Working with United Sustainable Flight Fund to Accelerate Aviation’s Path to True Net Zero

Addressing climate change, while advancing America’s energy security, demands a dual strategy of rapidly decarbonizing, while simultaneously removing CO₂ already in the atmosphere. At Heirloom, we've focused intensively on the latter challenge, developing breakthrough technology to remove CO₂ from the air cost-effectively and at scale.

Today, we're excited to share something we’ve been working on for the past year that will expand our impact to help tackle the first part of the equation: decarbonizing hard-to-abate industries. The United Airlines Ventures Sustainable Flight Fund^SM has entered into an agreement with Heirloom for the right to purchase up to 500,000 tons of carbon dioxide removal (CDR) – to be delivered for the production of sustainable aviation fuel (SAF) or permanently stored underground. In addition, they’ve made an equity investment in Heirloom, building on our recent $150 million Series B. This is the Fund’s first investment in a direct air capture (DAC) technology.

The Aviation Challenge

Aviation represents 2.5% of global CO₂ emissions – nearly all from burning hydrocarbon fuels. Unlike ground transportation, which can transition to electric vehicles, aviation faces a fundamental physics challenge that makes decarbonization extraordinarily difficult: energy density.

Consider this comparison. A Honda Civic can travel about 360 miles on just 78 pounds of gasoline. If you took an electric car and gave it a battery weighing the same as that gasoline, it could only travel 21 miles. Electric cars compensate for this by using much larger batteries and making the rest of the vehicle lighter. This is a fundamental part of decarbonizing ground transportation, but for industries like aviation, pursuing the same solution is not currently feasible: Replacing the jet fuel used by a Boeing 747-300 to travel five hours with an equivalent battery would increase the plane’s weight by 5.8 million pounds. The plane quite literally couldn't get off the ground.

Solving Aviation’s Decarbonization Challenge

Given the unique challenges of transitioning to zero-carbon fuels in aviation, getting to Net Zero will require a strategy that mirrors the one we’re already using to address climate change on a global scale: reducing emissions as much as possible AND removing any residual emissions that can’t be eliminated. In the global context, we think mostly about DAC as a lever to solve the second issue. But in the aviation context, DAC can be a valuable tool for both emissions reduction and removing residual emissions.

On the emissions reduction side, DAC can be transformative. By capturing CO₂ from the atmosphere and combining it with green hydrogen, we can produce SAF that isn't limited by feedstock availability, meaning it can be produced in virtually unlimited quantities. Importantly, this approach creates a circular carbon flow – reusing carbon already in our atmosphere rather than extracting new carbon from deep underground – and enlists America’s workforce to build more sustainable fuel right here at home. The resulting environmental benefit is substantial, creating a fuel that is up to 94% less carbon intensive than those developed through fossil fuel generation.

Of course, even the lowest-carbon SAF will still result in CO₂ emissions when burned. And this is where DAC is fundamental to solving the other side of aviation’s decarbonization challenge: removing the residual emissions that exist even after conversion to a lower carbon intensive fuel.

The Path to True Net Zero Aviation

This dual strategy of emissions reductions and carbon removal is aviation’s path to True Net Zero. And DAC can be a linchpin of both strategies. But how will this look over the next 10, 20, and 30 years? The answer is: we will need a lot more DAC.

Think about the need for DAC in the coming decades as going into two buckets: the SAF bucket and the removals bucket. As the development of SAF ramps up, there will be a huge and constantly growing need for DAC to fill the SAF bucket – a need that will grow until SAF is fully on board, and then will continue to grow at the rate of air travel. And as we approach deadlines for Net Zero there will be a growing need for DAC to fill the removals bucket to handle the residual emissions even after full conversion to SAF. The end result is that, no matter the mixture of SAF and removals to reach Net Zero aviation, the demand for DAC will grow exponentially, fueled by the dual needs of emissions reductions and removals.

And this can be bigger than just aviation. Other hard-to-decarbonize industries like shipping are in a similar position, requiring both cleaner fuels to propel emissions reductions and carbon removal to address those that can be reduced. Heirloom is uniquely positioned to help these industries achieve Net Zero.