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Air Quality and Emissions

Safety & Environment

Air Quality and Emissions

The majority (over 90%) of Consolidated Edison Company of New York, Inc.’s (CECONY’s) non-greenhouse gas (GHG) air emissions are generated by powering our steam system. One of the many characteristics that makes New York City unique is its reliance on steam, which provides space and hot water heating for large segments of Manhattan. The steam system customer base includes approximately 1,600 buildings throughout Manhattan equating to roughly 500 million square feet of prominent NYC real estate. Many historic landmark high-rise buildings and major cultural institutions are steam customers that would have significant difficulty converting to another heat source. Our challenge is to continue to provide efficient steam heat to our community while decarbonizing our system to meet the clean energy goals of our company and New York State.

Air Quality / Non-GHG Emissions

We’re proud to say that since 2005, we have reduced our direct emissions of nitrogen oxides (NOx) by around 70% and sulfur dioxide (SO2) by around 99%. We achieved large reductions in NOx emissions by adding natural gas capability to several generating units at our steam plants. We also installed emissions-reducing controls such as low NOx burners. Increasing the proportion of cleaner-burning natural gas used to produce steam was a key factor in these emission reduction efforts. Our steam stations comply with New York State NOx limits, and stations monitor NOx targets throughout the year to meet these limits. We have also drastically reduced our SO2 emissions by using predominantly natural gas and low-sulfur fuels. Sixty percent of CECONY’s annual steam production comes from co-generation, which reuses waste heat from boilers or gas turbines to produce additional energy. This efficient use of waste heat, in addition to advanced pollution controls on some of CECONY’s units, also helps to reduce the per-unit non-GHG emissions such as NOx.

While we predominantly use natural gas for steam and electricity production (over 99% of the fuel used in our steam and electric generating units in 2021 was natural gas), we retain backup fuel sources to maintain reliability during periods of natural gas-system limitations. No. 4 oil and kerosene are the backup fuels currently used at our steam and electric generating stations. By the end of 2024, all generating units that use No. 4 oil will be fully transitioned to No. 2 oil, which is lighter and has a lower concentration of criteria pollutants. No. 2 oil also aligns with a New York City mandate aimed at reducing local air pollution by requiring steam and electric generating facilities to cease the use of No. 4 oil in boilers by January 1, 2025.

Over its 140 years of operation, the CECONY steam system has continued to evolve its fuels from using coal as a fuel source, to heavy fuel oils, and currently to natural gas. One of our most prominent challenges in the coming decades will be adapting our steam system for its next evolution to become a significant factor in the decarbonized clean energy future. What alternative fuels and technologies will come next, and how will we incorporate them into our steam system? Our engineers are working on it. We’re looking forward to keeping our community and stakeholders abreast of our progress toward a net-zero-emissions future.

Non-GHG Emissions Nitrogen Oxides (NOx) & Sulfur Dioxide (SO2) (thousands of metric tons)

  • NOx
  • SO2

GHG Emissions Reductions

In 2019, New York State enacted the Climate Leadership and Community Protection Act (CLCPA) that established a goal that 70 percent of the electricity procured by load serving entities regulated by the New York State Public Service Commission (NYSPSC) be produced by renewable energy systems by 2030. And it requires the statewide electrical system to have zero emissions by 2040. In addition, the law establishes a Climate Action Council to recommend measures to attain the law’s greenhouse gas (GHG) limits, including measures to reduce emissions by displacing fossil-fuel fired electricity with renewable electricity or by implementing energy efficiency measures to achieve an 85% reduction of GHG emissions by 2050. In support of the State goals, Con Edison is committed to leading and delivering the transition to a clean energy future, through our updated Clean Energy Commitment. We are committed to building a resilient, 22nd Century electric grid that delivers 100% clean energy by 2040. We are aiming for net-zero Scope 1 Emissions by 2040, by decarbonizing our steam system and other company operations and reducing our fugitive methane emissions from our natural gas delivery system to net zero by 2040.

Our Energy Vision is to take a leadership role in the delivery of a clean energy future for our customers. We will do that by investing in, building, and operating reliable, resilient, and innovative energy infrastructure, advancing electrification of heating and transportation, and aggressively transitioning away from fossil fuels to a net-zero economy by 2050. To achieve our vision, we are committed to reducing our carbon footprint. We firmly support efforts by local, state, and federal agencies to reduce greenhouse gas emissions. We have reduced our carbon emissions by 53% (39.9 million metric tons of CO2 equivalent) since 2005 – equal to taking more than 500,000 vehicles off the road.

Con Edison recognizes the international standard for delineating emission sources into various categories of “scope” based on whether the company was directly responsible, indirectly responsible, or facilitator to the emission of greenhouse gasses. These categories are roughly broken into 3 scopes of emissions:

  • Scope 1 emissions are those greenhouse gases emitted into the atmosphere by Company-owned assets. As with our non-GHG emissions, the majority of Con Edison’s Scope 1 GHG emissions (88%) result from CECONY’s operation of steam, electric, and co-generation plants, where fossil fuel is combusted, and greenhouse gases are emitted as a result. Additionally, fugitive Scope 1 emissions occur when pressurized equipment and infrastructure containing a greenhouse gas has a controlled or uncontrolled emission into the atmosphere. Fugitive Scope 1 emissions are principally composed of SF6 from electric distribution equipment (2%), and methane (CH4) from the Company’s natural gas distribution system (7% CECONY; 1% Orange & Rockland). The Company’s vehicle fleet is also a source, albeit relatively small (1%) for Scope 1 emissions.

2021 Con Edison, Inc. Direct GHG Emissions - Scope 1

  • CECONY Gas Usage for HVACon
  • CECONY Compressor & Heater Stationson
  • O&R CH4on
  • CEI Fleeton
  • Substationon
  • CECONY CH4on
  • Steam & CoGenon
  • Scope 2 emissions are generated when Company assets indirectly contribute to Scope 1 greenhouse gas emissions from a non-affiliated entity. The consumption of electrical power at Company facilities, for example, necessitates that an upstream power generator combust fossil fuels to generate electricity, which, in turn, leads to greenhouse gas emissions. For Con Edison, nearly all Scope 2 emissions originate as electric consumption by Company-owned assets, including losses in electric distribution and transmission (“T&D losses”), and metered consumption of electric power at Company-owned facilities.
  • Scope 3 emissions represent indirect emissions generated as a result of customers using Con Edison’s services. The vast majority of Con Edison’s Scope 3 emissions stem from the delivery of electricity and gas to our customers, which results in greenhouse gas emissions from either the generators supplying the electricity, or the customers’ combustion of gas. A second, and more difficult to calculate component to Con Edison’s Scope 3 emissions include the emissions resulting from the Company’s supply chain; specifically, those emissions resulting from the production of material, transportation, and labor associated for all Company activities.

The chart below presents the proportion of our Scope 1, 2 and 3 emissions, focusing on the Scope 3 emissions from the delivery to and use of electricity and gas by our customers (not including emissions associated with our supply chain or methane emissions “upstream” from the production and delivery of natural gas to the “city gate”).  Our Scope 1 emissions comprised largely of steam, electric, and co-generation plant operations make up 8% of our total GHG emissions, while Scope 2 emissions associated with T&D losses comprise 4%.  The majority (88%) of our total GHG emissions are Scope 3, nearly evenly split between the emissions associated with generating the electricity (45%) and customer combustion of natural gas (43%) that we deliver. 

Con Edison, Inc. Direct and Indirect GHG Emissions - Scope 1, 2, and 3

  • Scope 1: CECONY Steam / Electricon
  • Scope 2: T&D Losses and Company Used Electricon
  • Scope 3: Gas Deliverieson
  • Scope 3: Electric Deliverieson

Con Edison, Inc. Direct GHG Emissions - Scope 1 (thousand metric tons CO2e)

  • Avoided Emissions Compared to 2005 Baseline
  • SF₆ Emissions
  • Methane Emissions
  • CO₂ Emissions

This chart above presents Con Edison Inc. Scope 1 GHG emissions trend data from 2007 through 2021. They show a steady increase in avoided GHG emissions compared to a 2005 baseline, including significant reductions in SF6 and methane. Carbon dioxide emissions, which are largely from the steam, electric, and co-generation plant operations have been reduced over this time by switching to natural gas as a fuel source. Planning for future decarbonization efforts to drive further GHG reductions in these plants is well underway and we look forward to sharing our findings.

2009-2021 Con Edison, Inc. Indirect GHG Emissions – Scope 2 & 3


Indirect emissions – Scope 2 (million metric tons CO₂e)

Other indirect emissions or Scope 3 total (million metric tons CO₂e)








































Scope 2: Indirect greenhouse gas emissions associated with delivering products to customers (e.g., electrical transmission losses)

Scope 3: Indirect greenhouse gas emissions associated with customers using CEI products (e.g., customers’ use of delivered gas)

Steam Environmental Efforts

We provide customers with U.S. Food and Drug Administration (FDA)-quality steam, of which 60% is co-generated. Because the steam is co-generated, customers can apply for points toward their Leadership in Energy and Environmental Design (LEED) certification and increase their score in Energy Star’s portfolio manager. Our co-generated steam reduces carbon emissions by approximately 25% of what would have been otherwise emitted through traditional boilers—that is equal to removing approximately 200,000 vehicles from the road every year.

Our customers also benefit from the advantages of a centralized district steam system which reduces onsite emissions from boilers in customer buildings. These centralized investments benefit all customer buildings. The ability of the district system to aggregate a wide variety of customer load profiles also allows for a higher average efficiency than what can be achieved at a single location. All these benefits are reflected in the most recent NYC Local Law 97, where our district steam system was identified as the lowest greenhouse gas emitting energy source per unit of energy delivered.

In alignment with New York City’s and State’s commitments to significantly reduce greenhouse gases by 2050, we are evaluating opportunities to reduce our environmental footprint. We acknowledge that business as usual is not and cannot be the way of the future to achieve these goals, which is why we have recently updated our Clean Energy Commitment with a more detailed identification of the initiatives we are pursuing. As part of this update, we have pledged to reduce the Company’s emissions with a focus on decarbonizing our steam operations.

We are taking a more forward-thinking approach, conducting research, and evaluating opportunities for more efficient generation and customer programs, while using existing and emerging technologies. To continue supporting our customers in a changing environment, Steam Operations has been proactive in several efforts, such as benchmarking with district steam systems in other cities that are using their district energy networks to achieve their carbon reduction goals. Additionally, we have also been an active member in discussions and studies as regulations for the city and state plans evolve.

Steam Operations has also established an internal cross-functional team dedicated to evaluating the feasibility of carbon-reduction technologies and strategies with the existing steam system. Technologies include alternative fuel sources, carbon capture, production via electric boilers with renewable energy, expanding and/or converting to hot water systems, wasted heat recovery sources, and other emission reduction technologies. In the next few years, we hope to implement demonstration projects for the technologies that seem most promising for carbon-free steam generation.

Reduction of SF6 Emissions

In accordance with a 1999 memorandum of understanding between the U.S. Environmental Protection Agency (EPA) and Consolidated Edison Company of New York, Inc. (CECONY), we agreed to reduce our emissions of SF6 gas (sulfur hexafluoride) by 5% annually from our 1996 baseline. In 2021, we released about 98% less SF6 than in 1996, well ahead of our commitment to the EPA. SF6 is a nontoxic, nonflammable greenhouse gas, with a warming potential more than 22,000 times higher than carbon dioxide, that can remain in the atmosphere for up to 3,200 years. It is a highly efficient insulating medium and arc extinguisher used throughout the energy industry in different types of equipment, including high-voltage breakers and gas-insulated switchgear.

Currently there is no viable alternative to SF6 for high voltage equipment like that in CECONY’s electric system. There is research underway, particularly in Europe, to find alternative gases, but there are no viable substitutes that would replace the SF6 in existing equipment. Con Edison is a member of Electric Power Research Institute (EPRI) where we benchmark and stay informed of industry updates. EPRI is supporting research around alternative gases as well. Some utilities in the United States have replaced SF6-containing equipment, but those programs have so far been limited to lower voltage classes of equipment than used on CECONY’s system. Therefore, at the present time, limiting emissions is the best strategy for contributing to a healthier environment and helping to reduce global warming.

While we have greatly reduced our emissions in the past decade, we continue to reduce our remaining emissions. We established a five-year plan at the start of 2020 to reduce SF6 emissions by 500 pounds annually. This is a rate of more than five percent annually from current levels and we have so far achieved five percent annual reductions in 2020 and 2021.

To reduce SF6 emissions, we use programs developed by a dedicated team that established a process to address leaking equipment in a timely matter. For example, a team of specially-train technicians is constantly monitoring the emissions of all equipment daily using a tracking software program to enable quick and efficient detection and repair of SF6-containing equipment. The team also uses cameras designed to detect SF6 to monitor equipment in operation. We then follow best management practices, including innovative new leak-sealing techniques to make the necessary repairs, as well as handling the gas properly with minimal emissions.

We also have several targeted programs to retire or replace older SF6 equipment with new SF6-containing equipment, including circuit breakers, automatic ground switches and gas-insulated switchgear. New SF6-containing equipment used in replacements typically has a much lower leakage rate than earlier technologies, with new equipment warranted to a leakage rate of less than 0.5%.

CECONY SF6 Leakage Rate History % Nameplate Capacity

  • SF6 Emission Rate

Natural Gas Leaks

Consolidated Edison Company of New York, Inc. (CECONY) performs gas leak surveys that far exceed the survey interval requirements prescribed by federal and New York State regulations for identifying natural gas leaks timely. Our accelerated survey effort is supported by an aggressive leak repair program that also repairs leaks much sooner than the timeframe allowed by New York State regulations. The leak repair program includes the repair of Type 1 leaks which are an immediate hazard and the leak has to be worked to eliminate the hazard; Type 2 leaks which are not an immediate hazard and the repair can be scheduled and completed in the prescribed timeframe; and non-hazardous (Type 3) leaks that are not required by Code to be repaired. New York State regulations do not require repair of Type 3 leaks. The table below highlights the success of the Company’s leak identification and repair program on the time it takes to eliminate emissions.

Leak Type

Average Days until Permanent Repair (2021)

Leak Repair Code Requirement

Type 1


Inspect daily until permanent repair is complete

Type 2


6 months

Type 2A


Within 1 year

Type 3



This proactive leak identification and rapid repair program significantly reduces the amount of natural gas emissions that would have occurred if the Company had only met the State (code) repair requirements. In fact, the rapid identification and repair program reduces annual emissions from leaks by approximately 90% compared to the emissions that would occur under the timelines in the State-mandated program and assumes Type 3 leaks to have a 12-month repair cycle when code does not require Type 3 leaks be repaired at all. CECONY has calculated these savings by applying emission rates determined by a study focused on the Company’s gas distribution system undertaken by the Environmental Defense Fund (EDF) and performed by Colorado State University, a nationally recognized leader in the field of emission detection and quantification.

To enhance the effectiveness of our overall leak identification process, CECONY is investigating new leak detection technologies. Ongoing work with Colorado State University to evaluate advanced leak detection technologies will enhance the performance of our survey crews and will help to further reduce emissions associated with leaks.

CECONY is also beginning to use a natural gas capture device called “ZEVAC”. ZEVAC captures natural gas in mains that are undergoing repairs. The captured gas is transferred to other portions of the piping system so that the gas is not emitted into the atmosphere. Although the use of ZEVAC technology is currently limited to use in the high-pressure portions of the distribution system, the Company is committed to expand its use going forward.

Methane Challenge

In 2016, Consolidated Edison Company of New York, Inc. (CECONY) joined 40 other local distribution companies as a founding partner in the EPA’s Natural Gas STAR Methane Challenge. The goal of this program is to reduce methane emissions by replacing a significant number of natural gas mains. Our participation in this program was a natural extension of our participation in the Natural Gas STAR program, which we helped found in 1993.

The Natural Gas STAR Methane Challenge is an EPA/partner company collaboration that promotes and tracks ambitious, transparent commitments to voluntarily reduce methane emissions beyond regulatory requirements.

Our goal is to replace 4% of our cast iron and unprotected steel mains each year. Since 2017, we have replaced 448 miles of such mains, which represents an average replacement rate of 4.5%.

CECONY also performs monthly leak surveys of the entire distribution system to detect methane emissions and make associated repairs to the gas system. In addition, CECONY is looking into several initiatives to meet the requirement under New York’s Climate Leadership and Community Protection Act of having zero carbon emissions by 2050. In 2020, CECONY joined 36 other natural gas companies in the ONE Future Coalition to reduce company methane emissions to 1% or less by 2025. We are also exploring new tools and technologies that would aid in mitigating emissions during normal operations and continue to conduct field trials of enhanced leak detection tools.

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