Our Commitment to Environmental Sustainability

Fast Company's World's Most Innovative Companies 2024 awards winner, Corporate Social Responsibility

At United, our mission is connecting people and uniting the world. Every day, we celebrate the people and communities across our planet — which is why we understand the need for bold action now to combat climate change. United is committed to reducing our emissions, so that we can continue to appreciate the wonders of this world, today and into the future.

From our CEO

"We're embracing a new goal to be 100% green by 2050 by reducing our greenhouse gas emissions 100%. And we’ll get there not with flashy, empty gestures, but by taking the harder, better path of actually reducing the emissions from flying. We (also) realize there's a limit to what a single company can do alone. That's why we are continuing to seek opportunities to collaborate with other industries. We must reach across industries to develop coordinated efforts to accomplish what must be our collective goal of carbon neutrality."

— Scott Kirby, Chief Executive Officer

This isn't your average sustainability story

Sustainable aviation fuel, hydrogen engines and electric planes may sound like something from a sci-fi story. But our airline (and over 65,000 heroes) are working every day to take that idea from fiction to reality.

It's the true story of our vision to do the right thing, the smart thing and the hard thing. Because it’s worth it to us when good leads the way.

Watch how.

  • In June 2024, we were recognized in the Time 100 Most Influential Companies list for United Airlines Ventures, our first-of-its-kind investment fund dedicated to supporting technologies to help decarbonize aviation one day.
  • In May 2024, United Airlines Ventures’ Sustainable Flight Fund was named the Investing winner of Fast Company’s 2024 World Changing Ideas list, recognized for the Fund’s forward-looking mission and scalable design.
  • In March 2024, we received the No. 2 spot as Fast Company's "World’s Most Innovative Companies" award in the Corporate Social Responsibility category. The recognition highlights the Sustainable Flight Fund, a first-of-its-kind investment fund designed to support startups innovating to decarbonize air travel.
  • In February 2024, we announced the close of the UAV Sustainable Flight Fund, which convened $200 million in partner and customer contributions for start-ups focused on decarbonizing air travel by accelerating the research, production and technologies associated with SAF. Over 115,000 United customers contributed over $500,000 to the Fund.
  • In May 2023, the Science-Based Targets initiative (SBTi) approved our 2035 near-term emissions reduction target. This significant milestone represents independent, external validation that our near-term target is science-based. SBTi determined our near-term target ambition is in line with a trajectory that seeks to limit global warming to well below 2.0°C above pre-industrial levels. Our SBTi-approved target is our ambition to reduce scope 1, 2, and well-to-wake jet fuel GHG emissions, including scope 3 category 4, upstream transportation and distribution 50% per revenue tonne kilometer (RTK) by 2035 from a 2019 base year. footnote1, footnote2
    The GHG Protocol, the preeminent methodology for calculating GHG emissions, breaks Scope 3 emissions into 15 different categories. Our near-term emissions reduction target incorporates Scope 3, Category 3 emissions: GHG emissions from conventional jet fuel production, referred to as "well-to-tank" (WTT) emissions. This allows us to capture the full lifecycle emissions of conventional jet fuel usage, i.e. the "well-to-wake" (WTW) emissions which allows us to chart both Scope 1 and Scope 3 emissions reductions from conventional jet fuel. SAF lifecycle emissions are also reported on a WTW basis, with biogenic emissions from SAF combustion reported as a separate, non-scope line item. United’s emissions from regional partner airlines are also included in our near-term target and categorized under Scope 3, Category 4: Upstream Transportation and Distribution. For additional information on our GHG inventory and reporting, see our 2023 Corporate Responsibility Report.
  • In February 2023, we launched the UAV Sustainable Flight Fund, a first-of-its-kind investment vehicle designed to support start-ups focused on decarbonizing air travel by accelerating the research, production and technologies associated with SAF.
  • In February 2023, we became the first U.S. airline to show customers an estimate of each flight's carbon footprint in their search. Consumers who book travel through United for travel within or from the U.S. will now see an option to contribute to supplement United's investment in the UAV Sustainable Flight Fund before check-out.
  • In January 2023, United formed a joint venture with Tallgrass Energy and Green Plains to develop and then commercialize SAF technology that uses ethanol. The tech was developed by researchers at the U.S. Department of Energy's Pacific Northwest National Laboratory. If successful, United will get up to 135 million gallons of ethanol based SAF annually and 2.7 billion gallons in total – the company’s largest offtake agreement.
  • In November 2022, United announced a strategic equity investment in Natron Energy, a battery manufacturer whose sodium-ion batteries have the potential to help United electrify its airport ground equipment like pushback tractors and operations at the gate.  United has made substantial investments in companies developing technology to reduce aircraft emissions, but Natron is the first that has the potential to reduce the greenhouse gas footprint from United's ground operations.
  • In November 2022, United became the first U.S. airline to invest in a biofuel refinery. United could invest as much as $37.5 million if NEXT hits benchmarks. NEXT’s Oregon facility will produce sustainable diesel, SAF, and other renewable fuels. The facility will open in 2026 and could produce as much as 50,000 barrels a da once at full production.
  • In September 2022, United announced a $15 million investment and a conditional purchase agreement for 200 four-seat electric aircraft plus 200 options, expecting the first deliveries as early as 2026 – becoming the first major airline to publicly invest in two eVTOL companies.
  • In August 2022, United was the winner of the Environment, Social & Governance award. According to FlightGlobal, this award is given to an airline demonstrating "an unwavering commitment to the environment and sustainability, exhibited by the airline’s actions through any of the following: environmental protection and consciousness; embedding long-term sustainability objectives into business planning and culture; innovating with new technological or business developments to help achieve environmental goals; support of underprivileged classes or groups; humanitarian aid; and good corporate citizenship."
  • In June 2022, United and United Airlines Ventures (UAV) announced an investment in and commercial agreement with Dimensional Energy – an additional carbon capture and utilization investment. Dimensional Energy’s power-to-liquids process makes SAF using renewable thermal energy to combine CO2 from the air with hydrogen from water. United has also agreed to purchase up to 2 billion gallons of SAF from Dimensional.
  • In May 2022, United signed a purchase agreement for the right to buy up to 52.5 million gallons of Neste MY Sustainable Aviation Fuel™, produced from 100% sustainably sourced renewable waste and residue raw materials. This is the first time a U.S. airline has signed an international purchase agreement for sustainable aviation fuel (SAF).
  • In March 2022, United Airlines Ventures (UAV) and Oxy Low Carbon Ventures announced an investment in biotech firm Cemvita to commercialize the production of SAF intended to be developed through a revolutionary new process using CO2 and synthetic microbes.
  • In December 2021, United became the largest airline to invest in zero-emission, hydrogen-electric engines for regional aircraft, through an equity stake in ZeroAvia.
  • In November 2021, United participated in COP26, the UN's Climate Change Conference, with the only airline CEO in attendance, supporting net-zero emissions for air travel through the use of SAF and other technologies.
  • In September 2021, United made a joint investment with Honeywell UOP in Alder Fuels, a new cleantech venture developing a first-of-its-kind SAF, also agreeing to purchase 1.5 billion gallons of SAF. This purchase agreement is the largest publicly announced SAF agreement in aviation history.
  • July 2021, United Aviate Ventures (UAV) announced that along with Breakthrough Energy Ventures, we have invested in Heart Aerospace, an electric aircraft startup which is developing the ES-19, a 19-seat electric aircraft that has the potential to fly customers with zero emissions when powered by renewable electricity.
  • In July 2021, Air Transport World magazine named United its Eco-Airline of the Year for the second time since the award has been in existence and was awarded by Air Transport World as the top environmental honor for the third time.
  • In April 2021, United announced the launch of the first-of-its-kind Eco-Skies Alliance, a group of more than a dozen leading global corporations that are contributing to purchase SAF to reduce their aviation-related impact on the environment. United announced the second round of corporations participating in its Eco-Skies Alliance program in December 2021.
  • United is a founding member of the Biden Administration's First Movers Coalition, a collective of leading companies committing to purchasing low-carbon technologies in hard-to-abate sectors. As part of its membership, United has committed to a target of replacing at least 5% of conventional jet fuel demand with SAF that reduces lifecycle emissions by 85% or more compared with conventional jet fuel by 2030.
  • In 2019, we operated the Flight for the Planet, which represented the most-eco-friendly commercial flight of its kind in the history of commercial aviation.
  • In 2016, we became the first airline globally to use SAF in regular operations on an ongoing basis by using a SAF-blend from World Energy for flights out of LAX.
  • In 2015, we invested $30 million in Fulcrum BioEnergy. This SAF producer plans to convert trash to low-carbon jet fuel. This is the largest known investment by any airline in a SAF producer and, at the time, was the largest publicly announced SAF agreement in aviation history.

Going 100% green by 2050

We're planning to become 100% green by reducing greenhouse gas (GHG) emissions by 2050 without relying on traditional offsets. Making significant investments in sustainable aviation fuel and carbon capture and sequestration will help us get there.

Sustainable fuel sources

Sustainable aviation fuel (SAF) is an alternative to fossil fuels, emitting up to 80% less carbon on a lifecycle basis. As the cleanest fuel substitute for traditional jet fuel, SAF is the fastest and most effective way to reduce GHG emissions across our fleet.

Carbon capture and sequestration

Climate change calls for big solutions, so we’re making a multimillion-dollar investment in carbon capture and sequestration technology to reduce our net GHG emissions.

Innovation for the future

United's corporate venture capital fund, United Airlines Ventures, allows the airline to continue investing in emerging companies that have the potential to influence the future of travel sustainably

Aircraft modernization and operational efficiency

We're increasing fuel efficiency and reducing GHG emissions through technology and process innovation in the air and on the ground.

Eco-Skies Alliance

The Eco-Skies Alliance is a first-of-its-kind program involving leading global corporations working with United to help power flying in a more sustainable way. Through this innovative program, our corporate customers have the opportunity to reduce their environmental impact and help make sustainable aviation the norm.

Be part of the change

United believes in a future of sustainable aviation, and we want you to join us to help make our vision a reality.

United Eco-Skies Alliance

Join the Eco-Skies Alliance

The Eco-Skies Alliance program allows corporate customers the opportunity to pay the additional cost for sustainable aviation fuel. This contribution goes beyond traditional carbon offsets and will show there is demand for low emissions fuel solutions. Enroll your company today to participate in our alliance program and reduce your carbon emissions from your United flights.

Join now

Our climate disclosure

Corporate Responsibility Report

To learn more about how we support the environment through our business practices, view our Corporate Responsibility Report.

View report

Climate Lobbying Report

To learn more about our global advocacy activities and policy engagement – both direct and indirect – in alignment with the goals of the Paris Agreement.

View Report

At United, our purpose of "Connecting People. Uniting the World." extends beyond just getting you to your next destination. Our commitment to operating an environmentally sustainable and responsible airline means acknowledging our climate impact, working to chart a more sustainable course for the future, and holding ourselves accountable.

We recognize the role we play in contributing to climate change and our responsibility in solving it. The aviation sector as a whole is responsible for ~ 3% of global GHG emissions. That's why we've embraced the goal of becoming 100% green by reducing our greenhouse gas (GHG) emissions 100% by 2050 – without relying on traditional carbon offsets such as planting trees or voluntary offsets.

United was the first airline to commit to achieving net zero GHG emissions by 2050 without relying on traditional carbon offsets, such as planting trees or voluntary offsets. And we have a mid-term goal of reducing our carbon intensity 50% compared to 2019 by 2035. We are continuing our efforts by investing in solutions that will reduce our environmental impact through four key pathways:

  • Reducing United’s environmental footprint;
  • Innovating for potentially transformative carbon reduction technology;
  • Removing carbon emissions in the atmosphere; and
  • Collaborating with employees, customers, airports, suppliers, cross-industry partners and policymakers.

You may read more about each of these four pathways in our Corporate Responsibility Report (CRR). To learn how you can help our efforts, click here.

In some cases, we don’t know. In other cases, we have estimates of the dates by which these technologies could become part of our operation which are set forth below, but these are just estimates and not firm guarantees. We’re focused on taking immediate action today to reduce emissions, and on investing in longer term bets that could reimagine how aviation works.


In 2021, we announced an agreement to work with Archer to accelerate production of electric vertical takeoff and landing (eVTOL) aircraft that have the potential for future use as an “air taxi” in urban markets. These are not intended to replace United’s existing flights, but rather reduce vehicle traffic. Once the aircraft are in operation and have met United's operating and business requirements, United, together with Mesa Airlines, plans to acquire a fleet of up to 200 of these eVTOL aircraft. Archer plans to launch consumer eVTOL flights in 2024.

Cemvita Factory

In 2021, United and UAV announced a collaboration with Houston-based biotech firm Cemvita Factory to commercialize the production of sustainable aviation fuel (SAF) intended to be developed through a revolutionary new process using CO2 and synthetic microbes. We are very excited about the promise of this new technology, but unfortunately, we cannot provide an estimated timeframe for the commercialization of SAF through this process.

Dimensional Energy

In 2022, United and UAV announced an investment in and commercial agreement with Dimensional Energy, where United agreed to purchase at least 300 million gallons of SAF over 20 years from Dimensional. We are very excited about the promise of this new technology, but similarly, we cannot provide an estimated timeframe for receiving SAF from Dimensional.

Heart Aerospace

Heart Aerospace’s ES-19, a 19-seat electric aircraft with the potential to fly customers up to 250 miles, could enter the market as early as 2026. In addition to the UAV investment, United conditionally agreed to purchase 100 ES-19 aircraft, once they meet our safety, business and operating requirements. Once operational, the ES-19 would not be used for long-haul flights, but could operate on more than 100 of United's regional routes out of most of its hubs.


Through our investment in ZeroAvia, we expect to buy up to 100 of the company’s zero-emission, 100% hydrogen-electric engines. Once they are fully developed and certified by regulators, these engines could be retrofit to existing United Express aircraft as early as 2028.

The fastest way for United to lower its GHG emissions is by using SAF. That’s because most of our GHG emissions come from burning jet fuel, and the technology for zero-emission aircraft does not exist yet (zero-emission aircraft in development will only be available for short flights). Only liquid fuel has enough energy density with a volume small enough to create enough lift to fly an aircraft long distances like from New York to Chicago, or San Francisco to Denver, or across the ocean.

What is SAF? It’s a low-carbon alternative to regular, petroleum-based jet fuel, made from plants or waste like used cooking oil or animal grease. SAF is a ‘drop-in’ fuel, meaning it can be safely used in existing aircraft and airport systems without changes to the infrastructure. The SAF available today has up to 85% lower GHG emissions compared to regular jet fuel on a lifecycle basis, and potential SAF pathways under development by others could result in carbon negative SAF in the future.

A fuel's 'lifecycle' refers to the GHG emissions produced during the fuel's entire process, from extracting or collecting the feedstock to refining, transporting, and ultimately using the fuel. SAF significantly reduces the amount of GHG emissions produced during the 'lifecycle' as compared to conventional jet fuel by either avoiding GHGs (e.g., by preventing a waste byproduct from decomposing and releasing GHGs) or capturing GHGs, either by using plants, or future feedstock in development like using CO2 that was removed from the atmosphere in the recent past. By contrast, regular jet fuel using fossil fuels are using CO2 taken from the atmosphere millions of years ago. With some exceptions for non-CO2 emissions, the actual GHG emissions from an aircraft that flies with SAF are the same as those from an aircraft flying on regular jet fuel, it is the feedstock that makes a difference.

Before we answer that question, we’d like to tell you our story. For over a decade, United has led the U.S. airline industry in the development of SAF. For example, we have been using a blend of SAF and conventional jet fuel on a daily basis for our LAX departures since 2016. In December 2021, United made aviation history by operating the first passenger flight using 100% SAF in one engine. After our recent announcement of a joint venture formed with Tallgrass and Green Plains, United’s agreements for purchases of SAF, since 2017, were approximately 41% of the entire airline industry's based on publicly announced agreements.1 We’re very happy to see that this number has decreased from 50% in October 2021, as a large number of airlines joined us in agreeing to purchase SAF over the past year.

Although we’re proud of our leadership in this area and how much more SAF is in the pipeline today, the entire industry, United included, has a very long way to go. Decarbonizing aviation is complex and will require more than incremental changes. As stated in our CRR, in 2021, we only used 1 million gallons of SAF. In comparison, we used over 2 billion gallons of regular jet fuel over the same period. That means that in 2021 SAF only made up 0.05% of our overall fuel use, and reduced our GHG emissions from burning jet fuel by only 0.03%! To achieve our goal of net zero GHG emissions by 2050, based on current operations, we’d need to reduce our GHG emissions from jet fuel by 99.97%. Add to that, we are planning on growing our fleet. How will we do this? Through the removal of current barriers like regulations requiring SAF to be blended with regular jet fuel and advocating to bring down the higher prices of SAF. The good news – as more and more airlines purchase SAF, and as our customers participate through programs like the Eco-Skies Alliance and contributing to our Sustainable Flight Fund Account, our hope is that the demand for SAF will lead to the development of more and more of it, which we believe will lower the price. Once that happens, we’ll be able to buy even more SAF to replace regular jet fuel at greater levels, achieving greater reductions in GHG flight emissions.

1 Based on our calculations from the volumes announced in press releases for airline SAF purchase agreements from 2017 to January 31, 2023.

Burning regular jet fuel does emit other pollutants aside from CO2 – nitrogen oxides (NOx), particulate matter (soot), and sulfur gases. Some of these pollutants may affect atmospheric composition and cloudiness which can contribute to climate change. Because this warming effect is not caused by GHGs, it is called a non-CO2 impact. SAF has lower levels of aromatics as compared to regular jet fuel, which may also reduce non-CO2 impacts from flying.

Contrails, or condensation trails, are the clouds sometimes produced by an aircraft engine’s exhaust, typically at cruising altitude in the upper atmosphere. They are composed primarily of ice crystals and, according to the U.S. EPA, do not pose health risks to humans. Certain contrails that persist and spread out, are of concern, as they create clouds that, on balance, may contribute to climate change.2 A 2021 study by NASA and the German Aerospace Center found that SAF can produce 50%-70% fewer contrails. United is committed to working with others within the industry to help improve the science around the climate change impact of contrails and non-CO2 impacts, and develop solutions.

2 This is not a straightforward issue, as clouds both trap heat already on earth and reflect heat from the sun back into space, resulting in cooling. However, the heating force from the clouds is believed to be greater than the cooling force.

While flying less would reduce our GHG emissions quickly, we don’t think this is a common-sense path forward for the industry. If all airlines had to decrease the size of their operations and become smaller, they wouldn’t have the funds needed to invest in the new technologies to decarbonize aviation.

Also, our mission is to connect people and unite the world. As a result, we view aviation as necessary for a functional, civil society, to promote peace and collaboration across borders, and national security. Trains, cars, trucks, and ships can’t transport people and things as quickly as an aircraft, as seen during the COVID-19 pandemic. When our aircraft were needed for those critical missions where time was of the essence, we stepped up. We transported 82 million pounds of crucial medical equipment and PPE during the pandemic. We also transported approximately 3.7 million 8-ounce bottle equivalents of baby formula during a national shortage. Finally, we were proud to transport Afghan refugees in 2021 as part of the U.S. government’s Civil Reserve Air Fleet. None of this would have been possible without airlines.


For further information about our environmental impact, review United's Corporate Responsibility Report and Annual Report on Form 10-K, available at www.united.com/en/us/fly/company/responsibility/our-environmental-commitment.html and www.ir.united.com.

Eco-Skies Alliance and the Eco-Skies Alliance Logo are trademarks of United Airlines, Inc. related to its customer SAF purchase program.

*These donations are not tax deductible. United is unable to allocate emissions reductions to participants for their travel or provide documentation concerning the use of SAF on specific flights. Donations may be used to purchase SAF from entities in which United holds an equity or other financial interest. There is no assurance as to the timing of the use of donated funds to purchase SAF, SAF-blended products or on initiatives we believe will help decarbonize aviation. For example, purchases may be delayed, including because of unavailability of sufficient quantities of SAF or SAF-blended products, or the price of SAF or SAF-blended products. Donations are not a pre-purchase of air transportation and no travel credit will be provided, unless specifically agreed in writing by United. Donors retain no legal interest in the amounts donated, which amounts belong entirely to United, or in any investments, financings, or purchases made by United with donated funds. United retains the right to make decisions regarding the use of these funds on the purchase of SAF, SAF-blended products or on potential decarbonization initiatives in its sole and absolute discretion.


1The target boundary includes biogenic emissions and removals from bioenergy feedstocks.

2Non-CO2e effects which may also contribute to aviation induced warming are not included in this target. United Airlines Inc. commits to report publicly on its collaboration with stakeholders to improve understanding of opportunities to mitigate the non-CO2e impacts of aviation annually over its target timeframe.