Bioenergy is the largest contributor of global renewables, simultaneously providing energy security to billions and stimulates rural development. The growing industrial demand of wood pellets for ...bioenergy coupled with sustainability issue have encouraged many to produce fuel pellets from non-woody biomass. The production and utilization of fuel pellets from varied feedstocks have therefore opened up opportunities and challenges for the existing technologies. The paper presents a state-of-the-art review on production and utilization of fuel pellets from biomass. This includes different aspects of pellet making process including pre-possessing of biomass for pelletization, influence of process parameters on pellet quality and various ways to utilize pellets. Finally the review ends with a discussion on the economic feasibility of fuel pellets for energy utilization.
Display omitted
•Review of biomass fuel pellets production has been presented comprehensively.•Main emphasis is on review of technical parameters of pelletization.•Fuel pellets applications in different areas have been discussed.•Techno-economic feasibility of pellets and recent patents has been reviewed.
Display omitted
•Garden waste with three different particle size distributions was pelletized.•Internal particle size distributions of produced pellets were studied.•Effect of milling sizes on pellet ...quality was not significant in the pilot scale.•Use of fine shredded biomass reduced specific energy consumption in pelletization.
This work investigates the effect of biomass milling size on pelletization process and pellet quality, using garden waste (a non-woody biomass feedstock). Three different milling sizes were considered, viz. ‘as received’ (>25.4 mm), coarse (25.4 mm), and fine (6.25 mm) at a moisture content of around 10% and a die size of 15 mm. The particle size distribution plots showed a significant difference in ‘median particle size diameter’ (D50) for all three cases. Nominal changes in pellet quality parameters (density, dimension, and durability) were observed during pilot scale pelletization with different milling sizes. However, the results showed an increased throughput capacity (29.5 to 60 kg h−1) with decrease in milling size from 'as received' to fine. In addition, the wet disintegration method was performed to analyze the internal particle size distribution of pellets. The results revealed that the difference in D50 values for the internal particle size of produced pellets was insignificant in above cases. Furthermore, the specific energy consumption value reduced from 141.2 to 100.2 kWh ton−1 by reducing biomass milling size from coarse to fine. The production cost reduced by 23% for fine feedstock as compared to coarse while producing pellets under given conditions.
Pelletization of garden waste, without additional binder, was investigated to produce high quality fuel pellets for energy utilization. The influence of pelletization parameters viz. feedstock ...moisture content (5, 15, 25, and 35%), milling size (25.4 and 6.25mm) and die size (12 and 15mm) on pellet quality and pelletization process was studied. The results showed that the studied parameters had significant effect on pellet quality. A reduction in average durability value (95.0% to 92.5%) was observed when moisture content of garden waste increased from 5% to 15%. Appropriate regression models were also developed for each quality attribute by using multiple linear regressions. Eventually, a feedstock moisture content of 5±1%, milling size of 6.35mm and die size of 15mm were found to offer standard quality pellets with optimum throughput capacity. Scanning electron microscopy image analysis showed a closer agglomeration of biomass particles when feed materials were pelletized at low moisture content. The equilibrium moisture content due to adsorption for garden waste pellet was found to be 14.6% which was quite low as compared to other feedstocks. Furthermore, we deduced from the combustion test that garden waste pellets may be conveniently used in a residential cookstove. In a nutshell, pelletization of garden waste biomass has been demonstrated at pilot scale in this study.
•Pilot scale study for pelletization was conducted using garden waste biomass.•Standard quality fuel pellets were prepared from garden waste without using binder.•Appropriate regression models were developed for each pellet quality attributes.•Best pelletization run was 6.35mm milling size, 5±1% feed moisture and 15mm die.•Combustion test confirmed the suitability of pellets in a residential cookstove.
•Improvement in fuel properties by preheating.•Utilization of heat from exhaust gas.•Performance of preheated Jatropha oil vis-à-vis diesel.•Lowered ignition delay for preheated Jatropha oil as ...compared to diesel.•Lower emissions with preheated Jatropha oil as compared to diesesl.
The viscosity and density of CJO (crude Jatropha oil) were reduced by heating it using the heat from exhaust gas of a diesel engine with an appropriately designed helical coil heat exchanger. Experiments were conducted to evaluate the combustion characteristics of a DI (direct injection) diesel engine using PJO (preheated Jatropha oil). It exhibited a marginally higher cylinder gas pressure, rate of pressure rise and heat release rate as compared to HSD (high speed diesel) during the initial stages of combustion for all engine loadings. Ignition delay was shorter for PJO as compared to HSD. The results also indicated that BSFC (brake specific fuel consumption) and EGT (exhaust gas temperature) increased while BTE (brake thermal efficiency) decreased with PJO as compared to HSD for all engine loadings. The reductions in CO2 (carbon dioxide), HC (hydrocarbon) and NOx (nitrous oxide) emissions were observed for PJO along with increased CO (carbon monoxide) emission as compared to those of HSD.
•Formulation and comparison of five equilibrium models for biomass gasification.•The best predictive model, with specific set of reactions, was identified.•Model was used to predict product ...composition for 50 different biomass species.•A new semi-empirical approach was used to develop correlations for gas composition.
The paper provides a comparison of five distinct models, often used in thermodynamic equilibrium modeling that allows the study of feedstock effect on gasification process. The five models were thus formulated and solved using MATLAB software. The results were compared with published experimental data. The model based on equilibrium constant derived using methane formation reaction and water gas shift reaction showed comparatively better performance. Once the model was selected, the response surface analysis was employed to predict the parameters, such as reactor temperature and feedstock moisture content, for a maximum heating value of the producer gas. Simulations were performed for 50 different biomass feedstocks and simplified correlations were developed from simulated producer gas composition using multiple linear regression. These correlations may be suited for the quick comparison of different feedstocks in gasification process.
Display omitted
•A conceptual framework was designed for a bioenergy system for rural India.•Agro waste potential was estimated through survey.•Techno-economic analysis of an integrated system was ...conducted.•Uncertainty was assessed through Monte-Carlo simulation.
This paper presents a holistic approach to promote bioenergy in India by designing a conceptual framework that combines resource, technology and market. The proposed concept is an attempt to integrate pelletization and gasification technology for bioenergy system development through an end-to-end approach. The potential of bioenergy resource (i.e. agro waste) was estimated based on survey. The study further assessed the economic feasibility of agro waste pelletization. The economic evaluation was made using indicators such as net present value (NPV), internal rate of return (IRR), discounted payback period (DPBP) etc. Pellet plant capacity of 0.5 ton h−1 showed acceptable economics and the NPV, IRR and DPBP were ₹9.35 million ($0.13 million), 41% and 2.8 years, respectively. Moreover, the larger capacity plants (>2 ton h−1) were subjected to more risk under low pellet prices (< ₹5 kg−1 or $71.4 ton−1). The cash flow statement showed a strong debt paying ability for the project. Pellet price was the most sensitive factor followed by annual operating days on pellet plant economics. Monte Carlo simulation predicted an average NPV of ₹9.3 ± 2.0 million ($133.2 ± 29.1 thousand). The economics of fuel pellets utilization in a gasifier for energy applications was also evaluated. The pellet fed gasifier system appeared to be cost competitive with commercial liquefied petroleum gas (LPG) and wood at a pellet price range of ₹6.3–8.8 kg−1 ($90–126 ton−1) in a select scenario. Overall, the designed framework appears to reduce over-dependency on wood or fossil sources, and facilitate bioenergy promotion in rural areas.
Display omitted
•A gasifier system was proposed as an alternative to wood- or LPG-based cooking.•The gasifier system reduced 25% cooking time and saved 28% fuel vis-à-vis a Chulha.•The average PM10 ...and PM2.5 values for gasifier were 59 and 21 µg m−3, respectively.•Co-design of the gasifier system was undertaken with users.•SWOT analysis was applied for the biomass gasifier project in Indian context.
Gasification of waste biomass can offer a cleaner and renewable alternative to wood and fossil fuel-based cooking systems. However, field evaluations of biomass gasifiers for institutional cooking are rarely reported in the scientific literature. This study was aimed to develop a fuel-efficient gasifier system for institutional cooking in the Indian context. We conducted field experiments in both rural and urban settings using collaborative approaches. The results demonstrated significant improvements in gasifier-based cooking including up to a 25% reduction in cooking time, about 28% lower fuel consumption, and 82% less fine particulate matter emissions, within the permissible limits, when compared to cooking via traditional chulha (clay stove). Through collaborative design with users, the gasifier system underwent further modifications to achieve a substantial reduction in cooking time (around 25–30%) across various testing scenarios. Furthermore, the gasifier system was successfully demonstrated to supplement a liquefied petroleum gas (LPG)-based cooking system, and the latter showed around 25% faster cooking performance and a 12.5% lower energy input. Practical problems encountered during biomass gasifier field trials were documented and analyzed, along with a project SWOT (Strengths, Weaknesses, Opportunities, and Threats) analysis. The results of gasifier field trials imply significant potential when compared to the traditional cooking in a rural setting. Overall, the proposed gasifier system could serve as a sustainable technology alternative for bioenergy applications in the developing world.
In this paper, an economic evaluation for agricultural waste pelletization is presented. In the view of a small scale, village level bioenergy system for India, we considered a 2 tonnes/day capacity ...pelletization plant as base case. The capital investment and annual operating expenses were $41250 and $34282, respectively. The raw material cost shared the largest among all elements of annual operating expenses. The results showed that the pelletization plant appears to be feasible, considering the selling price of pellet is greater than $120 per tonne. Sensitivity analysis showed a strong influence of pellet price on profitability parameters (NPV and IRR).
The production of wood pellets has more than doubled between 2010 and 2015 to over 30 million metric tons. It is expected to grow to even more than 50 million metric tons by 2025. Thus, increasing ...demand for wood pellets for its energy utilization has prompted researchers to search for non-woody feedstocks. In this context, a potentially huge underutilized biomass such as garden waste can be explored as an alternative feedstock. The key factors affecting the quality of fuel pellets were evaluated during the garden waste pelletization process. Experiments were performed using a flat die pellet mill to investigate the effect of feedstock moisture content, die size, and milling size on pellet quality. Quality parameters such as pellet moisture, pellet length, bulk density, and durability were measured as per ASABE standards. Feed moisture content had a significant effect on durability and bulk density, with high quality pellets produced at the low feed moisture content (< 20%). The quality parameters of produced pellets were evaluated as per standards. It is concluded from the investigation that pellets produced at 5-10% feed moisture content using 15 mm die and fine shredded biomass satisfies the ISO standard and other norms.
PDF
