Born-Again Batteries: How ReJoule is Building a Circular Economy
This is the sixth blog post in our series on second-life batteries. This time we’re going to discuss how ReJoule is working to create a circular economy in which retired electric vehicle batteries can be used to store energy generated from renewable sources.
The lithium-ion batteries in electric vehicles (EVs) won’t last forever. Worldwide, six and a half million EVs were sold last year and the batteries in each of those will be retired one day. What if those decommissioned EV batteries could be used to power millions of homes, with energy generated from renewable sources?
ReJoule is planning ahead, creating the building blocks for a circular economy, so EV batteries can be repurposed, rather than prematurely recycled in a costly process that is itself one more source of pollution.
But what is meant by repurposing?
The idea is that the same battery that is no longer suitable to power an electric vehicle can be used again in another application, for example to store energy generated from renewable sources for years to come. But how? If the batteries are no longer suitable for transportation, what makes us think they can be employed in other applications?
The energy storage needs of a vehicle are quite different from those of, say, a building. A car requires extraordinary instantaneous power to accelerate. It is also subject to shock (think, potholes), vibration, and extreme weather. And then there is range anxiety. When a car sold to travel 240 miles can no longer go more than about 170, warranties begin to kick in, and those battery packs are replaced. While no longer suitable for transportation, the decommissioned battery may still have 70 percent or more of its remaining capacity. The demands of stationary storage are modest by comparison. A decommissioned EV battery can easily store the energy for a house. Put enough of them together, and they could power an entire city.
The management consulting firm McKinsey & Company put it this way in a report on repurposed batteries: “During the next few decades, the strong uptake of electric vehicles (EVs) will result in the availability of terawatt-hours of batteries that no longer meet the required specifications for usage in an EV.” They continue: “To put this in perspective, nations like the United States use a few terawatts of electricity over a full year.”
So why aren’t we repurposing all the batteries that have been retired from vehicles already?
One of the biggest challenges is grading them. If the state of health (SOH) of one battery module is 75%, it would be unsafe to pair it in a storage project with another whose state of health is, say, just 65%. The SOH of every module must be known before repurposing it. Which is where the roadblocks to repurposing begin to be evident. (Read more about the challenges with grading in our second blog here.)
The current state-of-the-art battery health assessment entails removing the pack from the vehicle and shipping it to a central location where highly trained technicians cycle it on expensive equipment for as long as ten hours. If the aim is to forge a vast, market-driven circular economy for EV batteries, the economic and environmental costs of this approach short-circuit the whole dream. Enter ReJoule.
How ReJoule is slashing the cost and complexity of battery diagnostics
Without the need for installing costly machinery, our patent-pending technology can assess a battery’s state of health in minutes, rather than hours. And using our technology requires far less training, opening up the possibility of expanding employment in the EV sector to those without higher education or extensive training. Best of all, the technology is portable. Rather than shipping a battery pack weighing half a ton or more to a central facility—possibly overseas—ReJoule’s technology can travel wherever batteries are found, slashing the greenhouse gas emissions and overall cost of the grading process while completely obviating the need for premature recycling of a battery with a decade or more of useful life remaining. We’ve already shipped our first few testers to customers. (They say it’s a good looking device 😉). Right now we’re working to build one that can test the state of a battery while it is still inside the vehicle, by connecting through a standard charging port.
To be sure, there are other challenges to overcome before we see a flourishing circular economy for EV batteries. But everything starts with diagnostics and analytics. For instance, who would warranty a used battery without any means of predicting how long it will last?
How ReJoule is working to demonstrate the viability of repurposing
Under an innovative California Energy Commission program, ReJoule was awarded a grant to couple retired EV batteries with solar at two commercial sites. One aim of the project is to show that energy generated from a renewable source can be stored in repurposed batteries, offering both 24 hours of resilience for critical loads in the case of a grid outage as well as significant savings on electricity.
Another goal is to explore pathways to reducing total installed cost versus new batteries by 30%. A third is to reduce annual capacity loss of the used battery storage to 3% or less. This can be achieved through technical enhancements or operational strategy.
As we embarked on this journey, we uncovered more challenges of the larger circular economy, from sourcing the batteries, to accurately and cost-effectively testing them in a novel process, to designing a safe and effective energy storage system and getting the whole project certified and permitted in the absence of clear regulations on the use of repurposed batteries. As you know, we have been actively documenting our learnings in our blog series. In our next blog, we’ll explore the planning for a particular project in which we will pair solar and repurposed batteries and help the host to establish a community cooling center.
They say the definition of a circle is a collection of points (a circumference) equidistant from one single point (the center). In the circular economy we’re helping to build for electric vehicle batteries, that center point is called grading. A cost-effective, convenient, and rapid way of knowing a battery’s state of health is a precondition to seeing all the points on the circumference. We’re helping to draw those too, as we’ll explore in future blogs.
Contact us at info@rejouleenergy.com if you want to leverage our technology to test your batteries. What are your thoughts? Did we leave anything out? Please comment and share so we can all engage in conversation and learn from each other.
Cheers,
The ReJouligans
Legal notice:
This document was prepared as a result of work sponsored by the California Energy Commission. It does not necessarily represent the views of the Energy Commission, its employees, or the State of California. Neither the Commission, the State of California, nor the Commission’s employees, contractors, or subcontractors makes any warranty, express or implied, or assumes any legal liability for the information in this document; nor does any party represent that the use of this information will not infringe upon privately owned rights. This document has not been approved or disapproved by the Commission, nor has the Commission passed upon the accuracy of the information in this document.©2021 ReJoule Incorporated. All Rights Reserved.
