Battery-electric flight: Is lithium nirvana?
There are many reasons for electric flight. But the strongest argument is environmental. Which means that batteries need to be sustainable.
The vast majority of electric aircraft are relying on lithium-ion – batteries. Lithium has to be extracted from the earth and processed around the globe. This raises some questions over the element’s validity as a sustainable solution. How carbon intensive is lithium to extract, manufacture and eventually recycle?
Joe Biden’s Inflation Reduction Act (IRA) has poised the US lithium market for growth. This is good news on the surface for the largely US and Europe-based electric aviation industry.
Lithium prices are already high and expected to go higher still. Following over a decade of decline, volume-weighted average prices for lithium-ion battery packs have increased 7% in 2022 to $151/kWh. Sales of electric vehicles (EV) have increased over 98% in the past decade, with compound annual growth predicted at 23.1% through to 2030.
Estimates on the earth’s lithium reserves vary from 14m tonnes to 95m tonnes. And it is finite. Methods of extraction (or mining) of lithium from ore, such as spodumene, also vary in their carbon intensiveness. From a mining perspective at present output levels in the so-called lithium triangle – made up of Argentina, Chile, and Bolivia containing about half the world’s known lithium – the process is about as sustainable (and cheap) as it gets, according to Sam Jaffe, vice president, Battery Storage Solutions, E Source.
“Mostly it is coming out of the salt brines in South America and the main source for extracting the energy is solar,” he tells Revolution.Aero. “The problem is we will begin to hit the ceilings on what can be extracted from those brines, which means a lot more hard rock mining.”
Hard rock mining, is a harder process. Ore is dug up in Australia, shipped to China, where it is roasted at over 1000degC, mixed with sulphuric acid and roasted again. The product of the exothermic reaction then needs to get to battery makers. “It is produced under very carbon intensive processes. Over the next five to 10 years I think there is a question about energy usage, pollution in production and carbon consumption,” says Jaffe.
China, which holds around 25% of global reserves, processed and refined 65% of the world’s lithium, according to Norwegian research firm, Rystad Energy.
Those international networks are about to get a lot more complicated, according to Jaffe. The recent IRA Bill offers a $7,500 tax credit for EV buyers, however the amount you get is staggered according to the origin of the materials. Lithium mined in Australia and processed in China would receive a lesser tax credit than lithium mined in Australia and shipped to the US for processing. “In the next couple of years this whole new infrastructure around the technicalities of the IRA Bill are going to start to play out,” says Jaffe.
Jeffrey Belt, PhD, Battery Technical Fellow, Electric Power Systems, agrees that lithium can become a bottleneck for electrification in the automotive, heavy truck, boat, and aircraft (fixed wing and EVTOL) industries as production increases. Belt estimates around 7.5kg of lithium will be required per DA-40 (the system EPS is producing for Diamond’s electric aircraft). “Electric aviation cells will need more power capability (specific power-W/kg) than automotive based cells and be packaged to contain thermal runaway,” says Belt.
The other big issue is recycling. So far, that has not been an issue because the batteries largely have not reached the end of their life cycle. “The cars are still on the road that were made 10 years ago and 15 years ago we didn’t make electric cars,” says Jaffe. “We are just starting that recycling process with the first cars.” E Source ran a UK-based project to see how much will be recycled and how much lithium will be recovered from lithium-ion batteries. By 2032, the firm says 17% of global lithium for batteries will come from recycled batteries.
Redwood Materials, a company started by JB Straubel (the founding chief technical officer of Tesla) is doing this. The reason Straubel left Tesla in 2019 is because he had no good answer for what to do with battery packs when they reach the end of their lifecycle. Redwood is able to reclaim up to 99% of raw materials from the dead battery, in effect creating a circular economy where the recycled battery is sold back to the end user.
There are lithium mines opening in the US, in Nevada in particular, but the work of firms like Redwood Materials, Princeton NuEnergy and Ascend Elements begin to create a self-sustaining domestic feedstock. Good news for eVTOL OEMs looking for end of life cycle solutions.
Cyrus Sigari, co-founder, UP Partners, said at our Revolution.Aero 2022 conference in September: “[Redwood] It solves one of the big issues that the United States has, which is getting access to raw materials. So, the way we talk about SAF, where you need to go get the feedstock of pig fat, human waste or whatever it may be, you’ll start to see a very similar thing happen in battery technology, because of the scarcity of the materials.”