Assessment of Quality Indicators of Pressed Biofuel Produced from Coarse Herbaceous Plants and Determination of the Influence of Moisture on the Properties of Pellets

Abstract

Three coarse herbaceous energy plants—such as Miscanthus (Miscanthus sinensis), sida (Sida hermaphrodita Rusby) and cup plant (Silphium perfoliatum L.)—were grown and investigated in the experimental fields of Vytautas Magnus University Agriculture Academy, and the technical means of plant processing and utilization for solid biofuel were investigated. The physical–mechanical properties and quality indicators (moisture content, biometrical properties, density, and resistance to compression) of coarse stem herbaceous plants milled and compressed into 6 mm diameter pellets were investigated. The moisture content of the tested pellets was sufficiently low and ranged from 8.7% to 9.6%. The highest density was that of sida pellets (1072.3 ± 43.4 kg m−3 DM), and the lowest density was that of Miscanthus pellets (713.5 ± 67.1 kg m−3 DM). In order to evaluate the influence of moisture content on the properties of biofuel pressed into pellets, the density and the destructive compressive force of the different-moisture pellets were investigated and their change in the range of 5–15% pellet moisture content was evaluated. Criterion k was calculated to determine the effect of moisture on the pellet quality indicators (density, destructive compressive force, and lower heating value), and the following results were obtained: the highest influence of moisture on density was observed in sida (k = 34.280), on destructive compressive force in Miscanthus (k = 14.5), and on the lower heating value, also in Miscanthus (k = 0.198). After a comprehensive investigation and evaluation of these properties, an empirical model suitable for practical use was developed and prepared. Emissions of harmful gases, such as carbon monoxide, carbon dioxide, and nitrogen oxides, were determined when various coarse stem herbaceous energy plants were burned. The determined emissions of harmful gases into the environment did not exceed the permissible values.

Assessment of the Characteristics of Corncobs Used for Energy Needs

“…When evaluating the compressive deformation of pellets, which was the highest in 12.39 ± 0.07% moisture pellets, it reached 2471.5 ± 48.5 N. Unlike in the research of other authors, we can note that the analysis of this corncob index was not found. In studies of pellets from Artemisia dubia by Jasinskas et al [56], when the density of the pellets was 1192.44 kg m −3 and the moisture content was 9.98%, the compressive strength withstood a pressure of 560.36 N. The compressive force of Sida pellets ranged from 557 to 356 N (when the humidity increased from 5% to 15%, the diameter of the pallets was 6.0 ± 0.3 mm) [57]. However, it can be assumed that this indicator was influenced by the size of the pellet under study (the diameter of the pellet ranged from 6.22 to 6.39 mm, and the average pellet length varied from 21.82 to 25.77 mm), since it was produced by a granulator.…”

Calorific Value of Festuca rubra Biomass in the Phytostabilization of Soil Contaminated with Nickel, Cobalt and Cadmium Which Disrupt the Microbiological and Biochemical Properties of Soil

“…In biomass, this parameter is determined mainly by the type of biomass (chemical composition) [19]. Despite the fact that Festuca rubra is a perennial grass, plants native to Asia and North America are more suitable for energy generation because they are more efficient, bind more CO 2 and contain less ash as a by-product of combustion [20,21]. While the calorific value of Festuca rubra is lower than the plants shown in Table 7, its advantage is the fact that it is relatively resistant to soil contamination with heavy metals.…”

“…Energy crops should also be characterized by high nutrient and water use efficiency, as well as a favorable energy balance between energy inputs and outputs. These crops should also be resistant to pests, disease and adverse environmental conditions [21].…”

Exploring the Potential of Perennial Nectar‐Producing Wild Plants for Pellet Combustion

“…[ 39,40 ] On the other hand, direct combustion faces three main disadvantages: reduction of efficiency associated with burning high‐moisture fuels, ash fouling and agglomeration due to alkali compounds found in biomass and the provision of sufficient supplies of bulky biomass. [ 40,41 ]…”