Wind Power May Not Reduce Carbon Emissions As Expected: Argonne

Adding wind power to the existing electric grid may not have the effect of reducing carbon emissions as much as expected, according to a new study published by researchers at Argonne National Laboratory.
Because the wind blows inconsistently, power companies would have to turn fossil-fuel plants on when windmills fall still. Turning fossil-fuel plants on and off adds inefficiencies, producing carbon emissions just to heat up boilers before energy production can begin.
“Turning these large plants on and off is inefficient. A certain percentage of the energy goes into just heating up the boilers again," said Lauren Valentino, one of the authors of the study, which was published in the journal Environmental Science and Technology.
These inefficiencies may cancel some of the carbon savings of the wind power.
"We did find there was a net reduction, it just wasn't proportional," said ANL spokesman Louise Lerner. "As you add more turbines [the carbon emissions are] not reduced in a linear way."
In the researchers own words:
The reduction in emissions during operational periods is great enough that the trend of total emissions is clearly decreasing with increasing wind power penetration. However… we see that for most pollutants, the marginal emissions benefits are reduced for high wind power penetration levels, mainly driven by the higher start-up emissions [of fossil-fuel plants].
Fossil-fuel plants also operate less efficiently at less than full power, so reducing demand for their power, without eliminating it, can offset carbon savings, according to the researchers.
Argonne researchers are working on one possible solution to this problem: batteries that can store wind power for use when the wind stops blowing—as well as store solar energy for use at night.
The researchers modeled their study on the electric grid in Illinois, which depends on a large number of coal and gas plants, and where the wind blows strongest at night, when demand is lowest.
"The analysis in this paper is limited to the state of Illinois, where the results show that wind power to a large extent replaces coal-fired generation with relatively high emissions," the researchers write. "However, the analytical framework is general and could be applied to any region. The emissions implications of increased wind power penetration is to a large extent determined by the portfolio of other power plants."
CORRECTED to reflect that researchers did find a net reduction in carbon emissions from the addition of wind power, just not a proportional reduction or as significant a reduction as expected.

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