VALPARAISO — In 2020, Luke Ventrsom and Peter Krenzke placed a couple makeshift batteries on a shelf at Valparaiso University, where the two serve as professors and researchers in the mechanical engineering department. Three years later, they pulled the batteries and were still able to release their energy.
These weren't ordinary batteries, however. They were charged using solar energy.
Solar energy has been around for a long time, but there are major roadblocks to implementing it on a mass scale to fulfill the needs of our technologically advanced and high-energy incumbent society. One of those roadblocks has been storage — how to store the energy so it can be used at night or on cloudy days.
Researchers have only been able to figure out how to do this on a large scale for up to eight to 12 hours, Venstrom said. That's why he and Krenzke believe they've made a breakthrough — storing energy for three years and releasing it with virtually no loss.
"The idea is to store up excess solar energy," he said. "There is more than enough solar energy in the summertime in a place like Northwest Indiana to meet all the energy needs in the summer and the winter, when we don't have as much sunlight. The only challenge is that we don't right now have a way to store it and release it in the winter when we need it. That's the challenge we're trying to solve."
Venstrom and Kenzke, who have undertaken other projects with concentrated solar, hope this battery can solve this issue.
To create it, they heated up a block of a special material called metal oxide to about 1,400 degrees Fahrenheit using a giant solar furnace they have on campus, Venstrom explained.
That solar furnace consists of an array of mirrors that channels sunlight and heat onto one concentrated object, in this case, metal oxide. However, the researchers needed the metal oxide to be heated evenly.
"I sometimes think of it like trying to heat up egg in a microwave," he said. "A frozen egg patty heats terribly in a microwave. The inside always stays frozen and it tends to heat from the outside in. It's the same idea."
Venstrom said they had turn the material into a sand-like powder while they processed it and had to rotate it so the powder got mixed up and heated evenly. To achieve this, they created a rotating reactor under the solar furnace.
"Think of it like a cement truck, but it doesn't spin quite as fast. But it's up, and the open end of the cement truck has concentrated light in it."
They inserted the powder into one end of the reactor. Because of the heat from the solar furnace, when it emerged from the reactor, it came out really hot. They then turned it back into a solid block.
Three years later, they were still able to access that heat, which can be used to create electricity the same way it would've if it had been harnessed from the sun that day.
"We chose three years," Venstrom said, "but I think if we would've kept this thing sitting there for 10 years, it would've had the same result."
While he's extremely excited about the breakthrough, Venstrom cautioned that they haven't yet come close to creating a workable model that can be implemented on a large scale to truly solve this storage dilemma.
"We have demonstrated that it is technically feasible," he said. "It is technically possible. The question now is, can we make it happen at a cost that is low enough to be interesting in the marketplace? And that's the next question. That's really where we're at now."
One key aspect to that challenge, for example, is the fact that there are many types of metal oxide, and they want to identify which is the best for this purpose.
"We've demonstrated that it's technically possible with a couple of candidates," he said, "but which one is going to be the lowest cost?"
Venstrom said two candidates seem most promising: iron oxide, which is really inexpensive but wasn't one they included in their original experiment, meaning they'll have to ensure it works the same way as the others; and cobalt oxide, which they proved was a really effective battery but is pricier.
Venstrom believes that within the next two to three years, they'll begin constructing models of what it would actually cost to build these systems to scale in hopes that a company might be interested in taking it to market.
Venstrom and Krenzke aren't the only ones working on this issue, though. Euronews reports that a group of Swedish scientists at Chalmers University of Technology in Gothenberg have created a system in a lab that can reportedly store energy for 18 years.
Additionally, a group of researchers from Michigan State University and Arizona State University have received a $2 million grant from the U.S. Department of Energy to tackle this problem, according to the MSU news bureau.
"This is the next big thing in energy storage," Venstrom said. "We have figured out how to do short-term energy storage up to six, eight, maybe even 12. As soon as you start talking about storing energy up and releasing it a week later, a month later, six months later, a year or two later, nobody has any idea how we're going to do that cost-effectively.
"Lots of potential solutions exist. No one knows what the lowest-cost option is going to be. We think our little metal oxide material has a lot of promise, but we have a lot of work to do."
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