Metals Tech

Last week, a company called B2U Storage Solutions announced that it had started operations at a 25 Megawatt-hour battery facility in California. On its own, that isn’t really news, as California is adding a lot of battery power. But in this case, the source of the batteries was unusual: Many of them had spent an earlier life powering electric vehicles.

The idea of repurposing electric vehicle batteries has been around for a while. To work in a car, the batteries need to be able to meet certain standards in terms of capacity and rate of discharge, but that performance declines with use. Even after a battery no longer meets the needs of a car, however, it can still store enough energy to be useful on the electric grid. So it was suggested that grid storage might be an intermediate destination between vehicles and recycling.

But there are some significant technical and economic challenges to implementing the idea. So we talked with B2U’s CEO, Freeman Hall, to find out why the company decided it was the right time to put the concept into action.

Supply and demand

While the idea may go back a while, implementing it required two things: a steady supply of end-of-life car batteries and a regular excess of cheap power to charge the batteries with. Hall said his company started with solar project installs in California and began to see what’s called the “duck curve,” where solar generation starts to occur in excess in the mid-afternoon. The growth of electric vehicles had also started to ensure there was a steady supply of high-quality batteries to store the power in. “We’re in the early days of the end-of-life EV batteries being available,” Hall said. “But there has been a steady stream of those batteries becoming available.”

Even after heavy usage in cars, the batteries can often hold a significant amount of charge. And, by working with battery OEMs, B2U is getting access to a number of batteries that never spent much time in cars. “They do have some powertrain warranty dynamics where they’re replacing batteries that didn’t meet certain promise specs, and there have been some pack replacement programs for some of the early vehicles like the Leaf,” Hall said. “There are R&D batteries that are out there, they’re going to use for R&D and then becoming available. There are other sort of industry growing pains where you get some batteries that are produced that don’t quite meet specs for automotive use that can still be used for stationary storage.”

The result is a growing collection of batteries that can still hold roughly 65-85 percent of their original capacity but can no longer provide the performance expected for automotive use. While the performance will continue to degrade over time, grid-level power storage doesn’t require the rapid charge or discharge behavior that puts the most stress on the battery’s capacity. So the company expects to get significant use from them before they’re sent on for recycling. “These batteries work very well,” Hall told Ars. “They’re engineered for very demanding use cases, and the use case in stationary storage is far less demanding.”

Come as you are

To save on costs, B2U is using the batteries as intact packs, rather than breaking out the cells and installing them in a new housing. To do so, it has had to build a translation layer that sits between the software that manages the storage facility and the battery management system on the battery. This layer serves several purposes. It controls the battery’s charging and discharging and helps monitor the health of individual batteries, flagging situations where there are potential problems that can affect future performance.

The company is very cautious about how its software responds to any issues. “We’re setting ‘guard rails,’ if you will, that are fairly conservative,” Hall said. “Those are set far inside even the sort of nameplate specs that the OEMs provide. If anything was to ever get to our guard rails, we just shut down the batteries automatically.”

The translation layer also ensures that the general commands issued by the facility-control software get translated into the specific commands needed by batteries from different manufacturers. The California facility is using batteries built for Honda and Nissan vehicles, and B2U says it has tested its software on batteries made for GM and Tesla as well.

Understanding how a battery’s capacity has declined is essential for the facility’s operation. Hall said that, during charging, the company’s software has to recognize when an individual pack has reached its capacity and tell it to disconnect at that point to allow the stronger batteries to continue charging. Conversely, the system must handle batteries with differing amounts of capacity as the system discharges, allowing those that have emptied their capacity to drop out even as the facility as a whole continues to discharge.

All of that has to be handled seamlessly so that the 1,300 individual battery packs, all with distinct performance characteristics, look like a single unit from the grid’s perspective. Right now, the company is primarily focused on storing power generated by solar panels (the battery is located at a solar facility) and selling it in the evening as the Sun is setting.

Even second lives end

While grid-level storage can handle lower performance than cars, performance declines will eventually drop these batteries below the levels that make using them practical. Hall said the company is already working to ensure that end-of-life for the battery doesn’t mean end-of-life for the materials they contain. “We’re definitely working with OEMs and with the recyclers to make sure that that life-cycle management activity is handled properly,” he said. “Reuse needs to be fitting hand in glove with the recycling so that it’s all handled very effectively.”

Beyond that, the company expects that battery availability will only grow and is looking at expanding wherever solar is popular. Right now, that means it’s focused on California and Texas, but Hall doesn’t expect it to stay that way: “Solar is the cheapest form of energy in just about all 50 states, and you’re going to see the storage follow behind it.”

Ecobat, the global leader in battery recycling, is building its third lithium-ion battery recycling facility and its first in North America.

The new facility, located in Casa Grande, Arizona, will initially produce 10,000 estimated tonnes of recycled material per year, with plans to expand capacity to satisfy the increasing need to recycle lithium-ion batteries.

“We are thrilled to grow our global lithium-ion battery recycling footprint with a new facility in Casa Grande, Arizona,” CEO Marcus Randolph said in a media release.

“This facility, like our lithium-ion battery recycling facilities in Germany and the United Kingdom, represents a significant milestone in Ecobat’s strategy to grow our lithium-ion battery recycling business to a scale, similar to our world-leading lead battery recycling business,” he added.

Ecobat Casa Grande will repurpose lithium-ion batteries reaching end-of-life through diagnostics, sorting, shredding and material separation to produce a concentrated black mass containing the valuable materials in lithium-ion batteries.

It will be located approximately 1.6 km from the existing Ecobat Resources Arizona facility, which has been using state-of-the-art technology and a skilled workforce for 15 years to manufacture anodes. Start-up is expected in the third quarter of this year.

Earlier this month, Ecobat completed the sale of its Stolberg multi-metals processing plant in Germany to global commodities trader Trafigura.

DES MOINES, Iowa — Saturday is National Battery Day and this holiday weekend, plenty of people across Iowa are relying on their car batteries to drive to Des Moines for the state wrestling tournament or some other vacation. It’s important they take care of their battery so they don’t get stuck along the way.

Josh Reasoner, the General Manager at Batteries Plus in Des Moines, said though most car batteries fail during the winter months, they actually take the brunt of their wear and tear during summer.

He said heat affects the acidity of the car battery causing it to expand on the inside. That leads to it draining quicker. It’s important people check their batteries for corrosion during the summer months.

Reasoner said during the winter months, car owners should get their batteries tested. It’s also a good idea to turn the car completely off, not just the gas, when idling. People who don’t drive often should also take their car out for a spin every once in a while because the battery drains even when a car sits in the garage.

“If you’re using it like sparingly, you want to make sure you drive it once or twice a week definitely to make sure that battery is not just draining,” he said. “There’s something called a parasitic drain on car batteries and what that is, even when your car’s not being used, it’s connected to lights, all the electronics in your cars so those will start to wear on the batteries even when you’re not using them.”

Reasoner said car batteries last on average three to five years. In the Midwest, their lifespan tends to be on the lower end of that spectrum since they deal with all four seasons.

He also recommends everyone have jumper cables in their car in case their battery dies.

Researchers at Carnegie Mellon University have manufactured a copper-based flexible material that works as the interface between electronic chips and their cooling systems.

So far and despite advancements in cooling solutions, the interface between both layers has remained a barrier for thermal transport due to their components’ intrinsic roughness. This has implications for electronic devices when it comes to overheating and burning out.

The new solution, however, is composed of two thin copper films with a graphene-coated copper nanowire array sandwiched in between, which makes it safer and more reliable.

“Other nanowires need to be in-situ grown where the heat is designed to be dissipated so that their application threshold and the cost is high,” Rui Cheng, a postdoctoral researcher working on the new development, said in a media statement. “Our film isn’t dependent on any substrate, it is a free-standing film that can be cut to any size or shape to fill the gap between various electrical components.”

The “sandwich” builds out of lead researcher Sheng Shen’s supersolder, a thermal interface material (TIM) that can be used similarly to conventional solders, but with twice the thermal conductance of current state-of-the-art TIMs.

By coating the “supersolder” in graphene, Shen’s team enhanced its thermal transport capabilities and prevented the risk of oxidation, ensuring a longer service life. The “sandwich,” compared to the thermal pastes/adhesives currently on the market, can reduce thermal resistance by more than 90% when considering the same thickness.

Thanks to its ultra-high mechanical flexibility, the new material can also enable a wide range of applications in flexible electronics and microelectronics, including flexible LEDs and lasers for lighting and display, wearable sensors for communication, implantable electronics for monitoring health and imaging, and soft robotics

Moving forward, Shen’s team plans to explore ways to scale the material at an industrial level and lower its cost.

“We are very excited about this material’s potential,” Shen said. “We believe that a wide variety of electronic systems can benefit from it by allowing them to operate at a lower temperature with higher performance.”

For many years wind power, solar power, tidal power and many other sustainable solutions to electricity generation have been in place. But, what about harvesting the energy of human traffic on city streets and other environments?

Research published in the International Journal of Biomechatronics and Biomedical Robotics demonstrates how the energy of footfall from people simply going about their business on the streets, in shopping malls, the workplace, and elsewhere might be harvested to generate electricity without affecting how people walk on the surface nor being too costly to implement or maintain.

Dazzle Johnson, Mikhael Sayat, and Kean Aw of the Department of Mechanical and Mechatronics Engineering at the University of Auckland in Auckland, New Zealand, describe a pavement energy harvester.

The system can convert the pressure of footfall from human traffic on the pavement even though the vertical displacement is a mere 1.5 millimeters, which would be hardly noticeable to pedestrians walking on such as surface. That tiny movement of the ground beneath one’s feet would not affect one’s gait but with each footstep can generate 164 milliwatts of electricity across a 27-ohm load resistor. If someone jumps on to the power pavement area almost a Watt is generated (833 mW).

If we imagine a network of power pavement with millions of footsteps every hour in a busy shopping center, for instance, then the power generated would quickly add up to usable amounts that could be buffered by charging up embedded batteries and used to power lighting or power outlets. The team is currently testing the prototype system and will work to develop connected harvesters. They need to determine how much vertical displacement each slab might be capable of to generate more power without affecting the way people walk on the surface.

As carbon dioxide continues to build up in the Earth’s atmosphere, research teams around the world have spent years seeking ways to remove the gas efficiently from the air. Meanwhile, the world’s number one “sink” for carbon dioxide from the atmosphere is the ocean, which soaks up some 30% to 40% of all of the gas produced by human activities.

Recently, the possibility of removing carbon dioxide directly from ocean water has emerged as another promising possibility for mitigating CO2 emissions, one that could potentially someday even lead to overall net negative emissions. But, like air capture systems, the idea has not yet led to any widespread use, though there are a few companies attempting to enter this area.

Now, a team of researchers at MIT says they may have found the key to a truly efficient and inexpensive removal mechanism. The findings were reported this week in the journal Energy & Environmental Science, in a paper by MIT professors T. Alan Hatton and Kripa Varanasi, postdoc Seoni Kim, and graduate students Michael Nitzsche, Simon Rufer, and Jack Lake.

The existing methods for removing carbon dioxide from seawater apply a voltage across a stack of membranes to acidify a feed stream by water splitting. This converts bicarbonates in the water to molecules of CO2, which can then be removed under vacuum. Hatton, who is the Ralph Landau Professor of Chemical Engineering, notes that the membranes are expensive, and chemicals are required to drive the overall electrode reactions at either end of the stack, adding further to the expense and complexity of the processes. “We wanted to avoid the need for introducing chemicals to the anode and cathode half cells and to avoid the use of membranes if at all possible” he says.

The team came up with a reversible process consisting of membrane-free electrochemical cells. Reactive electrodes are used to release protons to the seawater fed to the cells, driving the release of the dissolved carbon dioxide from the water. The process is cyclic: It first acidifies the water to convert dissolved inorganic bicarbonates to molecular carbon dioxide, which is collected as a gas under vacuum. Then, the water is fed to a second set of cells with a reversed voltage, to recover the protons and turn the acidic water back to alkaline before releasing it back to the sea. Periodically, the roles of the two cells are reversed once one set of electrodes is depleted of protons (during acidification) and the other has been regenerated during alkalization.

This removal of carbon dioxide and reinjection of alkaline water could slowly start to reverse, at least locally, the acidification of the oceans that has been caused by carbon dioxide buildup, which in turn has threatened coral reefs and shellfish, says Varanasi, a professor of mechanical engineering. The reinjection of alkaline water could be done through dispersed outlets or far offshore to avoid a local spike of alkalinity that could disrupt ecosystems, they say.

“We’re not going to be able to treat the entire planet’s emissions,” Varanasi says. But the reinjection might be done in some cases in places such as fish farms, which tend to acidify the water, so this could be a way of helping to counter that effect.

Once the carbon dioxide is removed from the water, it still needs to be disposed of, as with other carbon removal processes. For example, it can be buried in deep geologic formations under the sea floor, or it can be chemically converted into a compound like ethanol, which can be used as a transportation fuel, or into other specialty chemicals. “You can certainly consider using the captured CO2 as a feedstock for chemicals or materials production, but you’re not going to be able to use all of it as a feedstock,” says Hatton. “You’ll run out of markets for all the products you produce, so no matter what, a significant amount of the captured CO2 will need to be buried underground.”

Initially at least, the idea would be to couple such systems with existing or planned infrastructure that already processes seawater, such as desalination plants. “This system is scalable so that we could integrate it potentially into existing processes that are already processing ocean water or in contact with ocean water,” Varanasi says. There, the carbon dioxide removal could be a simple add-on to existing processes, which already return vast amounts of water to the sea, and it would not require consumables like chemical additives or membranes.

“With desalination plants, you’re already pumping all the water, so why not co-locate there?” Varanasi says. “A bunch of capital costs associated with the way you move the water, and the permitting, all that could already be taken care of.”

The system could also be implemented by ships that would process water as they travel, in order to help mitigate the significant contribution of ship traffic to overall emissions. There are already international mandates to lower shipping’s emissions, and “this could help shipping companies offset some of their emissions, and turn ships into ocean scrubbers,” Varanasi says.

The system could also be implemented at locations such as offshore drilling platforms, or at aquaculture farms. Eventually, it could lead to a deployment of free-standing carbon removal plants distributed globally.

The process could be more efficient than air-capture systems, Hatton says, because the concentration of carbon dioxide in seawater is more than 100 times greater than it is in air. In direct air-capture systems it is first necessary to capture and concentrate the gas before recovering it. “The oceans are large carbon sinks, however, so the capture step has already kind of been done for you,” he says. “There’s no capture step, only release.” That means the volumes of material that need to be handled are much smaller, potentially simplifying the whole process and reducing the footprint requirements.

The research is continuing, with one goal being to find an alternative to the present step that requires a vacuum to remove the separated carbon dioxide from the water. Another need is to identify operating strategies to prevent precipitation of minerals that can foul the electrodes in the alkalinization cell, an inherent issue that reduces the overall efficiency in all reported approaches. Hatton notes that significant progress has been made on these issues, but that it is still too early to report on them. The team expects that the system could be ready for a practical demonstration project within about two years.

“The carbon dioxide problem is the defining problem of our life, of our existence,” Varanasi says. “So clearly, we need all the help we can get.”