DCVC DTOR 2024: Drop-in replace­ments are a way to start decar­bonizing the economy, now

Certain realities seem inescapable. Planes burn fossil-derived jet fuel. Cows burp methane, and bacteria release more of it as they break down manure. Steel plants emit massive amounts of CO₂ as the oxygen is stripped from iron ore at high heat. Cement plants release more CO₂ in the process of breaking down limestone into lime. Both steelmaking and cement-making require huge amounts of energy (usually from burning fossil fuels), and so does capturing nitrogen from the air to make synthetic fertilizer. 

But there is, in fact, an escape hatch. With the right kind of deep-tech innovation in chemistry and biology, it’s possible to implement versions of all these industrial processes that emit far lower volumes of greenhouse gases, and sometimes produce no net emissions at all. These innovations often involve new materials or fuels that work exactly the same way and perform to the same spec­i­fi­ca­tions as the traditional versions and can therefore function as literal drop-in replace­ments — meaning customers don’t have to retool their businesses to use them. 

The idea is to ​“meet industry where it is” in order to buy time for the harder, longer transitions, says DCVC managing partner Zachary Bogue. ​“We’re building the tech­nolo­gies that we need for the future. But we also need to do something for the interim.” 

One of the most compelling examples of a drop-in replacement is E‑Jet, a form of sustainable aviation fuel (SAF) made using waste CO₂. E‑Jet’s manu­fac­turer is a DCVC-backed company named Twelve, after the atomic weight of carbon. Its founders invented a form of low-temperature elec­trol­ysis that can take in CO₂ captured from industrial sources (and, one day, from the atmosphere), combine it with H₂O, and release oxygen as well as syngas. A mixture of hydrogen and carbon monoxide, syngas can easily be converted into long-chain hydro­car­bons like kerosene, which powers jet engines. Elec­trol­ysis isn’t the only way to make SAF, but it leads to far lower carbon emissions and uses far less water than the competing processes.

Last summer, Twelve broke ground on a plant in Washington State that will produce up to a million gallons of E‑Jet per year. This year the European airline group IAG — an umbrella for British Airways, Iberia, Aer Lingus, Vueling, and LEVEL — signed a 14-year purchase agreement with Twelve for 785,000 metric tons of the fuel. Microsoft and Alaska Airlines are partnering with the company to use the fuel on demon­stra­tion flights, and eventually to reduce the climate impact of business travel on Alaska by Microsoft employees. 

“The aviation industry is serious about getting to net-zero carbon emissions,” Bogue says. ​“Twelve offers a way to get there with a product that, when produced at scale, can funda­men­tally change aviation’s carbon footprint without requiring changes to its infrastructure.” 

A similar story is playing out in a very different industry: the manu­fac­turing of cement, the key binding ingredient in concrete. To make ordinary Portland cement (OPC)— the world’s standard cement used in more than 90 percent of cement appli­ca­tions — limestone (calcium carbonate) is heated in large kilns, where it breaks down into quicklime (calcium oxide) and huge amounts of CO₂: over 900 kilograms for every 1,000 kilograms of cement produced. Combined with fly ash and slag from ore-smelting, quicklime forms clinker, which is ground up into cement powder. Brimstone, a DCVC portfolio company, has invented a new cement-making process that also results in OPC. But it starts with calcium silicate rocks such as basalt that are already rich in calcium oxide, meaning the company can skip the CO₂-producing step; if all OPC were made this way, the industry’s process emissions would go down by 60 percent. Not only that, but Brimstone’s rocks also contain magnesium, which binds with and permanently sequesters CO₂ from the atmosphere. That makes Brimstone’s overall process carbon-negative. And the more that the kilns and the remaining processes are powered with clean electricity, rather than coal, the more carbon-negative it can be. 

In the agriculture business, one of the steps innovators would like to skip is fixing ammonia — the main ingredient in synthetic fertilizer — from nitrogen in the air. Modern farming wouldn’t work without vast amounts of ammonia, and yet our main method for making it, the Haber-Bosch process, requires high pressure and temperature and is incredibly energy-intensive, using more than 1 percent of global energy production. (And that’s just from the energy that goes into making fertilizer. The full nitrogen supply chain, from manu­fac­turing to use, is responsible for about 5 percent of global greenhouse gas emissions.) Cambridge, U.K.-based Nium, where we invested in 2023, has built a reactor filled with a nanocat­a­lyst material that can synthesize ammonia from nitrogen and hydrogen at low temperature and low pressure. This clean ammonia— produced at a fraction of the price and pollution of the Haber-Bosch process — can act as an energy-dense, convenient vector for trans­porting hydrogen fuel, or it can be used in fertilizer. 

Unfor­tu­nately, we don’t yet have a drop-in replacement for the beef from cattle. But there is a way to cut the amount of methane cattle burp up as the result of fermen­ta­tion in their guts (estimated at up to 500 liters per day for every cow, bull, steer, and heifer). In 2021, we invested in CH4 Global, a Nevada-based company that makes a cattle-feed supplement from a species of seaweed called Asparagopsis. Bromoform, a chemical produced in the seaweed to make it less tasty to marine herbivores, blocks methane production by gut bacteria, while leaving more calories available for the animal’s own metabolism. Co-founder and CEO Steve Meller says reaching 150 million cattle — just 10 percent of the world population — with CH4’s Methane Tamer™ product would reduce methane emissions by 1.5 gigatons per year. The company announced in June 2024 that 70 head of cattle fed Methane Tamer™ at a feedlot in South Australia had been processed, making it the first and only reduced-methane beef selling into the Australian domestic market. 

It’s critical to note that progress on drop-in replace­ments is not a substitute for, or an excuse for delaying, the decar­boniza­tion of the broader economy. The 2015 Paris Agreement called on the nations of the world to cut overall greenhouse gas emissions by about 60 percent by 2035 and to reach net zero emissions by 2050, all toward the goal of keeping global temperature increases below 1.5 degrees Celsius. The lack of progress on emissions cuts in most nations, including the U.S., means that the 1.5‑degree goal is now ​“deader than a doornail,” in the words of legendary climate change researcher James Hansen, and that even a less ambitious 2‑degree goal may already be out of reach. That makes it all the more important that we ultimately phase out or abate all fossil fuels and reinvent every carbon-emitting industrial process. Finding smart substitutes for traditional fuels and feedstocks will be a key part of that push — but only a part.