**Preface to "Pretreatment and Bioconversion of Crop Residues"**

Crop residues are exceptionally important as an alternative to raw materials for producing energy carriers, chemicals, and new materials in a post-petroleum scenario. Next-generation bioconversion processes in future biorefineries will make possible to convert biomass components into most of the products that are produced today from fossil feedstocks, as well as to not-yet-developed products that will become basic commodities for the future society. Crop residues are a realistic feedstock option for biorefineries considering their large availability, low cost, and renewable nature.

A basic process step in biorefineries is the pretreatment, which is directed to separate biomass resources into their main components and to activate cellulose towards enzymatic saccharification. Biomass constituents are then converted into different kinds of value-added products following a concept that is analogous to the way that today's petroleum refineries produce fuels and products from petroleum.

Pretreatment research is today a hot issue, attracting attention not only from the academia, but also from the industrial sector, which looks forward to implementing the most promising methods in commercial-scale biorefineries. Pretreatment effectiveness is feedstock-dependent, and new research is required to develop efficient methods for different materials. This book covers some of the latest advances in research in developing efficient pretreatment methods and bioconversion approaches to be applied to crop residues of different nature.

The materials published in this book were written by experts in the pretreatment and bioconversion fields. I am confident that that reading the book will serve as a source of inspiration to scientists and entrepreneurs interested in making next-generation biorefineries of crop residues a commercial reality.

> **Carlos Mart´ın** *Editor*
