Our environmental commitment

FAQs on United’s Sustainability Journey

• What is United’s sustainability commitment?

  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.

• How does United plan to achieve its sustainability goals?

  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.

• When will the new aircraft technologies and SAF companies United’s corporate venture capital fund, United Airlines Ventures, Ltd. (UAV) has invested in, like electric aircraft, hydrogen-electric engines or CO2 to jet fuel, become part of United’s operation?

  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.

  Archer

  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.

  ZeroAvia

  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.

• What is sustainable aviation fuel and why is it important to United?

  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.

• Why does SAF have lower lifecycle GHG emissions than regular jet fuel and what does that mean?

  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.

• How much SAF does United use compared to regular jet fuel, and what is its impact on United’s GHG footprint?

  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.

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

• What about the non-CO2 impacts of flying and contrails?

  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.

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  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.

• Why doesn’t the airline industry just fly less and discourage everyone from flying?

  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.