Oct. 10, 2022, © Leeham News: Batteries are the best thing for the new generation of clean planes. Or so the proponents of the concept say.
However, few talk about the overall life cycle of the concepts, whether eVTOL, hybrid-battery aircraft or pure battery aircraft.
And there’s the rub. Batteries will be clean in operation. But they are far from being a panacea for clean aviation’s life cycle.
Some recognize that the power source for toll Batteries can be an eco-issue. Others recognize that RECYCLING batteries are an issue. Some acknowledge that today’s batteries don’t last long—they need to be replaced every 1,000 to 2,000 flights, depending on usage and other factors.
But for now, the real skunk at the lawn party is the fact that mining lithium, a key chemical for long-lasting batteries, is strip-mining, one of the most environmentally damaging ways to take anything from the earth.
Total life cycle
“When you start evaluating all these options, you have to do what they call a life cycle assessment,” said Graham Webb, the Chief Sustainability Officer for Pratt & Whitney. “You have to understand all the environmental implications from the time you tear the raw materials from the earth until you dispose of the product at the end of its life cycle.
“If you do those calculations, you should see that in the end, you’re doing better than what your alternatives are. In the case of lithium batteries, not all lithium is produced by strip mining. But China, in particular, is a very large supplier of lithium, which is the main means of extracting the mineral.
Webb said some companies, like Tesla, are talking about Texas putting a lithium refinery in a place that would allow them to have a little more vertical control over the entire economy. This includes the environmental implications of what they do with their batteries.
“But it’s a challenge and it’s really admitted that all of these, should we say ‘solutions,’ whether it’s lithium on the battery side, or we’re talking about hydrogen, require life cycle assessments,” said Webb. For hydrogen, he added, 95% or more of the hydrogen produced today is produced by steam reforming methane. The lifecycle assessment of these fuels is currently worse than the alternative, which is jet fuel kerosene.
Avoiding the life cycle
Most companies that talk about battery-powered planes, eVTOLs, or Air Mobility Aircraft (AAM) avoid talking about the extraction of chemicals. They don’t talk about recycling, let alone talk about complying with Federal Air Regulations. They also don’t talk about batteries that need to be replaced after 2,000 flights, and what you do with the batteries you take out.
Even all the companies that talk about this matter without talking about the life cycle easily ignore the facts of the life cycle.
Webb was more generous.
“It can have a little bit of ignorance as well. In some cases,” he said. that is, can we say no emissions, which I have heard some of them say. But in the end, it’s not just the batteries. Recharging the batteries from the grid. The grid is not always grainy, and in properties, there are emissions associated with recharging the batteries.
“They don’t always talk about the implications,” Webb said. “But really, people are becoming more aware of the implications and they’re passing that on to people to make sure they’re addressed as part of the overall equation of how these products come to market.”
Hydrogen is also not completely clean
Some point to hydrogen as a better alternative to batteries. In fact, as a fuel, it is easier to get the power needed for flight from hydrogen than from batteries. But there are significant challenges in integrating the design for a hydrogen-powered airplane. And the infrastructure, from production to fueling, is vast.
More to the point for green fuel advocates, hydrogen is not a panacea. Research is still needed to understand the effects of contrails released from hydrogen.
“When we start talking about contrails, contrails in terms of current theory are made from water vapor and the exhaust of gas turbine engines,” Webb said. “Kerosene has water, and it makes contrails we know that. Hydrogen has 250% more water vapor in its exhaust. If you start talking about something that has 250% that’s more water vapor, that’s where the concern arises. The other element where research needs to be done is how contrails form. That’s where the science is lacking.”
Webb continued, “How do you avoid the contrails, which some of our scientists have shown are equal to, if not worse than, the implications of carbon dioxide from aviation and climate impact? That’s where you see the test that Airbus will do in our competitor’s engine. They will go and find out if hydrogen creates contrails and what the mechanisms are to have a better understanding. Then, of course, that understanding will drive the avoidance or methods to prevent them from forming.”
Conclusion
Since air transportation is only two to three percent of the total problem, what air transportation does has a small impact on the climate. We hope that the intense focus and research done by aviation on the subject will benefit many sectors of society. Otherwise money and resources could be better invested in fields with a higher climate impact.
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