One of the most popular “future tech” topics I see discussed in comments here on CleanTechnica is “vehicle-to-grid” (aka V2G or “EV-to-grid”) technology. I think dozens if not hundreds of people have predicted here that this is the future.
People pushing the concept are not just “armchair experts” either — numerous research teams at prestigious universities around the world and some large automakers are exploring the possibility.
However, there has been a lot of criticism of the idea. Like wireless EV charging, whether or not this is the future has been one of those continuous cleantech debates that creates a divide between people who see the industry evolving into this futuristic tech versus skeptics who focus on the issues that hinder practical application in the electricity market.
Tesla CTO JB Straubel is one of the most respected battery experts on the planet, and a few weeks ago we shared an interesting video of him talking about batteries in which he touched on the topic late in the 36-minute video. His statements echoed what he has said previously (I think at the 2016 Tesla Shareholder Meeting), which I was already planning to write about, so I’m happy I can now highlight this video as a useful reference for future discussions.
V2G & smart charging: Notably, the summary is that JB makes the case that it doesn’t make economic sense for EVs to send electricity back to the grid, but that “dynamic charging” (aka “smart charging”) of EVs at times convenient to the grid is coming. (Note: I would characterise sending electricity back to the grid from an EV as V2G, but smart charging also often gets lumped in with the concept. Given the differences in viability, I would propose keeping “smart charging”/”dynamic charging” and “V2G” as separate concepts.)
Reusing EV batteries for grid storage: Just before discussing V2G tech, JB explained why another popular topic also isn’t as great as it sounds — using old EV batteries for grid storage — and this is one that I’ve actually promoted a little bit as logical/practical, so it’s perhaps even more useful to highlight this critique for readers here. On the face of it, a common assumption among cleantech enthusiasts is that EV batteries that have already completed their useful purpose in a car would be super cheap but still useful for grid storage. JB and the Tesla team seemingly thought so as well, as JB indicates they’ve looked into the matter a number of times. However, what they found is that this also doesn’t make as much sense as many people think. (Basically, the best thing to do with old EV batteries is seemingly to just recycle them and use most of the materials in new batteries.)
JB’s critical statements on these topics (which, for me, shut down arguments for both V2G and reuse of EV batteries for grid storage) are in response to a question that starts at 23:20 into this video. I’m transcribing JB’s answers in the next two sections for those who prefer to read or who want to reference the specific quotes later on.
Vehicle To Grid — Nope
If you want to jump straight to JB’s answer on reuse of EV batteries for grid storage, it begins at 25:50 in. Here’s the core bit via text:
“To your second question, about using vehicles as a buffer for renewable energy, this is definitely something that’s coming, and I think there’s two ways to implement this.
“The first is to use dynamic charging. This is essentially intelligently commanding when the vehicles absorb their energy from the grid, you know, to match up with when you have renewable energy available or cheap. You know, this is something we can do very easily with just essentially software and controls — we don’t have to change any hardware, and there’s no additional regulatory or certification work needed. It’s just essentially controlling the timing of when something otherwise would happen.
“If we want to actually send energy back from the car to the electricity grid, this gets much more complex, and, you know, that’s something that I don’t see being a very economic or viable solution — perhaps ever, but certainly not in the near term. You know, the additional wear and tear and degradation on your vehicle battery has a fairly high cost, and many of the people and small businesses looking at this today, you know, don’t take into account fully that degradation cost, and also the additional interconnection cost, because if you interconnect your vehicle, you do have regulations that play a part — it has to interconnect in the same way that a solar system would on someone’s home or on a business, which have different standards so that they can protect line operators and people on the grid.”
Yikes — no vehicle-to-grid magic, then. However, it’s great to see his comments about dynamic charging, which is an exciting concept that I’m eager to see implemented widely.
Used EV Batteries For Grid Storage — Nope
If you want to jump straight to JB’s answer on reuse of EV batteries for grid storage, it begins at 24:11 in. Here’s the core bit via text:
“We’ve looked at reuse or kind of the second life of automotive batteries for grid applications very closely, and you know, ultimately, every time we’ve studied this we’ve come to the conclusion that it’s not a very economical or very good use of those assets.
“You know, by the time they come out of a vehicle that’s lived its life, the technology will be quite old. We expect 10 maybe 15 year life at a minimum from these batteries. And, you know, the degradation is not entirely linear. By the end of their life, the efficiency has degraded on every cycle, you see lower efficiency, the capacity will have somewhat degraded, and for a lot of reasons, it makes it very difficult to deploy those efficiently back into a grid setting, where you want high reliability and you do want predictability.
“So, my view is that we’ll see new batteries dedicated to that market, that also have slightly different characteristics — they should have higher cycle life. In an electric vehicle that has 200+ miles of range, you don’t need as many cycles as you do on a battery that’s designed to charge and discharge every single day on the grid. There’s perhaps a factor of about 4 or 5 difference in the cycle life — so that’s one aspect.”
Here’s the full video if you want to watch it all:
Does this mean the discussion is closed on these topics? I’m sure not. I expect to see people debating the pros and cons of these options for many years to come. However, I’m definitely inclined to accept JB’s analysis of the tech, so V2G and reusing EV batteries for grid storage are now dead-in-the-water ideas to me.