Aerospace Technology Institute                                                                                                                ZAS0044

Written evidence from the Aerospace Technology Institute

About the ATI

The Aerospace Technology Institute was created in 2013 by the UK government and commercial aerospace sector with both sides committing £150m each per year to fund aerospace research and development. The ATI sets the UK’s aerospace technology strategy and funds a wide variety of transformative R&T projects, securing the UK’s global leadership in aerospace technology and enabling aviation to significantly reduce its environmental impact. The Institute is therefore at the heart of the government’s Jet Zero ambition and ideally placed to drive the transformation to sustainability and new forms of aerial mobility.  

Introduction

Decarbonising aviation belongs to the hardest challenges on the road to net-zero, but it must be addressed urgently.  Progress will be incremental, with different technologies coexisting until a complete switch to zero-emission. Sustainable aviation fuels will be important in the short and medium-term, particularly for large commercial aircraft, pending advances to hydrogen and electric-powered aircraft.

Although very challenging, this represents an opportunity to the UK, which has the right skills, infrastructure, and industrial and research base. A huge shift will be required in technology and infrastructure.  The ATI is submitting proposals to the forthcoming spending review for an ambitious R&D programme to realise the government’s vision of achieving zero-emission transatlantic flight within a generation.  It would enable the UK to reduce global carbon emissions up to 2050 by over three gigatons – equivalent to three to four years’ global aviation CO2 emissions. Economically, the UK also stands to gain from embracing net-zero aviation.  With a potential global market of £5 trillion from now until 2050 for more efficient aircraft, the UK can grow its market share in civil aerospace from 13 percent today to over 20 percent by 2050, set to grow further as the fleet increasingly turns to zero-emission technology. This would benefit all regions of the UK, creating more than 50,000 jobs directly, and 70,000 in the supply chain.

Global regulatory action on aviation emissions is also essential. The UK government should lead work through the International Civil Aviation Organization (ICAO) to set a clear, long-term international CO2 target for aviation.

The ATI is happy to build on the points below and provide further evidence to the committee.

1. What contribution can operational efficiencies make to reduce emissions from aircraft and over what timescale could these have an effect on emissions?

Operational and Air Traffic Management (ATM) improvements offer the benefit of being suitable for implementation at fleet level simultaneously. The table below illustrates the types of flight operations, ground operations and ATM improvements alongside an estimate on when these could be deployed with the right support, and the estimated averaged amount of CO2 benefit to be gained per aircraft. Benefits depend on the aircraft class, the flight mission profile and scenario assumptions on amount of technology adoption and technology effectiveness. These have all been documented by Air Transportation Analytics et. al.[1].

Note that individual improvements may not be added arithmetically as in some cases their simultaneous implementation is not compatible.

In addition to CO2 emissions, aviation generates significant non-CO2 impacts through emissions of particulates, water vapour, nitrogen oxides (NOx), and others.  Aircraft contrails are deemed responsible for the largest proportion of radiative forcing - more than CO2 alone or net-NOx .  Experts consider that contrails could be avoided through aircraft operational changes. More research is required into climate science, weather prediction capabilities, atmospheric science, incorporation of new equipment on aircraft and through physical flight trials.

International standards exist only for some non-CO2 emissions during the landing and take-off cycles. Government should work with ICAO to develop standards for in-flight non-CO2 emissions.

In addition to emissions, operational procedures could further reduce aircraft noise.

2. How close are zero carbon fuels to commercialisation for aviation? How effective will the Jet Zero Council be in catalysing zero emissions technologies? What role should transitional fuels such as alternative hydrocarbon fuels play?

Zero carbon fuels

Batteries can produce carbon-free energy, provided the electricity used to charge them is green.

However, their potential in aviation is limited as they have very low power and energy densities. This is unlikely to change soon. Thus battery-powered aircraft will suit only short-range applications such as general aviation and the anticipated new markets for personal air vehicles and air taxis. These represent a small proportion of CO2 and NOx emissions. As many prospective battery-powered aircraft are intended for urban operation, they will need to be very low noise, posing a further challenge. The ATI programme is funding some battery all-electric and hybrid-electric projects. Most current batteries are optimised for automotive applications. The ATI sees a big opportunity for aero-optimised batteries and is working to launch a dedicated aerospace battery project.

Green hydrogen used in turbofan or turboprop engines, or in fuel cells could eliminate carbon emissions. This has potential in the next 10-15 years; the technology is ready, but production, distribution, and storage infrastructure would require high investment. Hydrogen has higher energy per unit mass than kerosene, but its energy per unit volume is much lower. Even for liquid hydrogen, which must be stored at -253°C, fuel tanks would be several times the size of the kerosene equivalent. It follows that if it were possible to use hydrogen in existing aircraft, with the same tank volume, the range would be considerably less than that from kerosene. The ATI programme is currently investing in several projects to develop a hydrogen fuel cell-powered aircraft powertrains. There could be a market for hydrogen-powered regional and subregional aircraft (20-130 seats) for entry into service within this decade.

ATI’s FlyZero project is exploring the feasibility of commercial zero-emission flight by 2030. FlyZero has conducted research into various energy sources such as batteries, hydrogen fuel cells, ammonia and both gaseous and liquid hydrogen. The most promising solution is liquid hydrogen combusted in a gas turbine. Other options are less attractive because of various physical characteristics such as energy density or toxicity.

The timing of entry-into-service of zero-carbon technologies depends on various factors.  ATI has modelled two scenarios:

• scenario 1: improvements to conventional aircraft combined with limited zero-carbon aircraft coming into the market by 2050;
• scenario 2: improvements to conventional aircraft combined with a breakthrough in technology leading to more and larger zero-carbon aircraft coming into the market by 2050 (this reflects Jet Zero Council ambitions).

In scenario 1, global aviation decarbonisation through technology could be around 2,400 Mt CO2 cumulative between now and 2050. Sixty-six percent of this would come from improvements to conventional aircraft (i.e. those still burning kerosene or SAF), with the remaining third from zero-carbon aircraft. Scenario 2 sees global aviation being decarbonised by 3,300 Mt CO2 cumulative in the same period – equivalent to three to four years’ global aviation CO2 emissions. This would be shared equally between improved conventional aircraft and zero-carbon aircraft.  Reductions would increase considerably in the 2050s and 2060s as zero-carbon aircraft constitute ever more of the global fleet.

Jet Zero Council

The ATI is working closely with the Jet Zero Council to catalyse zero-emission technologies. The ATI’s FlyZero project will have direct inputs into Jet Zero’s Zero Emission Flight Delivery Group, and will be instrumental in enabling the UK to maintain and grow its position in developing and commercialising technologies for zero-emission aircraft. By early 2022, FlyZero will produce detailed technology roadmaps.  Developing these technologies should lead to a demonstrator programme aiming for first flight in 2027, funding permitting.

Alternative hydrocarbon fuels

Alternative hydrocarbon fuels (often referred to as sustainable aviation fuel, or SAF) will be essential to help aviation reach net zero by 2050, particularly for large, long-range aircraft. SAF usage at scale will require several barriers to be overcome. One of the main barriers is affordability: While bio-derived HEFA SAFs[2] are currently the least expensive, power-to-liquid SAFs, or “e-fuels”[3] are likely to become the most economical in the long -term as renewable energy prices fall. They also have the lowest environmental footprint and are the most scalable. 

Power-to-liquid SAFs do not exist today at commercial scales. Significant volume increases will be necessary over the coming years to match total aviation fuel usage and R&D will be needed to establish how best to achieve this.   

SAFs will to an extent be able to use existing fuel infrastructure, but new systems will also be required. Distribution infrastructure like pipelines, storage and blending facilities may be required in different locations due to different production processes leading to development of new plants outside the existing supply chain.

Pure SAF (i.e. unblended) is not compatible with current aircraft, requiring new infrastructure for manufacture and blending initially.  The objective however will be increase blending ratios, ultimately up to 100%.  This will require further research. Appropriate fuel handling standards will also need to be developed.  To enable pure SAF utilisation engine and airframe design changes will also be necessary to maintain optimal engine performance. 

Sustainable pricing mechanisms are required to close the price premium of SAF and scale-up production and uptake. Mandates could be effective ways to incentivise SAF scale up but must be regionally aligned to keep UK competitive.

3. What new technologies are there to reduce emissions from aircraft and how close to commercialisation are they? 

There is a range of available or soon-to-be-ready technologies to be deployed with the potential for a further step change in aircraft performance, in conjunction with zero-emission technologies and SAF.  

A summary of the aircraft platforms and major technologies is summarised in the figure below (note that pictures are only for illustration purposes).

Improved conventional aircraft

Improved aircraft that continue to burn kerosene or SAF are expected to come into the market in the late 2020s (potential single-aisle/narrowbody) and throughout the 2030s (potential widebody).  They are expected to produce between 20-25% less CO2 than the aircraft they substitute. Of these improvements, about 10-12% will come from more efficient and lighter propulsion systems, 9-10% will come from improved airframe and structures, with the remainder being the contribution of reducing the weight in systems.

Zero carbon or zero emissions aircraft

Zero-emission aircraft could represent the most effective long-term solution to decarbonise air transport, with battery (zero-emission) and hydrogen (zero-carbon) technologies currently the most promising.

Zero-carbon personal air vehicles and air taxis could enter the market in the mid-2020s. The ATI is already funding various projects in this area.  These developments can act as a steppingstone for exploitation into larger aircraft.

Airbus in 2020 unveiled three zero-carbon concepts, with the aim to deliver the first type by 2035. These are regional and single-aisle/narrowbody aircraft with ranges below 2,000 nautical miles and carrying circa 100-200 passengers. They would feature radically new propulsion systems using liquid hydrogen, either in fuel cells or being directly combusted through a modified gas turbine.

Initial research from the ATI’s FlyZero project suggests that larger aircraft with a range of 5,250 nautical miles and capacity of up to 280 passengers could be powered by gas turbines burning liquid hydrogen. These could fly to any destination in the world with only one intermediate stop.

Aircraft using hydrogen would require storage, distribution and other fuel systems for hydrogen, as well new wing designs and lightweight cryogenic and thermal management systems.  

Radically different airport infrastructure will be required for new aircraft using novel forms of propulsion. The ATI, in collaboration with Airports Council International, has modelled the impact of hydrogen aircraft on airports’ infrastructure and operations.

4. How should the Government’s net zero aviation strategy support UK industry in the development and uptake of technologies, fuels and infrastructure to deliver net zero aviation?

The ATI is responding in detail to the government’s Jet Zero consultation on a net-zero aviation strategy.  The ATI is also submitting proposals to the forthcoming spending review for an ambitious R&D programme to realise the government’s vision of achieving zero-emission transatlantic flight within a generation.  We will be happy to provide copies of these documents to the committee as they are submitted in the near future.  

The ATI has been investing in technologies since 2013 that will see a new generation of ultra-efficient aircraft that are forecast to be 20-25% percent more fuel efficient than the current generation. To achieve net-zero a major uplift and extension in aerospace R&T funding is required.  The Jet Zero consultation correctly adopts a “clear goal, multiple solutions” approach, recognising that “many of the technologies we need are in their infancy and will take time to develop.”  The government’s intention to adopt the findings and recommendations of the Jet Zero Council concerning the ATI’s FlyZero project is also welcome.  The ATI therefore recommends research into a wide range of technologies, including ultra-low emission technologies for long-haul aircraft; zero-carbon technologies for short-to-medium range aircraft; technologies connected with advanced air mobility (AAM) focusing on small and vertical take-off aircraft; and underpinning technologies including materials, digital design and validation, and competitive manufacturing.

Critically, advancing our zero-emission ambitions will demand the ability to integrate multiple technologies, prove whole aircraft concepts, and launch a series of flying technology demonstrators. These will require substantial new national R&D assets.

The consultation correctly identifies many other issues that need to be addressed, including regulation and infrastructure. Much of this will need to be agreed at international level.  One critical issue for the UK concerns the level of demand from aviation for hydrogen, with preliminary assessments from FlyZero indicating that aviation could use 8-20% of total hydrogen demand by 2050.

5. What is the most equitable way to reduce aircraft passenger numbers (e.g. reforming air passenger duty and taxes, frequent flyer levies, bans on domestic flights where trains are available, restrictions on airport capacity)?

See question 7.

6. What further action is needed by the International Civil Aviation Organization to drive emissions reductions? What can the UK Government do to drive international action on emissions?

Global action on aviation emissions is essential. The UK government should lead work through ICAO to setting a clear, long- term international goal for aviation CO2 emissions reductions in line with the UK net zero goal.  COP26 will present an opportunity for the UK to show climate change leadership on the global stage by progressing the international framework for aviation emissions to support delivery of the 2050 long-term CO2 target. 

In addition, international standards exist only for some non-CO2 emissions during the landing and take-off cycles. Government should work with ICAO to develop standards for in-flight non-CO2 emissions such as NOX

Work with ICAO must also start to address the provision, standardisation and regulation of hydrogen fuel at a global level, and to raise awareness amongst other states about the importance of adapting to new forms of sustainable fuel.  

7. How effective will the global offsetting scheme for international airlines (ICAO’s CORSIA) be at stimulating technology improvement and/ or behaviour change to reduce emissions from aviation?

Effective market-based policy measures linked to a global agreement are vital to ensure aviation’s net emissions will reduce in line with climate goals and to establish carbon pricing. 

While market-based policy measurers have a role to play in reducing emissions, they should not be viewed as an alternative to in-sector efforts such as technologies aimed at achieving true zero-emission aviation.  

Airline investment through offsetting instruments in renewable energy projects should be geared towards those that produce electricity to electrolyse water to produce green hydrogen that is then used for aviation purposes (to be used directly as a fuel or as feedstock to produce SAF). 

In addition, there is significant potential for carbon capture, direct air carbon capture (DAC) and carbon capture and storage (CCS) technologies and there is a clear role for them to play in the production of SAF. CCS in the long term represents an additional out-of-sector opportunity to deal with residual emissions, potentially able to take over from market-based measures as the technology develops. The required investment will be significant and the potential to accelerate current technologies to meet commercial market demand has yet to be fully assessed.  

The policy and regulatory framework to develop and roll out carbon removal technology should be in place as soon as possible; and the government should be clear in its long-term support for this high potential technology. If airlines contribute to carbon removal DAC/CCS/CCUS projects via offsets, that carbon could be recycled for use in synthetic power-to-liquid SAF. 

8. How should the UK define its ownership of international aviation (i.e. arrivals, departures or both) in order to include them in legislative targets?

Assigning international aviation share to departures only, as it is currently the case, avoids double counting.  Any ownership system should be agreed internationally to ensure consistency.

The ATI encourages government to ensure the UK is not disadvantaged by the way ownership of international aviation emissions is assigned. The UK sits at the edge of a continent, and has a greater share of long-haul flights connecting travellers from Europe and North America to the world than other nations because of its geographical location.

Contact details

For further details on the above, please contact:

Malcolm Scott

Corporate Development Officer

Aerospace Technology Institute

September 2021