The use of grape residues as a renewable energy source for combustion presents various problems. One of these is the excessive production of carbon monoxide and nitrogen oxides. Analyses and combustion tests were performed on white and red grape pomace as well as grape stems. To verify the possibility of a reduction in emissions, straw of Miscanthus sinensis was added to mixtures with red grape pomace. Emission concentrations of carbon monoxide and nitrogen oxides were determined on a grate combustion device with a nominal thermal output of 8 kW under steady-state conditions. In addition to these emission concentrations, the excess air factor and the flue gas temperature were monitored. The results show a high energy content in grape residues. In red grape pomace, the gross calorific value of dry matter reached 22.17 MJ kg⁻¹. Unfavourable properties included high ash and nitrogen contents. During combustion tests on all types of grape residue, the emission concentrations of carbon monoxide were above the legal limit for the combustion of solid fuels. The addition of Miscanthus straw improved the behaviour during combustion. The maximum content of grape pomace in the mixture capable of meeting legislative emission requirements was 50% wt.

Walnut, pistachio, and peanut nutshells were treated by pyrolysis to biochar and analyzed for their possible usage as fuels or soil fertilizers. All the samples were pyrolyzed to five different temperatures, i.e., 250 °C, 300 °C, 350 °C, 450 °C, and 550 °C. Proximate and elemental analyses were carried out for all the samples, as well as calorific value and stoichiometric analysis. For sample usage as a soil amendment, phytotoxicity testing was performed and the content of phenolics, flavonoids, tannin, juglone, and antioxidant activity were determined. To characterize the chemical composition of walnut, pistachio, and peanut shells, lignin, cellulose, holocellulose, hemicellulose, and extractives were determined. As a result, it was found that walnut shells and pistachio shells are best pyrolyzed at the temperature of 300 °C and peanut shells at the temperature of 550 °C for their use as alternative fuels. The highest measured net calorific value was in pistachio shells, which were biochar pyrolyzed at 550 °C, of 31.35 MJ kg⁻¹. On the other hand, walnut biochar pyrolyzed at 550 °C had the highest ash share of 10.12% wt. For their use as soil fertilizers, peanut shells were the most suitable when pyrolyzed at 300 °C, walnut shells at 300 and 350 °C, and pistachio shells at 350 °C.

This study focused on small gasification units for combined heat and power generation (CHP) up to 200 kW of electric power, which can use wood from salvage logging, and assessed the current feasibility of running commercially available units in the conditions of the Czech Republic. In total, the technical and economic parameters of 21 gasification units from ten major international producers were compiled. One of the most important parameters assessed was the net calorific value, which in the analysed samples of spruce wood was determined at 18.37 MJ kg⁻¹ on a dry basis. This complies to the requirements for fuel quality for these units. The economic profitability was determined for three investment variants with electric power of 10, 100, and 200 kW_el in an operating mode of constant power at 20 and 30 wt.% input moisture level of the wood. Economic analysis showed that smaller alternatives with an output of 10 and 100 kW_el produce economic losses. On the other hand, the 200-kW_el alternative produced operating profit and positive cash flow at both fuel moisture levels in the first year of operation. The evaluation of individual alternatives using dynamic investment evaluation methods also showed that only the alternative with an output of 200 kW_el with both fuel moistures was able to produce a positive net present value.

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.

The study aims to analyze and decompose the qualitative parameters of wood chips in Poland. The European Green Deal brings the new framework to support sustainability and elimination of emissions. The Wavelet coherence and Wavelet Discrete Decomposition are used for determination of relations among significant qualitative parameters. Thus, the possible uses are discussed. For the obvious relationship between moisture and calorific value there is evidence of strong correlation. The behaviour of these interrelations are different at frequencies in the long and short time. The wood chip price is inter-transmitter from moisture parameter to calorific value in a positive (in-phase) relationship. At both low and high frequencies there is evidence that the variables of moisture and calorific value are highly correlated. The transient effect of linkage is presented at values between 0.1 and 0.3 in coherence map. The empirical findings provide implication for local producers and policymakers.

The publication describes research investigating the effects of microwaves on seeds extracted from Norway spruce (Picea abies) and European larch (Larix decidua) cones. The objective of the conducted experiments was to determine how electromagnetic radiation influences the quality of those seeds. The study material was heated in a microwave-emitting device for 7 or 10 s at four power settings (800, 620, 440, or 130 W). The evaluated parameters included changes in the moisture content and weight of the studied cones following the applied time and power variants of exposure to microwaves, as well as the quality of the obtained seeds expressed in terms of germination energy (GE) and capacity (GC). Increasing the power of microwaves resulted in a greater decrease in the moisture content of cones, but it was not possible to find such a relationship for larch cones, especially for large cones. In most cases, the irradiation of larch cones with electromagnetic waves resulted in class I seeds, in contrast to spruce seeds, which could not be assigned to any class. Our findings show that for optimum results larch cones may be exposed to microwaves at a power not greater than 620 W and for a time not longer than 10 s. Spruce cones were found to be very sensitive to radiation; in their case no microwave treatment should be applied as it adversely affects seed viability.