Throughout history, maps have played a critical role in shaping decisions — helping people determine where they are going and how to get there. Now, maps are defining a way to address methane leaks, a potent contributor to climate change. Environmental Defense Fund and Google Earth Outreach have just launched a series of maps that show methane leaks from natural gas pipelines under city streets in Boston, Indianapolis and Staten Island. The new tool has the power to greatly improve how cities and utilities can minimize methane emissions.
Why care about methane?
A recent tide of scientific studies, such as a recent study of emissions in Pennsylvania, have examined how methane — the primary component of natural gas — is escaping from the natural gas supply chain. Such research has made it clear how much that leakage is affecting global carbon dioxide levels.
One of natural gas's potential benefits over other fossil fuels is that, when burned, it produces less carbon dioxide — half as much as coal — to yield the same amount of energy. If used wisely to rapidly displace dirty coal-power plants, for example, natural gas could help the country dramatically reduce overall greenhouse-gas emissions.
Unburned, however, methane is 84 times more powerful as a greenhouse gas than carbon dioxide for the first 20 years after it is released. While methane doesn't linger as long in the atmosphere as carbon dioxide, it is initially far more devastating to the climate because of how effectively it absorbs heat. If too much methane escapes along the supply chain — anywhere between the well and the end user — it could postpone the climate benefits of fuel switching, a delay we can ill afford. According to the Intergovernmental Panel on Climate Change, roughly one-third of methane emissions in the United States come from the oil and gas industry, and one third of the warming we are currently experiencing comes from anthropogenically released methane in the atmosphere — addressing methane leakage in the natural gas supply chain is critical.
With great data comes great responsibility
For our analysis of methane emissions from local distribution pipes, Google equipped three Street View cars with methane analyzers and drove through large portions of Boston, Staten Island and Indianapolis collecting methane concentration data, GPS data and wind speed and direction data every half second. Our science team, in partnership with Colorado State University (CSU) researchers, developed a first-of-its-kind algorithm to translate the patterns of concentration data collected by the Street View cars into methane-leak rates for individual leaks. These data and the accompanying maps are designed to help the public, utilities and regulators better understand the pattern and scale of urban methane leaks.
For example, we observed one leak per mile of road driven in Boston and Staten Island, a borough of New York City. Depending on the size of those leaks, the climate impact over the next 20 years — for each leak — ranged from the equivalent of driving a car 100 miles every single day up to driving more than 9,000 miles every day. These data will allow utilities to better prioritize which leaks to repair or pipes to replace, enabling them to get rid of the larger leaks much faster than was possible before.
Helping utilities help themselves
The local utilities — like National Grid, the utility in both Boston and Staten Island, and Citizens in Indianapolis — helped validate the data and provided insight into where their repair efforts should be targeted. Leaks even larger than those we saw in our surveys are of the greatest public safety concern; but those leaks are usually identified and fixed quickly. Smaller leaks are monitored by the utilities, but can go unfixed for long periods of time, spewing significant amounts of climate pollutants into the atmosphere. The new methodologies developed to produce the maps hold the potential to benefit both public health (as leaks can sometimes trigger explosions) and the climate.
In addition to providing a picture of leak rates across cities, these maps clearly show the value of investing in a modern natural-gas infrastructure. Older pipes made of cast iron and unprotected steel can corrode as they age, making them more vulnerable to leaks. Plastic pipes, which are used in newer systems, are more durable over time and leak much less. The 200-times-lower frequency of leaks in Indianapolis, versus Boston and Staten Island, clearly indicates the value of Indianapolis's decision to upgrade to plastic pipes.
Investing in newer infrastructure pays off three-fold:
- Minimize safety risks from explosions;
- Climate benefits;
- Keeps marketable product out of the air and in the pipeline.
In the early 80s, the utility Citizens in Indianapolis made replacing the city's aging pipelines a priority. Today, pipes vulnerable to corrosion make up only one percent of Indianapolis's local distribution system, and leak rates there are congruently low. Our efforts found only five leaks in the pipelines examined — one leak for every 200 miles mapped. While Boston, where about half of the pipes are made of materials vulnerable to corrosion and have been in the ground for more than half a century, averaged roughly one leak per mile mapped.
EDF has focused on "finding the ways that work" for almost 50 years, and this collaborative mapping project is indicative of our commitment to tapping the power of science in pursuit of effective solutions. This project takes a major step toward providing local gas-distribution utilities and regulators the scientific tools to better understand methane leaks and should spur meaningful local efforts to reduce emissions of climate pollutants — with more opportunities for effective action. By continuing our collaborations with Google, CSU, local utilities and the public, we can broaden the scope of what we know, map more pollutants in more cities and spark changes to slow the planet's warming.
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