New Plant Could Process 20 Percent of U.K.’s Waste Tires

Norwegian rubber waste recycler Wastefront will launch a $120 million plant in Sunderland, England late in 2024 or early 2025 that will leverage pyrolysis to make tire-derived oil (TDO) to be refined into combustion fuels, including diesel.

 The company says the new fuel will be cleaner than fossil diesel and cost-comparative (depending on grade). It will be cheaper than hydrotreated vegetable oil, a paraffinic bio-based liquid fuel, and similar biofuels.

Energy and commodities company Vitol will buy all the TDO, and Wastefront has signed agreements with offtakers for two other products that will come from end-of-life tires:  recovered carbon black (rCB) to go into new tires to reinforce them and steel to be sold on the spot market.
The plan is to install 45 percent capacity at launch and increase to 100 percent within a year, at which time capacity will reach 80,000 tons per year – 20 percent of all waste tires in the U.K.

“We use commercial and readily available technology in our process. So, there is not much new to this, but the output depends on how you manage the process. We are applying existing technology in a more clever way,” says Henrik Selstam, Wastefront chief technology officer.

Tires are sorted, shred, and fed into a pyrolysis reactor. Rubber becomes oil and carbon, and gases are used to feed the heater, with the excess used to make electricity to run the plant. What isn’t used is burnt in a regenerative oxidizer, which removes toxic gases and converts them to carbon dioxide (CO2) and water.

What will be different at the Sunderland plant is the preprocessing or preliminary step—that and the scale of production. The preliminary step entails using a laser reader to identify and track each tire to monitor output against input so the process can be adjusted for incoming feedstock.

Wastefront has also specified the temperature and residence time to optimize the output—both oil and carbon black.

“That means that we will get the highest quality of oil without sacrificing too much of the carbon quality. Usually, you just get good quality of one or the other,” Selstam says.

Pyrolysis is a depolymerization process, which in this case cuts tires into shorter carbon chains to make liquid, which will be further refined in the same way as crude oil, but from a non-fossil source. 

There is almost no oxygen involved in the process, thus mitigating resulting nitrogen oxides (NOx), sulfur oxides (SOx), and volatile organic compounds (VOCs). What oxygen does exist in the carbon chains will reside in the fuels rather than be emitted, Selstam says.

Lifecycle analyses, done by DNV GL in the U.K., show the process will avoid 60,000 tons of CO2 equivalent (CO2e) a year compared to using raw fossil fuels, or 1.8M tons of CO2e in the Sunderland plant’s planned lifetime.

Using rCB instead of virgin carbon black will reportedly further reduce the carbon footprint as much as another 10,000 tons CO2e.

The liquid hydrocarbons used to produce the biofuels are instrumental to storing large amounts of energy, making them useful for transportation, Selstam says. He believes the commodity should serve as a bridge as transportation decarbonization technologies evolve.

“Even with the best intention to replace all fossil-fueled vehicles, it will take time to do so in a sustainable manner. Replacing the need for fossil hydrocarbons with our TDO is one way to minimize the environmental damage meanwhile,” he says.

There are still obstacles to overcome. For instance, with rCB, potential end users are skeptical. 

“The acceptance of recovered carbon black is very limited due to mistakes by early adopters. The ASTM is defined according to very traditional manufacturing making soot out of crude oil. In some respects, we’ve found that our recovered carbon black supersedes ordinary carbon black. Getting an understanding of that in the market has been a challenge,” Selstam says.

Finding universal testing that’s relevant for all technologies is also yet to happen.

Traditionally with carbon black there is a transmittance test to gauge the amount of compounds in the carbon. But when it comes to rCB, transmittance has no relevance.

There are still questions around what processes result in what is considered “end of waste.” Selstam and his team are working with the Renewable Transport Fuel Association (RTFA), a trade association in the U.K. working to deem how waste will be treated to be considered sustainable.  

“It’s an ongoing process, and we need to spend time and energy to be sure the industry is doing the right thing without compromising the bottom line too much,” he says.

One change is happening that’s working in the favor of companies like Wastefront: the industry’s receptiveness. 

“We started four years ago talking to tire manufacturers and they just listened and shrugged. About two years ago they started talking to us. Now they are listening with keen interest. Policy has evolved in that time and their customers want more sustainability,” Selstam says.

Partner Hulteberg’s role in the purification process has been to work with contaminants contained in the oil, mainly sulfur that’s removed with help from hydrogen. Hulteberg also works with alternative methods for stabilizing the oil to make it more suitable for transportation. 

“We see [this partnership with Wastefront] as a natural prolongation to the work we have been doing over the last decade with nontraditional feedstocks for renewable and recycled fuels. In the past, we have developed technology, including catalysts and operating conditions to maximize the production of fuels from a wide range of starting materials,” says Christian Hulteberg, managing director, Hulteberg, and a professor in chemical engineering at Lund University.

What else the project has meant for the company, is it’s provided the opportunity to develop the catalysts and operating conditions needed to increase the value of the pyrolysis oil by purifying it. And the opportunity to develop new approaches that will result in more efficient storing and handling of the oil, Hulteberg says.

Selstam is optimistic about possibilities for Wastefront too.

“End-of-life tires are abundant no matter where you are in the world. The need for a solution to landfilling tires is huge. Our process works everywhere, and we have many initiatives in several continents. We hope to be able to present some of them during the course of 2023.”