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On the Cutting Edge of Vehicle to Grid

Using the energy in our car batteries to power our homes during emergencies and our electrical grid during times of peak usage has felt like the holy grail where electrical vehicles, renewable energy, and efficient buildings all intersect.

Using the energy in our car batteries to power our homes during emergencies and our electrical grid during times of peak usage has felt like the holy grail where electrical vehicles, renewable energy, and efficient buildings all intersect. In advance of a webinar my nonprofit is holding on this topic this week, I thought I’d ask one of the companies on the cutting edge of vehicle-to-grid (V2G) technology where things stand in this all-important sector. I interviewed Marc Trahand from Nuvve about their work with electric school buses and when he sees V2G coming to consumers in the US.

Forth: Marc, tell us about why Vehicle to Grid works well with electric school buses.

Marc Trahand: Nuvve’s focus in the US is to promote V2G technologies through electric school buses. This application of V2G is ideal and quite unique around the world. School buses are taking kids to school in the morning and bringing them back in the afternoon, and thus are parked for a long time. If you couple that with big batteries and big chargers (right now 60 kW and very soon 120 kW), it’s a huge amount of power and energy available to utilities. It’s like the ideal poster child for V2G. That’s been a focus here in the US, but Nuvve’s original foray in V2G was with normal, light-duty vehicles.  

Nuvve has been running V2G in Denmark for four years

Forth: Tell us about a day in the life of a typical school bus that would be used in a V2G program.

Marc: The driving patterns are really predictable with school buses. Driving is obviously the #1 purpose for these buses, so at any single time, we make sure that the batteries have the energy they need to drive. In the case of a school bus, when the drivers come in in the morning, they’ll have the vehicle precharged for the day. It might be 100% if the school bus is driving far that day, but it might not be 100% — there’s no need to overload a battery if it’s only going to do 20 miles that day. That school bus will probably be back in the depot at 10 in the morning and it can provide grid services from 10 am until around 2 pm when it’s going to go back out to bring kids home from school. Most of the buses are back at the depot by 4 or 5 pm, and at that point, it’s a matter of plugging the buses in, and then our software takes over automatically.  

Forth: Will the buses have enough energy when they return and plug in to help power the grid during peak times?

Marc: It really depends on what service you want to do. Sometimes you help push back energy to the grid through demand response and those markets are sometimes heavy on the energy requirements and you have to make sure your bus is pre-loaded for that. Another type of service where you don’t need much energy is frequency regulation, for example, where you make available a power capacity to the grid and you’re paid for that but it doesn’t necessarily use a lot of energy. Some of the batteries that provide that service — say, over the course of two hours — only vary 4 to 5 percent in actual state of charge. And you don’t know if it’s going to go up or down — you’re just following the frequency, you’re following orders from the grid operator on what they want you to provide.  

School buses as big batteries that can help districts save money and utilities balance peak loads.

Forth: Which services will V2G providers offer in the future?

Marc: It depends on where you are. In California, where the energy markets are not really open, it’s more behind-the-meter optimization, demand charges, and time of use. But you move over to other states — like in Delaware today we’re doing mostly frequency regulation because we can access the markets there. So, it really depends on the state, and sometimes even on the utility, what they want you to do and what they allow you to do.

We also work heavily on the regulation side to try to change the rules so we can access markets. Utilities are going to push back for sure. They don’t like this because they own or have stakes in power plants and don’t want competition. But bit by bit they’ll see the benefit of V2G. Different utilities have different levels of maturity on this as well. System operators also have a lot to benefit from V2G because we can provide a lot of value to them.

There are three levels where we can help. There’s at the parking lot level with buildings attached to it, then there’s the distribution where we can help with local peaks and help alleviate loads on certain transformers, and then there is system level, where we diminish the load during peak hours, push it back out, and do frequency regulation for operators. So, there are three real tiers there.

We think the big part is going to be at the utility distribution system, but it’s not the mature part yet. The mature parts are at the other ends, the meter side and the system operator side.

Forth: Where do you see electric school buses going in the future — do you see them adopting V2G on a mass scale?

Marc: Definitely, and we’re working to be able to provide complete packages for school districts. The package includes many things, including financing for a school bus. By working directly with the automaker and the utilities, the school bus can become a lease. These school buses are expensive, school districts are strapped for cash, and a new electric bus costs $300,000. If we can make school districts revenue from the grid by selling power back during periods of peak demand, that will help lower the cost of electrifying their bus fleets and would be ideal. We’re trying to bring the electric school bus to the same price as a diesel school bus, and if possible allow school districts to pay for them with monthly payments rather than a big cashout. So, the packages we’re putting together include the bus, the chargers, some support on installation, maintenance, and in some cases when working with the OEMs, we can package a financing option for the bus. The idea is to lower the cost for the community so they can access clean buses.

Forth: When you look in your crystal ball, do you see Vehicle to Grid as predominantly a fleet thing or do you see it as available to consumers?

Marc: Initially, we’ve started with fleets and light-duty vehicles. It’s what has made the most sense. You have one parking lot and put the wiring all over the place. Also, the first V2G chargers were really big, they weren’t suitable for installing at home, they were just too big, like 5 feet tall and 300 pounds and nobody wants that in their home. The new technology coming is much much smaller — we’re talking boxes on the wall that are going to be 20 pounds. So, when we get those in 2021, and we’re starting to do the first trials in Europe, we’ll be able to put them in people’s garages. There’s definitely a demand for this. However, a lot of homes in the US are single phase. If you put anything that’s more than 7 kW, you’re probably going to blow the fuses, so we have to be careful about what products we offer to consumers.

And the complimentary technology that goes with charging at home is workplace V2G. Ideally, when one uses an electric car, they’ll charge it at work, drive it home, and whatever energy they have left, they’ll push it back out into the house because that’s the peak of the evening. There will still be lots of energy left over in cars after arriving at home, and consumers will be able to use that for the grid and be compensated for it. Then, during the night, you’ll be able to use your car for other ancillary services and your car will make you money while it sits there.

What’s your response to the worry about battery degradation with Vehicle to Grid charging?

That’s a good question and one we get quite a lot. The key thing about battery degradation really revolves around the use cases. Lithium-ion batteries don’t like working at the top or bottom of the battery. When you’re in the middle of the battery, you can do fluctuations without really damaging the battery at all. We work closely with auto manufacturers to understand these parameters. The more information we can get from the battery, the better off we are — like battery temperature, maximum rate of charge, and discharge at any given time. Working upfront with automakers helps us deliver a better and safer vehicle to grid for the battery.  

We’ve also published studies. I published a study with Honda, for example, that showed that the biggest issues causing lithium-ion battery degradation were driving, regenerative braking, fast charging, and just regular aging, in that order. We gave them all the profiles we used for V2G. They put it through their accelerated degradation protocols and automatic simulations and they came back with a degradation of 2% over the 8 years the battery is under warranty. They told us that since V2G takes only 2% on top of the 10% degradation that they expect, that they’re fine with that and will cover the battery warranty even when you use it for V2G. We did that with Nissan, with Mitsubishi, with PSA in Europe, and they’re all coming back with the same answers that they’re okay to cover the warranty.  

And the chemistry is getting better and better. The Nissan Leafs we’ve been working with for 4–5 years have a battery that was designed years ago and is really archaic in today’s terms — it’s not even liquid cooled. So, when you look at the future batteries, we’re going to have cycling of batteries that are way way better.

Do you envision more automakers being willing to cover battery warranty with V2G charging?

Oh yeah. It’s the same with Blue Bird Buses on the heavy-duty side. Now, of course, they’re all a bit cautious, because they don’t know what they’re getting into. For some of them, it’s the first time they’re selling electric vehicles, so they’re cautious about everything. But they do see V2G as a way to lower the cost of electric vehicles, which will help them sell more vehicles.

What do you see as the trends in V2G in both the fleet and consumer side over the next 10 years?

V2G charging supported the grid during recent California blackouts

I think bit by bit this is going to become embedded in many different systems. What we’re seeing in our agreement with utilities in Europe is that they’re commercializing the V2G technology we’re providing. If you buy an EV and a charger from them, it’ll have V2G embedded in it, so these smart algorithms will end up being embedded in charging technologies. Nuvve will still be controlling some of these algorithms behind the scenes, but from the consumer side, it’s going to become a regular offering, probably coming most often from the utility. In some cases, it might come with the auto manufacturer. One of our investors, Toyota, is asking us to embed V2G algorithms directly in its vehicles, for example. Today, while we’re working hard to set up a lot of V2G demonstration projects, in the future, V2G will become embedded in charging systems whether it’s through an auto manufacturer or a utility.  

If you’re interested in learning more, join Forth for a webinar on V2G charging on Tuesday, October 20, as part of Oregon’s Sustainable Building Week.

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Written By

Joe lives in Portland, Oregon, and works for the nonprofit New Buildings Institute, which promotes electric and decarbonized buildings. He also volunteers with Electrify Now because he believes that electrifying everything, from transportation to homes, is the quickest path to an equitable, clean energy future. And of course, Joe and his family live in an all-electric home and drive an EV.


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