The concept of ‘biorefining’ has emerged over many decades, more recently stimulated by the drive for sustainability. The underlying aspiration is that renewable feedstock can be processed to partially replace the non-renewable fossil fuels that currently provide the bulk of our energy and chemicals. Of course, ‘biorefining’ is not new, as the exploitation of biomass for food, fuel and materials precedes the industrial revolution.

In the modern context there have been numerous attempts to define and describe the complex nature of biorefining. The International Energy Agency’s Bioenergy Task 42 has agreed that ‘Biorefinery is the sustainable processing of biomass into a spectrum of marketable products (food, feed, materials and chemicals) and energy (fuels, power and heat)’. Hence, the term ‘biorefinery’ is loosely defined, and can refer to a process, a plant, clusters of facilities, or a concept. Indeed, biorefining can range from the simple modification of biomass for use ‘as is’ in the production of materials, through to the complex extraction of molecular components followed by their bioconversion into higher value chemicals and fuels.

The biorefining industry is beset with many socio-economic and envi­ronmental challenges. At the time of writing, biorefining is dominated by the global production of ethanol from grain and sugar. The consequent exploitation of food-grade feedstock has stimulated an on-going debate regarding food vs. fuel. Additional arguments concerning the use of land for producing non-food feedstock are developing around the issue of indirect land use change. A further challenge to successful biorefining is the requirement to operate at scales and efficiencies which are both economically viable and environmentally sustainable. However, whilst biorefining approaches are often sought to produce environmentally beneficial products that replace current fossil-derived materials, they are competing with well — established products which have a number of key economic advantages. Fossil-derived products are relatively cheap, usually commodities, and serve mature global markets that have developed alongside the petrochemical industry over the last century. In contrast, the biorefinery industry is relatively new, undergoing rapid change as it develops, and requires the application and integration of a wide range of highly specialist disciplines, from the biosciences through to advanced chemical and process engineering.

The aim of Advances in biorefineries is to provide a comprehensive and systematic reference on the advanced processes used for biomass recovery and conversion in biorefineries. The volume comprises contributions from internationally recognised experts who have reviewed the latest developments in the area of biorefining, and is divided into two parts:

• Part I, ‘Development and optimisation of biorefining processes’, contains 12 substantial chapters. The first chapter introduces the concept of green chemistry with reference to exploitation of waste streams. This is followed by several chapters considering economic and environmental impacts and sustainability. The remainder of Part I assesses recent developments and optimisation strategies for key unit processes (including biomass pretreatment, catalytic conversion, enzyme development and separation technologies) and a range of biorefinery models.

• Part II, ‘Biofuels and other added value products from biorefineries’ comprises 14 chapters which concentrate on the creation and optimisation of products from biorefineries. Highlighting the diversity of products that can be created from biomass, these chapters provide up-to-date knowledge across a variety of outputs from the improvement of liquid biofuels in internal combustion engines, and the production of platform chemicals, proteins, lipids and carbohydrates through to the creation of high value and specialist products, including adhesives, films and coatings and bio-based nutraceuticals.

Keith Waldron