The photo on the left shows a biomass fuel receiving pit (empty) for Gundersen Health System’s new biomass boiler and the photo on the far right shows the pit when it is partially full of woodchips. There are two of these pits that are used as temporary storage receptacles for biomass fuel. Each pit has a set of 4 scrapers located in the bottom. Each scraper has a hydraulic piston (center photo) that drives the scraper forward and backward. The scrapers also have a set of triangular-shaped wedges that push the wood chips over themselves as they are driven forward in the pit and then pull the woodchips toward the fuel conveyor at the back of the pit as they’re retracted. Once the woodchips are unloaded into the pit, human intervention is no longer required. Proximity sensors at the fuel conveyor signal the hydraulic pistons to engage when more fuel is needed. As the conveyor fills up with woodchips, the proximity sensor detects the level and shuts the pistons off until fuel is required again. Depending upon the time of year, between 20 and 60 tons of woodchip fuel will be used per day to power the biomass boiler which creates steam for Gundersen’s medical campus in La Crosse, Wisconsin.