The Political Economy Research Institute at the University of Massachusetts Amherst recently released the Greenhouse 100 index, which ranks U.S. companies on the basis of their greenhouse gas (GHG) emissions.
Electrical power companies lead the list, with American Electric Power (NYSE: AEP), Duke Energy (NYSE: DUK) and Southern Co. (NYSE: SO) as the top three. According to PERI, the three companies emit more than 5 percent of all GHG in the U.S.
The U.S. government came in fourth on the list, partially because of its ownership of power plants through the Tennessee Valley Authority. Berkshire Hathaway, whose subsidiary MidAmerican Energy Holdings Co. recently acquired NV Energy (NYSE: NVE), was fifth on the index.
The index was put together based on 2011 data from the U.S. Environmental Protection Agency Greenhouse Gas Reporting Program. Researchers at PERI matched the individual facilities to their owners to produce the Greenhouse 100 rankings.
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