This work deals with the unconventional biomasses used in the Czech Republic and Spain and their comparison. Initial chapters describe the need of use of unusual biomass, international projects, agreements, and legislations. The following ones consider unusual biomass from food industry of each country with the detailed explanation and comparison of the residues of the sunflower production process and olive production process. The final chapters include detailed comparisons between the biomass from the Czech Republic and Spain, from the perspective of the purchase prices, heating value, and...