In literature, various types of biorefineries are dealt with (IEA Bioenergy, 2010), viz.:

• Green Biorefineries (GB), using ‘nature-wet’ biomass such as green grass, alfalfa, clover or immature cereals.

• Whole Crop Biorefineries (WCB), using raw materials such as cereals or maize.

• Lignocellulosic Feedstock Biorefineries (LCFB), using ‘nature-dry’ raw materials such as lignocellulose containing biomass and residues, including the more technology and/or main intermediate based concepts:

— Thermo-chemical Biorefineries (TCB)/Syngas Platform (SG)

— Bio Chemical Biorefineries (BCB)/Sugar Platform (SG)

— Two Platform Concept Biorefineries (TPCB)

— Forest Based Biorefineries (FBB)

• Marine Biorefineries (MB), using micro — or macro-algae (seaweeds), including:

— Micro Algae Biorefineries (MAB)

— Seaweeds (macro algae) Biorefineries (SB).

IEA Bioenergy Task 42 developed a more general classification system, better describing raw materials used, main intermediates (platforms) produced (a measure for the complexity of the biorefinery concept dealt with), and final products delivered.

The background for the proposed biorefinery classification system is the current main driver in biorefinery development, i. e. efficient and cost-effective production of transportation biofuels, to increase the biofuel share in transportation sector, whereas for the co-produced bio-based products additional economic and environmental benefits are gained. The classification system is based on a schematic representation of full biomass to end products value chains, distinguishing: raw materials, primary conversion processes, main biomass constituents (carbohydrates, lignin, proteins, fats, etc.), secondary conversion processes, platform intermediates, conversion processes and end products (see Fig. 21.1).

The platforms (e. g. C5/C6 sugars, syngas, biogas, bio-oil) are intermediates which are able to connect different biorefinery systems and their processes. The number of involved platforms is an indication of the system complexity of the biorefinery facility/concept. The two biorefinery product groups are energy (e. g. bioethanol, biodiesel, synthetic biofuels, power and heat) and products (e. g. chemicals, materials, food and feed). The two main feedstock groups are ‘energy crops’ from agriculture (e. g. starch crops, short rotation forestry) and ‘biomass residues’ from agriculture, forestry, trade and industry (e. g. straw, bark, wood chips from forest residues, used cooking oils, waste streams from biomass processing).

In the classification system, four main conversion processes are differentiated, including: biochemical (e. g. fermentation, enzymatic conversion), thermo-chemical (e. g. gasification, pyrolysis), chemical (e. g. acid hydrolysis, synthesis, esterification) and mechanical processes (e. g. fractionation, pressing, size reduction).

The biorefinery processes/concepts can be classified as:

A <specific platforms concerned> platform biorefinery for the production of final products produced> from <name raw materials used>.

Some examples of classifications are:

• A C6 sugar platform biorefinery for the production of bioethanol and animal feed from starch crops.

• A syngas platform biorefinery for the production of FT-diesel and phenols from straw.

• A C6 and C5 sugars and syngas platform biorefinery for the production of bioethanol, FT-diesel and furfural from saw mill residues.