This study investigates the potential use of biochar derived from residues-such as spruce wood, spent coffee grounds, tea waste, and nutshells-as a sustainable coal substitute-to enhance the decarbonization of European energetic systems and decrease the dependence on fossil fuels. The biomasses were pyrolyzed at 250-550 °C, analyzed for calorific value and composition, and evaluated for energy retention and mass loss. The results show significant energy density improvements, with optimal temperatures varying by material (e.g., spruce wood reached 31.56 MJ·kg-1 at 550 °C, retaining 21.84% of its mass; spent coffee grounds peaked at 31.26 MJ·kg-1 at 350 °C, retaining 37.53%). Economic analysis confirmed pyrolyzed biomass as a cost-effective alternative to coal, especially considering emission allowance costs. Integrating biomass pyrolysis into regional energy systems supports decarbonization, reduces emissions, and advances us towards a circular economy.

• Klíčová slova
• biochar, biomass, calorific value, energy residual, nut shells, spent coffee ground, spruce wood, tea waste,
• Publikační typ
• časopisecké články MeSH

As a push towards alternative and renewable resources for heat and power generation, biomass and thermally treated fuels from biomass may be viable options in the upcoming economic reality. This study the verified mass and energy balance of spruce woody biomass after low temperature pyrolysis between 250 and 550 °C. The results showed that low-temperature pyrolysis can yield high-grade biochar suitable for substitution of fossil fuels. Crucially, the net calorific value of biochar processed at 350 °C substantially exceeded that of brown coal. An economic analysis was carried out on the assumption of the current economic reality in the Czech Republic. It was shown that even if the price of the biochar slightly increased, it would still be beneficial to invest in torrefaction technology over paying carbon credits.

• Klíčová slova
• biochar, economic analysis, renewable fuels, spruce, torrefaction,
• Publikační typ
• časopisecké články MeSH

Spent coffee ground is a massively produced coffee industry waste product whose reusage is beneficial. Proximate and ultimate and stochiometric analysis of torrefied spent coffee ground were performed and results were analyzed and compared with other research and materials. Spent coffee ground is a material with high content of carbon (above 50%) and therefore high calorific value (above 20 MJ·kg-1). Torrefaction improves the properties of the material, raising its calorific value up to 32 MJ·kg-1. Next, the phytotoxicity of the aqueous extract was tested using the cress test. The non-torrefied sample and the sample treated at 250 °C were the most toxic. The sample treated at 250 °C adversely affected the germination of the cress seeds due to residual caffeine, tannins and sulfur release. The sample treated at 350 °C performed best of all the tested samples. The sample treated at 350 °C can be applied to the soil as the germination index was higher than 50% and can be used as an alternative fuel with net calorific value comparable to fossil fuels.

• Klíčová slova
• biofuel, biomass, calorific value, phytotoxicity, spent coffee ground,
• Publikační typ
• časopisecké články MeSH