ABSTRACT
Rural bioreneries offer an alternative to traditional ethanol production by providing the opportunity to produce fuel on site to reduce costs associated with biomass transportation thus making the fuel economically viable. Widespread installation of rural bioreneries could lead to increased uptake of biofuels and could help meet biofuel standards in the upcoming years. Unfortunately, even with reduced transportation costs at a rural biorenery, biofuel is still not competitive with traditional gasoline fuel due to high processing costs and inefcient processes. Various technologies and processes that are available for conversion of biomass to biofuels and bioproducts can be grouped under two platforms, namely syngas and sugar. Under the syngas platform, the biomass is rst thermochemically converted to syngas (which is primarily a mixture
CONTENTS
8.1 Introduction .......................................................................................................................... 155 8.2 Feedstocks ............................................................................................................................ 156 8.3 Ethanol .................................................................................................................................. 157
8.3.1 Economics................................................................................................................. 158 8.3.2 By-Products .............................................................................................................. 158 8.3.3 Challenges................................................................................................................. 158
8.4 Anaerobic Digestion ............................................................................................................. 159 8.4.1 Biogas Cleanup ......................................................................................................... 160 8.4.2 Challenges................................................................................................................. 160
8.5 Integrating Anaerobic Digestion of Wastes into a Biochemical Rural Biorenery ............. 161 8.6 Conclusion ............................................................................................................................ 164 References ...................................................................................................................................... 164
of carbon monoxide and hydrogen) at high temperatures. The syngas is a precursor for the production of fuels and chemicals using catalytic processes. In the sugar platform, the polysaccharides in biomass are rst saccharied to sugars by employing a combination of chemical, thermal, and enzymatic pretreatments. The sugars are then biochemically converted to fuels and chemicals using microbial biocatalysts. Biochemical options in industrial use require expensive pretreatment and hydrolysis costs that drive up nal prices and that are not feasible in a rural setting. This chapter aims to identify biochemical options that can be employed in a rural locale and still produce an economically viable biofuel product.
