Tons of pounds of fuel are required per launch, and over 50 tons of carbon dioxide is typically emitted. But Edinburgh-based private space company Skyrora is working on a novel solution to minimize the environmental impact of the space industry while tackling one of the world’s biggest environmental issues — the disposal of plastic waste.

The world produces about 400 million tons of plastic waste per year, most of which ends up in landfills, or is incinerated. This amount could triple by 2060 according to an OECD (Organization for Economic Co-operation and Development) estimate. Only about 9% of plastic waste is recycled.

Much of this plastic waste, including PVC (used in tubing, kids’ toys, trays, and furniture), LDPE (used in plastic wrap and coating for food cartons), and polystyrene (used in disposable cutlery) cannot be easily recycled and ends up clogging landfills. But what if this unrecyclable plastic waste could be given a new life and turned into something useful?

Skyrora is developing technology that can convert previously unrecyclable plastic waste into high-performance rocket fuel, similar to premium kerosene. “This all came about with Skyrora looking for ways to become a greener launch company. We wanted to see if we could [make our launches] smaller, cleaner, and better for our environment,” says Derek Harris, Business Operations Manager at Skyrora.

“One of our chemists came back with the idea of using a system that used pyrolysis to treat previously unrecyclable plastic waste and they went through hydro treatment for catalysis to turn it into usable fuels. What makes it really significant in our point of view, is the fact that we can produce different types of fuel with this as well, from aviation fuel, rocket fuel, to the fuel used in regular vehicles and even heating oils,” he adds.

Pyrolysis is the thermal degradation of plastic at various temperatures, in the absence of oxygen, to produce liquid oil, and is usually performed in a pyrolysis plant.

Using plastic waste collected from local municipal authorities, Skyrora’s Ecosene technology uses low-temperature catalytic pyrolysis to convert it into Ecosene fuel, which is similar to kerosene and can be used as rocket propellant, or in regular vehicles. Each ton of plastic, depending on the quality, can produce between 650 liters to 750 liters of usable fuel.

While pyrolysis and other processes that convert plastics into fuel have been attempted before, what sets Ecosene technology apart is the ability to process even low-grade plastics, that are usually not accepted for recycling and may not be suitable for other forms of pyrolysis. This includes polyesters and polystyrenes, and metalized packaging from snacks or chips, as well as plastic that has been impacted by UV rays or salt water.

“How to improve the sustainability of plastics is a big engineering problem,” says George Huber, researcher, Harvey Spangler Professor of Chemical Engineering at the University of Wisconsin-Madison and Director at the Center for Chemical Upcycling of Waste Plastics. “I think pyrolysis is a very promising technology for making oil from waste plastics. The biggest challenges I see are getting enough feedstock and being able to scale large enough to be economical."

While a gallon of rocket fuel costs about $13, Ecosene can be produced for less than a fifth of that. Skyrora plans to make Ecosene plants commercially available in a few years, once all licenses and certifications are in place.

In contrast with incinerating a ton of plastic waste, which releases about 900 kilowatt hours of energy, Ecosene fuel produced from a ton of plastic can generate up to 10 times more energy. Although this is yet to be independently verified, tests have indicated that Ecosene has a cleaner burn than traditional fuels such as kerosene, and produces fewer sulfur emissions.

“Every technology has emissions – it’s just about trying to minimize them,” says Huber. “Pyrolysis can be very clean. There are very few emissions, and it’s a lot cleaner than incineration of plastics."

In October this year, Skyrora attempted their first space launch from the Langanes peninsula in Iceland, with the launch vehicle Skylark L. Although the rocket fell back into the water 500 meters from the launch pad, it marked a significant milestone for the company, especially since the launch happened amidst severe storms and freezing temperatures.

“We proved that we were able to launch basically between two storms — we just needed a very small window to do so. And that was all because of our fuel, our oxidizer and the agility of our mobile launch complex. So for me, it was very much a success, even if the vehicle didn't get as high as we wanted,” says Harris.

Earlier this year, Skyrora also opened the UK’s largest rocket engine manufacturing and testing facility, in Midlothian, inside a used quarry. The facility will aid in accomplishing Skyrora’s goal of becoming the first British company to complete an orbital launch from UK soil.

“One of the biggest things that has made me happy is having the local community involved. People could get upset very easily if you are doing something like this near their homes. But I have sat in on community meetings, we have tried to bring them for site visits, basically we try to demystify things for the local community, to show them that there is no danger, no noxious gasses or anything to be worried about,” he adds.

The next step for Skyrora is to try licensing Ecosene technology and sell it commercially, allowing plastic waste to be collected and processed on site, and the fuel to be produced and used locally.

“I think we’ve got a good 40 to 50 years before the plastic problem is really solved. [Ecosene technology] can work with polystyrene (like the kind used in packing peanuts), low and high density polyethylenes, and more. To be able to give [all that plastic] a second life as fuel is a big deal," concludes Harris.