Climate

The difference was visible the moment the blow torch hit the wicks wedged into a series of liquid-filled glass jars.

The jar labeled “petroleum jet fuel” sent up a steady plume of black smoke as its yellow-tinged contents combusted. The flame coming from the jar labeled “sustainable aviation fuel” burned just as bright, but the clear liquid created little to no smoke.

The demonstration took place at a lab in Paramount. There, Boston-based World Energy is converting a former 65-acre petroleum refinery into one of just a few plants worldwide that uses hydrogen to turn used cooking oil and tallow into cleaner-burning, more climate-friendly jet fuel.

Today, World Energy is producing about six million gallons a year in Paramount, employing many of the same workers who once refined crude at the site. By year’s end, the goal is to be producing 30 million gallons. And when the plant’s $2.5 billion conversion is complete, in 2025, the goal is 250 million gallons a year.

Much of that sustainable aviation fuel is slated for use in planes at LAX, though some will be used at John Wayne, Ontario, Van Nuys, Long Beach and other airports.

If you’ve flown out of one of these airports in the past few years, a small but growing fraction of the fuel powering your flight came from World Energy’s Paramount plant. Southern California airports — with their proximity to the manufacturer and purchase agreements from a handful of airlines — are unique in providing a fuel mix that already is partly sustainable.

That’s good news for people who live near these airports, since the new fuel produces less soot and other pollutants that are emitted in greater quantities during landings and takeoffs. It’s also good news for everyone who is concerned about climate change but who also likes, or needs, to travel by jet. Using waste or plant material in place of fossil fuels to power jets can reduce lifecycle carbon emissions of each flight by up to 85%.

Flying without sustainable aviation fuels, or SAFs, can be damaging.

A traveler on a single, long-haul flight powered by traditional jet fuel generates as much carbon as the yearly total created by the average citizen in dozens of lower-emitting countries around the world, per an analysis from The Guardian. Aviation is responsible for more than 2% of the world’s annual emissions, with roughly a quarter of those polluting flights originating in the United States. And, despite growing concern about climate change, air travel has almost fully rebounded from the COVID-19 lapse and is now poised to grow at a rate of about 4% annually.

That means if California, the United States and some other countries want to hit legislated targets for transitioning to carbon-free economies, they need to grapple with emissions from planes.

But the aviation sector is considered difficult to decarbonize, since technical and safety hurdles have so far prevented some of the substitutes that work in other transportation sectors from translating to aviation. So while zero-emission electric or hydrogen-fueled jets could be solutions in the future, many airlines, regulators and industry experts view SAFs as the best option to neutralize the industry’s carbon footprint today.

United Airlines is so optimistic about the potential of SAF that Rohini Sengupta, the company’s director of Environmental Sustainability, said leadership felt comfortable jumping from a commitment made in 2018 to reduce carbon 50% by 2050 to the airline’s current goal to hit carbon neutrality by that same year. That goal has since been adopted by much of the aviation community.

That doesn’t mean SAF is a silver bullet to decarbonize aviation.

Sarah Burt, a deputy managing attorney with Earthjustice, said her organization, along with other environmental advocates and climate experts, has questions about the carbon footprint of SAF manufacturing. Also, many wonder if SAF production and distribution ever can be scaled up to fully replace traditional jet fuel. Currently, just 0.03% of the 106-billion-gallon-a-year global market is covered by SAF.

“It could be that SAF is actually very effective. We just don’t know,” said David Victor, a public policy professor at UC San Diego who heads the school’s Deep Decarbonization Initiative. “That makes me concerned that the U.S. National Transportation strategy is really focusing on one solution, which is SAF and SAF alone.”

Victor added: “It’s just kind of the Wild West right now in terms of the possible solutions.”

Traditional jet fuel is a refined kerosene liquid made from crude oil. It’s lightweight but packs a ton of energy, which is why for decades it’s been the fuel of choice for jets.

But burning jet fuel, as with other types of fossil fuels, emits high levels of atmosphere-warming carbon dioxide that was previously trapped in underground reservoirs. Kerosene combustion also produces soot and other particulates that are harmful to respiratory health. For those reasons, among others, climate and public health advocates have long pushed for stricter regulations and alternatives to traditional jet fuel.

Even before the first test flights with SAF took off, in 2008, the aviation sector had already made a dent in its emissions just by implementing more fuel-efficient operations and re-designing planes for efficiency. A study by the International Council on Clean Transportation found that aircraft in 2019 burned 41% less fuel than jets in 1970.

Still, per that same ICCT report, “If commercial aviation were counted as a country, it would rank sixth, after Japan, in terms of CO2 emissions.”

So aside from staying grounded, the best bet for companies and travelers to reduce their carbon output today is to buy offsets. But given the lackluster results of many such programs, everyone is looking to solutions that can actually decarbonize aviation.

The most appealing option to many environmentalists for making flights carbon neutral is electric jets. They’d emit no carbon or other pollutants. And if the electricity to power them is made from renewable sources, such as solar and wind, the entire life cycle of the power source would be clean.

The challenge with that option is that, with current technology, batteries needed to power big jets over any distance would be too big and too heavy to be practical.

Then there’s the safety factor. There are instances of lithium batteries catching fire in electric vehicles, laptops and other devices. That’s a scary enough prospect when you’re on the road, but it could be catastrophic in the air.

Safety also is a concern with the other alternative fuel source under consideration — hydrogen — which is more flammable than other types of gas. (The idea of hydrogen-powered jets evoke images of the Hindenburg disaster or, in a modern setting, a scene from the movie “Glass Onion: A Knives Out Mystery.”)

Pure hydrogen also doesn’t exist in nature. Instead, it occurs in compounds such as water and methane, meaning that before you can use hydrogen as an energy source you’ve got to separate it out from some other molecule. Currently, the process of doing that almost always means burning fossil fuels.

Perhaps even more problematic is that with both electric- and hydrogen-powered options, jets would need to be redesigned. And as Gene Gebolys, CEO of World Energy, pointed out, most airplanes last for around 30 years.

“The airplanes that we have today will still be flying in 2050,” Gebolys said.

“There are lots of ideas about electrifying aviation and using hydrogen for aviation — a million different ideas,” he said. “The only way to decarbonize aviation is through the fuel tank. … You have to be able to get into the existing infrastructure and the existing fleet of airplanes to decarbonize in any kind of meaningful timeframe.”

The biggest appeal of SAF is that it’s considered a “drop-in ready” solution, since it meets nearly all of the same technical and safety requirements as conventional jet fuel.

The first SAF test flights were in 2008. Three years later, regulators gave the go-ahead to blend up to 50% SAF in jet tanks and, that year, KLM flew the first commercial flight partially fueled by SAF.

The main reason SAF is still an additive, and not used as 100% of a jet’s fuel, is that most SAFs currently on the market, including the fuel made in Paramount, don’t include some polluting aromatics used in traditional jet fuel that help engine seals swell and prevent leaks, Gebolys explained. New engines are being designed with that in mind, and recent test flights by United and other airlines and aviation companies using 100% SAF have added cleaner aromatics to address the issue.

Advocates are confident that 100% SAF will get regulatory approval. Instead, the problem they see is that supply and distribution have yet to keep pace with demand, even with the fuel ratio capped at 50%, said Samantha Bricker, chief sustainability officer with Los Angeles World Airports.

In 2017, Bricker said some 4.7 million gallons of sustainable aviation fuel or SAF was delivered to LAX. In 2022, that number had jumped to about 7.2 million gallons, still just 0.6% of all the fuel used at the airport. If more SAF was available, she’s confident the numbers would be higher.

In California, Gebolys said skyrocketing interest in SAF has been driven by the state’s 12-year-old Low Carbon Fuel Standards program that requires a pivot to lower-carbon transportation fuel. Also, in 2021, the Biden Administration announced the Sustainable Aviation Fuel Grand Challenge, which aims to boost annual production of sustainable aviation fuels to at least 3 billion gallons by 2030. And everyone is looking to take advantage of the billions of federal dollars in the Inflation Reduction Act and other measures aimed at making SAF more readily available.

Even if companies like World Energy can scale up their operations quickly, Burt said there’s a big question about whether they can get enough feedstock, such as plant materials, to make all of that SAF. If forests are cleared to grow crops like palm oil to make the SAF, she said the result might be more environmentally damaging than sticking with traditional jet fuel.

Dozens of sources, from algae to decomposing waste, can be used to manufacture SAF. But the most common SAF, like the fuel produced by World Energy, is made from plant and animal fats, oils and greases.

“Nobody slaughters cows for their fat,” Gebolys said. “So we use, effectively, waste streams. We’re not driving net new land use intensity. We’re not driving, you know, more cattle to exist or anything else.”

World Energy is now primarily using beef tallow brought in on by rail on a spur that ends on their property, explained Samir Sukhtankar, director of operations at the Paramount plant. Hydrogen converts the tallow from lipids to hydrocarbons, which are then further treated to make jet fuel.

The process itself isn’t much different than refining crude oil, according to Sukhtankar, who worked at the site before the conversion. So they’re able to use many of the same towers, storage tanks and pipelines, which are being repurposed for this new sort of refining.

The use of hydrogen raises alarm bells for Burt, with Earthjustice. Gebolys said they’ve been working to make the hydrogen they use as green as possible, though about half will now be produced using natural or methane gas.

The other major producer of commercial SAF is Neste, based in Finland. Using much the same process as World Energy, Neste says it is on track to make 500 million gallons of sustainable aviation fuel annually by the end of this year.

Other companies are experimenting with different types of SAF production. Gevo, out of Colorado, plans to use fermented corn, molasses and other agricultural products to make its version of SAF. The company aims to start construction this year on a 55-million-gallon plant in South Dakota and has already signed deals with Alaska Airlines and other carriers to use SAF made there starting in 2026.

One major obstacle ahead for SAF is cost. It now costs two to four times more than standard fuel. That’s why, so far, Sengupta with United said it’s primarily airlines’ corporate customers who are paying for SAF, using a system known as “book and claim.”

Corporations around the world contract with airlines to buy sustainable fuel to power their planned flights. But carbon gains from SAF would be lost if that fuel was shipped halfway around the world to wherever that company is based. So the corporation receives an environmental credit — which often translates to both tax credits and goodwill with customers — for the purchase, even though the physical SAF will be sent to a nearby airport. It’s how United’s Eco-Skies Alliance program makes it possible for Swiss-based Zurich Insurance Group to pay for some of the SAF that might power your family’s flight from Los Angeles to Hawaii.

But Gebolys estimates no more than 20% of traditional aviation fuel can be displaced by using SAF made from sources his company uses today. That’s where he and others are looking at a “second generation SAF,” called power-to-liquid. It would be made using hydrogen and carbon scrubbed from the air.

World Energy is building a second SAF plant in Houston. Gebolys said they haven’t yet decided if power-to-liquid SAF will be made there or in Paramount, though Texas seems to have an edge.

“Texas is going to be where really big carbon capture projects happen first,” he said.

Some environmental groups remain critical of carbon capture. Most projects have underperformed, and they worry that letting industries capture emissions just gives them a green light to generate more.

No solution will win approval from everyone, Gebolys acknowledged.

“We know that it’s not innovative to just sit and wait for the perfect solution to exist,” he said.

“We’re using what we can do today, while we’re really seeking to do better tomorrow.”

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