July/August 2020

TRANSPORATION n to be selling aircraft capable of carrying up to 100 passengers. It predicts that emission-free aircraft with more than 200 seats and a range of more than 5,500km will be possible by 2040 without requiring any fundamental scientific breakthroughs. ZeroAvia says that hydrogen fuel cell powertrains will offer the same zero-emission performance of battery power, but with much more promising energy-to-weight ratios, making them viable for commercial operations at a much larger scale and in shorter timeframes. It also expects the hydrogen-electric powertrains to have lower running costs because of the high cost of battery cycling in high-use regional aircraft. A hydrogen refuelling infrastructure has recently been commissioned at Cranfield, and ZeroAvia has completed ground-based simulations for its long-distance hydrogen flights. Its first hydrogen-electric test flights are planned for later this summer. The aim of the initial battery-powered test flights was show that they could match the performance of the plane’s original 350hp six- cylinder engine. According to Miftakhov, the biggest challenges were thermal management of the converted plane’s electric motor, inverter and heat exchangers. The intercoolers were replaced by radiators that acted as heat exchangers for the motor and inverter. ZeroAvia is not revealing details of the aircaft’s 250kW powertrain at this stage. Miftakhov describes the test flights as “the latest in a series of milestones that moves the possibility of zero-emission flight closer to reality. We all want the aviation industry to come back after the pandemic on a firm footing to be able to move to a net-zero future, with a green recovery. That will not be possible without realistic, commercial options for zero-emission flight – something we will bring to market as early as 2023.” Miftakhov asserts that the energy density of a fuel cell power system will be five times higher than a battery system and points out that it is not subject to the typical 1,000-2,000 cycle-life limit of high-energy batteries. This is a particularly important factor for short-haul regional routes, where a plane may take off and land up to eight times a day. Miftakhov reckons that fuel-cell-powered aircraft could cost about half as much to operate compared to battery-powered planes for these duties. But several challenges still need to be overcome, such as how to store sufficient hydrogen fuel safely on board a plane. Government support The £5m HyFlyer project is being supported by the ATI programme – a joint Government and industry investment scheme to maintain and grow the UK’s competitive position in civil aerospace design and manufacture. The programme is addressing technologies, capabilities and supply chain challenges. ZeroAvia has received a £2.7m grant from the UK government to support the HyFlyer project. There are several other partners in the project, including: n Loughborough-based Intelligent Energy , which develops and manufactures PEM (proton exchange membrane) fuel cell systems, and is optimising its proprietary high-power evaporatively-cooled fuel cell technology for aviation applications. n Emec Hydrogen – an arm of the European Marine Energy Centre (EMEC) that focuses on hydrogen innovation and demonstration – it is harnessing renewable energy (in the form of wind and tidal power) to produce “green”hydrogen for use in the fuel cells. n Cranfield Aerospace Solutions (CAeS) is helping to integrate ZeroAvia’s powertrain into the Piper airframe and is hosting ZeroAvia team at its hangar. ZeroAvia has also formed a technology partnership with Cranfield University to benefit from its expertise, and aerospace and powertrain knowledge. n ZeroAvia’s vision for zero-emission flight is to use renewable energy to electrolyse water to produce hydrogen to fuel its fuel-cell-powered planes