Distributed Energy Resources, Energy Storage  -  May 23, 2022 - By Dr. Wolfgang Bauer, Michigan State University

Electric Vehicle Charging Infrastructure Needs a Fundamental Redesign

We Americans love our cars and trucks. They are an expression of individuality and freedom. But there is a price to pay for this love affair, monetarily, even geo-politically, but most importantly environmentally. In the USA we consume approximately 350 million gallons of gasoline and another 120 million gallons of diesel fuel per day. Combustion of these fuels generates 1.6 billion tons of carbon dioxide each year. This amounts to slightly more than one-quarter of the total carbon dioxide emissions of the country and is a very significant contribution to global warming.

Electrical vehicles (EVs) promise to reduce this greenhouse gas generation, but can only do so in a meaningful way if the electricity is not generated from burning fossil fuels.  Several attractive electric cars and even trucks are on the market now, with many more to come in the next few years.  Buyers are attracted by the much lower operating costs of these vehicles, as well as their potential to help the planet.

As of 2020, almost 1.8 million EVs were registered in the US, an increase of more than 200% over 2016. While these cars and trucks presently only amount to a small percentage of new vehicles purchased in the US, now is time to make plans for how to charge all these EVs once they become the dominant form of transportation. This will happen soon.  In the country of Norway, by the way, this future is here today, with EVs constituting three-quarters of new car sales in 2020.

The number of charging stations needs to increase by perhaps a factor of 100, but an even larger challenge is generating the additional electricity needed.  It will take a doubling of our electricity production to convert all vehicles on the road into EVs.  And the demand profile will not be flat, but likely be strongly peaked around lunch hour, during which truckers will want to recharge after perhaps 5 hours of driving.  Satisfying this demand will be close to impossible if we want to rely exclusively on renewables like solar and wind. 

What is the solution?  It is the same one that makers of cordless power tools have already embraced during the last decade: swappable batteries.  Nobody wants to wait for their cordless drill, sander, or saw to recharge for an hour. And therefore, the default solution is to purchase two or more battery packs, which can be snapped in and out of the tools easily. One of these can operate the tool, while another recharges. 

If we design cars and trucks to use batteries that can be exchanged easily and quickly with purpose-built robots, then we can charge batteries slowly outside the vehicles at a time when the renewable power sources produce electricity.  Slow charging also extends a battery’s life significantly compared to charging them with 350 kilo-Watt fast chargers.  And with swappable batteries, a recharging stop could take as little as a minute, a shorter time than that required to fill the tank of a diesel-rig. Compare this to the hour that it takes to recharge a large truck battery on the fastest charger available! 

A commercial vehicle that is forced into long waiting times for its battery to recharge constitutes dead capital during that time.  If this battery recharge is coupled to required rest periods for the vehicle’s driver, this is acceptable.  However, as we enter the era of self-driving cars, trucks, tractors, and buses, waiting for batteries to charge while forcing the entire vehicle to be not operational becomes more painful.  Currently, batteries constitute only a quarter or less of the overall investment in an electric vehicle.  Separating those from the rest of the vehicle thus improves the capital utilization significantly. 

This model of battery swapping would effectively mean that a vehicle’s owners do not need to own the batteries in their vehicle. They might only rent them. This is a model similar to the one that supplies propane to your backyard grill: you can own your tank and have it refilled at a gas station, or you can swap your empty tank for a full one at, for example, a home improvement store.  In our proposed model, you would simply pull into a recharging battery depot, have your batteries removed, get credit for the energy still left in them, have full batteries plugged into your vehicle, and you would be on your way again. 

Battery performance is increasing steadily at a rate of between 5% and 10% per year, and batteries are becoming progressively less expensive.  And therefore, EVs batteries could be gradually updated in range and performance as the years pass by, instead of being stuck with obsolete technology. Failing battery modules could be replaced easily instead of resulting in a very costly rebuild, as is the case now.  Battery recycling at the end of its useful life would be greatly simplified. Perhaps best of all, electric vehicle lifetimes would not be limited by their batteries anymore. 

Pickup trucks, like the Ford F-150 Lightning or the Chevrolet Silverado, are entering the market only now, and heavy-duty trucks to be used in 18-wheelers are next. Both vehicle types, as well as electric farm tractors or delivery trucks, would only require minimal redesign and reengineering to make this vision a reality.  The same goes for electric buses. But sedans and SUVs could also be designed to accommodate swappable batteries, albeit with different form factors. 

Yes, what I am proposing amounts to an entirely new multi-billion-dollar infrastructure, with depots of rechargeable batteries and their chargers, likely concentrated along the Interstate freeways.  Clearly, this constitutes a new business opportunity and a growth industry. At-home overnight charging would still be possible, just like before, and the existing networks of charging stations could still be used, too. But the vast time savings and convenience for long-distance travel, the end of range anxiety, as well as the enormous potential for reduction of stress on our electricity grid and the bridging of intermittency in renewable electrical power generation, make swappable car and truck batteries something we need to consider very seriously.

Dr. Wolfgang Bauer is a University Distinguished Professor at Michigan State University.  He has been a co-author of the university’s Energy Transition Plan, as well as the lead author of the university’s Mobility Plan. Dr. Bauer is a member of Smart Energy Decisions' Advisory Board.