Electric propulsion of aircraft is a growing phenomenon in a sector subject to mounting scrutiny with regard to its environmental impact. We review some of the political, industrial and regulatory developments.
In recent years there has been visible commitment of key transport industries to limit environmental impact. In the aviation industry, the EU's 2003 'Greenhouse Gas Emissions Allowance Trading' system (ETS) currently impacts over 500 aircraft operators flying between EEA airports. Additionally, the implementation pilot phase of ICAO's Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) will begin in 2021. CORSIA seeks to offset annual increases in aviation carbon dioxide emissions above 2020 levels. Offsetting will be achieved by purchasing qualifying credits from other industries or projects that offset greenhouse gas emissions.
Whilst regimes such as CORSIA and EU ETS provide an opportunity for impact mitigation, they should not be relied on in isolation when addressing environmental impact within the sector. These regimes should be adopted alongside other measures such as the sustainable development of biofuels, fuel efficient engines, hybrid and electric aircraft and even practical measures such as effective air traffic control in order to reduce the unnecessary fuel burn of circling patterns and indirect traffic routes.
The UK's Department for Business, Energy & Industrial Strategy (BEIS) announced a £225m investment scheme into clean aeronautics at the 2018 Farnborough Air Show. The money has been split between 18 research and technology projects, including those committed to the development of electric and hybrid-electric aircraft.
One major beneficiary of the BEIS scheme is the E-Fan X project, which has received £58m of funding. The E-Fan X is a hybrid-electric aircraft developed by a joint venture involving Airbus, Rolls-Royce and Siemens. The project will start test flights by the end of 2020. Hybrid-electric models such as this consist of a gas turbine engine which drives electric generators, supported by a lithium battery pack. Similar technology is used in hybrid-electric cars. Pure electric models have had a number of prohibitive issues, including flight time, battery weight, range and overheating.
At the EU level, the Clean Sky 2 initiative, part of the Clean Joint Sky Undertaking (CJSU) project, has €4bn available for investment in clean aviation technologies. Clean Sky 2 has provided funding to a multi-national research project developing hybrid-electric propulsion configurations for conventional aircraft involving research centres in Holland and Germany. The CJSU is underpinned by the EU’s Flightpath 2050 initiative, which aims for a 60% reduction in carbon emissions from aviation by 2050.
Airport operators have shown an interest in fostering growth of electric aviation. Heathrow Airport has announced that it will be waiving landing fees for hybrid-electric aircraft, a prize worth potentially £1m a year to compliant operators. Chief Executive John Holland-Kaye said of the scheme, we hope "to make [zero-carbon flying] a reality at Heathrow by 2030".
Commended by the Department for Transport, schemes such as these are aimed at encouraging uptake in the electric aviation sector. Differential landing charges were already used at Heathrow, amongst other EU airports, to reward reduced noise and air pollution, a policy which enjoys immunity from EU-derived airport fee harmonisation under Article 3 of the Airport Charges Directive (2009/12/EC).
Outside of the UK, the Norwegian government has said that it aims for all short-haul flights to be electric by 2040. Dag Falk Petersen, chief executive of Avinor, the country's airport operator, believes that all flights lasting up to 1.5 hours can be flown by aircraft that are entirely electric. Norway’s largest domestic carrier, Wideroe, has announced it will replace its conventional Bombardier fleet with electric aircraft from 2025. Norway's mountainous terrain and propensity for extreme weather provides for a particularly buoyant domestic aviation market; the nation has 46 commercial airports.
Airworthiness certification and a robust regulatory regime will be key to securing the success of electric propulsion. Concerns regarding battery safety are heightened, particularly in light of the issues suffered by Boeing in its Dreamliner programme. An experimental hybrid-electric aircraft developed by Siemens crashed in Hungary in 2018, killing both persons on board, with battery fire cited as a possible cause. Regulators will need to review these concerns and devise suitable standards.
Participants may be given hope by recent industry-wide consultation and collaboration involving major manufacturers, industry bodies and regulators. In October, EASA launched a public consultation on their proposed airworthiness standards for small electric vertical take-off and landing (eVTOL) aircraft. The consultation was intended 'to develop the first component of the regulatory framework to enable the safe operation of air taxi and electric VTOL (eVTOL) aircraft in Europe', and could be seen as an encouraging attempt at regulatory calibration.
The eVTOL market has set out to develop clean urban transport opportunities, rather than larger passenger aircraft which are the focus of projects such as E-Fan X. Proponents of eVTOL have highlighted their potential to replace traditional public transport systems and transform ride-hailing apps such as Uber. The latter's Uber Elevate division is currently developing electric-powered aerial ridesharing in conjunction with major aviation manufacturers.
Moreover, in the US, the Society of Automotive Engineers (SAE), an influential standards developing organisation with a membership of over 120,000 engineers and technical experts, has set up its Electric Aircraft Steering Group, at which manufacturers and regulators, including EASA, the FAA, Boeing and Airbus have convened to discuss 'standardisation activities necessary to support full-electric and more electric aircraft applications'. The SAE has highlighted that electrification of aircraft propulsion could reduce aviation’s carbon footprint by 50% between 2005 and 2050.
Similarly, the General Aviation Manufacturer's Association has set up its Electric Propulsion and Innovation Committee, which in 2017 produced a publication to assist with measuring performance standards for electric and hybrid-electric aircraft. Both the FAA and EASA were involved in the devising of the standards.
These developments demonstrate that there is clear and growing political, industrial and regulatory appetite to improve environmental performance within the aviation sector, notwithstanding the current state of technological infancy. The continued participation of airport authorities, regulators and policy makers will be key to securing financier, operator and consumer participation.
 SAE Electric Aircraft Steering Group Charter.