By Jonathan Peress, Environmental Defense Fund.

The most important takeaway from a study released today by Washington State University (WSU) is that despite improvements, large amounts of methane continue to leak from the nation's local natural gas systems. Because methane is a particularly potent greenhouse gas, these yearly emissions are comparable to the CO2 from as many as 19 coal-fired power plants.

The estimated value of the gas escaping each year, by the way, is up to $195 million.

Although these figures represent a major ongoing challenge for gas utilities, they do reflect substantial improvement over the past two decades, thanks to a combination of effort and investment by utilities, along with a series of both state and federal policy changes enacted since 1992.