From Boston, More Troubling News about Methane Emissions

3279565519_b95c881c39_z The everyday use of natural gas across the greater Boston area is resulting in much higher emissions of methane than previously thought, according to a study published this month in the Proceedings of the National Academy of Sciences. These emissions represent the waste of a valuable energy resource as well as an important source of greenhouse gas, since methane—the main component of natural gas—is 84 times more potent than carbon dioxide for the first 20 years it is in the atmosphere.

The reported emissions are more than two times higher than previously estimated using state emissions inventory data, with a yearly average loss rate from delivery and use of natural gas in the Boston urban region of 2.7 percent (with a margin of error of 0.6 percent). That’s enough natural gas to fuel about 200,000 homes each year.

While EPA data indicates that investments by many gas utilities in reducing leaks have made a difference, this study, led by scientist at Harvard University, demonstrates that the national statistics may mask significantly higher emissions in some parts of the country.

Though the Boston area is home to a large proportion of old, cast iron natural gas distribution pipes, that aging infrastructure does not necessarily fully explain the high emissions rates found in this study, suggesting that there may be sources of natural gas emissions that are not currently accounted for. The study points to the importance of collecting data about emissions from appliances and industries for which there is little current information.

These additional emissions might be coming from a diversity of end uses, e.g., incomplete combustion in furnaces, boilers, hot water heaters or in power plants and industrial applications.

However, a recent decision by Massachusetts—to encourage accelerated replacement by natural gas utilities of the cast iron and uncoated steel pipes used to distribute natural gas to customers—will certainly help reduce the methane losses observed. Recent surveys highlight the location and magnitude of those losses.

Looking Beyond End-Use Sources

The fact that there are unaccounted for emissions suggests that state policies focused on end-use efficiency of natural gas may also be of value in reducing methane emissions in the state. The study is another among a growing number of recent analyses documenting methane emissions along the natural gas supply chain – from the well sites where the gas is produced, to the facilities that process the natural gas, as well as through the many thousands miles of pipes and compressors that bring the gas to our homes and businesses.

If natural gas is going to help reduce greenhouse gas emissions in the near term, emissions of methane from the entire supply chain must be substantially reduced to less than one percent of the total natural gas produced.

In 2012, EDF launched a major research effort working collaboratively with nearly 100 different groups (universities, research institutes, government and companies) to undertake a series of 16 independent, peer-reviewed studies designed to understand how much and from where methane is escaping into the atmosphere across the entire natural gas supply chain. This analysis is one of those studies.                                            

Groundbreaking Methods

A team of scientists from Harvard and collaborating institutions gathered data at four sites, two on the top of buildings in downtown Boston and two at upwind locations outside the city. Continuous methane observations were collected for a year from the four stations and, using a high-resolution atmospheric model, the regional average methane emissions were calculated.

To understand how much of the observed emissions were coming from natural gas rather than biological sources such as landfills and sewer systems, the team also measured ethane, which is found in natural gas but is not associated with biologically produced methane. The scientists found that depending on the season, natural gas accounted for 60 to 100 percent of the total methane emissions observed. The methods deployed by the researchers can be used as a model for monitoring natural gas emissions in other cities around the world.

Important Implications

Methane emissions are bad for the environment.  But they are also bad for customers.  Natural gas emissions in the urban environment mean that some of the natural gas purchased to meet customer needs does not serve a useful purpose; it is lost either on the way to being delivered or in the process of getting burned.  Imagine a tanker truck full of home heating oil driving down the street, with a spigot that isn’t tightly closed, then delivering to a home with a leaky holding tank—you get the idea.

The good news is that national and state policymakers are increasingly realizing the importance of addressing methane emissions and are taking steps to tackle the problem.

The Obama administration just announced a plan for reducing methane emissions across the oil and gas industry by 40 to 45 percent, and Massachusetts recently enacted a new law intended to improve the classification, reporting and repair of natural gas leaks from the local gas distribution pipes. Putting new emissions standards in place through regulations at the state and federal levels is a critical step to ensure that methane emissions are reduced.

Local Utility Working to Improve

I am pleased to note that National Grid, the local gas utility in Boston, has been working closely with EDF on ways to improve how the utility measures leaks from its distribution pipes. National Grid will use that information to make its existing efforts to reduce leaks across its system more effective.  Thus far, National Grid is the only gas utility in the United States to support the Obama administration’s plan to reduce methane emissions across the oil and gas industry by 40 to 45 percent.  There’s more for National Grid to do, but it deserves credit for being constructively engaged.

These results are yet another call to action on natural gas. The study also suggests that in addition to reducing emissions from gas delivery infrastructure, we need to take a closer look at how natural gas is used and where emissions can be reduced or eliminated on the customer side of the meter.

Photo source: Flickr/Michael Krigsman

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