PLEASE USE SPARINGLY: HOW HYDROGEN CAN PRESERVE DWINDLING LITHIUM RESERVES
© Dan Lundberg, CC BY-SA 2.0
Battery plans depend on unobtanium
One of our favourite engineers is Gill Pratt, the Chief Scientist of Toyota. His impressive title is not the reason we listen to him, though. We listen because he has an unrivalled track-record of looking at conventional forecasts about automotive technology and figuring out which ones are right, and which ones require the industry to ignore inconvenient facts. In 2016, when Nissan, Ford, GM and Tesla were all predicting autonomous cars by 2020, Pratt stood out as a lone voice saying it was far more complex than people understood, and it could not be done in that time-frame, or anything like it.
His current focus is to how best to electrify vehicles. Now Toyota comes in for a bit of stick for keeping faith with hybrids and not being fully committing to battery-electric vehicles (BEVs). However, Toyota tartly points out that it will be making 3.5 million BEVs by 2030, which is more than the total production of many carmakers.
Gill Pratt’s point is that we face a shortage of lithium – or, rather, refined lithium. There is plenty of lithium in the ground, but mining it is difficult and dirty work (see previous blog for some figures on this). With the average lithium mine taking 16 years to get into production, it could be 2039 before a mine planned today starts supplying a battery factory. Toyota reckons that, in 2040, there may only be enough lithium to electrify one-third of the world’s car production.
Spread thinly for best results
If that is the case, the question is how to use the lithium we do have in the most effective way. To simplify Pratt’s model somewhat, if we have 100 petrol-powered cars and 100kWh of batteries, we can put those batteries into one Tesla-sized EV. In that case, we reduce tailpipe CO2 emissions by 1%. Alternatively, we can put them into 100 hybrids, reducing the tailpipe emissions of 100 cars by 10%.
If Pratt’s arguments have big implications for cars, they have even bigger ones for trucks. A 44-tonne truck is going to need at least a 600kWh battery pack, and truck makers don’t want to be battling with car makers for scarce supplies. If the problem is how to decarbonise trucks without running out of refined lithium, we need a zero-emissions solution that minimises the use of lithium.
How fuel cells can save batteries
The clear front-runner in that race is the fuel cell electric powertrain. Ironically, fuel cell vehicles are a type of hybrid: fuel cells are very efficient at generating energy at constant speeds, but are slow to respond when acceleration is needed. Hence fuel cell powertrains also have battery packs. While most designs use fuel cells as range-extenders to charge large battery packs (up to 140kWh), the Viritech solution is to use fuel cells to power the vehicle directly at a cruise, and small, fast discharge/fast recharge battery packs (20kWh – 30kWh) to supply power for acceleration.
By reducing the size of the battery pack by 95% compared to a battery-electric truck, the demand for lithium is thus hugely reduced. It is important to note that we are not anti-battery – we are not trying to get batteries out of the powertrain. We are simply trying to use batteries in the most efficient way.
As a powertrain director (who was responsible for a major BEV programme) told us, “Once you need much more than 50kWh of energy, you should really start looking for an alternative to batteries.” Hence small and medium-sized cars make perfect sense as BEVs, but the calculation becomes progressively less favourable as the vehicle size increases. By the time the size reaches 44-tonnes, there is barely any case to be made for BEVs.
Our goal is a fuel cell powertrain, with a battery pack of less than 40kWh, that can power any road-going vehicle. That way, we achieve zero-emissions, and we maintain demand for lithium at manageable levels.