Abstract

Over the last century the world has depended on the oil industry to provide the greatest majority of the raw material necessary for the production of chemical products, textiles, pharmaceuticals, and fuels. Countries with no oil reserves have the necessity to seek new cleaner and sustainable technologies to fulfill its requirements. Lignocellulosic biomass has the potential to replace oil as the raw material to produce chemicals and fuels under a biorefinery concept. To develop this new concept of industry, BioEnercel, a Chilean Consortium was created to design a strategy to obtain sugars and lignin from wood as raw materials for the production of fuels and high-value products: Bioethanol or bio-oil production from sugars fermentation, and generation of biomaterials from lignin. This strategy includes a pilot plant design and operation. The plant was designed to handle a variety of feedstocks; the process stages are batch to optimize each step individually and the process as a whole. It also considers a wide range of operation options for process flexibility. The equipment includes a wood digester for biomass pretreatment, a disc refiner, a high consistency horizontal mixer (pre-hydrolyzer) and a hydrolyzer for the enzymatic hydrolysis, a fermenter and a distillation column. Pre-hydrolyzer, hydrolyzer and fermenter are combined with a filter press to adjust the operation to a simultaneous saccharification and fermentation process or to a separate hydrolysis and fermentation process. Additionally, all the complimentary equipment is in place for this pilot plant to successfully mimic a biorefinery. This work shows a pilot plant experience using hardwood (eucalyptus wood) to obtain ethanol using autohydrolysis pretreatment and simultaneous saccharification and fermentation with high solids loads. Preliminary results of the wood-to-ethanol process evaluated in the pilot plant showed 73% yield base on the initial cellulose present in the wood converted into ethanol compared to 79% obtained at bench scale. These promising results were used to assess a preliminary technical-economic evaluation considering the production of ethanol from the sugars and electricity from the solid residue. For a base value of US$ 74 per dry ton of wood and an estimated selling price of ethanol and electricity of US$ 770/m3 and 100 US$/MWh, respectively, the net present value reaches US$ 112 million, the internal return rate 14% and the payback time 5.7 years.