Air Conditioning Technology Revolution – How United Airlines Leads the Way to Net Zero

Airlines worldwide have pledged to at least aim for net-zero carbon emissions by 2050. Meanwhile, some are more willing than others to make the investments and commitments needed to scale decarbonization technologies, rather than just sitting around waiting for other parts of the value chain to solve the problem.

To say that United Airlines is a leader in airline sustainability could be considered an understatement. In 2015, it committed to the world’s largest sustainable aviation fuel purchase agreement. A year later, United was the first airline in the world to continuously use SAF in regular operations. The airline has signed deals and investments with a number of companies committed to decarbonizing the hard-to-reduce aviation sector.


Simple Flying recently had the opportunity to sit down for a chat with Lauren Riley, United’s Chief Sustainability Officer and Managing Director, Global Environmental Affairs, to delve deeper into what drives the airline’s committed environmental agenda.

Photo: United Airlines

The Sustainable Fuel chapter: PtL the future of flying

Some of United’s most notable recent deals include an investment in biotech Cemvita Factory, which is developing a way to produce SAF through a revolutionary new process using CO2 and synthetic microbes. In the field of alternative drives, the airline is also involved in the hydrogen fuel cell developer ZeroAvi. The company is expected to purchase 100 ZA2000-RJs as early as 2028 to retrofit existing United Express aircraft.

But for United, SAF is the most important current component on the most immediate path to decarbonization. After operating the first passenger flight with 100% SAF in one engine, the airline has invested far more in sustainable aviation fuel than any other airline in the world.

In September 2021, United jointly entered into a commitment with Honeywell for 1.5 billion gallons of SAF from Alder Fuels, the largest SAF purchase agreement to date. And like the cleantech company’s CEO, Riley is excited about the prospect of developing zero-emission SAFs as various technologies mature.

“If you look at the amount of fuel United burns in a typical year, pre-pandemic numbers, it’s about four billion gallons of fuel. So there’s no way you can talk about climate leadership without talking about replacing that fuel. What is The great thing about SAF is that today it produces up to 85% less CO2 emissions over the life cycle compared to fossil fuels. And the prospects of the technology mean it could be zero, which I find really fascinating and exciting.”

Photo: United Airlines

Last year, the airline formed the Eco-Skies Alliance, through which a dozen leading companies contributed to the purchase of approximately 3.4 million gallons of SAF in 2021. In addition, the volatility of the fuel supply due to the consequences of the war in Ukraine could make itself felt and lead to a further push towards SAF and the associated improved overview of the security of supply. Riley explained

“The value of sustainable aviation fuels is that you’re looking at things like ? All of this is known. And so, in that capacity, it’s not necessarily a geopolitical concern.”

Today we may fly with FOGs (Fats, Oils, and Grease) and biomass. However, Riley believes the future of SAF — albeit a long one — lies in power-to-liquids.

“There is no shortage of CO2 in the atmosphere. And if there’s an opportunity for us to really scale that solution and fly our jets on what I like to call closed loop, it’s the CO2 that comes out of the tailpipe is captured through carbon removal, made into fuel and then back on our jet – that’s the future of flying in my personal opinion.”

Photo: Airbus

The chapter eVTOL and urban mobility

United has also invested in electric vertical takeoff and landing vehicle (eVTOL) maker Archer Aviation and its Midnight aircraft, as well as Embraer’s eVTOL project EVE, and signed a conditional purchase of 200 four-seat electric aircraft plus 200 options. Riley commented on the choice of partnerships and the role of advanced air mobility in United’s overall strategy,

“The hydrogen, the electricity, the supersonic and everything else related to that, I think that’s really just an extension of our existing service to our customers. For example if you think about eVTOL, I live in suburban Washington DC and I would like an eVTOL that costs the same as an Uber X, that means less CO2 emissions and it can take me straight to Dulles, and I don’t have to be stuck in traffic. win in sustainability, customer experience and urban planning.”

Photo: United Airlines

The airline has also invested in Swedish electric aircraft developer Heart Aerospace, signing up for its ES-19, a 19-seat electric aircraft capable of zero-emission flights when powered by renewable energy.

The carbon removal chapter

One thing United doesn’t buy is carbon credits through offsets. Most airlines have said their net-zero strategy will rely to some extent on carbon offsetting. However, United’s net-zero goal by 2050, as well as the airline’s interim goal of reducing its carbon intensity by 50% by 2035 from 2019 levels, does not use offset as a strategy. Riley calls it a “very principled decision” and says:

“We are an industry that is difficult to slow down. We don’t have perfectly baked solutions, we don’t have a market that can actually support the industry. We need to look for solutions that permanently eliminate and reduce emissions from flying. So when we set our goal of 100% green, the conversation we had with our CEO, Scott Kirby, was really, “We need to roll up our sleeves.” We need to lead the industry and that’s what we need to do. So for us it was more about setting the North Star and making sure that we have our priorities clear and that we don’t deviate and call success by taking out a carbon credit that has nothing to do with how we work has to do with our business or what decisions we make or what airline or plane we choose to buy.”

Image: Boom Supersonic

Air conditioning revolution – no better place than aviation

And United are just getting started. The airline works with a range of different partners from academia, start-ups, national laboratories and governments. The airline notably supports direct air capture and other carbon removal technologies, whether for permanent capture, reuse as fuel, or both, but acknowledges it will take time to mature.

Like many others working in aviation sustainability, Lauren Riley is confident in the industry’s potential to reach its net-zero goal – particularly given the technological advances currently taking place.

“What makes me so optimistic about our chances of meeting our 2050 goals is that we are right in the middle of this climate engineering revolution and at its core is sustainability. Honestly, there’s no better place for this conversation about decarbonizing a hardware-based industry. There is no better place for that.”


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