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

Algirdas Jasinskas,Rolandas Domeika,Dionizas Streikus,Gvidas Gramauskas,Marvin T Valentin,Vytautas Kleiza,Edvardas Vaiciukevičius

doi:10.3390/su14031068

Algirdas Jasinskas, Rolandas Domeika + Show 5 more

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https://doi.org/10.3390/su14031068

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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.

Highlights

IntroductionAs countries develop and pursue sustainable economic growth, there is an increasing focus on renewable energy resources
The density of compressed biomass depends on the temperature of the material and the moisture content of the material
The recommended pellet density is given in various standards, ranging from 600 to 1200 kg m−3 [36,37,38]

Summary

Introduction

As countries develop and pursue sustainable economic growth, there is an increasing focus on renewable energy resources. These are solar, wind, hydro, geothermal energy, and plant biomass, which is widely used in Lithuania and other countries [1,2]. Biomass is an environmentally friendly energy source, which can reduce carbon emissions, and the use of biomass can be an alternative to fossil fuels, which can reduce GHG emissions. Researchers around the world are investigating and developing biomass compaction technologies, such as granulation, briquetting, and others [3,4]

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