The Replacement of Oil Refineries
The fossil resources (petroleum, coal and natural gas) exploitation technology, the traditional oil refinery, is being questioned from the ecological and economic points of view due to the huge amounts of resources that consumes and the large waste flows that produces . In this sense, the Biorefinery concept represents the path towards the integrated systems technologies in which sustainable resources are used . Analogously to the common petroleum-based refineries, the Biorefinery aims to diversify a feedstock into several profitable products, but starting on the renewability, sustainability and availability that distinguish the biomass from oil.
Regarding the exploitation of biomass and oil, two major differences can be found. The main difference between biomass and petroleum feedstock lies on its composition, in terms of heterogeneity and oxygen content . Biomass contains from 10 to 45 % of oxygen, while petroleum has essentially none, making the chemical properties of biomass derived products very different from those obtained from petroleum. Furthermore, referring to the composition homogeneity, fossil resources present the advantage of being more or less fixed hydrocarbons mixtures, whereas biomass shows a very complex structure formed by different constituents. The second difference, highly dependent on the first one, concerns to the required transformation and products obtaining processes (Figure 5).
Initially, the biomass processing technology is similar to the petroleum one, since it must be first fractionated, i.e., separated in its main constituent components. However, as commented above, the biomass presents high heterogeneous composition, entailing more complex and consecutive separation and transformation stages than petroleum for its proper exploitation. The existing petroleum-based infrastructure and the optimized large-scale facilities  make it difficult for the biomass to compete with these well established products from an economic point of view.
Figure 5. The use of natural resources in oil and biomass-based refineries.
In this sense, for the substitution of petrochemical products by the new bioproducts, the Biorefinery technology should focus on the development of bio-sourced intermediate chemicals with an indirect replacement approach, that is, on generating products that would perform similar functions as the existing chemicals at a lower cost, or products with specific properties different from the oil-based products ones.