Opportunities for solar assisted biogas plant in subtropical climate in Australia: A review

© 2019 The Authors. Published by Elsevier Ltd. Household waste generation has become a serious environmental issue in recent years. However, some technologies are available to convert household domestic waste into energy. One of such techniques is the biogas generation using household waste. The biogas generation technique is not a new method of energy generation, but its production efficiency is questionable. Biogas yield from domestic waste are influenced by pH level, temperature, HRT and C/N ratio. Moisture and the temperature levels in the biogas generation systems are very critical to its production efficiency, especially this is highly affected in the colder weather condition. Solar assisted biogas plant may provide better production efficiency compared to the traditionally designed biogas plant. In this paper, the scopes and opportunities of solar assisted biogas generation are reviewed. Possible benefits and challenges associated with the solar assisted biogas generation are highlighted

Resource recovery from waste coffee grounds using ultrasonic-assisted technology for bioenergy production

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). Biodiesel is a proven alternative fuel that can serve as a substitute for petroleum diesel due to its renewability, non-toxicity, sulphur-free nature and superior lubricity. Waste-based non-edible oils are studied as potential biodiesel feedstocks owing to the focus on the valorisation of waste products. Instead of being treated as municipal waste, waste coffee grounds (WCG) can be utilised for oil extraction, thereby recovering an energy source in the form of biodiesel. This study evaluates oil extraction from WCG using ultrasonic and Soxhlet techniques, followed by biodiesel conversion using an ultrasonic-assisted transesterification process. It was found that n-hexane was the most effective solvent for the oil extraction process and ultrasonic-assisted technology offers a 13.5% higher yield compared to the conventional Soxhlet extraction process. Solid-to-solvent ratio and extraction time of the oil extraction process from the dried waste coffee grounds (DWCG) after the brewing process was optimised using the response surface methodology (RSM). The results showed that predicted yield of 17.75 wt. % of coffee oil can be obtained using 1:30 w/v of the mass ratio of DWCG-ton-hexane and 34 min of extraction time when 32% amplitude was used. The model was verified by the experiment where 17.23 wt. % yield of coffee oil was achieved when the extraction process was carried out under optimal conditions. The infrared absorption spectrum analysis of WCG oil determined suitable functional groups for biodiesel conversion which was further treated using an ultrasonic-assisted transesterification process to successfully convert to biodiesel

Opportunities for solar assisted biogas plant in subtropical climate in Australia: A review

Akbar, DH ORCiD: 0000-0002-2269-5056; Rasul, M ORCiD: 0000-0001-8159-1321Household waste generation has become a serious environmental issue in recent years. However, some technologies are available to convert household domestic waste into energy. One of such techniques is the biogas generation using household waste. The biogas generation technique is not a new method of energy generation, but its production efficiency is questionable. Biogas yield from domestic waste are influenced by pH level, temperature, HRT and C/N ratio. Moisture and the temperature levels in the biogas generation systems are very critical to its production efficiency, especially this is highly affected in the colder weather condition. Solar assisted biogas plant may provide better production efficiency compared to the traditionally designed biogas plant. In this paper, the scopes and opportunities of solar assisted biogas generation are reviewed. Possible benefits and challenges associated with the solar assisted biogas generation are highlighted. © 2019 The Authors. Published by Elsevier Ltd

Opportunities for solar assisted biogas plant in subtropical climate in Australia: A review

Household waste generation has become a serious environmental issue in recent years. However, some technologies are available to convert household domestic waste into energy. One of such techniques is the biogas generation using household waste. The biogas generation technique is not a new method of energy generation, but its production efficiency is questionable. Biogas yield from domestic waste are influenced by pH level, temperature, HRT and C/N ratio. Moisture and the temperature levels in the biogas generation systems are very critical to its production efficiency, especially this is highly affected in the colder weather condition. Solar assisted biogas plant may provide better production efficiency compared to the traditionally designed biogas plant. In this paper, the scopes and opportunities of solar assisted biogas generation are reviewed. Possible benefits and challenges associated with the solar assisted biogas generation are highlighted. © 2019 The Authors. Published by Elsevier Ltd

A comprehensive review of the recent development and challenges of a solar-assisted biodigester system.

The extensive use of fossil fuels and the environmental effect of their combustion products have attracted researchers to look into renewable energy sources. In addition, global mass production of waste has motivated communities to recycle and reuse the waste in a sustainable way to lower landfill waste and associated problems. The development of waste to energy (WtE) technology including the production of bioenergy, e.g. biogas produced from various waste through Anaerobic Digestion (AD), is considered one of the potential measures to achieve the sustainable development goals of the United Nations (UN). Therefore, this study reviews the most recent studies from relevant academic literature on WtE technology (particularly AD technology) for biogas production and the application of a solar-assisted biodigester (SAB) system aimed at improving performance. In addition, socio-economic factors, challenges, and perspectives have been reported. From the analysis of different technologies, further work on effective low-cost technologies is recommended, especially using SAB system upgrading and leveraging the opportunities of this system. The study found that the performance of the AD system is affected by a variety of factors and that different approaches can be applied to improve performance. It has also been found that solar energy systems efficiently raise the biogas digester temperature and through this, they maximize the biogas yield under optimum conditions. The study revealed that the solar-assisted AD system produces less pollution and improves performance compared to the conventional AD system

Assessment of physical, chemical, and tribological properties of different biodiesel fuels

Fuel properties of biodiesels are influenced by the physical features of the fatty acid composition, such as the degree of unsaturation, the percentage of saturated fatty acid, monounsaturated fatty acid, and polyunsaturated fatty acid. Fuel properties are the key factors in determining the suitability of any fuel as an alternative fuel. In this study, biodiesels from five different feedstocks have been characterized for their physical and chemical properties. Gas chromatography has been carried out to find out the ester composition of these five biodiesels, and correlation between composition and fuel properties of these five biodiesels have been developed. Fuel properties were measured according to standard procedure ASTM D6751 and EN 14214 and estimated based on the previously published correlation. Also, the quality of these biodiesels was assessed and compared with commercially available biodiesels through multivariate data analysis using PROMETHEE-GAIA software. In the last part, wear and friction of selected biodiesel fuels have been studied and compared with diesel fuel. The result shows that the properties of produced biodiesel are within the acceptable limit of ASTM and EN standards. Highly linear correlations were found between the composition and cetane number, iodine value, oxidation stability, and cold flow plugging point with the regression value of 0.9965, 0.9983, 0.7044, and 0.9985, respectively. Overall, this study found that, among the biodiesels studied, the palm biodiesel was the most suitable alternative followed by the macadamia, moringa, and jatropha, and beauty leaf biodiesel

Performance Assessment of Solar Assisted Anaerobic Digester System: Simulation and Application in Central Queensland Region

Biogas as an energy source is increasing its popularity in both small- and large-scale applications. The anaerobic digestion (AD) process requires heat to produce biogas effectively, which can be supplied via a solar system. The suitability of integration of solar thermal energy in anaerobic digestion was researched through this paper. With the help of TRNSYS software, a 0.2 m3 simulation model of the digestor reactor along with a 2m2 PV solar thermal system was built. A study was done in an atmospheric condition of Rockhampton in Central Queensland based on the thermal activity and dynamic behavior of the structure. Cow manure was used as a feedstock in the system. The simulation was run for predicting the daily average temperature within the AD of a typical month in summer and winter. The simulation was also done for predicting the biogas production in typical summer and winter months, and for all seasons in Australia. The simulated temperature was found to be the temperature of the biogas production at a mesophilic temperature of about 35°C. The result showed that the maximum predicted temperature was found to be 35.98 °C in the summertime and 35°C in wintertime. The result also showed that the maximum biogas production is 84.45L/day in summertime and 72.33 L/day in wintertime. So, the solar heating system can help increase the bio-digester temperature which contributes to the production of biogas in the AD system. Thus, the developed model can be considered as an accurate tool to predict biogas production in Central Queensland (Rockhampton) climate for solar assisted AD systems. It is expected that the simulation model can be extended to predict biogas production from solar-assisted AD systems in other climatic conditions

Assessment of physical, chemical, and tribological properties of different biodiesel fuels

Rasul, M ORCiD: 0000-0001-8159-1321Fuel properties of biodiesels are influenced by the physical features of the fatty acid composition, such as the degree of unsaturation, the percentage of saturated fatty acid, monounsaturated fatty acid, and polyunsaturated fatty acid. Fuel properties are the key factors in determining the suitability of any fuel as an alternative fuel. In this study, biodiesels from five different feedstocks have been characterized for their physical and chemical properties. Gas chromatography has been carried out to find out the ester composition of these five biodiesels, and correlation between composition and fuel properties of these five biodiesels have been developed. Fuel properties were measured according to standard procedure ASTM D6751 and EN 14214 and estimated based on the previously published correlation. Also, the quality of these biodiesels was assessed and compared with commercially available biodiesels through multivariate data analysis using PROMETHEE-GAIA software. In the last part, wear and friction of selected biodiesel fuels have been studied and compared with diesel fuel. The result shows that the properties of produced biodiesel are within the acceptable limit of ASTM and EN standards. Highly linear correlations were found between the composition and cetane number, iodine value, oxidation stability, and cold flow plugging point with the regression value of 0.9965, 0.9983, 0.7044, and 0.9985, respectively. Overall, this study found that, among the biodiesels studied, the palm biodiesel was the most suitable alternative followed by the macadamia, moringa, and jatropha, and beauty leaf biodiesel

Estimation of the sustainable production of gaseous biofuels, generation of electricity, and reduction of greenhouse gas emissions using food waste in anaerobic digesters

Food waste is a type of organic waste generated by restaurants, food processing plants, households, and commercial and institutions. This study aims to assess the sustainable biofuel, electricity production and greenhouse gas emission reduction potential of food waste using anaerobic digestion technology. Food waste data was collected from the Australian government database to estimate the biomethane and biogas yield and to evaluate the opportunities to convert the biomethane into electricity and heat. This study found that food waste can yield 47% biomethane and hence for Australia, an estimated total of 0.07 million m3 to 1.54 million m3 of biogas can be produced and up to 414,898 tonnes of greenhouse gas emissions reduced annually. The study also estimated that the generated biogas can replace fossil fuel-based electricity generation of up to 52.36 GW and 554.4 TJ heat per year. The environmental assessment indicated that the complete conversion of food waste can lower greenhouse gas emissions (GHG) by up to 5,07,434 tonnes per year and Australia can earn about $52.38 M revenue from electricity production. Therefore, conversion of food waste into biofuel through the anaerobic digestion process can play a significant role in generating electricity from non-fossil-based sources, reducing GHG emissions and earning revenue

Food waste as a source of sustainable energy: Technical, economical, environmental and regulatory feasibility analysis

Anaerobic digestion (AD) is a viable technique to address food waste (FW) problems by converting FW into sustainable energy. Despite the advantages of the AD process, large-scale AD plants like in Germany and the USA have not been developed in Australia. Therefore, this paper aims to study the technological, economic, and environmental feasibility of sustainable energy production from household FW in Australia. In addition, this paper discusses the different waste to energy (WtE) technologies along with the operational parameters as well as the challenges in developing a biogas plant. The energy and economic potential analysis of the AD process indicates that the processing of 10% FW from Australian states and territories can generate 1.22 GWh to 35.4 GWh electricity which can subsequently earn AUD 0.54 million to AUD 15.7 million in revenue per year. The greenhouse gas (GHG) emissions analysis indicates that conversion of the 10% of Australian FW has the potential to lower GHG emissions by 639,852 tonnes per annum. Hence, it can be said that FW plays a vital role as a promising source of sustainable energy and is capable of benefiting the country's economy significantly and reducing GHG emissions