In most cities, the single-largest source of greenhouse gas emissions is electricity usage. Businesses and communities can play a huge role in reducing emissions, improving public health and boosting local job markets by using sustainable energy.

On Sept. 24, the U.S. Environmental Protection Agency (EPA) honored such businesses and communities with its 12th annual Green Power Leadership Awards, which recognize success in promoting the U.S. renewable electricity market. Winners across seven categories include 24 Green Power Partners such as Lockheed Martin, Bloomberg L.P., Coca Cola and Staples. Winners, who were chosen from more than 1,300 partner organizations, advanced green power in a number of ways -- from installing large-scale solar panels to buying 100 percent renewable electricity.

“Our 2012 Green Power Leadership Award winners have not only demonstrated commendable civic leadership in their efforts to use renewable energy sources, they’ve also helped to reduce our carbon footprint and cut back on pollution -- all while supporting America's growing renewable energy industry,” said EPA Administrator Lisa P. Jackson. “Thanks to their commitment -- and the commitment of all of our Green Power Partners -- our country is one step closer to a cleaner, more sustainable energy future.”

"Green power" is electricity that comes from renewable resources like solar, wind and geothermal and that creates no net increase of greenhouse gas emissions.

The EPA also presented the winners of its second annual Green Power Community Challenge, which tracked communities to see which could (1) use the most renewable energy and (2) which could use the greatest percentage of renewable energy. Oak Park, Ill. won the Green Power Community of the Year award as well as reaching the highest percentage of green energy use at 92 percent. For the second year in a row Washington D.C. won the challenge for using the most renewable energy annually with more than one billion kilowatt-hours (kWh).

By the end of the challenge, the participating communities were using a total of almost 5 billion kWh of green power per year, cutting greenhouse gas emissions equal to the carbon dioxide emissions created annually by more than 426,000 homes running on regular electricity.