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UT-Austin’s Texas-Sized Goal: Cut Methane Emissions Even Further

CO2 emissions are at a 25-year low—and now we’re crunching data on reducing methane, too. Glimpse the tech that’s making it happen.

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December 2, 2019

The world has made a number of energy transitions over the course of history, shifting from wood to coal, from coal to petroleum, and now, according to David Allen, to clean natural gas — a bridge that can help us reduce greenhouse gas emissions, while transitioning toward more renewable energy.

The use of natural gas has helped to bring U.S. carbon emissions to a 25-year low. To build on that progress, Allen and others are looking at ways to reduce emissions of methane, a powerful greenhouse gas that’s released in the natural gas supply chain during production and transportation.

David Allen

Allen has spent the last 35 years working on issues at the intersection of energy and the environment. He has received several awards for his work in air quality and emissions and served as chair of the U.S. Environmental Protection Agency Science Advisory Board from 2012 to 2015.

Today, he is a chemical engineering professor at the University of Texas at Austin and director of the Center for Energy and Environmental Resources, a research center focused on energy and environmental systems.

We talked to Allen about his research on methane emissions, significant findings in the field from the last decade and the future of energy in America. 

What drew you to this area of research?

Research about methane emissions started appearing in scientific literature around a decade ago, as the use of natural gas for energy in the U.S. really took off. That kicked off discussions about the burden of methane emissions from various energy supply chains.

At the time, we didn’t have much data on modern natural gas systems and emissions. I had the opportunity to lead a field study measuring methane emissions at natural gas production sites throughout the United States, sponsored by natural gas producers and the Environmental Defense Fund. That work began in 2012 and, ever since then, I’ve been looking at how we could best use that data to understand where and how methane emissions happen and what we can do about them.

Why is measuring methane emissions important in the process of supplying people with natural gas?

Generating energy with natural gas leads to lower carbon dioxide emissions compared to other, traditional energy sources. But when you’re looking at whether natural gas leads to lower greenhouse gas emissions than other energy sources, methane makes the difference. Methane is a very potent greenhouse gas, so measuring it has become very important in determining the climate benefits of switching to natural gas as a transition fuel.

For example, if you’re looking at replacing coal with natural gas for generating electricity, natural gas starts with a large advantage of lower CO2 emissions, but that advantage is eroded by methane emissions.  A methane escape rate of between 3% and 6% in the natural gas supply chain still leads to less atmospheric warming than the greenhouse gases emitted by coal. But if you’re looking at replacing petroleum with natural gas, you need a much lower escape rate — typically around 1% — for natural gas to have a climate advantage.

What have you found so far in your research?

There have been two significant findings in work done by my group and others. First, the national average for the percentage of methane that escapes throughout the U.S. natural gas supply chain is about 2%. That means we’re eroding some of the climate benefits that we get from using natural gas as an energy source. Even so, there’s still a clear climate benefit when we use natural gas to generate electricity instead of coal.

Second, a small fraction of sites account for most emissions. This has been called the “super emitter” issue. It’s similar to how about 10% of vehicles on the road account for 50% of emissions. The same phenomenon applies to the natural gas supply chain.

We get our cars inspected regularly to check our emissions levels. Similarly, we need to be looking, for those high emitters in the natural gas supply chain so we can fix the problem and reduce those emissions. Many companies are already doing that with annual or semi-annual inspection programs, much as car owners get annual emissions inspections. Technology may now enable much more frequent checks on emission levels at costs comparable to current inspections. If we can do that, we can drive methane emissions much lower and give natural gas even more of a climate advantage over traditional energy sources.

What do you see for the future of energy in America?

We’re on the verge of a new phase in understanding methane. Seven years ago, we were just becoming aware of the importance of including methane in our thinking about the greenhouse gas burdens of various types of energy. Now, because of advances in sensors and other technologies, we are beginning to be able to very cost-effectively go out and get continuous emissions measurements, rather than occasional snapshots, as has been the case until now. This will be a major leap in our understanding of what methane emissions are at any given time and improve our ability to dramatically reduce them.

Continuous monitoring networks have been demonstrated in other sectors. For example, we had set up monitoring networks in regions with multiple petroleum refineries and watched for unexpected emissions. When our systems detected them, we notified the operators, who could then go out and look and immediately see whether or not there was something happening at the refinery that they needed to address.

The information provided by these networks helped to substantially decreased emission levels for specific compounds. With new types of methane monitors, we can take a similar approach for methane emissions in natural gas supply chains.

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