TERU Focus Report - Bioenergy Facility Tour

Woody Biomass to Energy Field Tour, November 17, 2010: Big, Small & Tiny 
November 20, 2010 -- Michael Theroux

Orchestrated by the Center for Forestry, University of California Berkeley, 30 plus people boarded a bus in Lincoln and got a chance to see a variety of facilities up close that convert woody biomass into combined heat and power (CHP). Nominal buy-in included lunch; the rest was sponsored by the California Association of Resource Conservation and Development (RC&D) Councils, UC Berkeley Cooperative Extension, USDA Forest Service State and Private Forestry, Central Sacramento Valley RC&D and the California Biomass Collaborative. Representatives from each organization and agency participated, making for informative side-bar discussions.

The tour started at the Sierra Pacific Industries (SPI) sawmill in Lincoln, with a thorough guided exploration of the saw mill and the direct biomass combustion cogeneration facility. Our tour guide explained that the SPI Lincoln mill is one of the most diverse and busiest lumber mills right now in the US, taking in vast amounts of pine, cedar and fir (no redwood) and turning out every shape and size of lumber “sticks”, from 1” x 4” slats to massive support beams. 20-foot piles of fine sawdust dry in the sun between the mill works and the co-gen operations. Four-story tall stacks of logs are kept wet to reduce splitting by spraying with water that is reclaimed and continuously recycled in a closed loop flow. The operation of the plant requires 6 to 7 megawatts of electricity (MWe), about one third of the 20 MWe continuously generated on-site through direct combustion of biomass feedstock. Daily economics dictate whether to use site sawdust for bioenergy or ship north for sale to pulp and paper mills. At tour time, 90% of the fuel comes from regional agriculture, purchased by SPI at about $36 per bone dry ton (bdt) and coming into the plant at “field moisture” of 30% to 50%, about a truck an hour. Unlike most California bioenergy facilities, SPI Lincoln uses little urban wood waste, perhaps one truck a day. Heat from the biomass combustion makes steam, which drives an Alstom turbine and an ABB generator. The entire operation is constantly monitored electronically for emissions, with all data sent directly to the Air Pollution Control District.

Mid-day, we visited the converted metal ag-products storage building on the Wallace Ranch in Woodland that now houses the Woodland Biomass Research Center, home of West Biofuels since 2007. The sub-commercial scale research and development systems are now in “Phase II - Pilot-Plant Demonstration”. The systems were shut down for tar removal at the time of the tour, and everything smelled faintly of “Liquid Smoke”. Standing perhaps 30’ tall were a pair of inter-connected retorts, a reformer and a regenerator. The reformer circulates super-heated sand to heat biomass to drive off combustible synthetic gas. The second regenerator uses the carbon char from the reformer as fuel to re-heat the sand. Since the syngas is produced without air or oxygen, it contains very little nitrogen (abut 4% NOx), and is rich in hydrogen, usually around 25%. The current testing phase runs the syngas from the 75 bdt fluidized bed dual allothermic (no air) steam gasification system into an internal combustion engine, producing around 3 MWe from wood chips. West Bioenergy plans to later test various locally sourced feedstocks, primarily wheat and rice straw, grass straw, tomato residues, grape pumice, and urban green waste. In the long-term, coproduction of food and fuel is envisioned. Research will then shift focus to use of the Fischer/Tropsch process to catalytically convert the syngas to liquid fuels.

The afternoon found us on the west side of Davis near Winters, motoring through the organic walnut orchard to the Dixon Ridge Farms walnut processing facilities. There, tall stacks of walnut shells await conversion to heat. The well-packaged biomass gasification system developed by Community Power Corporation (CPC) out of Colorado sits at one end of an impressively large open-span metal warehouse. This is CPC's mid-sized

biopower unit, the 50 kilowatt (kWe) “BioMax 50”. Producer gas from the gasifier primarily replaces the use of propane in the processing plant for product drying, and to run an off-the-grid adsorption chiller for product cold storage. The equipment is fully automated and computer monitored; CPC can watch and adjust operations at any time. CPC’s website shows that the demonstration unit has over 18,000 run-time hours, with over 14,000 hours producing electricity and an additional 4,000-plus run for strict heat production, summing to better than 1,266,000 kilowatt hours (kWhrs). Dixon Ridge Farms hope in the future to increase the number of modules, eventually producing all of the heat they need and an excess of electricity for sale. CPC is also working on conversion of their syngas to liquid fuels, which could replace diesel for the farm’s equipment.

Representatives from each site provided detailed information on each technology and responding to all of our questions. Special kudos go to Rob Williams (UC Davis), John Shelly and Gareth Mayhead (UC Berkeley) for their planning and facilitation of the tour. The UC Berkeley Center for Forestry’s next event is a Woody Biomass to Energy Workshop, scheduled for December 2, 2010 in Ukiah, Mendocino County; registration is now open through the Center’s website.