A two-decade engineering push has culminated in what is the world’s first production facility to sustainably manufacture medium-density fiberboard (MDF) from post-harvest rice straw waste that has no added formaldehyde. 

California law bans the burning of leftover rice stalks after harvest, so flooding fields and letting the stalks rot has been the only way to prepare for future planting. The CalPlant LLC facility on 276 acres in the Sacramento Valley now uses the waste to make Eureka MDF, a board that matches the performance of traditional wood and can be a component for furniture, cabinetry, doors and moldings. The company sources its rice straw from within an average 25-mile radius of the plant, providing a local benefit in both jobs and sustainability. The region produces 20% of the country’s rice.

Plant refines waste rice straw fibers to make medium-density fiberboard that performs like wood but without added formaldehyde.
Photo: Industrial Projects Consulting

German engineer Siempelkamp helped devise a hot press of 1,000 individual parts to refine the hollow stalks and produce MDF at a rate of 300 ft per minute. The straw bales, weighing on average 1,100 lb each, require the same machines as in a wood plant but with a different steam pressure in the refining process to fully saturate the 3-ft-tall hollow stalks and explode them into fiber bundles in about 15 seconds. 

The project required a four-year construction process that included a mandated 100-ft height reduction to the plant’s main tower. “It required a pretty significant redesign effort midway to reduce the height,” Larry Persinger, owner of Industrial Projects Consulting, told ENR in September.  

Jerry Uhland, CalPlant founder and president, also told ENR that the Eureka boards have performed in the marketplace on par or better than traditional MDF. While the plant has not yet reached full production and recently filed in federal court to financially restructure, its developer said it will continue to operate without disruption and has sufficient liquidity to meet obligations to vendors, customers and employees.