In the ARBAHEAT project an existing 731 MWe Ultra-SuperCritical coal-fired power plant will be transformed into a biomass-fired Combined Heat and Power plant by repowering with thermally-treated biomass produced on-site. This demonstration encompasses: (1) Transformation into CHP: This will be demonstrated by delivering a minor amount of heat to the on-site biomass treatment process, while envisaging large-volume heat delivery to nearby industry. This will provide renewable local heat, enhancing the overall efficiency of the plant from 46% electricity-only to 70-90% in CHP mode, (2) Biomass feedstock: An integrated thermal pre-treatment process will enable utilisation of diverse sustainable biomass feedstock. This will minimise investment and operating cost while broadening the possibilities in term of geographical feedstock sourcing and quality (3) Biomass pre-treatment: The thermal biomass upgrading process of ARBAFLAME will deliver biomass fuel with handling and milling characteristics approaching that of coal, allowing for retrofitting with minimal adaptations to the existing power plant. The technical capacity of the demonstration plant will allow for maximum flexibility in upscaling the technology for future replication, (4) Integration into power plant: The biomass pre-treatment and heat delivery system will be physically integrated within the existing power plant. Eliminating several cost and energy intensive steps (steam production, pelletizing) will be investigated, towards more cost-effective final design. This demonstration of an integrated very low-costs concept in large-scale energy production will pave the way to subsequent multiplication in commercial industrial projects, thus increasing the EU capacity for renewable power and heat generation. The renewable ARBAHEAT solution therefore has the potential to significantly contribute to the replacement of fossil-fuel in the heat and power sectors and increase the decarbonisation of the energy market.