWh of power, giving 33% efficiency. Environmental controls Flue gas emissions Fly ash particulate was removed from the flue gas by hot-side electrostatic precipitators (ESPs) and SO2 scrubbers. The ESPs, constructed as part of the original plant, removed 99% of particulate. Scrubbers removed an additional 50% of what remained in the flue gas after passing through the ESPs. Sulfur dioxide (SO2) emissions were controlled by forced oxidation wet scrubbers. The scrubbers consisted of two countercurrent–flow absorber vessels on each unit, using limestone slurry sprays to remove more than 92% of SO2 from the flue gas. The three scrubbers in total consumed about 24 MW of power, and used 130,000 tons of limestone and of water per year, producing 200,000 tons of gypsum per year. Prior to installation of the scrubbers, SO2 emissions were about 71,000 tons per year. Nitrogen oxide emissions were controlled in the combustion process by the use of low-NOx SOFA burners. Prior to 2009 when installation of the new burners began, NOx emissions were about 34,000 tons per year. The new burners reduced NOx emissions by about 14,000 tons per year, or more than 40%. Fine particulate measuring 2.5 micrometers or less (PM2.5), of concern for its potential effect on health and visibility, primarily results from reactions of SO2 and NOx in the atmosphere to form sulfate and nitrate aerosols. NGS combined permit limits for these precursors has been , lower than 94% of all U.S. coal steam units, while the actual NGS rate in 2011 was . Carbon dioxide (CO2) emissions from NGS were seventh highest of all U.S facilities in 2015, largely a result of the amount of energy it produced. In the same year, however, its CO2 emissions