21 January 2009 -- In 2007, for the first time, renewable energy sources other than conventional hydroelectric capacity made up the largest portion of capacity additions, according to data released January 21 by the Energy Information Administration (EIA).
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Total net summer capacity rose 13,845 MW in 2007. Wind capacity accounted for 5,186 MW of this new capacity. Natural gas-fired generation accounted for 4,582 MW. Two new coal-fired plants with summer capacity totaling 1,354 MW were placed in service in 2007.
However, retirements and downward adjustments to existing capacity resulted in a 217 MW net reduction in coal-fired capacity. Altogether, EIA said 4,439 MW of net summer generating capacity retired during 2007. That included 1,196 MW of coal and 2,741 MW of natural gas capacity.
Record Coal
At the same time, coal-fired generation in 2007 hit an all-time high, eclipsing the previous record set in 2005. The record reflects a one percentage point increase in the average capacity factor of coal-fired generation to 73.6 percent.
Additionally, two coal-fired power plants in the Pacific Northwest returned to service during 2007. The Boardman Plant in Oregon returned to service in May 2006 following a series of outages that began in October 2005. Net generation from the Transalta Centralia Generating Plant in Washington State, increased in 2007 following a reduced level of production in 2006, when the plant conducted a test burn of Powder River Basin coal.
EIA said coal-fired electricity production was further enhanced by the start of commercial operations at the Walter Scott, Jr. Energy Center Unit No. 4 in Council Bluffs, Iowa (923 MW nameplate rating) and the Cross Generating Station No. 3 in South Carolina (591 MW nameplate rating).
Emissions
Unlike 2006, when carbon dioxide, sulfur dioxide and nitrogen oxides emission declined, carbon dioxide emissions from conventional electric generation and combined heat and power plants rose 2.3 percent in 2007. Sulfur dioxide and nitrogen oxides fell 5.1 percent and 3.9 percent, respectively. Since 1997, sulfur dioxide and nitrogen oxides emission have been reduced by 32.9 percent and 43.8 percent, respectively.
Coal, natural gas and nuclear energy consistently provided between 84.6 and 89.5 percent of total net generation between 1997 to 2007, the EIA data show. Petroleum's relative share of total net generation was unchanged in 2007 from 2006 at 1.6 percent.
Conventional hydroelectric power continued to decline. In 2007, conventional hydroelectric generating capacity accounted for 6.0 percent of total net generation, as compared to 10.2 percent in 1997. Renewable energy sources, excluding conventional hydroelectric generation, contributed 2.5 percent of total net electric generation in 2007. This marks the fourth consecutive year in which renewables' share of total net generation has increased, EIA said.
In 2007, electricity generation from coal-fired capacity increased 1.3 percent, reversing the decline from 2005 to 2006. Coal-fired generation increased from 1,991 million MWh in 2006 to 2,016 million MWh in 2007. This new record exceeded the previous all-time high of 2,013 million MWh set in 2005.
In spite of setting a record level for generation in 2007, coal's share of total net generation continued its downward trend in 2007. It accounted for 48.5 percent of total net generation in 2007 as compared to 49.0 percent in 2006 and 52.8 percent in 1997.
The decline was attributable to continued increase in the share of total net generation produced by natural gas-fired and nuclear capacity, as well as renewable sources, other than conventional hydroelectric capacity.
Rising Natural Gas
Net generation from natural gas-fired capacity increased 9.8 percent, from 816 million MWh to 897 million MWh in 2007. This was the second largest one-year increase in natural-gas fired generation since a 10.8 percent increase in 1998. Natural gas-fired generation accounted for 21.6 percent of total net generation in 2007 as compared to 20.1 percent in 2006. For the second consecutive year, natural-gas fired generation was the second leading contributor to total net generation, surpassing nuclear generation, which historically was the second leading source of total net generation after coal.
Nuclear Generation
Net generation at nuclear plants rose 2.4 percent in 2007 to 806 million MWh. Between 1996 and 2007, nuclear generation ranged from an 18.0 to 20.6 percent share of total net generation with an annual average growth in net generation of 1.6 percent from 1996 through 2007.
The continued growth in nuclear generation is due to improved capacity utilization and the resumption of commercial operations at the Tennessee Valley Authority's Browns Ferry Unit 1 after a 22-year shutdown. Since 1996, average capacity factors for nuclear plants increased from 76.2 percent to 91.8 percent. In 2007, nuclear power plants operated at their highest average capacity factor, once again setting a record for net generation.
EIA said the increase in nuclear generation during 2007 appears to be primarily a function of improved plant performance. In 2007, nuclear plant operators reported a 47 MW increase in net winter capability and a 68 MW decrease in net summer capability. This is the first year since 1999 in which the net summer capability of nuclear plants declined, a departure from the annual increases in net summer capacity of existing nuclear plants that occurred between 1999 and 2006. During this period net summer capability of existing nuclear plants rose by 2,293 MW. That equates to an average annual increase of 418 MW of net summer capability.
Falling Hydro, Rising Renewables
Net generation from conventional hydroelectric plants declined 14.4 percent from 289 million MWh in 2006 to 248 million MWh in 2007. EIA said the decline is consistent with the drought conditions, which according to the National Climatic Data Center prevailed over the West and Southeast for much of the year.
Net generation produced by renewable energy sources, excluding hydroelectric generation, grew by 9.0 percent as compared to 10.5 percent growth in 2006. Renewable energy accounted for 2.5 percent or 105 million MWh of total net generation in 2007.
Wind generation was the second largest renewable energy source, contributing 34 million MWh or 0.8 percent of total net generation in 2007. Geothermal power plants supplied 15 million MWh of net generation and other biomass 17 million MWh.
Wind generation is rapidly gaining a larger share of total renewable generation. In 2007, wind accounted for 32.7 percent of total net generation from non-hydroelectric renewable sources, as compared to 4.3 percent in 1997. The annual growth in solar thermal and photovoltaic generation has been sufficient for this renewable source to account, on average, for 0.5 percent of all non-hydroelectric renewable energy.