It’s no surprise that air travel creates lots of carbon dioxide and other harmful emissions. What’s worse is that most of those emissions are injected high into the Earth’s atmosphere, far away from the carbon sinks like trees on the Earth’s surface that could potentially sequester some of them. The air travel industry is aware of the problems, and companies like United Airlines and Airbus are searching for ways to lower their carbon footprint.
United Focuses On Ground Support Systems
The system of vehicles and equipment that supports air travel on the ground relies heavily on diesel engines. They power the tankers that refuel aircraft, the vehicles that take luggage back and forth to the planes, the vehicles that push planes back from the gate, and the buses that shuttle passengers to and from the airport.
The FAA says 1.7% of all emissions associated with air travel come from that ground support infrastructure. That may seem like a trivial amount — air travel itself is responsible for about 3% of all global emissions — but it’s still a lot. On a positive front, United announced this week it is investing in sodium-ion battery maker Natron Energy as part of its larger efforts to curb emissions all across its operations.
Sodium-ion batteries are nonflammable and can be made from relatively cheap, abundant, and nontoxic materials, including iron and manganese. They also can recharge tens of thousands of times before they degrade and need to be replaced, and they do not have the risk of thermal runaway like lithium-ion batteries do — an important consideration for equipment operating in close proximity to thousands of gallons of jet fuel.
Natron’s batteries could be used to electrify ground equipment, such as forklifts and pushback tractors, and to store renewable energy onsite — which might eventually be needed to recharge the batteries in electric passenger jets or flying taxis. “Aviation is an emerging space for us that appears to be potentially very high impact from a decarbonization perspective,” Colin Wessells, CEO of Natron Energy, told Canary Media.
While sodium batteries only have about half the energy density of their lithium-ion counterparts, that is less of a concern for stationary applications and heavy-duty equipment that mostly stays in one place. “This opens up the opportunity to safely electrify a lot of airport operations,” Wessells said.
United has recently invested in a number of companies that are searching for ways to transform its airplanes from oil guzzling machines to climate friendly aircraft powered by hydrogen fuel cells, batteries, or alternative jet fuels. “United is going to lead the way in decarbonizing this business, and this [investment] is another piece of that puzzle,” Michael Leskinen, president of United Airlines’ venture capital division, told Canary Media.
Airbus Experiments With Hydrogen Combustion And Fuel Cells
Airbus is one of the largest aircraft manufacturers in the world. Like United Airlines, it is working to lower the emissions associated with air travel. In an announcement this week, Airbus said it is developing a hydrogen-powered fuel cell engine. The propulsion system is being considered for use in the zero-emission aircraft it expects will enter service by 2035.
Airbus will start ground and flight testing this fuel cell engine architecture onboard its ZEROe demonstrator aircraft towards the middle of the decade. The A380 MSN1 flight test aircraft for new hydrogen technologies is currently being modified to carry liquid hydrogen tanks and their associated distribution systems.
“Fuel cells are a potential solution to help us achieve our zero-emission ambition and we are focused on developing and testing this technology to understand if it is feasible and viable for a 2035 entry-into-service of a zero-emission aircraft,” said Glenn Llewellyn, vice president for zero emission aircraft at Airbus.
“At scale, and if the technology targets were achieved, fuel cell engines may be able to power a one hundred passenger aircraft with a range of approximately 1,000 nautical miles. By continuing to invest in this technology we are giving ourselves additional options that will inform our decisions on the architecture of our future ZEROe aircraft, the development of which we intend to launch in the 2027–2028 time frame.”
There are two ways hydrogen can be used as a power source for aircraft propulsion, the company says. First, via hydrogen combustion in a gas turbine. Second, by using fuel cells to convert hydrogen into electricity in order to power a propeller engine. A hydrogen gas turbine can also be coupled with fuel cells instead of batteries in a hybrid-electric architecture. An engine powered by hydrogen fuel cells produces zero NOx emissions or contrails, which adds additional decarbonization benefits.
In a separate announcement, Airbus and Renault said they have signed a research and development agreement that will accelerate their electrification efforts and improve their future products.
The Airbus and Renault engineering teams will join forces to improve technologies related to energy storage, which remains one of the main roadblocks for the development of long-range electric vehicles. The cooperation agreement will include energy management optimization and battery weight improvement. In addition, the two teams will look for the best way to move from current cell technology to solid-state designs which could double the energy density of batteries.
“For the first time, two European leaders from different industries, are sharing engineering knowledges to shape the future of hydrid-electric aircrafts. Aviation is an extremely demanding field in terms of both safety and energy consumption, and so is the car industry. At Renault Group, our 10 years of experience in the electric vehicle value chain gives us some of the strongest feedback from the field and expertise in the performance of battery management systems,” said Gilles Le Borgne, executive vice president for engineering for Renault Group.
“Driven by the same ambition to innovate and reduce the carbon footprint, our engineering teams are exchanging with those of Airbus to converge transversal technologies that will enable both hybrid aircraft to be operated and the vehicles of tomorrow to be developed.”
“This cross-industry partnership with Renault Group will help us mature the next generation of batteries as part of Airbus’ electrification road map,” said Airbus CTO Sabine Klauke. “Reaching net zero carbon emissions by 2050 is a unique challenge that requires cooperation across sectors, starting today.
“Bringing together Renault Group’s experience in electric vehicles with our own track record in electric flight demonstrators will allow us to accelerate the development of the disruptive technologies required for future hybrid aircraft architectures in the 2030s and beyond. It will also foster the emergence of common technical and regulatory standards in support of the clean mobility solutions needed to achieve our climate targets.”
Air travel is one of the wonders of modern technology. It shrinks time and distance so that you can board a plane at noontime in Sydney and be in LA in time for lunch the same day. (The International Date Line makes such weirdness possible.) But it raises the question of how much damage we are willing to tolerate for the convenience of flying.
United, Airbus, and Renault are far from the only companies focused on lowering emissions from air travel, and there is no guarantee they will be successful in their efforts. They deserve credit for at least addressing the issue. There is a lot of work to do yet, but if a way can be found to merge the convenience of air travel with zero-emissions technology, that will be good news for the environment and the planet.
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