Alternative fuels

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The dawn of a new fuels era

Fossil fuels have played a key role in enabling socio-economic growth to date.

However, humanity must move away from their use to harness low and zero carbon sources of power and energy. Only by doing so can countries around the world achieve net zero carbon economies by 2050, and avoid the worst effects of climate change.

Jessica Poole-Mather, Technology Business Lead

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“It’s vital that companies, governments, and individuals all take responsibility for global decarbonisation. Lower carbon alternative fuels will be vital across hard to electrify sectors to ensure we can reach net zero in all elements of society.”

Lower carbon alternative fuels

There are two main categories of sustainable fuel. Sustainable bio fuels are made by refining organic or waste substances. Synthetic e-fuels are created from captured CO2 using renewable or zero carbon electricity.

The carbon they emit when burned has already been recently captured from the air, by plants or other processes, so their lifecycle carbon impact is therefore lower than fossil fuels. However, the broader sustainability impact of bio fuels must be taken into account to ensure their production doesn’t compete with food supply or limit the use of fresh water and it must avoid deforestation. For aviation, Sustainable Aviation Fuels (SAFs) are being developed with much lower lifecycle carbon impacts than traditional jet fuel. For applications on the ground and at sea, a range of lower carbon alternative fuels, including hydrogen and methanol are also being developed. We’re working to ensure our products are compatible with alternative fuels, while helping to stimulate the growth of the lower carbon alternative fuels industry.

0.01%

proportion of global jet fuel made up of SAFs in 2019

312,000+

commercial flights that have operated using SAFs since 2011

500 mn

tonnes expected aviation industry demand for SAFs by 2050

6 bn

litres volume of SAFs airlines had committed to buy (at end 2019) in forward purchase agreements

Sustainable Aviation Fuels take wing

Current SAFs could cut carbon emissions from aviation by around 80% compared to fossil-based jet fuels. Future technologies may push that to 100% so that they have net zero CO2 emissions.

Good progress is being made in electric and hybrid-electric engines. However the energy storage limitations of even the most advanced batteries mean the technology today and in the foreseeable future cannot handle journeys beyond 600-1000 miles. We’re also researching the feasibility of hydrogen, however it cannot currently provide sufficient energy for long-range flights.

Two-thirds of current aviation fuel use occurs on journeys longer than 1,000 miles. SAFs therefore offer the greatest potential to make decarbonised, long-haul flight possible, allowing us to keep enjoying the benefits of aviation in a net zero carbon future.

Sustainability in Civil Aerospace

Dave Smith, Director, Central Technology, Rolls-Royce

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“We expect to see a lot of innovation and energy directed at creating sustainable fuel over the next 10-20 years, and we are here to support this growth in any way we can. Despite the challenges of affordability and scalability, we believe that Sustainable Aviation Fuels are the only solution to decarbonise long-haul aviation.”

SAF and the Defence sector
The potential use of alternative fuels including SAFs as life extenders for gas turbines and reciprocating engines is very pertinent to Defence.

A number of Armed Forces have begun setting themselves aggressive net zero targets as they look to decarbonise their full spectrum of operations. For the UK’s RAF they have set themselves a net zero by 2040 target for the totality of their operations. The use of drop in fuels such as SAF as an alternative to fossil fuels provides a credible first step to achieving their bold target and provides a wider benefit to aviation by providing the potential leadership in the test and certification of new fuel types.

Sustainable aviation fuels of the future
SAFs can currently be used when blended with a minimum of 50% conventional jet fuel. All but one of six certified SAFs (certified up to 50% blend) can be used in most of our engines.

Early tests conducted on a Trent 1000 engine, suggest 100% SAFs with zero fossil-derived content could be viable in our newer engines. We’re investigating the potential of a fully-synthetic Alcohol-to-Jet (ATJ) fuel made from ethanol and of a HEFA SAF, derived from vegetable oils, waste oils or fats, as ‘drop-in’ replacements for existing fuels. We’ve additionally conducted 100% SAF tests in a business jet engine – demonstrating that our current engines for large and civil business jet applications can operate with SAF as a full ‘drop’ in’ option, laying the groundwork for moving this type of fuel towards certification.

SAF testing in Indianapolis

We’ve been successfully testing SAFs for more than ten years at our facilities in Indianapolis.

To date, we have evaluated and gained approval for four blended SAFs, and continue testing other blended and 100% SAFs. We can use these approved fuel blends in our current engines. We have also performed both civil and military flight evaluations and developed new tests to check whether SAFs affect engines differently, causing changes in how they behave or how quickly parts degrade, for example.

Most excitingly, we have been testing a fully synthetic Alcohol-to-Jet (ATJ) fuel produced from ethanol. These tests are helping us understand the ATJ’s impact on seals called O-rings and other gaskets which can leak during operation, as well as its combustion behaviour and emissions profile. Initial results suggest that, with only minor differences to jet fuel, the ATJ could be a promising candidate as a fully synthetic ‘drop-in’ replacement for existing fuels.

Alternative fuels on land and at sea

We are also exploring a range of environmentally-friendly fuels for marine, infrastructure and agricultural power and propulsion applications.

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Natural gas is a fossil fuel, but it has much lower pollutant and carbon emissions than coal and oil. It has an important role to play as a transitional fuel.

Stationary natural gas engines have been an important part of our portfolio for decades. We have set a new standard with the world’s first high-speed gas engine for marine.

Our Series 4000 gas engines are equipped with multipoint fuel injection, providing dynamic acceleration capabilities, high power output, high fuel efficiency and reduced emissions. They are so clean that they have been fitted to two passenger and car ferries operating on the Wadden Sea, a UNESCO World Heritage Site in the Netherlands.

FIND OUT MORE ABOUT GAS ENGINE-POWERED FERRIES ON THE WADDEN SEA

Working together to scale up lower carbon alternative fuels

The high cost and limited supply of lower carbon alternative fuels are the two main barriers preventing their broader adoption.

SAFs are currently more expensive than conventional jet fuels, partly because they are relatively new. For them to play a significant role in combatting climate change, supply needs to be scaled up.

Forward purchase agreements with airlines are helping energy suppliers finance new sustainable fuel plants. Many new production facilities are being planned and built around the world. There could be 90-160 operational plants by 2030.

No single country or company can solve the alternative fuels problem. The aviation industry, fuel companies and others need to work together to develop the technologies involved, and to identify the regulatory and economic conditions to achieve the required scale up.

We are driving investment in alternative fuel technologies to help them become commercially viable. We are, for example, exploring whether small modular nuclear reactors could power plants producing synthetic fuels for use in aviation to decarbonise flight.

Alternative fuels can be a game-changer. Major progress has been made, but we must continue working with urgency to help them fulfil their potential to make a significant contribution to achieving our net zero goals by 2050.

A force for progress;
powering, protecting and connecting people everywhere.







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