Battery technology has been consistently improving for decades, making possible the shift to EV cars. Tesla’s North American Model S Long Range Plus now has an official range of 402 miles. At the low end EVs have ranges >250 miles. And every year they get a little better. At some point improving battery capacity will translate into smaller and cheaper batteries rather than just increased range. I wonder what that point will be. In other words, if you could have a car with a range anywhere from 500 miles to 5,000 miles, what would you pay for? Where is the optimal cost vs benefit?
Batteries are also increasingly a good idea for grid storage. Batteries have a lot of features that make them desirable for grid-level storage. They have good energy and power density, and can provide as-needed (dispatchable) energy almost instantly. You don’t need to ramp up a turbine – the energy is just there. They have great round-trip efficiency (rivaled only by pumped hydro), meaning little energy is lost in the storage and supply of energy. They maintain their energy for a long enough time (they have slow self-discharge). They also have decent lifespans – charge-discharge cycles.
There are already battery grid storage facilities with 100-300 megawatt capacity, with more in the works, including a 409 megawatt system in South Florida. It is now cheaper for some utility companies to build a battery storage facility to add dispatchable capacity then to build a natural gas powered plant. There are other methods of grid storage, but batteries have had an increasing share of storage capacity over the last decade. But anytime one technology scales up by orders of magnitude, we may run into resource and infrastructure limitations. At some point we are going to stress our supplies of lithium, for example. As we radically change our energy infrastructure, therefore, we need to plan for a sustainable system. That means we need to think about what happens to batteries throughout their lifespan.
Lithium-ion batteries, the current state-of-the-art for batteries, do have a limited lifespan, which really means that they lose energy capacity over charge-discharge cycles. How much depends on a lot of variables, but the good thing about grid storage is that it’s easy to optimize their life. It’s not like driving a car, where need and utility may trump optimizing battery life. Well-managed grid storage could more easily extend battery life. For example, when optimized lithium-ion batteries maintain 74% of their energy capacity even after 14,000 cycles. That would be one cycle a day for over 38 years. The batteries are not done at this point, they just have reduced (but still usable) capacity.
Reduced energy capacity means more for cars than grid storage – for cars, capacity translates into range. As the number of EV vehicles rapidly grow , that will result in the need for millions of high capacity batteries. Let’s say these batteries have a typical usable lifespan (for a car) of about 10 years. At that point they are still at around 80% of their original capacity (depending on how well the driver takes care of their battery). These used car batteries can then be repurposed for grid storage, where they will have decades more of useful life.
Such a system would put off the problem of what to do with spent lithium-ion batteries potentially for decades. Even still, now is a good time to build into this new infrastructure the ability to deal with these spent batteries, so they don’t just end up in land fills. This is where recycling comes in. Right now less than 5% of lithium-ion batteries are recycled. This includes all those cellphone and laptop batteries, which is currently more of an issue than car batteries. Building the infrastructure to recycle all those smaller batteries will prepare us for the oncoming spent car battery avalanche. Fortunately, the technology already exists to recycle these batteries. We just need to make it standard procedure.
Volkswagen, for example, has a new recycling plant in Salzgitter, Germany:
“As a result of the recycling process, many different materials are recovered. As a first step we focus on cathode metals like cobalt, nickel, lithium and manganese. Dismantled parts of the battery systems such as aluminium and copper are given into established recycling streams.”
This will make the lithium-ion battery industry more sustainable. You can even recycle some of the waste from the battery production process itself. While this is currently possible, it is a labor-intensive and somewhat dangerous process. Robotic automation, however, could allow for scaling it up.
Also keep in mind, the industry does not need to be sustainable forever, just long enough until the next technology comes along. If we can keep the lithium-ion battery technology going for another 30-40 years, by then we will likely have other options. Supercapacitor technology is developing nicely, and other chemical batteries, like salt-based batteries or ones based on iron. Developing a battery that uses extremely abundant raw materials, even if energy density or other features are not as good, may be ideal for grid storage.
Even conservatively extrapolating out current technology, batteries and related storage devices should continue to get better and meet all our needs as we transition to a future with renewable energy and electric vehicles.
Article: What Happens to Old Batteries?