Despite the high interest and rapid development of biomass-based fuels, it is not anticipated that oil-based fuels will be completely replaced by renewable fuels in a foreseeable future of 50 years [29]. Conventional refineries convert­ing crude oil to fuels, starting chemicals, and other products, therefore, will operate decades ahead. In the biorefinery literature it has been a common practice to compare conventional petroleum-based refineries with biorefiner­
ies [30,31], but to our knowledge a combination of the two refinery types has not previously been suggested. Integrating conventional and bio/catalytic refineries in the transition period from petroleum-based to biomass-based refineries might lead to several potential synergies with respect to processes, chemicals, and logistics.

Several process streams of intermediates, wastes, and heat from a conven­tional refinery might be utilized in a biorefinery (Fig. 6). Cooling water and some effluent water streams can be used as process water in the biorefinery. A conventional refinery has big volumes of low temperature energy, which could be exchanged and used as process energy in the biorefinery.

Products from the biorefinery can be used as input for various conven­tional refinery processes. As discussed elsewhere in this book, ethanol is mainly used as a blending component in gasoline products. Integrating the two refineries will improve the logistics of this mixed fuel production.

Hydrogen produced from fermentation processes of the biorefinery can for instance be used in the traditional hydrogenation processes of a conventional refinery. Methane produced in the biorefinery can be used as fuel gas, but also as a raw material for further catalytic reforming, producing more hydro­gen. It could also be used for production of H2/CO (synthetic gas), which is a feed gas for gas-to-liquids or methanol production. Introducing catalytic steps between the two refineries might further enhance the beneficial coup­ling since the hydrocarbon output from catalytic conversion of methane and ethanol might serve as a substrate for further refining and modification in the conventional refinery process streams.

Heat waste streams

Ethano

Fig.6 Combination of bio/catalytic refinery and petroleum-based refinery. cat indicates chemical catalytic conversion

5

Conclusion

In this chapter we have shown the potential of producing more than bioethanol out of biomass raw material. While carbohydrates will be the precursor for ethanol production, the rest of the biomass can be used for production of other fuels. By this integration the net energy production will increase and the CO2 reduction will be higher than in biorefineries with­out the integration. Furthermore, reuse of water and nutrient will allow for a more sustainable process with much lower environmental impact on the ecosystem.