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Study: Some coal plants generate more emissions
Coal plants run less efficiently and belch out more greenhouse gas emissions when more wind
due to added wind capacity
farms come online.
That is the conclusion of a soon-to-be released study by
market analytics company.
The study is based on data from 2006 through 2008 in areas of Colorado.
Gov. Bill Ritter
retail electricity sales from renewable sources by 2020. Previously, the state’s renewable energy
standard was 20%. According to the American Wind Energy Association’s “Year End 2009
Market Report,” Colorado
ninth overall in wind project installations, with 1,246 MW.
BENTEK Energy’s report found that some coal-fired plants owned by
increase in their emissions levels because they were powered up and down to accommodate
intermittent renewable energy sources, particularly wind.
The study was funded by the Independent Petroleum Association of Mountain States, a nonprofit
trade association. Marc Smith, executive director of IPAMS, declined to provide specific details
about the study’s findings. He did say, however, that the higher levels of emissions at the coalfired
plants were significant, with regional differences. “Our study doesn’t show that the public
utility increased its overall net emissions. In fact, across the system, the emissions may have
decreased systemwide,” Smith said. “But in localized areas where coal-fired power plants were
being cycled excessively to accommodate additions of wind energy, the emissions went up.”
Xcel Energy spokesman Mark Stutz said the company has questions about the study because it
has yet to see a copy of it. Cycling natural gas-fired plants is more efficient and produces fewer
emissions than coal-fired power plants. Xcel Energy does take that into consideration. However,
there are several other factors that the company must weigh when deciding how to provide
backup power for intermittent resources. “It might be the most economical at the time to cycle
back the coal plants, but we have to take into consideration all the other environmental
externalities, systems operations and other things of that nature, too,” Stutz said. “There are
going to be times when the right thing to do is cycle back coal for a number of reasons.”
Smith said that he hopes public utilities and Congress will carefully consider how best to use
natural gas and renewables to help repower America. “There’s a great opportunity to reduce
emissions using both natural gas and renewable energy. The key finding is you have to be careful
how you use those resources.”
Smith said that the study provides more questions than answers, and he said that the report was
not intended to be “a bomb,” but rather a “conversation starter.”
“We hope that [the report] begins to generate more holistic conversations about how best to meet
our future energy needs through the integration of various energy resources,” Smith said. “That’s
an important conversation to have, as is highlighted by this study.”