How 8 Hours of Constant Explosions Can Help Make Concrete Carbon Neutral
National Renewable Energy Laboratory (NREL) Research Group Manager Dan Schell says he gets to do the fun part.
“I get to use a big piece of equipment and turn wood into very small particles with continuous explosions,” Schell said.
DTE Materials co-Founders Jose Urizar and Tanner Jolly pose next to their Stonefiber concrete blocks at the University of California–Davis Demo Hut grand opening. Photo from DTE Materials
Schell’s team conducts experiments like these to help DTE Materials, which has access to NREL expertise and equipment through the Shell GameChanger Accelerator Powered by NREL (GCxN) program. DTE’s patented process, called Clearwash, is designed to make anatomical changes to biomass to make it integrate with ceramic binders more effectively.
With NREL equipment, Schell is performing steam explosions repeatedly to test the feedstock from DTE Materials. They will run the equipment over an eight-hour day, followed by a second round of testing in about two weeks.
“What we are doing is operating the reactor in different conditions,” he said. “It’s going to produce material with different properties, and DTE will determine which conditions produce the best material for them.”
The explosions are well controlled and not hazardous, and Schell describes it as a release of pressure.
DTE Materials (DTE stands for "down to Earth") wants to create bioaggregates to mix in with cement for a new method that would yield carbon-neutral concrete. The feedstock is debris from agriculture and forestry. If that debris is left to degrade, it will naturally degrade the biogenic carbon back into carbon dioxide (CO2) in the atmosphere. By entombing it in the concrete, DTE Materials stops that process. Unprocessed biomass has multiple issues when introduced into cement that this steam process alleviates. Clearwash also standardizes the bioaggregates for performance because there is so much diversity across feedstock sources.
Stonefiber blocks are mass produced at a global manufacturing partner's facility. These blocks contain between 21% and 40% by volume bioaggregate depending on the end application. Photo from DTE Materials
“Over time that turns the biomass into a mineral,” said Tanner Jolly, chief technology officer for DTE Materials. “We’re replacing what concrete is traditionally made of. By entombing that carbon into cement, we’re trapping it there.”
The aggregates mixed with cement are traditionally made up of a specific type of sand that is not sourced from a beach or a desert. It often comes from a riverbed and is increasingly hard to find due to the unique shape created by this type of erosion that takes decades to complete. DTE Materials gets debris either directly from a sawmill or secondary processing sources. Currently, the startup is working with a wooden-pallet manufacturer, which brings its wood directly from the forest. DTE’s Clearwash process can tune to other agriculture feedstocks including rice husk, corn stover, sugarcane bagasse, and others depending on regional availability.
“The cement companies already buy their pallets from these companies,” Jolly said. “So, it’s a nice circular economy.”
DTE Materials hopes the data gleaned from the explosions will lead them to optimize their feedstock. NREL will also help perform a techno-economic analysis after the explosion testing is complete. The hope is that the costs will be less expensive than sand on a volumetric basis.
“We want to find the right conditions that produce the best material,” Jolly said. “There will be a sweet spot where everything is optimized in terms of performance, cost, and energy input.”
Jolly says the help from NREL and GCxN could speed up the company’s time to market by six to 12 months and save six figures in costs.
“If we were to do all these things in isolation, it would require working with three to four different groups and then piecing that together,” he said. “NREL also adds a source of validation for our investors and our strategic partners.”
Schell hopes the steam-explosion testing on DTE Materials’ feedstock will start in the near future.
“It’s rewarding to help new companies to try and commercialize technologies, and we hope they succeed,” Schell said. “That’s all I can really do is try and bring our expertise and knowledge and equipment to bear, and where we can facilitate their success, we can do that.”