The aircraft of the future is projected to be much simpler to operate due to a rare convergence of technologies, mainly Electric Propulsion and Information Technology. PAUL STEIN, a board member and chief technology officer of Rolls-Royce, one of the world’s leading aircraft engine manufacturers, speaks to MICHAEL WAKABI about the limits of electric propulsion and what engine makers are doing to reduce aviation’s environmental footprint.
WAKABI: In spite of being responsible for only 2% of global emissions, aviation is the target of increasingly prohibitive environmental levies. Does this skew the picture away from where the world should be looking?
STEIN: All industries need to revolutionise to support our growing, increasingly urban population. We have entered an era where sustainability is key to not only economic survival, but for us as a species.
Global passenger traffic is increasing by 5% year-on-year. Africa alone will need an additional 1,000 aircrafts within the next 20 years. As a leading industrial technology company, our activities have a profound effect on society and the environment, and we are at the forefront of developing innovations that mitigate industrial impact.
The Advisory Council for Aeronautics Research in Europe has set a target to reduce carbon dioxide per passenger-kilometre by 75% by 2050, and as such, we have set ourselves the target of 30% reduction in specific fuel consumption, compared to the first Trent engines (an engine family produced by the company and used in Boeing).
Over the past two decades, improvements of the power plant, particularly the gas turbine, have been the driving force towards efficiency gains and greener aviation. How far can the envelope be stretched to make the gas turbine leaner and greener?
Rolls-Royce has been pioneering for over 100 years. We created the first turboprop, the first jet engine, powered the first passenger airliner, and powered the first and only commercial supersonic jet (Concord).
We have crafted seven variations of our world-leading Trent family since its launch over two decades ago; each has pushed the boundaries of what is possible.
The gas turbine remains essential to our future – the Trent XWB, which powers the Airbus A350, is the most efficient in-service aero-engine ever created and will be flying for decades. We are now taking this proven technology through another evolutionary step. The Ultrafan will be 25% more fuel-efficient than the first Trent engine, with a new geared architecture and bypass ratio treble that of the Trent 700. The fan blades will be manufactured from the very latest carbon or titanium composites.
Electric propulsion has been proposed as the future of aviation. To what extent can it be a substitute to the gas turbine?
Electrification is impacting many transportation systems, and is set to have a similar impact on aviation like when gas turbines replaced piston engine propulsion. For medium to long haul flights with larger aircraft, the gas turbine will remain the main source of thrust as only chemical fuels can deliver the power required for such heavier aircraft.
However, electrification will enable simplification of gas turbine internal design, unlock new methods of managing aircraft drag, and open new benefits at platform level.
Rolls Royce recently acquired Siemens’ electric propulsion business. What are the limits if any, of electric propulsion and to what extent can they be addressed in the foreseeable future?
The recent acquisition of Siemen’s electric and hybrid-electric aerospace propulsion business, known as eAircraft, is a fantastic opportunity and has strengthened our capabilities.
We are engaged in several electrification programmes, for instance: our E-Fan-X programme will demonstrate hybrid-electric flight by replacing an engine from a 100-seater jet with a 2MW Hybrid-Electric Propulsion Unit, powered by a gas-turbine-driven 2.5MW generator and a battery system.
This will be the world’s most powerful flying generator. Another example is the ACCEL programme which we hope will break records and be the fastest ever, all-electric aircraft reaching a speed of 300-plus mph. This will require the most powerful battery ever built for flight, powerful enough to beat speed and performance records, light enough to fly, and stable enough not to overheat.
Our current view is that weight will limit all-electric flight to small aircraft flying short-range missions. Larger aircraft flying higher loads on longer ranges will need to be powered by gas turbine technology for the foreseeable future with an increasing degree of hybridisation over time.
Besides unmanned air vehicles, what large scale applications in commercial aviation can electric propulsion feasibly support in the near term?
Soon, we shall see electrical, vertical, take-off and landing aircraft (EVTOLs) demonstrating the same versatility of helicopters.
Many of the early concepts rely solely upon battery power and require extensive charging infrastructure. But, as battery technology improves, these aircraft will fly longer ranges and at higher speeds.
The projected market size for early versions is roughly £1 billion per year. Rolls-Royce’s hybrid EVTOL is based around the hybridisation of our M250 engine, capable of carrying four to five people and travelling at 250mph over a range of over 500 miles.
The industry has also been pushing for the development of sustainable aviation fuels. From an engine manufacturer’s perspective, what hurdles need to be overcome before these fuels can be considered a viable alternative to fossil fuels?
Rolls-Royce is committed to doing what it can to support and accelerate the availability of Sustainable Aviation Fuels (SAF), including the development and certification processes.
Our engines can operate on any alternative fuel that has the same characteristics as kerosene. Several Rolls-Royce airline customers already use blended fuels (SAFs with fossil). Egypt Air’s recent delivery flight of their fifth Rolls-Royce Trent 1000 TEN powered Boeing-787 was fuelled by Sustainable Aviation Fuel.
IATA has also set itself rather ambitious emissions reduction goals. What mix of technologies will it take to meet those commitments?
There are three fundamental pillars that lead the decarbonisation of the aviation sector; continuous development of aircraft and engine technology to improve efficiency; development of low carbon alternative fuels; development of novel aircraft and propulsion technology, including the electrification of flight.
We are continuously driving fuel efficiencies in today’s products, achieving an average of one percent increase in fuel efficiency each year. This is thanks to advanced analytics from data collected from engine health monitoring, which shows us how well an engine is functioning. We can then advise our customers how they can optimise fuel efficiency and whether an engine requires maintenance.
In Africa, Rolls Royce tends to be associated more with aviation. How big and diverse is your product portfolio on the continent?
Rolls-Royce is dedicated to delivering vital power, in whatever form. We have three divisions, civil aerospace, defence and power systems. Our civil aerospace division has supported African aviation for almost 100 years.
Today, we serve 20 operators, powering over 60 wide body aircraft, with another 50-plus aircraft on order. Roll-Royce powered ‘flying hours’ in Africa has increased by over 50% over the last five years.
Our Power Systems business provides innovative solutions ideally suited to meet Africa’s rapidly growing societal demands for energy and mobility. We provide a range of power generation solutions and capacities for any electrification requirement. From standby power generation sets for hospitals and data centres to rural hybrid micro-grid solutions and highly efficient power plants delivering electricity to towns and cities.
We employ 120 people across Southern Africa, with offices in Cape Town, Johannesburg and a regional office in Zambia, as well as satellite offices strategically situated to serve our customers.
Rolls-Royce’s defence business is a market leader in aero-engines for military transport and patrol aircraft with strong positions in combat and helicopter applications. We have a significant scale in naval markets across the world and pride ourselves as the technical authority for the through-life support of nuclear power plants for submarines.
Our defence division has also retained solid relationships with a number of African countries for several decades, serving many forces, namely Algeria, Tunisia and South Africa. As the world evolves its energy sources to address climate change, Rolls-Royce will be providing solutions. Innovation is at the heart of our culture, and we are adapting to meet the power demands of tomorrow’s world.
WHO IS PAUL STEIN
Chief technology officer, Rolls Royce
He was appointed to the Rolls-Royce Executive Leadership Team as Chief Technology Officer in April 2017 to be accountable for the company’s technology investment and for ensuring close alignment with business strategy to maintain a competitive edge. Prior to that, Paul was Research & Technology Director accountable for the company’s global investment in R&T, as well as fostering innovation and promoting and sustaining specialist engineering talent.
He joined Rolls-Royce in 2010 as the Chief Scientific Officer and for two years concurrently acted as the Engineering and Technology Director for the Company’s Nuclear business.
Paul was Director General, Science and Technology, at the UK Ministry of Defence immediately prior to joining Rolls-Royce. Prior to that, he was Managing Director of Roke Manor Research which was then owned by Siemens, and in 2003 was appointed to the Siemens UK Executive Management Board, leading technology and contributing to business strategy.
Paul holds an Electrical and Electronic Engineering degree from King’s College, London. He is a Fellow of the Royal Academy of Engineering, the Royal Aeronautical Society and the Institution of Engineering and Technology.