Can biofuels make spaceflight greener? UK space startups reveal plans for cleaner rocket launches

Rocket launches can inject huge amounts of soot into higher layers of Earth's atmosphere, depending on their fuel, possibly contributing to climate change. A pair of British rocket startups now claim their rocket technology can reduce spaceflight's environmental footprint by switching to renewable fuel. Both of these startups plan to launch their rockets from different spaceports located in Scottish wilderness, and being green has been part of their pitch from the start. While Edinburgh-based Skyrora plans to fly their rockets using rocket fuel made from non-recyclable plastics. Their counterpart, the Inverness-based Orbex, is betting on biopropane, a natural gas made as a byproduct during biodiesel production. Last week, Orbex released a study by experts from the University of Exeter in the U.K., which claims that the company's bio-propane-powered rocket Prime, a micro-launcher, will produce 86% less emissions than a similar-sized fossil fuel launcher. The comparison was made with launchers that burn RP-1, or Rocket Propellant 1, a refined form of aviation fuel kerosene. RP-1 is widely used by rocket builders all over the world. SpaceX's Falcon 9 uses this fuel in both of its stages. The fossil fuel also powers Russia's workhorse Soyuz rockets and the first stages of America's Atlas V.

The U.K. rocket startup Skyrora tested its Skylark Micro suborbital rocket last year. In the future, the company's rockets will be powered by a renewable fuel made from non-recyclable plastics. (Image credit: Skyrora)

Most of the carbon dioxide emissions reductions achieved by Orbex come from the negative carbon footprint of the biofuel production rather than by the launcher emitting considerably less, according to the report's executive summary. The company that supplies the biopropane, U.K.-based Calor, makes the fuel from a mixture of waste residues and "sustainably sourced materials", according to Calor's website.

However, most experts are not that concerned with the carbon dioxide emissions of spaceflight, simply because there are currently not that many rocket launches. In an earlier interview this year, Martin Ross, of the U.S. Aerospace Corporation, a leading expert on atmospheric effects of rocket launches, told Space.com that the space industry burns only about 1% of the fossil fuel consumed by aviation.

There is another component of rocket exhaust that climate experts are concerned about: soot. Rockets inject huge amounts of it into the otherwise pristine upper layers of Earth's atmosphere, where it could trigger possibly far-reaching changes.

And here, technology such as Orbex's biopropane-fueled Prime rocket could make a difference. The University of Exeter study says that the Prime vehicle, which is 62 feet (19 meters) long and designed to carry small payloads of up to 330 lbs. (150 kilograms) to low Earth orbit, will emit much less soot than a similar micro-launcher using RP-1. The company added in a statement that Prime "almost entirely eliminates" soot emissions.

Soot in the atmosphere can absorb heat and affect the temperature of the higher layers of the atmosphere — the mesosphere and the stratosphere. Orbex said in its statement that 120 rocket launches emit as much soot as the entire global aviation industry emits in a year.

Overall, a single Orbex rocket launch will generate a total of 15 tons (13.8 tonnes) of greenhouse gas emissions, which is equivalent to the annual carbon footprint of an average U.K. citizen, Orbex said in the statement.

The Prime micro-launcher of U.K. company Orbex uses sustainably sourced biopropane that emits much less soot compared to rocket fossil fuel RP-1. (Image credit: Orbex) 

Orbex expects to fly its reusable 3D-printed Prime rocket for the first time next year from the Space Hub Sutherland on the northern coast of Scotland. The spaceport recently received planning permission after winning a court case against a billionaire landowner who questioned its environmental impact.

Orbex's counterpart Skyrora hasn't launched its three-stage Skyrora XL orbital rocket yet either but has performed several successful test flights of their sub-orbital missile Skylark Micro, which reached the altitude of up to 17 miles (27 kilometers). In 2020, the company tested a small prototype of its engine, which runs on fuel made from non-recyclable plastics. According to the company's website, the new fuel, called Ecosene, showed a 1- 3% better energy profile compared to RP-1.

Derek Harris, CEO of Skyrora's Ecosene division, told Space.com that Ecosene comes much cheaper than RP-1, at about $2 per gallon.

"The plastics that we are using actually come from waste disposal," Harris said. "We even get paid to take it, so feedstock is a negative value."

Harris said the company's experiments show the Ecosine-fuelled rocket engine, which uses hydrogen peroxide as an oxidizer to burn with the fuel, produces about 40% less emissions overall, including carbon dioxide, carbon monoxide, soot and sulfur.

Harris said the company hopes to fly its rocket prototype in late 2022 from a spaceport on the Shetland Islands north off the coast of Scotland.

Orbex and Skyrora are not the only ones pursuing biofuel. In February this year, American start-up bluShift Aerospace flew its first stage rocket prototype Stardust 1.0, which uses proprietary solid biofuel made from agricultural waste. The test rocket reached less than one mile in altitude.

The UK's first complete ground rocket test in 50 years takes place in Scotland

The UK's Space race heats up as Skyrora effectively made the UK ready for launching rockets into space after a team successfully built a mobile launch complex and completed a full static fire test with the Skylark-L rocket on it - in only five days. Skyrora's combined achievement also signifies the first vertical static fire test of this magnitude in the UK since the Black Arrow Programme, 50 years ago. The Skylark L rocket could be ready to launch from a British spaceport as early as spring 2021 and the inaugural launch of the low Earth orbital (LEO) Skyrora XL rocket by 2023. The ground test at the mobile launch complex at Kildemorie Estate in North Scotland earlier this month, saw Skyrora's launch vehicle, Skylark-L perform all actions of a launch while restrained to the ground and prevented from taking off. Skylark-L is a bi-liquid propellent launch vehicle. It is Skyrora's first sub-orbital flight vehicle, ready to reach a height of approximately 100km, just on the Karman line, and carry a payload of up to 60kg. Skylark-L uses a propellent combination of Hydrogen Peroxide and Kerosene which are pressure fed into a Skyrora 30kN engine. Building up to the static fire test, the rocket engine itself has gone through three hot fire tests before integration into the vehicle. When commercial, the company plans to use their own Ecosene, an equivalent Kerosene fuel made from un-recyclable plastic waste. In Skyrora's rocket suite, its aim is to start with launching sub-orbital rockets and move to orbital by 2023.

The full static firing test, fully checked out the design and in-house manufacture, making sure the vehicle itself is ready for launch. It was also successful in the feed system validation tests leading up to the full static fire test. During the test, Skylark-L was supported by Skyrora's transporter-erector that was fixed to a trailer.

In order to complete this test, the Skyrora team accomplished the build of a mobile launch complex in record time right in the heart of the Scottish Highlands. The mobile complex was made up of several modules including, a command centre, oxidiser and fuel handing containers and a compressed gas container. During the test, the Bells and Two Tones Fire and Rescue team were onsite ready to perform any necessary procedures if anything was to go wrong.

Leading the operations of Skylark-L's static fire testing, Dr Jack-James Marlow said: "It is very hard to oversell what we have achieved here with this test; the whole team has pulled through again to deliver another UK first. We have successfully static tested a fully integrated, sub-orbital Skylark L launch vehicle in flight configuration. This means we performed all actions of a launch but did not release the vehicle. The rocket engine successfully burned, with all vehicle systems showing nominal operation.

"The test did not only validate the vehicle, it also tested our mobile launch complex's ground equipment and performed many cold flow and fuel/defuel tests. In all, there were over one hundred unique operations and the team has gained vital experience. This collection of tests, combined with the 25 other engine tests this year, allow us to take another step along our technology roadmap to orbital launch.

"This is the first time a launch vehicle of this magnitude has been tested in the UK for many years and I am very proud of my team for achieving this. The vehicle is now ready for flight and we are one step closer to putting the UK back into space."

Skyrora's chief executive officer, Volodymyr Levykin said: "As the launch aspect of the UK's new Space industry starts to emerge, there will be many events that have never happened here previously and this is one of them. This was a mammoth effort in very trying circumstances, so it is quite an achievement to be proud of.

"The operation was carried out while having to adhere to very strict social distancing measures, and in an extremely remote location, providing additional challenges, all of which were handled expertly by all the team.

"We see this as being the first significant step towards reaching space from our own soil and are very proud to have taken that step as part of the UK's Space ambitions. We are now in a full state of readiness for launch. It is this milestone that is the start of the UK's new space revolution, a fantastic example of the potential of what the UK Space holds for future.

"With the expertise in place and all the necessary hardware at the ready, we are poised to take the next steps in making the UK a serious leader in the Space business once again".