**Preface to "Selected Papers from 27th European Biomass Conference & Exhibition (EUBCE 2019)"**

Biomass is all around us. All living things are biomass, although we might prefer to limit our definition of biomass to plant matter that grows in forests, fields and water and can eventually be used for essential day-to-day products and bioenergy after appropriate conversion. Before the Industrial Revolution and the age of increasing fossil fuel use, there was a well-established bioeconomy and at the same time a relatively constant level of carbon dioxide in the Earth's atmosphere. Global warming that we know today had not begun. The needs of plant life to absorb carbon dioxide from the atmosphere for growth while emitting oxygen provided the environmental balance essential for maintaining a stable ecosystem for all life on our planet Earth. Nature itself has been performing carbon capture and storage for millennia. The life we humans choose to live has put severe strain on the fine carbon balance, and we now realize the urgency of redressing that balance to avoid an environmental disaster. The European Biomass Conference and Exhibition (EUBCE) addresses the many key questions as to how biomass should be used in a modern post-fossil fuel age. The EUBCE has for about 40 years been involved in scientific research both into biomass utilization for bioenergy and increasingly into the role of biomass in an emerging global bioeconomy. Over the last couple of decades, the conference has also included a view of the many large-scale biomass utilization projects to have emerged from earlier research, the challenges of technology scale-up and the adaptations made to achieve commercial viability. Use of woody biomass directly as a fuel for heating is long-established but clean and efficient technologies are still developing, particularly with respect to emissions to air. Biofuels have long been used, and in recent times new processes have received close attention, with large volumes now being produced in many countries. While biorefineries are not new, there are many exciting and very promising innovative processes capable of yielding a very wide range of biochemicals and biomaterials that can not only be used to replace fossil-derived equivalents but can also create new opportunities in our fast-developing world. The potential for biomass harvests is increasingly better understood, whether in managed forests or on land used for farming. Biomass crops can be grown on low-grade or contaminated soils where food crops are not favored. The aquatic world is also a source of biomass, particularly for algae, and particularly in contaminated waters, for example in over-fertilized agricultural regions. Residues from many processes, for example food production, and wastes are a key source of biomass feedstock for conversion processes. There are so many options and possible ways in which all the available biomass can be used. The main questions are how biomass should actually be treated in the modern bioeconomy, and if it is used as a feedstock, what are the best options for utilization. It would be very nice if all the possible options for biomass use could be listed in order of priority according to some simple rules, but this is simply not possible. There are far too many variables and far too many possible pathways from raw biomass to final product. However, substantial progress in narrowing down options has been made and many good technologies have been developed, some of which do work at industrial scale. Nevertheless, there are still questions about not only economic and technical viability, but also the wider environmental impacts of these processes over the long term. Political policy makers are in real need of sound technical guidance to build appropriate policy frameworks to ensure the success of the transition away from the fossil fuel era. There are sound pathways for biomass exploitation in the emerging modern bioeconomy. The editors of this book are keen to show some of the areas of research that are contributing to the emergence of this bioeconomy. The book contains a small selection of reports from a range of projects designed to push forward the knowledge base supporting sustainable biomass use in the bioeconomy. The contents of all the papers presented here are derived from projects presented and discussed at the EUBCE conference that was held in Lisbon, Portugal, from May 27th to 30th 2019.

> **David Baxter, Solange I. Mussatto** *Editors*

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