An emerging energy storage technology could soon have an unexpected ally thanks to research at Montana State University: the pulp left over from processing sugarbeets into sugar.
Backed by a $1.7 million grant from the U.S. Department of Energy, a team of scientists will study how the byproduct of the starchy root crop can be refined into cellulose nanocrystals that shows promise for improving how heat is captured and recycled in a variety of industrial settings. The project also includes two federal labs and North Dakota State University, with MSU receiving $353,000 of the funding.
“This is a totally new application of cellulose nanocrystals,” said Dilpreet Bajwa, professor in the Department of Mechanical and Industrial Engineering in MSU’s Norm Asbjornson College of Engineering, who is leading the MSU effort.
Bajwa, an expert in the tiny, extremely hard particles derived from breaking down biomass, previously found that the nanocrystals significantly increase the efficiency of certain salts used to absorb and store heat. The salts, which melt when heated, can store much more heat per a given volume than materials like water. They are commonly used in power plants that concentrate the sun’s rays to generate heat that can then spin electricity-generating turbines. They also have a range of potential applications in other industries, including saltwater desalinization and oil production, according to Bajwa.
“A lot of industry produces so much heat that’s lost, so finding a low-cost way to store and reuse it could have a lot of benefit,” Bajwa said. “What we’ve found is that if you add even a relatively small amount of cellulose nanocrystals to the salt, it improves the efficiency significantly, by almost a third.”
The heat-storing salts also have a crystalline structure, which tends to break down over the course of heating and cooling cycles, reducing efficiency. It’s thought that the nanocrystals may act like a scaffold that helps prevent that, Bajwa noted. “We think there’s some kind of unique chemical bonding structure that’s happening, but we don’t know what it is. That’s what we want to find out.”
The MSU team, which includes Daniel Blake, a first-year doctoral student in MSU’s interdisciplinary materials science program, will start by analyzing how typical cellulose nanocrystals derived from wood interact with various solutions of the heat-storing salts. Collaborators at North Dakota State University will then measure how the nanocrystal-enhanced solutions perform.
“It’s exciting to be working on a project that has such a practical application and could have such a widespread impact,” said Blake, who said the project aligns with his longtime interest in energy sustainability.
In a second phase of the project, the tests will be repeated after the MSU researchers explore methods for creating the cellulose nanocrystals from sugar beets. Typically, making the tiny particles involves subjecting woody material to intense heat and chemicals to break down the cell walls, but extracting sugar from sugar beets may preemptively aid that process, Bajwa said.
The material is abundant. In 2020, Montana ranked sixth in the nation for sugarbeet production, with farmers producing 1.2 million tons of sugarbeets valued at $42.5 million, according to the USDA.
“There’s a lot of mulchy pulp left over from sugar processing that right now has very little value,” Bajwa said.
Researchers at Idaho National Laboratory will focus on a study of how the nanocrystals improve the durability of the salt over the course of heating cycles. Oak Ridge National Laboratory will compare the performance of the nanocrystal-enhanced salts to other methods of heat and energy storage.
“We’re optimistic that we can help solve one of the weaknesses of existing salt-based energy storage technologies,” Bajwa said, “and also open the door for a high-value byproduct for the sugarbeet industry.”