PROVIDENCE — Every day, thousands of Rhode Islanders drive or walk past one of the state’s biggest sources of greenhouse gas emissions without ever knowing it.

Located along the Providence River, and easily visible from major highways running through the city, the Manchester Street Power Station has had an indelible impact on the city’s skyline and on its environment.

The 510-megawatt (MW) station has powered Providence for more than a century, first opening as a coal-fired power plant in 1903, before later switching to oil, and later, in 1996, natural gas, as environmental concerns over fossil fuels spurred utilities to “clean up” the power grid. Since the abutting South Street Station was decommissioned in 1995, the Manchester Street Power Station is Providence’s oldest operating electrical generator.

It’s box-like shape and three smokestacks, each towering some 300 feet, make the building itself something of an icon — if any image of the Providence skyline includes more than the Superman and Fleet Bank buildings, it’s likely the power station anchoring the image.

Thanks to its status as a natural gas-fired power plant, it’s also the second-biggest single emitter of greenhouse gas (GHG) in Rhode Island. In 2022, the power station emitted 464,454 metric tons of carbon dioxide, according to data from the Environmental Protection Agency. The facility emitted another 226 metric tons of carbon dioxide equivalent (C02e) of methane, and another 293 metrics tons C02e in nitrous oxide.

The Manchester Street Power Station is far from alone in that regard. Of the 10 facilities required by federal law to report their annual GHG emissions to the EPA, five are listed as natural gas-fired power plants. These five facilities account for 87% of the emissions reported to the EPA. Not a huge surprise in a state where most residents — 83% according to the Energy Information Administration — use electricity generated by natural gas plants.

The other five facilities on the EPA’s list emit building and heating emissions, methane leaks, and waste. In total, the 10 facilities are responsible for 3,159,000 metric tons of carbon dioxide equivalent emissions; just under a third of all emissions from Rhode Island. They include large campuses such as Brown University and Rhode Island Hospital and the Central Landfill in Johnston.

Below is a complete list of the state’s 10 biggest emitters, including who owns the facility, what emissions it produces yearly, and in what emissions sector. All data is derived from the last available year of reports to the EPA (2022) and is listed in metric tons of carbon dioxide equivalent (mtC02e), a key measure used to determine the impact different greenhouse gases have on the climate.

Rhode Island State Energy Center

Where: Johnston
Owner: Majority stake owned by Carlyle Group Management LLC
GHG sector: Electricity generation
Emissions: 1.2 million carbon dioxide, 577 methane, 688 nitrous oxide
Located just south of the Central Landfill, next to the upper Simmons Reservoir, this little-known natural gas-fired plant is actually Rhode Island’s single-biggest GHG emitter. In 2022 alone, it was responsible for 13% of all climate emissions released in the state, the bulk of it as straight carbon dioxide. It consists of two natural gas turbines and has a nameplate capacity of 596 MW. It first came online in 2002.

OCEAN STATE POWER

Where: Harrisville
Owner: LS Power Equity Partners
GHG sector: Electricity generation
Emissions: 670,872 tons of carbon dioxide, 323 tons of methane, 414 tons of nitrous oxide
Built in 1990 amid stiff local opposition to its construction, this 508-MW facility is one of the state’s few remaining natural gas-fired power plants still producing electricity in Rhode Island. In 2022 the town of Burrillville signed a tax agreement with the facility. Ocean State Power agreed to pay $2.1 million over a three-year period in return for decreases in its property tax obligations for its natural gas facility. The facility also came under scrutiny from local residents in May 2022 after a breaker blew at a nearby substation for reasons never disclosed by the company. State records show the facility violated its state air permit a number of times between 2010 and 2020.

MANCHESTER STREET POWER STATION

Where: Providence
Owner: Lotus Infrastructure Partners
GHG sector: Electricity
Emissions: 464,454 tons of carbon dioxide, 226 methane, and 293 in nitrous oxide
A notable anchor to Providence’s skyline, this natural gas-fired power plant began operations in 1903. It was originally powered by coal. It’s the third-biggest emitter in the state by volume; releasing thousands of tons of carbon dioxide into the atmosphere annually.

TIVERTON POWER

Where: Tiverton
Owner: Carlyle Group Management LLC
GHG sector: Electricity
Emissions: 405,047 tons of carbon dioxide, 188 tons of methane, and 224 tons of nitrous oxide
The second of two natural gas plants owned by the New York-based Carlyle Group, it’s been operational since 200. The 265-MW plant receives its natural gas from the Algonquin pipeline located off Fish Road.

NARRAGANSETT ELECTRIC COMPANY

Where: Providence
Owner: Rhode Island Energy/PPL Corp.
GHG sector: Petroleum and natural gas systems
Emissions: 126,401 metric tons of methane in C02e, 152 tons of carbon dioxide
While all the other emitters in Rhode Island release GHG on purpose during the course of normal operations, this is the only facility listed with the EPA tracking methane leaks. The Rhode Island Department of Environmental Management typically estimates a 1% leakage rate in the state’s natural gas distribution infrastructure, but previous studies have found northeastern cities such as Boston and New York may be drastically undercounting just how much is escaping, with one 2016 study suggesting it may be as high as a 7% leakage rate.

Toray Plastics Inc.

Where: North Kingstown
Owner: Toray Industries
GHG sector: Other
Emissions: 100,102 metric tons of carbon dioxide, 47 tons of methane C02e, 56 tons of nitrous oxide C02e
One of the few industrial sites generating significant GHG emissions in Rhode Island, like the name says, Toray Plastics manufactures a number of plastic-related products, for packaging, labels, houses, and cars, as well as a number of plastic-based foams for use in motor vehicles and flooring.

BURRILLVILLE COMPRESSOR STATION

Where: Pascoag
Owner: Enbridge Inc.
GHG sector: Petroleum and natural gas services
Emissions: 59,284 metrics tons of carbon dioxide, 3,463 tons of methane in C02e, and 33 tons of nitrous oxide in C02e
The fossil fuel-powered Clear River Energy Center may have been quashed, but that doesn’t mean all the natural gas infrastructure was abandoned. ecoRI News reported in 2019 that Enbridge was planning to expand its 1,100-mile Algonquin Gas Transmission Pipeline with infrastructure upgrades through a series of smaller additions to increase natural gas flow to the region. The compressor station in Pascoag was planned to be expanded to 32,500 horsepower as part of the Access Northeast Expansion project.

RHODE ISLAND HOSPITAL

Where: Providence
Owner: Lifespan
GHG sector: Other
Emissions: 52,195 tons of carbon dioxide, 29 tons of methane C02e, 44 tons of nitrous oxide, C02e
Rhode Island Hospital is one of the few big emitters in the state whose emissions primarily come from heating its campus. According to its permit filed with DEM, the hospital has three boilers onsite. Last year ecoRI News reported the facility had been tardy with filing its emissions report with the EPA; that has since been rectified, according to a hospital spokesperson.

BROWN UNIVERSITY MAIN CAMPUS

Where: Providence
Owner: Brown University
GHG sector: Other
Emissions: 23,925 tons in carbon dioxide, 11 tons of methane C02e, and 14 tons of nitrous oxide C02e
Similar to Rhode Island Hospital, the EPA lists Brown University’s emissions as stemming from heating its buildings. The university has pledged to reach net-zero emissions by 2050, with a target of a 75% reduction by 2025. Last fall it dug three geothermal wells to explore sustainable heating.

CENTRAL LANDFILLL

Where: Johnston
Owner: Rhode Island Resource Recovery Corporation
GHG sector: Waste
Emissions: 226 tons of carbon diocide, 4,462 tons of methane C02e
Rhode Island’s only large emitter of waste, the Central Landfill’s emissions are primarily methane. While some 4,400 metric tons of methane C02e are released into the atmosphere, the landfill estimates it recovers some 184,000 metric tons in methane.