Most biorefineries have the capability to produce biofuels as well as high value chemicals. An important question that is obviously expected to arise in this context is, whether a biorefinery should be energy oriented or product oriented. A hybrid biorefinery or, as it is more commonly called, an integrated biorefinery, which can produce both category products efficiently, and has the capability of switching over to alternative feedstocks as and when required, is the answer to this question. An integrated biorefinery employs various combinations of feedstocks and con­version technologies to produce a variety of products with a main focus on pro­ducing biofuels. Thus an integrated biorefinery would involve the integration of all the above-mentioned biorefineries with respect to feedstock used and biomass conversion processes employed, in order to get maximum benefits from the bi­orefinery concept. The World’s first integrated biorefinery project was launched in October 2003 as a joint effort between the U. S. Department of Energy’s National Renewable Energy Laboratory (NREL) and Du Pont. Since then, a large number of such integrated biorefineries, at various stages of development, and operating with a variety of feedstock, yielding a range of products, have been successfully set up globally. Table 1.12 gives a list of integrated biorefineries operating in the US [54]. There are other such biorefineries being set up in the UK [55] and other parts of the world, which progressively incorporate state-of-the-art biomass conversion technologies and produce biofuels and other products in an effort to reduce GHG emissions and provide for a viable alternative to the fossil fuels.

For an integrated biorefinery to become a reality, it should be cost-effective. The logistics of feedstock availability, its generation and utilization will need to be very carefully planned for the purpose. Simultaneously, the bioconversion pro­cesses will also have to be integrated in a manner that is technically and eco­nomically feasible. The U. S. Department of Energy—Energy Efficiency and Renewable Energy has proposed a comprehensive outline for such a project (Fig. 1.30).