Rolls Royce ultrafan engine – Rolls-Royce
Less than a fortnight after the final 747 rolled off the assembly line in the US, Rolls-Royce debuted its biggest ever jet engine – just about able to pass through a London Underground tunnel.
As Boeing ditches the Jumbo Jet for lack of interest, Rolls-Royce is hoping UltraFan, unveiled on Monday, will help it to solve the problem of green air travel.
While aviation accounts for about 2.5pc of carbon dioxide emissions, the industry is under pressure to move towards zero emissions by 2050.
Around the world, engineers are attempting to crack the seemingly impossible challenge of fuelling long-haul flying without generating large emissions.
For smaller craft, top-end batteries can be used for the shortest, taxi-like routes and hydrogen at low pressure may be deployed for short-haul flights.
For long-haul, the hardest to decarbonise, jet fuel offers an unbeatable package of stable energy storage and efficiency.
Hydrogen can offer more energy and a lower carbon footprint, but must be stored at incredibly low temperatures for the longest routes.
A synthetic version of jet fuel can, with a few small modifications, power existing jet engines. As well as recycling carbon dioxide, Sustainable Aviation Fuel, known as SAF, produces less in the way of particles that are blamed for helping warm the earth. SAF is likely to be needed for long-haul flights until technology catches up.
However, in current engines it costs five times as much as its fossil fuel counterpart. No business in their right mind would make the switch – or survive for long if they did.
rolls-royce ultrafan – Steve M Smith FBIPP
Rolls-Royce is aiming to narrow the cost gap with the UltraFan.
The engine will be 25pc more fuel efficient than its 1990s-era predecessor. It achieves this by being very big – 3.5m across. Rather than shifting air more quickly, as other incrementally better engines have in the past, it will shift more air through a bigger fan, thus improving efficiency.
Simon Burr, director of product development and technology at Rolls-Royce, says that this strategy, combined with falling SAF prices as technology improves, offers the potential to get “much, much closer” in price to jet fuel, he says. And with it, bring the prospect of guilt-free flying closer.
The fuel that will be used in UltraFan testing is made from used cooking oil. This is not a long-term solution because there will never be enough to fuel the world’s planes.
However, SAF can be made in a number of ways, says Andrew Cornell, chief executive at Advanced Biofuel Solutions, which is developing the means to make jet fuel from waste.
Household waste is the obvious raw material to use, he says. It is run through a number of chemical processes to make first gas and then liquid fuel which, just like oil, can be refined into jet fuel.
Biomass, another feedstock, is broadly carbon neutral because it starts off as plants capturing carbon dioxide.
“You’re recycling carbon dioxide rather than generating new carbon dioxide,” he says.
This can be combined with carbon capture to reduce the carbon output of the fuel to zero.
UltraFan facts
Another approach to making SAF is using electrolysis to split water molecules and combining the hydrogen produced with carbon dioxide in the air, though this is a more energy intensive process.
“You’ll need both because overall demand is huge,” says Cornell.
However, these processes will be more expensive than jet fuel for a long while, he says, since it will take years for the nascent industry to catch up with the fossil fuel sector, which has had a 100-year head start.
Henrik Wareborn, chief executive of rival biofuel developer Velosys, estimates that SAF could ultimately cost twice as much as jet fuel as a comparison today, but high tax on fossil fuels and low tax on green fuels could squeeze the difference.
“You need to ask yourself what price should those burning fossil fuels that release a huge amount of CO2 into the atmosphere pay? How much are they supposed to pay to clean up their mess?” he asks.
Rolls-Royce UltraFan – Rolls-Royce
Over the weekend the EU reached a deal on the world’s first carbon border tax, which will force importers to cover the cost of their carbon emissions. Under systems such as these, SAF may become more attractive.
For holidaymakers, Mr Wareborn believes the higher costs of SAF won’t hurt demand. Fuel typically makes up about 20pc of an airline’s expenditure depending on price at the time, and so doubling the price may only add 20pc to a ticket.
“Which by the way, has already happened,” he says, as a result of rising oil prices earlier in the year, “and demand just keeps going up anyway.”
Velosys’ process for creating SAF uses urban waste run through several chemical processes to make hydrogen and carbon monoxide. These are then run through the company’s reactor and catalyst to make jet fuel, diesel and other fuel.
SAF can be used in existing jet engines with a few modifications – mainly making sure the seals still work with the new fuel – but Rolls-Royce is hoping the UltraFan proves to be a breakthrough moment that ushers in a new era of mass adoption. Testing starts next year.
The company hopes to have both existing engines and new ones using these new fuels by 2030.
Rolls’s Simon Burr says recent moves to improve supply and test the fuel have given the industry some impetus. The UltraFan design itself can probably be squeezed for an extra 10pc efficiency by experimenting with the kind of new, “exotic” materials the prototype uses, he says.
“We feel that things have moved quite rapidly over the last year, in particular, and more demonstrations are giving people confidence,” he says. “And that can only increase over time.”
Technological developments in the future could also help, he says. While SAF from water and the air is expensive now, as more wind power comes online, something will need to be done with the excess power it produces. SAF is much easier to store than hydrogen alone.
“You’ll get to a point where we think that sustainable aviation fuel is just normal,” Burr predicts.
Keyword: How the biggest ever jet engine built by Rolls-Royce is paving the way for an era of low-cost green flying