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Electric flight prepares for takeoff

As emissions from global aviation rise, companies are beginning to look closely at the idea of using electric planes for short-haul flights as a potential solution

Emissions from global aviation are on the rise as more and more people take to the skies for weekend breaks, business trips and holidays in distant destinations. This trend is far from compatible with the need to drastically reduce greenhouse gas emissions to have the best chance of avoiding the worst effects of climate change. Increasing attention is being paid to electric planes as a possible solution, at least for short-haul flights

A three hour flight from Berlin to London produces roughly 177 kilograms of carbon dioxide emissions per person. Making the journey by car takes seven hours longer, but emissions are reduced to around 122 kilograms. Travelling the distance by train slashes personal emissions to just 32 kilograms, but escalates the length of the journey to 19 hours. In a world where time is of the essence, few opt to reject the convenience of the plane in favour of longer, more climate-friendly options. Some airline companies are starting to investigate whether the electrification of their fleet could be an answer to this growing problem. Direct carbon dioxide (CO2) emissions from global aviation are forecast to reach 897 million tonnes in 2018. This is 4.4% higher than in 2017 and means they will account for more than 2% of overall global greenhouse gas emissions. Passenger numbers are due to double over the next two decades and the International Air Transport Association (IATA), which represents most global flight operators, believes net CO2 emissions from aviation can only be stabilised at forecasted 2020 levels. Any further air travel growth will have to become carbon-neutral with offsetting measures, says IATA. It cites the Carbon Offsetting and Reduction Scheme for International Aviation, which is due to begin as a pilot in 2021, but will not become mandatory for the around 70 participating countries until 2027. Such a slow response means efforts to stabilise emissions at 2020 levels are likely to fail. By 2050 global aviation could account for 12% of the cumulative 205 billion tonne CO2 emissions budget cap, which scientists say the world needs to keep below to ensure global warning stays under 1.5˚C, or face the irreversible collapse of eco-systems. Since CO2 emissions per rail passenger are just a fraction of those per plane passenger, expanding electric high-speed rail to oust regional fossil-fuelled air travel could achieve big climate benefits. But just as rail proponents build their case for more high-speed rail routes, the aviation sector has pulled a joker out of the hat — electric flight. Clean electric aviation could be cheaper and simpler than building and maintaining new high speed rail infrastructure and could improve the sector‘s climate outlook, notably for short-haul flights. The European Regions Airline Association estimates that 30% of all passengers worldwide are flying distances under 560 kilometres and 50% distances of less than 950 kilometres. Electric flight has so far hardly figured in climate forecasts. The 1.5˚C global warming report released by the Intergovernmental Panel on Climate Change in October 2018 merely notes some progress has been made on the use of electricity in planes (and shipping) though no commercial applications have arisen”. Similarly, Europe’s expected aviation electrification rate to 2050 is a tiny 2-5%, according to the Decarbonisation pathways - European economy” report by Eurelectric, a European electricity industry federation, in May 2018. Modelling for the study was done by McKinsey, a consultancy company, based on current trends and developments. The low aviation direct electrification rates assume no big breakthroughs towards lightweight and high capacity batteries, and suggest any direct electricity use in European aviation will probably be limited to regional and domestic flights.

Norway leads

It is in this space that Norway may be triggering a new and cleaner aviation future. The motivation lies in reconciling the need to combat climate change with the transport problems associated with its mountainous countryside and numerous islands. The geographical conditions often make flights, ranging mainly between 40 and 170 kilometres, more attractive than slower road, rail and boat travel, especially in winter snow. The Norwegian government has requested that state-owned Avinor, operator of the country’s 46 airports, develops a programme to commercialise electric aircraft, with the aim of electrifying Norwegian domestic aviation by 2040. This is a realistic aim. The aircraft industry expects the first commercial all-electric aircraft to be available by the mid-2020s and to achieve a flight range of 1000 kilometres by 2030, [with] all-electric aircraft being used to cover shorter distances and hybrid machines deployed for longer distances,” says Kristian Loksa from Avinor. The work is in the starting blocks, but has already attracted worldwide interest, he adds. A feasibility study of Norway’s ambition by Green Future, an advisory company on pioneering technologies, highlights energy consumption savings since an electric motor is up to three times more efficient than a fuel combustion engine. Electricity costs may also be lower than buying conventional kerosene fuel, state the authors. Planes with electric motors are also quieter, lighter and more responsive, making them potentially more socially acceptable to residents living near airports and needing less runway space. Maintenance and operation is also reduced, cutting costs and outage times, finds the study. Avinor adds that infrastructure and charging issues, such as whether depleted aircraft batteries will be swapped or charged while the plane is on the ground, still need to be investigated, but grid connections are unlikely to be a problem. Only airports in remote areas will possibly need an electric transmission grid extension, says Loksa. In general, the electrical infrastructure is not a problem since the electricity requirement for short-haul internal flights of around five terawatt hours (TWh) a year, or 4% of Norway’s net annual electricity consumption of 123.4 TWh, is not large in the grand scale of things. Electricity will be bought, like jet fuel currently, in the market, states Loksa.

State owned

Project coordination in Norway is fairly simple because, like Avinor, the electric grid company Statnett and all of Norway’s renewable electricity generators are state-owned. The country regularly runs an annual net electricity export surplus that would easily cover the 5 TWh needed for electric domestic flights and 7.4 TWh for electric mobility, with more to spare for electricity in industry. Christer Gilje from Statnett says there will generally be a power surplus in Norway and the Nordic region in the coming years as renewable power production keeps on rising. There are already wind farms planned that can be profitable without subsidies” and Norway will continue to cooperate with other Nordic countries to ensure the power system works and security of supply is maintained. Following Norway‘s initiative, EasyJet, a UK airline, generated headlines in October 2018 saying the transition towards an all-electric commercial passenger jet capable of flying passengers across EasyJet’s UK and European network was in sight. Wright Electric, its American partner, has lodged a patent application for an electric motor design for a 500-kilometre range, EasyJet-sized aircraft (up to 186 seats), a sign that aircraft builders may concentrate on electric propulsion in their next generation of aircraft for regional flights. A clutch of aircraft builders have announced similar projects, including prominent names like Airbus, Rolls-Royce and Siemens that are collaborating on electric airplanes for short-haul flights by the mid-2030s. Prior to that US company Zunum Aero, founded in 2013, plans to have a 12-seater, hybrid electric 700-mile (1100 km) commercial aircraft ready to deploy by the early 2020s. Johan Lundgren, CEO of Easyjet, thinks a route like Amsterdam to London, Europe’s second busiest flight path, could become the first electric flyway given the target range of an electric plane is around 500 kilometres. Indeed, he believes the Netherlands could lead the way” if its government and airports encourage airlines to operate in the most sustainable way and incentivise them with a suitable battery charging structure. Local inhabitants could also benefit from significant reductions in noise and carbon emissions from the multiple, daily take offs and landings.

Ever ready

Batteries are already capable of storing sufficient electric power for short routes and the technology to power electric motors on a plane is within grasp. Nonetheless, Green Future expects the first commercial electric aircraft to be hybrid to make it easier to meet commercially necessary legal requirements for energy reserves such as having to land at a more distant airport. A hybrid plane would augment the electric battery with a combustion engine. The fuel used could be conventional aviation kerosene, green kerosene produced from biomass or through electrolysis combined with further chemical processes. Hydrogen could even play a role, although transporting hydrogen in liquid form at -250˚C would make it a demanding choice to augment batteries. Hybrid plane designs focus mainly on those where electric motors provide the propulsion, but where a combustion engine connected to a generator is ready to provide back up electricity if needed, and those where the electric motor and combustion engine dovetail their operations for least use of energy. Within ten to 15 years, driven mainly by developments in the electric automobile sector, batteries are expected to have sufficient capacity to enable one hour flights or at least 500 kilometres, with an energy density of 500 watt-hour per kilogram or double what is currently available, says Green Future. With electric two-seater battery powered aircraft already being tested, it sees 20-70 seaters with hybrid systems using batteries and electric motors becoming commercially available by 2030. Even if only regional flights go pure electric, this on its own is anything but a niche market”, says the European Regions Airline Association, given the significant amount of short haul flights worldwide. Pure electric driven flight looks unlikely for long-haul flights due to the weight of the batteries required. Planes for international travel will indirectly use electricity, burning fuels that are carbon-neutral made with decarbonised electricity, predicts Henning Hader from Eurelectric. The EU has limited ability to push the decarbonisation of air travel at a global level, he says, but hybrid solutions could help to reduce conventional fuel consumption and keep emissions down during ground operations.

Keep it green

Whether direct or indirect, electric aviation is fine as long as the electricity used is green”, stresses Manfred Treber, transport expert at Germanwatch, an organisation working for climate protection and sustainability. Eurelectric expects there to be enough decarbonised electricity available to meet requirements within Europe, even with an overall estimated increase in demand of 4800-6000 TWh by 2050 for the electrification of transport, buildings, industry and additional electricity demand” (such as for power-to-gas applications) to achieve a 38-60% direct electrification rate. Adding in the potential need of around 135 TWh for the electrification of European aviation — based on 27 member states using Norway’s expected 5 TWh of electricity for aviation — makes no substantial difference to the forecast overall huge increase in electricity demand, equivalent to the output of 680-860 gigawatt-size conventional power stations operating virtually around the clock. Analysis underway for Eurelectric anticipates this extra supply can be fully sourced from EU and EEA countries, with some 80% of it renewables-generated. There are good signals on performance and prices including for electricity storage,” says Hader. Cost and capital expenditure are not the main obstacles, but rather the effort and initiatives needed to maintain public acceptance for the changes in electricity supply technologies, namely a significant increase in solar, onshore wind and offshore wind stations. Although electric aviation looks doable, the advantages of high-speed rail remain persuasive. Current electricity consumption by the European railway network is around 60 TWh a year with the electrification rate at around 70%. With electrification expected to rise to 93% by 2050, electricity use would rise to at least 80 TWh a year, but this would still be only two-thirds of the potential electricity use of regional electric aviation passenger business. High-speed rail travel at up to 400 kilometres per hour can rival electric aviation travel speeds and is capable of moving a lot more people, says Treber, pointing to the 500 kilometre rail route between Tokyo and Osaka in Japan on which 12 to 15 well used” trains each carrying 1000 people travel 12 to 15 times an hour in both directions at 400 kilometres per hour. In Treber‘s view, electric aviation makes most sense in areas where the population is small and geographical conditions disfavour rail. But he concedes that building up high-speed rail requires political decisions to accelerate planning and to cover expenditure for upgrades and the building of new rail routes, while the minimum requirement for electric aviation is a strip of concrete to take off and land on. For the future, it seems that just as now, regional distance planes, albeit electrically powered, are unlikely to provide transport for millions of ordinary commuting folk, but they could offer a more climate-friendly option for weekend and business trips.

Writer: Sara Knight, Image: Zunum Aero