Itaconic acid (IA) is an unsaturated dicarbonic organic acid. It can easily be incorporated into polymers and may serve as a substitute for petrochemical-based acrylic or methacrylic acid. It is used at 1-5% as a co-monomer in resins and also in the manufacture of synthetic fibres, in coatings, adhesives, thickeners and binders. The favoured production process is fermentation of carbohydrates by fungi, with a current market volume of about 15,000 t/a. Due to the high price of about US$ 4/kg, the use of IA is restricted. At present, the production rates do not exceed 1 g l(-1) h(-1), accompanied by product concentrations of about 80 g l(-1). New biotechnology approaches, such as immobilisation techniques, screening programmes and genetic engineering, could lead to higher productivity. Also, the use of alternative substrates may reduce costs and thus open the market for new and increased applications.

There are numerous possibilities for replacing chemical techniques with biotechnological methods based on renewable resources. The potential of biotechnology (products, technologies, metabolic pathways) is for the most part well known. Often the costs are still the problem. Biotechnological advances have the best chances for replacing some fine chemicals. While the raw material costs are less of a consideration here, the environmental benefit is huge, as chemical-technical processes often produce a wide range of undesirable/harmful by-products or waste. In the case of bulk chemicals (<1 US dollar/kg) the product price is affected mainly by raw material costs. As long as fossil raw materials are still relatively inexpensive, alternatives based on renewable resources cannot establish themselves. Residues and waste, which are available even at no cost in some cases, are an exception. The introduction of new technologies for the efficient use of such raw materials is currently being promoted. The utilisation of residual wood, plant parts, waste fat, and crude glycerol, for example, provides great potential. For industrial chemicals (2-4 US dollars/kg), process and recovery costs play a greater role. Here, innovative production technologies and product recovery techniques (e.g. on-line product separation) can increase competitiveness.

This paper deals with a biorefi nery classifi cation approach developed within International Energy Agency (IEA) Bioenergy Task 42. Since production of transportation biofuels is seen as the driving force for future biorefi nery developments, a selection of the most interesting transportation biofuels until 2020 is based on their characteristics to be mixed with gasoline, diesel and natural gas, refl ecting the main advantage of using the already-existing infrastructure for easier market introduction.This classifi cation approach relies on four main features: (1) platforms; (2) products; (3) feedstock; and (4) processes. The platforms are the most important feature in this classifi cation approach: they are key intermediates between raw materials and fi nal products, and can be used to link different biorefi nery concepts. The adequate combination of these four features represents each individual biorefi nery system. The combination of individual biorefi nery systems, linked through their platforms, products or feedstocks, provides an overview of the most promising biorefi nery systems in a classifi cation network. According to the proposed approach, a biorefi nery is described by a standard format as 'platform(s) -products -and feedstock(s)'. Processes can be added to the description, if further specifi cation is required. Selected examples of biorefi nery classifi cation are provided; for example, (1) one platform (C6 sugars) biorefi nery for bioethanol and animal feed from starch crops (corn); and (2) four platforms (lignin/syngas, C5/C6 sugars) biorefi nery for synthetic liquid biofuels (Fischer-Tropsch diesel), bioethanol and animal feed from lignocellulosic crops (switchgrass).This classifi cation approach is fl exible as new subgroups can be added according to future developments in the biorefi nery area.

Biotechnologically produced itaconic acid (IA) is a promising organic acid with a wide range of applications and the potential to open up new application fields in the area of polymer chemistry, pharmacy, and agriculture. In this study, a systematic process optimization was performed with an own isolated strain of Aspergillus terreus and transferred from a 250-mL to a 15-L scale. An IA concentration of 86.2 g/L was achieved within 7 days with an overall productivity of 0.51 g/(L h), a maximum productivity of 1.2 g/(L h), and a yield of 86 mol%. A cultivation of other well-known A. terreus strains with the developed process showed no significant differences. Based on this, a process is developed providing a high final IA concentration independent of the used strain combined with high reproducibility.

The aim of this study was to optimize a biotechnological process for the production of 1,3-propanediol (1,3-PD) based on low-quality crude glycerol derived from biodiesel production. Clostridium butyricum AKR102a was used in fed-batch fermentations in 1-L and 200-L scale. The newly discovered strain is characterized by rapid growth, high product tolerance, and the ability to use crude glycerol at the lowest purity directly gained from a biodiesel plant side stream. Using pure glycerol, the strain AKR102 reached 93.7 g/L 1,3-PD with an overall productivity of 3.3 g/(L*h). With crude glycerol under the same conditions, 76.2 g/L 1,3-PD was produced with a productivity of 2.3 g/(L*h). These are among the best results published so far for natural producers. The scale up to 200 L was possible. Due to the simpler process design, only 61.5 g/L 1,3-PD could be reached with a productivity of 2.1 g/(L*h).