The main research strategies regarding thermochemical processing of biomass are concentrated on rising the sustainability of the process. These include measures to increase the efficiency, to reduce the GHG emissions, and to realise a cost-competitive production of advanced biofuels and bio-products.

The identified research areas/objectives are related to:

• Development of primary thermochemical conversion processes;
• Downstream processing;
• Advanced biofuel and intermediate carrier value chains.

For these objectives to be reached, KPIs are determined with a prospect levels of 2030 compared to 2020 ones. In the context of these KPIs and the challenges that they impose, the underlying principles in the research strategies are specified. They include:

• Simplification and integration of the thermochemical conversion process in order to increase its reliability;
• Increase the feedstock repertoire: use of waste or high- and low-grade biomasses, and new biomass sources (e.g. algal biomass);
• Co-use of biomass processing products with other sources or use of bio-based products for obtaining biofuels;
• Create negative GHG emissions by combining bioenergy with carbon capture.

The primary thermochemical biomass conversion processes are gasification (more 3.2.3), torrefaction (more 3.2.4), hydrothermal processing (more 3.2.5), and pyrolysis (more 3.2.6).

The processing of downstream products needs optimisation is terms of cleaning, conditioning, and upgrading (more 3.2.7).

To realise successful conversion of biomass into advanced biofuels and intermediate bioenergy carriers with high GHG savings, the individual unit operations must be unified into a smart biomass-to-side-streams value chain design (more 3.2.8).

The scope of this research strategy is to implement the biochemical and chemical processes and technologies for co-production of advanced biofuels other bio-based products in biorefinery approaches, including the biogas from anaerobic digestion, the syngas from thermochemical biomass and bio-waste processing, and the hydrogen from biological and renewable origin.

Alongside the entire conversion schemes, from the biomass pre-treatment to the recovery of side-streams and integration of bioprocessing technologies, needs have emerged for technological innovations and novel concepts development in the field of (bio)catalysis. New or improved process catalysts are desired to enhance the biological efficiency and product yields from the conversion process. The development of such catalysts is emphasised as a major research, development and innovation challenge.

The KPIs defined in the corresponding research strategy are an increase in the net efficiency of biomass conversion and a significant reduction in the production costs. To satisfy the KPIs, the main research areas are identified as:

• Development of enzymes and cell factories;
• Increasing the efficiency of microbial and algal biochemical pathways;
• Design of novel pathways and microorganisms to biochemically convert biomass into advanced biofuels and bio-based products.

The enzymes and cell factories research area involves improving the robustness and efficacy of the total enzymes mixture used in biochemical processing of biomass while reducing the costs, and respectively - the cost of the technologies. Additionally, the design of novel enzyme possessing improved catalytic activity of broader substrate spectrum is also considered. The approaches for development of new/optimised enzymes foresee obtaining biocatalysts with increased efficiency and reduced production costs. This improvement will reflect the whole conversion process, since the enzymes are its main component regarding the technology economics.

Here, metabolic engineering strategies are concerned with the scope to deregulate the metabolism of the microbial cells in a way that the negative influence on the conversion processes is minimised. These strategies encompass tuning appropriate metabolic chains to increase the efficiency of the natural biochemical pathways in microbial and algal cell factories. Among others, the following research topics are identified:

• Construction of microbial strains with uncoupled growth and fermentation to achieve maximal fermentation activity in non-growing cells;
• Construction of microbial strains with metabolic rearrangements that result in increased yield of the desired final products (e.g. through increasing the activity of auxiliary metabolic pathways);
• Genetic engineering of microbial strains with improved characteristics for syngas conversion;
• Induction of mixed cultures or engineered microbial strains to express a larger number of the enzymes involved in the conversion processes. Examples in this context can be genetically engineered bacterial strains that express a coctail of hydrolytic enzymes involved in fermenting lignocellulose or non-conventional yeasts with increased carbon conversion efficiency in the production of long-chain fatty acids.

This is an ambitious goal whose strategic recourse reaches beyond 2030 and envisages construction of artificial cell factories.

In addition to these research areas, other strategic research priorities include:

• Improvement of the current technologies and developing new ones for feedstock preparation, deconstruction and fractionation on the basis of flexible pretreatment methods.
• Development of solid materials for syngas and biogas cleaning and up-grading, such as catalytic membranes, zeolites or novel solid absorbents.
• Improvement of the current methods and developing new ones for algae fractionation through a cascade approach. This approach considers not only the efficient separation of the biomass processing fractions but also the preservation of the characteristics of the high-value, bio-based products thus obtained. Examples of such novel product-friendly technologies are supercritical fluids, ultrasound and microwave assisted extractions, and pressurised extraction.
• Improvement of the pre-treatment stage. Here, the efficiency of bio-processing for ethanol, higher alcohols, fatty acids, hydrocarbons, and hydrogen are regarded. The research topics on this issue are the development of more robust production strains (yeasts and bacteria), with higher resistance to inhibitory compounds present in the cell factories, and with the capacity to transform inhibitory fermentation products into bio-based products (e.g. engineered Clostridium sp. strains transforming butanol into non-toxic ethers or esters).
• Improvement of the efficiency of (bio)catalytic upgrading of intermediate bioprocessing products into advanced bio-based products. For instance, the development of novel solid materials for direct catalytic upgrading of biomass hydrolysates to produce bio-based products from alcohols contained in fermentation broths.
• Improvement of carbon conversion efficiency to achieve the cost-competitive conversion of gas flows from biomass thermochemical and biological processing into advanced biofuels and bio-based products. Increasing the cost competitiveness of using algae and bacteria to produce bio-hydrogen and biomethane is also a key issue for the long-term future production of advanced biofuels and bio-based products.

Process, mass and energy integration coupled to waste and side streams integration is the overall goal of any conversion technology focused on minimising GHG emissions and aiming to reach zero effluents. These challenges are research priority, addressed by:

• Development of in situ product recovery (ISPR) technologies that result in increased product yields and reduced economic and energy costs.
• Life Cycle Analysis of the value chains of the bio-based products obtained in the biochemical-based biorefineries: from feedstock to final product use and disposal or recycling. This is a well-recognised tool to determine the economical, environmental, and social dimensions of the conversion prcess.
• Recovery of process side-streams into biofuels and other bio-based products. The aqueous fraction resulting from the fractionation of bio-oils, which contains a diversity of organic oxygenated compounds, can be used as a source of hydrocarbons and aromatics obtained through the application of newly-designed solid catalyst that allows this transformation.