UC Riverside has completed a pilot facility that processes forestry and agricultural waste into pulp for use in textiles and other fiber-based consumer products. The project, led by associate research professor Charles Cai, features a two-story system using CELF (co-solvent enhanced lignocellulosic fractionation), a patented method designed to be cleaner and more energy-efficient than conventional kraft pulping.
“It’s cleaner, milder, and uses less energy than traditional kraft pulping,” said Cai, who also invented the process. “It doesn’t compete with lumber because it can transform substandard wood waste into an on-spec high-value pulp product.”
The pulp produced at the UC Riverside facility meets standards for textile-grade dissolving pulp, commonly used to make fabrics such as rayon and lyocell. Sustainable fashion brands including Patagonia and Lululemon use lyocell for sportswear and undergarments.
CELF operates at lower temperatures and pressures compared to kraft mills. It uses about half the energy of traditional systems by processing low-quality biomass like forest debris or agricultural trimmings—materials that are typically burned or left to decompose, which can contribute to air pollution.
The CELF method avoids generating “black liquor,” a toxic byproduct associated with kraft pulping that poses risks to air and water environments. Instead, it produces non-toxic dissolving pulp alongside purified lignin, fermentable sugars, and gypsum. Lignin extracted through this process is used in products such as bio-polyurethane foam insulation panels for homes; gypsum can be used in drywall manufacturing.
“Lignin is a natural polymer found in the cell walls of plants that is cleanly extracted by our pilot system to make bio-polyurethane foam panels for home insulation, among other biopolymer products,” Cai said.
The facility began operation recently by processing wood debris from California forests cleared under state wildfire prevention efforts. Its first client is The Hurd Co., based in Santa Monica, which is evaluating CELF technology’s potential to turn almond orchard waste into high-grade dissolving pulp suitable for making lyocell activewear. The Hurd Co.’s equipment donations helped finish building the pilot plant after federal grant funding was suspended during the Trump administration.
UC Riverside aims to license CELF technology through agreements with additional companies interested in producing biomass-based fibers. Because CELF systems can operate on a smaller scale than standard mills, they could allow distributed production closer to sources of waste—such as farms or forest management sites—enabling growers or agencies to process their own material onsite.
Cai noted that this initiative seeks not to introduce new fibers but rather improve how existing materials are manufactured: “We’re not introducing a new textile fiber. We’re using a cleaner and cheaper process to make the same dissolving pulp—but from what used to be waste,” he said.
“In most cases, we’re also solving a waste problem,” Cai added. “We’re turning what would be a landfill or burn pile liability into something valuable—and doing it in a way that avoids the environmental costs of black liquor processing or deforestation.”
