Cooling tower at power plant, by Flickr user Paul J Everett (Used under CC License)Enlarge Photo
While renewable energy gets significant press as an alternative to coal in electricity generation, it isn't the main factor in decreasing the use of that carbon-intensive fuel.
Thanks to its generally lower cost, natural gas is quickly displacing other fuels in the nation's power plants.
In addition to its cost benefit for electric utilities, natural gas comes with the environmental advantage that burning it to generate electricity generates significantly lower carbon emissions per kilowatt-hour than coal.
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But a new study indicates natural gas may in fact be quite harmful to the environment in its own way.
Methane emissions from natural-gas power plants are 21 to 120 times higher than originally estimated, said researchers from Purdue University and the Environmental Defense Fund.
These findings are based on measurements of methane emissions at three power plants and three refineries in Utah, Indiana, and Illinois, according to DeSmogBlog.
Natural gas flaring from oil well [licensed under Creative Commons from Flickr user Sirdle]Enlarge Photo
Methane is a greenhouse gas 34 times more damaging than carbon dioxide.
"Power plants currently use more than one third of natural gas consumed in the U.S., and the volume used is expected to increase as market forces drive the replacement of coal with cheaper natural gas," the Environmental Defense Fund said in a press release.
The potentially-devastating impact of methane emissions was demonstrated in 2015, when a leak of a single natural-gas well in Aliso Canyon, California, released massive quantities of the greenhouse gas.
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The leak was first detected in October 2015, and took several months to fix.
In that time, greenhouse-gas emissions equivalent to the annual emissions of 1.7 million cars were released from the leaking storage well site.
Coupled to the potential for methane emissions is the controversial process of hydraulic fracturing, used to extract large quantities of natural gas from the earth.
California Citrus State Historic ParkEnlarge Photo
Commonly known as "fracking," it allows access to previously-untapped sources of natural gas, but opponents cite deleterious effects from water contamination to greater likelihood of earthquakes.
But despite major increases in renewable-energy generating capacity, natural-gas remains the default alternative to coal and oil for utilities.
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It allows them to continue using some existing infrastructure, rather than replacing it at substantial cost.
So while more solar and wind farms are being built, the question is really whether they are replacing existing generating capacity, or just augmenting it.