Scouting Maine’s top greenhouse gas emitters by satellite

New data shines a light on the sources of planet-warming greenhouse gas emissions.
Aerial view of the Dragon cement plant
The Dragon cement plant in Thomaston is one of the largest greenhouse gas emitters in the state, according to satellite data. Photo courtesy Dragon Products.

Editor’s Note: The following story first appeared in The Maine Monitor’s free environmental newsletter, Climate Monitor, that is delivered to inboxes for every Friday morning. Sign up for the free newsletter to get important environmental news by registering at this link.

New data from the nonprofit Climate TRACE is shedding new light on Maine and the world’s largest, and hardest to quantify, sources of planet-warming greenhouse gas emissions. Today we’re taking a look at these numbers to get a sense of how Maine’s biggest emitters stack up in the global context.

The New York Times describes Climate TRACE as a “coalition of environmental groups, technology companies and academic scientists,” with funding sources including Al Gore and Google. “Climate TRACE says it can produce emissions estimates that are more up-to-date than existing ones, and that rely less on information reported by governments about their own countries’ emissions,” the NYT wrote. “It does this largely by mining satellite imagery and other data to get a more precise measure of individual facilities’ production activity, then estimating their emissions.”

The data, which experts emphasize is not yet peer-reviewed, was recently updated to cover 2021. It now spans nearly 80,000 direct and indirect emissions sources — not just power plants and drilling sites, but factories, landfills, farmland and more.

The caveat, before we explore the top emissions sources listed for Maine, is that this data is not yet comprehensive. For example, Climate TRACE’s map does not show any of Maine’s fossil fuel-burning power plants, which we know from federal data are major sources of emissions. According to the group’s methodology files, their data is still a patchwork — it may only list the top 500 emitters for some sectors, or only facilities with certain kinds of available data. I pulled federal data on Maine power plants for comparison purposes, and threw it together with Climate TRACE in a spreadsheet you can explore.

Now, the global context: Climate TRACE shows the top source of emissions in the world as the Permian Basin in Texas, home to thousands of oil and gas drilling operations that are seeing record productivity this year. Other oil and gas fields in Russia, Iran, the U.S. and China cover the top 14 emitters in the 2021 data. Next on the list, at 15th in the world, is a steel plant in China.

Zooming in, we see the biggest emissions source in New England — which doesn’t produce its own fossil fuels, but relies heavily on importing them for heating, transportation and electricity — is Boston Logan International Airport, which caused nearly 830,000 tons of carbon dioxide-equivalent emissions in 2021. (CO2e, as it’s known, is a way of normalizing and adding up the warming effects of different greenhouse gases.) Logan ranks 3,752th out of the world’s emissions sources — between a crop-growing area in China, and a refinery in Belarus.

The city of Boston itself doesn’t crack the top 1,000. The data shows Boston’s 2021 emissions were comparable to those of Dallas-Fort Worth International Airport (reportedly the second-busiest in the world as of 2021), or Exxon’s Beaumont petrochemical refinery in Texas.

With that in mind, let’s go way down the list to the emissions sources for Maine. The biggest emitter listed is Casella’s Pinetree Landfill in Hampden, ranked 7,510th globally, between the Adelaide, Australia airport and a copper mine in Peru. Climate TRACE says Pinetree emitted more than 260,000 tons of greenhouse gases in 2021. Landfills put out carbon and methane as the trash inside them — much of it plastic, which is made of fossil fuels — decomposes.

The state’s many other, smaller landfills round out the list. For example, Waste Management’s Crossroads Landfill in Norridgewock is 4th among emitters listed in Maine and 10,670th globally, akin in its emissions to a large cargo or cruise ship. Climate TRACE says Casella’s Juniper Ridge Landfill in Alton (the 15,568th-largest emitter listed globally) emits a little less than a coal mine in Indonesia.

The second-biggest emitter listed for Maine is Dragon Products’ cement plant in Thomaston. The energy required to make cement makes the industry one of the largest polluters globally — if it was a country, it would be the third-biggest emitter in the world, according to Carbon Brief. The Thomaston plant ranks 8,798th in the world overall for its emissions, putting out more than 152,000 tons of CO2e in 2021.

The other big feature of the list is Maine’s airports, where carbon-dense jet fuel and gas or diesel for ground transportation are major emissions sources. The Portland International Jetport is listed third for Maine and 9,333rd in the world, akin to a landfill in Malaysia or a coal mine in South Africa. The Bangor airport (the 11,936th-largest emitter in the world, according to Climate TRACE) emits a little more than a particular dairy cattle feedlot in California.

I noted earlier that Climate TRACE does not list emissions for power plants in Maine, so I went digging in the Energy Information Administration‘s data mines for something to compare. The EIA lists carbon emissions (not CO2e) for individual electricity generation facilities through 2020, including ones that feed the regional power grid and that only power specific industrial facilities.

There are three of these power plants in Maine that, in 2020, emitted more carbon than the amount of greenhouse gases Climate TRACE says came from Pinetree Landfill or the Dragon cement plant in 2021: the gas-fired Westbrook Energy Center, a grid-facing power plant owned by Calpine; the Androscoggin Energy Center, which uses gas to power the Pixelle paper mill in Jay that is slated to close next year; and the solid waste-burning Rumford Cogeneration Plant that powers the large ND Paper mill.

Two more facilities rank above the Portland Jetport: ND Paper in Rumford again, with the coal it burns when it doesn’t have enough trash to meet its energy needs (many items in EIA’s data are individual burners or turbines at the same facility, and ND Paper appears yet again later on the list with emissions from gas); and the gas-fired turbine that powers the Woodland Pulp paper mill in Baileyville.

Taken together, these datasets paint a picture of large-scale Maine emissions that come primarily from landfilling, air travel and the paper and cement industries. And there is one other missing piece to consider, which even an innovative analysis like Climate TRACE’s would struggle to pin down: the many individual gas-powered cars and trucks, and home oil, propane and wood burners, that keep Mainers warm and on the move. Transportation and heating oil are the major priorities in the state’s climate plan. As the world gets better at analyzing its emissions sources, these policy solutions may evolve and grow too.


To read the full edition of this newsletter, see Climate Monitor: Scouting Maine’s top emitters by satellite.

Annie Ropeik has been given the keys to the Climate Monitor newsletter while its regular author, the Monitor’s environmental reporter Kate Cough, is on leave. Reach Annie with story ideas at:

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Annie Ropeik

Annie Ropeik is an independent climate journalist in Camden. She previously reported for Spectrum News Maine in Portland and spent about a decade as a local public radio reporter in Alaska, Delaware, Indiana and New Hampshire. Her award-winning energy and environment reporting has appeared in Energy News Network and Inside Climate News and on NPR, the CBC and podcasts such as Outside/In and Living on Earth. A Maryland native and Boston University graduate, Annie serves on the board of the Society of Environmental Journalists.
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