Conversion of Organic Waste to Value-added Products

Abstract

Canada is committed to reducing its greenhouse gas (GHG) emissions to mitigate the effects of global warming. A major source of GHG emissions is coal-based power generation. Replacing (fossil) coal with biomass-based feedstocks for the generation of electricity could help reduce these emissions. Another source of GHG emissions is landfills, as the most common method for disposing waste currently is landfilling. Landfilling organic wastes is being phased out in many jurisdictions because many associated problems. The main focus of this research is to assess the utilization pathways of different organic wastes and by-products available for the production of value-added products. Specifically the focus is on the use of black liquor (a by-product of the forest industry), yard waste, agricultural waste, manure, and algae. Several thermo-chemical conversion processes – wet and dry torrefaction, gasification, and combustion – are evaluated. Process models have been developed for conversion pathways. These process models have been further used for to develop techno-economic models for estimating the production cost of the value-added products. Finally, net energy ratio and life cycle GHG emissions are estimated. It was found that the production costs of ammonia from black liquor and of bio-coal from yard waste, woodchips, wheat straw, grape pomace, and manure can compete with the market price of fossil-based ammonia and coal in Alberta. The information developed in this study can be used for investment decision making and policy formulation.