Energetic and thermal characteristics of Lavatera thuringiaca L. biomass of different age produced from He-Ne laser light stimulated seeds

The article presents the studies on the biomass yield, heating value and thermal decomposition process of the shoots of Lavatera thuringiaca L. plants (solid biofuel) of different age (one to three years old) grown from He-Ne laser stimulated seeds. Five combinations of Lavatera biomass characterized by different pre-sowing seed exposure times to laser light (1-30 min) were investigated. The results showed that the exposure time of, respectively, 10, 15 and 30 min had the most pronounced effect on the increase of biomass yield for two-year old shoots and the heating values for one-, two-and three-year old shoots biomass in relation to the control. Over the three experimental years, significant differences in the H, N, fixed carbon and ash content between the combinations of shoots were found. For the tested biomass after the exposition to laser light as well as for older plants, the ignition and burnout temperatures were shifted towards higher values. Stimulation with laser light affected the maximum mass loss rate as well as corresponding temperature for the investigated shoots. The two-year old combinations were characterized by better combustion index in comparison to one-and three-year old ones. As mentioned above, laser light stimulation of Lavatera seeds can contribute to the heating value and biomass yield increase and, as a result, to a more effective fossil fuel replacement. (c) 2021 Elsevier Ltd. All rights reserved.