Airbus partners with Siemens and Rolls-Royce to compete in the electric air race
Energy Digital takes a look at the race to deliver the first commercial electric aircraft. Mark Cousin, SVP Flight Demonstrators CTO at Airbus, talks about the company’s collaboration with Rolls-Royce and Siemens.
The great electric air race is underway. European aviation heavyweight Airbus is collaborating with Rolls-Royce and Siemens, while budget airline easyJet has teamed up with California’s Wright Electric, with both partnerships targeting the introduction of electric energy storage.
Analysts agree the probability of purely electric shorthaul airliners in the next decade is realistic, but these will be relatively small aircraft carrying 15-20 passengers. Energy storage capacity will be too low to fly a full journey on a 100% electric flight, so we won’t see 100-passenger aircraft flying from London to Amsterdam in 10 years’ time. The airlines involved in this endeavour are starting to ask whether their future fleet will still consist of large 100-plus seat aircraft, or if they’ll have a fleet of smaller aircraft flying shorter routes on full electric.
“We could see a proliferation of smaller aircraft flying out of the less congested airports on relatively short one-hour routes,” suggest Mark Cousin, SVP Flight Demonstrators CTO at Airbus. “This would change the dynamics of air transport and pave the way for autonomous aircraft with no pilot on board, resulting in aviation costs falling dramatically, while maintenance for an electric aircraft will be much cheaper than for one powered by gas turbines.”
Cousin is at the forefront of the Airbus Demonstrators initiative. The programme’s goal is to set an objective not achievable with today’s technologies to force the development of innovations – in this case, the future of hybrid electric propulsion. “In the next couple of years, we’ll see three major demonstrators,” reveals Cousin. “The first is being developed by our colleagues in Silicon Valley – Vahana is a tilt wing single person urban air mobility vehicle. By the end of 2018 we expect the first flight of the City Airbus, a proof of concept of a four-seater air taxi. And we’re also due to announce the successor to our E-Fan, the E-Fan X. The only way we can learn what the issues will be, and how we can overcome them to improve our product, is by flying and testing.”
Cousin identifies four key challenges Airbus has chosen to focus on…
Energy Storage Density
“Improvement in the power-to-weight ratio, or energy storage density, of batteries is required. Even when we take into account the favourable efficiency difference of electric motors versus gas turbines, the conversion of energy from kerosene to thrust is 50 times as high as the conversion we see with energy storage systems. That is going to limit how much energy you can carry and how far you can fly.”
“The weight of hardware with new electric propulsion systems will be greater than traditional aircraft with electric motors and power electronics in the system adding to the payload. A hybrid electric aircraft will be heavier so improvements will be needed to boost overall efficiency when compared with today’s traditional aircraft.”
“We’re running a 2MW motor directly powering a turbo fan which will generate thrust, so in order to achieve efficiency in the megawatt class, you need to transmit the power at a very high voltage. We’ll be transmitting power around the E-Fan X at 3,000 volts DC, yet the highest voltage on aircrafts flying today is 230 volts – it’s a big step. The challenge at 3,000 volts is what we call partial discharge. You get a corona effect. Unless you put massive amounts of insulation around the cables, there is currant leakage from the transmission line to any conducting elements. At sea level in trains and boats it’s not a big issue because air can be a good insulator, but at altitude the air is much thinner and that effect is less powerful. We need to establish the right levels of insulation on the wiring and the separations between cables and structure to control this difficult phenomenon.”
“Today, high-powered electric motors are around 96% efficient, which means the other 4% is coming out as heat. We need to get those losses down to less than 1% in the motor and transmission systems. All of these elements need to be addressed or the hybrid system will be less attractive compared to a traditional gas turbine because you can’t waste the energy you store and transmit.”
Tesla CEO Elon Musk states that once batteries are capable of producing 400 Watt-hours per kilogram, the potential for energy density to beat the weight problem and deliver pure electric transcontinental flight becomes ‘compelling’. Currently, it would be impossible to fly from London to Singapore with pure electric power because an aircraft would have to carry too much weight in battery to have any room for passengers. Until that goal is reached, Cousin believes larger, longer range aircraft will follow a hybrid model. “Initially we’ll see a large generator (2MW) installed between the thrust-producing fan and the gas turbine, and that motor/generator will be used throughout flight to either inject or extract power depending on the phase of flight you’re in,” he predicts.
When taxiing along the runaway, planes could operate purely electrically and during take-off would use the energy storage as back up. Then, if an engine failed during ascent, power could be injected into the other good engine to boost its thrust-producing capability. Gains could also be made at the top of a climb to deliver extra thrust to reach cruise altitude.
“We’re seeing efficiencies of over 50% which is as good as the best diesel engines,” adds Cousin. “However, they are horribly inefficient when they’re operating in off-design points. For example, in descent when you’re idling the engine so it’s ready to give power within eight seconds if the pilot pushes the throttles forward – it’s burning a lot of fuel to produce almost no thrust. We would hope to see the engine operated largely electrically in these types of descent phases, putting very little fuel into the engine, but still keeping it at a speed to deliver thrust via injection if needed. Big savings could come from that, especially on short range operations where a large portion of the flight is in descent (London to Paris would be 30%). In the first iteration aircraft will become hybridised.”
The hybrid model with electric energy storage could fill the gaps to allow a gas turbine to run at continual peak efficiency. It’s the sort of combination found in big ships, and even trains. The thermal engine will run at certain points in the journey, generating power at its peak efficiency. Once the power requirement drops, or the energy storage is full, the engine is shut down and the vehicle runs electrically, then when the battery’s down, the engine will start again. “It’s what you’re seeing with hybrid cars today,” notes Cousin. “Running the engine at peak efficiency then shutting it down to run electrically when the thermal efficiency of the engine would be low. For aircraft, it’s not a question of if, but when.”
Indeed, when Energy Digital spoke with Honeywell’s Mike Stewart, Aerospace VP for Advanced Tech, he confirmed Cousin’s vision: “Hybrid propulsion is already being supported by Honeywell with its 1MW generator. In fact, three 1MW generators are being used on Aurora’s LightningStrike demonstrator to exhibit the capabilities of hybrid-electric propulsion for vertical take-off and landing.
“The most recent solar power plant to go online in the UAE is generating electricity at three cents per kwh, which is half of what you can achieve today by burning natural gas and a quarter of what we see from suppliers of nuclear power,” says Cousin. “If that trend of lower costs continues, you can see this form of transport becoming even cheaper. The big advantage is that it’s very light on infrastructure. That might not make a difference in the UK, which has substantial rail networks, but there is a belief amongst many of the players that in markets where the rail and road infrastructure do not exist, this approach could be a more efficient way of putting in place mass transport.”
With electric aircraft, the only requirement would be the building of relatively small aerodromes at either end of the journey corridor. “Electric vehicles, by the nature of having very few moving parts, will be cheaper to maintain,” argues Cousins.
Energy Digital also heard from Cyient’s Anand Parameswaran, Senior VP Aerospace & Defence, who noted “increasing pressure from the European Union to cut aviation pollution” as a factor in the likely acceleration of the adoption of new tech. “An effective hybrid solution would cut noise pollution as well as CO2, while airlines could slash one of their biggest and most unpredictable running costs in jet fuel, thus areas of focus for 2018 hybrid development are reducing the weight of batteries and the cooling equipment they require.”
The Airbus collaboration boasts the involvement of Siemens, one of the market leaders in terms of the design and manufacture of large electric motors and power transmission systems. In 2016, it flew the largest lightweight electric motor to date – a 260kw motor on an aerobatic Extra 330LE plane. “We’re drawing on their expertise of lightweight high efficiency electric motors,” maintains Cousin. “We’re also leveraging the expertise of Rolls-Royce in the provision of highly efficient gas turbines for aviation, seafaring vessels and power plants where they operate in a mode of fixed power and peak efficiency. Airbus brings the knowledge on how to integrate these technologies into the airplane.
“Building is relatively easy. For example, in the air mobility, air taxi market we’re seeing more than 50 companies working on concepts, but I don’t believe any more than a handful of these will ever succeed in certifying vehicles as safe for flight in the urban environment.”
Carbon dioxide removal revenues worth £2bn a year by 2030
Carbon dioxide removal revenues could reach £2bn a year by 2030 in the UK with costs per megatonne totalling up to £400 million, according to the National Infrastructure Commission.
Engineered greenhouse gas removals will become "a major new infrastructure sector" in the coming decades - although costs are uncertain given removal technologies are in their infancy - and revenues could match that of the UK’s water sector by 2050. The Commission’s analysis suggests engineered removals technologies need to have capacity to remove five to ten megatonnes of carbon dioxide no later than 2030, and between 40 and 100 megatonnes by 2050.
The Commission states technologies fit into two categories: extracting carbon dioxide directly out of the air; and bioenergy with carbon capture technology – processing biomass to recapture carbon dioxide absorbed as the fuel grew. In both cases, the captured CO2 is then stored permanently out of the atmosphere, typically under the seabed.
The report sets out how the engineered removal and storage of carbon dioxide offers the most realistic way to mitigate the final slice of emissions expected to remain by the 2040s from sources that don’t currently have a decarbonisation solution, like aviation and agriculture.
It stresses that the potential of these technologies is “not an excuse to delay necessary action elsewhere” and cannot replace efforts to reduce emissions from sectors like road transport or power, where removals would be a more expensive alternative.
The critical role these technologies will play in meeting climate targets means government must rapidly kick start the sector so that it becomes viable by the 2030s, according to the report, which was commissioned by government in November 2020.
Early movement by the UK to develop the expertise and capacity in greenhouse gas removal technologies could create a comparative advantage, with the prospect of other countries needing to procure the knowledge and skills the UK develops.
The Commission recommends that government should support the development of this new sector in the short term with policies that drive delivery of these technologies and create demand through obligations on polluting industries, which will over time enable a competitive market to develop. Robust independent regulation must also be put in place from the start to help build public and investor confidence.
While the burden of these costs could be shared by different parts of industries required to pay for removals or in part shared with government, the report acknowledges that, over the longer term, the aim should be to have polluting sectors pay for removals they need to reach carbon targets.
Polluting industries are likely to pass a proportion of the costs onto consumers. While those with bigger household expenditures will pay more than those on lower incomes, the report underlines that government will need to identify ways of protecting vulnerable consumers and to decide where in relevant industry supply chains the costs should fall.
Chair of the National Infrastructure Commission, Sir John Armitt, said taking steps to clean our air is something we’re going to have to get used to, just as we already manage our wastewater and household refuse.
"While engineered removals will not be everyone’s favourite device in the toolkit, they are there for the hardest jobs. And in the overall project of mitigating our impact on the planet for the sake of generations to come, we need every tool we can find," he said.
“But to get close to having the sector operating where and when we need it to, the government needs to get ahead of the game now. The adaptive approach to market building we recommend will create the best environment for emerging technologies to develop quickly and show their worth, avoiding the need for government to pick winners. We know from the dramatic fall in the cost of renewables that this approach works and we must apply the lessons learned to this novel, but necessary, technology.”
The Intergovernmental Panel on Climate Change and International Energy Agency estimate a global capacity for engineered removals of 2,000 to 16,000 megatonnes of carbon dioxide each year by 2050 will be needed in order to meet global reduction targets.
Yesterday Summit Carbon Solutions received "a strategic investment" from John Deere to advance a major CCUS project (click here). The project will accelerate decarbonisation efforts across the agriculture industry by enabling the production of low carbon ethanol, resulting in the production of more sustainable food, feed, and fuel. Summit Carbon Solutions has partnered with 31 biorefineries across the Midwest United States to capture and permanently sequester their CO2 emissions.
Cory Reed, President, Agriculture & Turf Division of John Deere, said: "Carbon neutral ethanol would have a positive impact on the environment and bolster the long-term sustainability of the agriculture industry. The work Summit Carbon Solutions is doing will be critical in delivering on these goals."
McKinsey highlights a number of CCUS methods which can drive CO2 to net zero:
- Today’s leader: Enhanced oil recovery Among CO2 uses by industry, enhanced oil recovery leads the field. It accounts for around 90 percent of all CO2 usage today
- Cementing in CO2 for the ages New processes could lock up CO2 permanently in concrete, “storing” CO2 in buildings, sidewalks, or anywhere else concrete is used
- Carbon neutral fuel for jets Technically, CO2 could be used to create virtually any type of fuel. Through a chemical reaction, CO2 captured from industry can be combined with hydrogen to create synthetic gasoline, jet fuel, and diesel
- Capturing CO2 from ambient air - anywhere Direct air capture (DAC) could push CO2 emissions into negative territory in a big way
- The biomass-energy cycle: CO2 neutral or even negative Bioenergy with carbon capture and storage relies on nature to remove CO2 from the atmosphere for use elsewhere