Researchers in Alaska have been mimicking natural relationships between trees and fungi in hopes of creating a new material to keep Alaskans warm in the winter.
The technique produces a type of organic building insulation by encouraging the mycelium of a common Alaska fungus to pig out on the pulp of locally-harvested, dead spruce trees.
The project isn’t over, but the researchers say the data they’ve gathered so far look promising. Philippe Amstislavski, a materials scientist and public health professor at the University of Alaska Anchorage, said they hope to finalize a process Alaskans can recreate in-state on small or commercial scales as an alternative to shipping in materials that serve a similar function.
“If we can make this locally, that would be a big game changer,” he said.
In August, the team took apart some of the so-called “celium walls” they’d put up to see how their insulation is working. The researchers had installed the walls, with the experimental insulation, on a small test cabin tucked behind the National Renewable Energy Laboratory (NREL) in Fairbanks.
One section of the cabin’s wall has been lined with the wrinkly, sand-colored fungi-spruce board for nine years. On afternoon in early August, its time there came to an end, as lab staff yanked off some of the cabin’s siding and cut out chunks of the insulation with a razor. That particular wall will help demonstrate the material’s longevity – or lack thereof.
“There is no data on aging on these foamed materials, right? Because nobody has ever done it,” said Amstislavski, who’s partnering with the national energy lab on the project.
At Amstislavski’s feet sat a pile of dirt that used to look a lot like the board in the wall next to him. That represents another key part of the project: making a material that reduces waste.
“And this is what it looks like if you put it in the ground,” Amstislavski said. “You can see bugs are crawling through it, and it just turns to soil.”
Samples from the nearly decade-old insulation weren’t the only ones that headed back to the main facility for closer inspection. The researchers also have been testing out newer versions of the material, which now have sustained their first winter, according to Robbin Garber-Slaght, a mechanical engineer at the energy lab.
“Last summer, we made a bunch of these large-form boards in Fairbanks, and installed them in a wall – a test wall,” she said.
They put that up in October of last year. This August, the team disassembled sections of that wall, as well, loading the foam boards into the bed of a truck and bringing them back to the lab.
The experimental insulation is created through a process Amstislavski has been working on for years.
It all starts with an insect – the spruce beetle – which kills spruce by eating tissue the tree relies on to feed itself. The most recent outbreak of the beetle in Alaska began about a decade ago. Since then, it’s affected more than two million acres of forest, leaving behind swaths of dry, damaged, discolored spruce.
“Which is all over the state, and just kind of stands there dead, and it catches fire,” Garber-Slaght said.
But the dead trees can meet a less fiery fate at the hands of these scientists – and some day, maybe at the hands of local manufacturers. Through Amstislavski's process, spruce is converted to chips, pulped, foamed and served to hungry fungus in a controlled environment. The UAA and NREL researchers won’t say exactly which species, for intellectual property reasons, but Amstislavski said it’s a variety of shelf fungus that grows in and on the side of trees in Alaska.
“The term is biomimicry,” he said. “We are mimicking the same behavior we are observing in the forest in this process.”
After the dead tree mixture gets poured into molds, the fungus spreads its root-like structure through the woody foam for about five days. The end product is a firm, dried board, a couple inches thick, with the dense, white webby network of fungus running across and through it. The scientists hope these boards can be an alternative to plastic materials shipped into the state, like expanded polystyrene (EPS).
But before that can happen, they need to figure out whether the fungus-spruce combo can compete with its plastic counterpart. That’s where the tests come in.
For one, their material will have to show it can stave off mold. This winter, the research team collected data to help them determine if the test walls were wicking moisture well enough to at least be on par with EPS in that regard, if not better.
“In many buildings in Alaska, we have mold problems because the mold loves moisture, and when you have a wall that’s warm and humid inside, it’s perfect, it’s like a gigantic petri dish,” Amstislavski said.
He said they’re also tracking how well the technology keeps the cold out. That’s measured by something called an R-value, which rates how well a given material prevents heat from traveling through it. Amstislavski said a common R-value for EPS is 4. One of their new boards tested at 3.9.
“So we are one decimal away from EPS, but this material you could put in your garden, and it will decompose,” he said.
The $2.5 million U.S. Department of Energy grant that’s been funding the project runs out in January, and it isn’t being renewed. NREL Communications Lead Molly Rettig said by email Tuesday that the next phase they’re looking to fund is a pilot plant, but there are “no leads on that yet.”