Search Results (29)

The expansion of sewage networks and treatment facilities results in considerable amounts of municipal sludge, which is essential for biogas production as part of energy diversification efforts. Principal Component Analysis (PCA) demonstrated a strong correlation between biogas production and its utilization in power generation units. Modernization efforts led to an increase in biogas utilization in power units but a decrease in boiler utilization, independent of the overall biogas production levels. The general linear model (GLM) further confirmed that biogas production was positively influenced by the amount of waste digested, while utilization in power units increased post modernization. A repeated measures ANOVA (Analysis of Variance) indicated significant increases in both dry matter and mineral content in digested sludge compared to raw sludge. SIMPER (Similarity Percentage) analysis revealed that the addition of glycerin water significantly reduced the nitrogen, ammonium nitrogen, and calcium content, while modernization increased these elements and slightly decreased the magnesium concentration. Multivariate dispersion analysis showed that samples treated with glycerin water exhibited less variability in metal content. Regression models explored the factors influencing mineral elements and dry mass in fermented sludge. The zinc content was positively associated with mineral content, while copper showed a negative correlation. The addition of glycerin water increased the mineral content, whereas modernization had the opposite effect. The nitrogen content was negatively correlated with dry mass. These findings provide valuable insights into optimizing sewage sludge treatment and biogas production processes by underlining the approaches for enhancing sludge properties to support efficient biogas production. Full article

Palm oil mill effluent (POME), a byproduct of palm oil processing, has substantial resource recovery potential. Its rich biodegradable content supports methane (CH₄) production via anaerobic digestion, enabling renewable energy generation. Additionally, the significant water content of POME can be reclaimed for use in boiler feed, irrigation, and drinking water. However, selecting appropriate technologies to recover valuable resources from POME is challenging, particularly for the purification and upgrading of biogas. Membrane technologies offer an effective approach for transforming POME treatment from an energy-intensive process into a resource recovery system, supporting the decarbonization of palm oil production and advancing global sustainability objectives. This technique is cost-effective and ecofriendly for biogas purification and water reclamation. For biogas purification and upgrading, membrane systems offer the lowest capital and operational costs at 5.654 USD/m³, compared to other technologies, such as 6.249 USD/m³ for water scrubbers and 6.999 USD/m³ for chemical absorbers. This review primarily explores the potential of membranes for gas purification from POME and examines their integration with other processes to develop advanced systems, such as ultrasonicated membrane anaerobic systems and membrane anaerobic systems, to enhance biogas production. In addition, water reclamation from POME is discussed, with ultrafiltration membranes emerging as the most promising candidates. Proton exchange membranes, such as Nafion, are used extensively in microbial fuel cells to improve electricity generation, and this is also summarized. Finally, challenges and future perspectives are highlighted, emphasizing the broader potential of membrane technology in POME wastewater resource recovery. Full article

The growing demand for energy biomass encourages the use of waste and by-products from agriculture. The aim of this study was to assess the suitability of tobacco stalks (TSs) for energy use in the combustion and anaerobic digestion (AD) process, as well as the technical and environmental effects of energy production from this waste raw material. Laboratory tests were conducted on the energy parameters of TS biomass, the chemical composition of ash from its combustion, and the efficiency and composition of biogas generated during the AD process of TS silage with various silage additives. The tests were conducted in accordance with the standards applicable to biomass fuels. The energy yield and emission reduction obtained by the replacement of conventional energy sources were calculated. The energy parameters of TS were inferior compared to the raw materials most often burned in boilers (wood, straw). The high ash content (7.31% in dry mass) and its chemical composition may adversely affect heating devices. Methane yield from TS silage was lower (18.55–24.67 m³/Mg FM) than from silage from crops grown for biogas plants (i.e., 105 m³/Mg for maize silage). Silage additives improved TS silage quality and methane yield (from 18.55 to 21.71–24.67 m³ CH₄/Mg in case of silages with additives. Energy yield and emission reduction were higher in the case of TS combustion, but AD is a process consistent with the circular economy. Both TS energy management processes are in line with the Sustainable Development Goals as they prevent the devaluation of agricultural waste, providing a valuable resource for bioenergy. Full article

This study demonstrates the benefits of comprehensive school building (SB) energy efficiency (EE) improvements through building envelope renovations, lighting upgrades, and changes to cleaner heat sources. The parametric study in the building energy simulation software was used to check the application of various interventions on the energy consumption of existing SBs while reducing CO₂ emissions with the most profitable return on investment (ROI). The energy savings from window replacements did not correspond with expectations. However, other measures such as the wall, roof insulation, and lighting modernization improved EE by up to 152 kWh/m² and 41 kg/m² CO₂/m² annually. The study also points to a significant trade-off between district heating (which reduces CO₂ but has a slower ROI) and other heating solutions. The results suggest that climate-specific insulation thickness and glazing type needs are required, and optimal insulation strategies are shown to improve EE by 48–56% and CO₂ reductions of 45–56%. Lighting replacement and biogas boiler use were both impactful. The findings support the importance of sustainable practices, which should stimulate educational awareness and environmental responsibility. This research presents actionable insights for EE and sustainable development from within educational facilities. Full article

This review presents a recent study on improving energy crops (ECs) in the EU and discusses the potential use of biostimulants to enhance CO₂ sequestration processes in these plants. The novelty of this study lies in demonstrating alternative directions for improving productivity and increasing plant yield without relying on introducing new hybrids (GM) or using advanced agrotechnology. There is a great deal of discussion about using energy crops for direct combustion or biogas production. However, there is a paucity of information regarding the use of biostimulants and their role in increasing the yield of energy crops, particularly in terms of CO₂ compensation. In CO₂ sequestration, increasing the intensity of the photosynthetic process is considered crucial for the more efficient growth of energy crops. Traditionally, fertilization aimed at improving photosynthesis results in a large amount of alkaline elements, which can cause negative effects in boilers. This paper describes the use of amino acid biostimulants extracted from industrial waste, either chemically or biotechnologically, and their different forms of application. It addresses the current challenges and benefits of using biostimulants in energy crops to increase photosynthesis without the use of genetic engineering tools in plants. Full article

To achieve carbon neutrality and address global energy supply issues by 2050, there is active progress in the industrial sector for waste energy recovery and commercialization projects. It is necessary to consider both the energy recovery efficiency and economic feasibility based on the production volume for the resource utilization of waste energy, along with eco-friendly processing methods. In this study, a waste heat recovery system was designed to recover a large amount of thermal energy from high-temperature exhaust gases of gas engines for power generation by using biogas produced from organic waste in industrial complexes. Types and sizes of components for a waste heat recovery system that were suitable for various engine sizes depending on biogas production were designed, and the energy recovery efficiency was analyzed. The waste heat recovery system consisted of a smoke tube boiler that generated superheated steam at 161 °C under 490 kPa of pressure from the exhaust gas as the heat source, along with two economizers for heating both supply water and hot water. Heat exchangers that were suitable for three different engine sizes were configured, and their performance and energy flow were calculated. In particular, when operating two engines with a power output of 100 kW, the boiler showed the highest steam production efficiency, and the superheated steam production from high-temperature exhaust gas at 600 °C was designed to be 191 kg/h, while hot water at 58 °C was designed to be produced at 1000 kg/h. In addition, further research on the heat exchanger capacity ratio confirmed that it was within a certain range despite the difference in heat exchanger capacity and efficiency depending on the engine size. It was confirmed that the heat exchange capacity ratio of the boiler was important as an optimal-capacity design value for the entire system, as it ranged from 46% to 47% of the total heat exchanger size. Full article

The article presents a new carbon-free heat production technology for district heating, which consists of a combined heat and power generation fuel cell (FC CHP) with CO₂ capture and a two-stage cascade high-temperature heat pump (TCHHP). The FC generates heat and electricity, the latter being used to drive the compressors of the TCHHP. During the winter period, the water temperature achieved can occasionally be too low, so it would be heated up with hydrogen gas boilers. The hydrogen would be produced by reforming natural gas, synthetic methane, or biogas. The results are presented with natural gas utilization—the ratio between the obtained heat flow transferred directly to the water for district heating and the input heat flow of natural gas. In the case of a return water temperature of 60 °C and district heating temperature of 85 °C, the TCHHP, whose heat source is groundwater, achieves plant efficiency of 270.04% in relation to the higher heating value (HHV) and 241.74% in relation to the lower heating value (LHV) of natural gas. A case with a TCHHP whose heat source is low-temperature geothermal water achieves a plant efficiency of 361.36% in relation to the HHV and 323.49% in relation to the LHV. Full article

The energy revolution prioritizes efficiency, sustainability, practicality, and concreteness. Conventional energy processes remain crucial and will continue to be essential for a long time if they are based on renewable and clean sources. Biofuels, particularly biomethane, are gaining significant attention for their potential to replace fossil fuels and contribute to a greener energy landscape. This paper focuses on enhancing the energy efficiency of an anaerobic digestion plant for biomethane production. Oversizing issues in technical plants often result in excessive energy and economic costs. Therefore, this study aims to analyze plant sections that can be improved to enhance performance. An energy analysis quantifies the energy requirements for different sections and sub-sections, guiding the selection of energy interventions such as pipeline resizing, heat generator modifications, pump enhancements, and energy recovery opportunities. The methodology is applied to an existing biomethane plant, and graphical software is used for redesigning the heat generator, pumps, and pipelines. The results demonstrated that implementing energy efficiency measures improves system performance. The heat generator’s capacity was successfully reduced by 100 kW, surpassing the initial design choice. Additionally, heat recovery from the biogas compression section has enhanced the overall thermal dynamics of the system. The estimated annual methane consumption in the boiler is approximately 12,000 Nm³, resulting in an expenditure of EUR 10600. These interventions have led to substantial savings, totaling EUR 133000 for the comprehensive thermal sustenance of the entire plant. Full article

This study investigates the efficiency of a biogas-powered cooling system through the utilization of energy and exergy calculations. Biogas, which can be generated and stored in small-scale plants as needed, serves as a viable fuel source for absorption cooling systems. The present research focuses on the biogas consumption of a triple-effect absorption cooling system specifically designed to supply a fixed cooling load of 100 kW under varying operational conditions. This study highlights the coefficient of performance and exergetic coefficient of performance values of the system, along with the exergy destruction rates of its individual components, at the optimal temperatures of operation. Furthermore, to determine necessary biogas consumption, this study explores the establishment of dedicated farms for various animal species, ensuring an adequate number of animals for biogas production. The findings reveal a coefficient of performance of 1.78 and an exergetic coefficient of performance of 35.4% at the optimized operating temperatures. The minimum mass flow rate of biogas is determined to be 0.0034 kgs⁻¹, facilitating the operation of the boiler with a methane content of 65%. This study concludes that a total of 290 head of cattle is required to generate the annual biogas consumption necessary for the cooling system. Additionally, the number of the cattle is enough to establish 284 biogas plants in Bursa Province in Türkiye. Full article

Moving bed heat exchangers (MBHE)s are used in industrial applications including waste heat recovery and the drying of solids. As a result, energy balance models have been developed to simulate the heat transfer between a moving bed and the gas phase. Within these energy balance models, phase change of components within the gas phase has not been considered as the liquefaction or desublimation of the gas phase does not occur in typical industrial applications. However, available energy balance models for cryogenic CO₂ capture (CCC) have only focused on fixed packed beds. The development of a suitable energy balance model to predict the energy duties for MBHEs that include phase change would be beneficial for CCC applications. This work investigated the development of moving bed energy balance models for the design of moving bed columns that involve phase change of CO₂ into frost, using existing models for MBHEs and fixed-bed CCC capture. The models were evaluated by comparison with available moving bed experimental work and simulated data, predicted energy duty requirements and bed flow rates from the suggested moving bed CCC models to maintain thermal equilibrium. The comparisons showed a consistent prediction between the various methods and closely align with the available experimental and simulated data. Comparisons of energy duty and bed flow rate predictions from the developed energy balance models with simulated cases for an oil-fired boiler, combined cycle gas turbine (CCGT) and biogas upgrading showed energy duty requirements for the gas phase with a proximity of 0.1%, 20.8%, and 3.4%, respectively, and comparisons of gas energy duties from developed energy balance models with energy duties derived from experimental results were compared with a proximity of 1.1%, 1.1% and 0.6% to experimental results for CO₂ % v/v concentrations of 18%, 8% and 4%. Full article

The current use of fossil fuels has a significant impact on increasing greenhouse gas (GHG) emissions. Subsequently, renewable energy is significantly needed to reduce GHG, thereby limiting the impact of extreme weather and climate while ensuring reliable, timely, and cost-effective supply. As a big country with a huge amount natural resource, the demand for renewable energy in Indonesia has increased along with the rise in consumption. Following this, energy consumption increased by 0.99%, which was approximately 939.100 million BOE in 2021 for biogas, oil, electricity, natural gas, coal, LPG, biodiesel, and biomass. Energy consumption in several sectors including transportation has the largest energy consumption with approximately 45.76% of oil. In industries and households sector, the consumption rates are 31.11% for boiler steam generation purposes and 16.89% for electricity as well as LPG. Furthermore, the commercial sector consumes 4.97% of energy for lighting and air conditioning, while the remaining 1.27% is used for other sectors. Meanwhile, Indonesia has high potential for renewable energy at 419 GW including 75 GW of hydro energy, 23.7 GW of geothermal, 32.6 GW of bioenergy, 207.8 GW of solar, 60.6 GW of wind, and 19.3 GW of micro-hydro. Therefore, the main focus of this paper is to provide a detailed analysis of the current status, prospects, and information on Indonesia’s renewable and sustainable energy sources. Furthermore, the novelty of this research entails updating the latest data related to renewable energy and its availability in Indonesia. The essence is to portray a picture of its potential development in the future. Full article

Rural energy is an important part of China’s energy system, and, as China’s agricultural modernization continues, integrated agricultural energy systems (AIES) will play an increasingly important role. However, most of China’s existing rural energy systems are inefficient, costly to run, and pollute the environment. Therefore, meeting various agricultural energy needs while balancing energy efficiency and costs is an important issue in the design and dispatch of integrated agricultural energy systems. In conjunction with hybrid energy storage (HES), which has been developed and matured in recent years, this paper proposes a new type of AIES structure and optimal dispatching strategy that incorporates HES, biogas generation (BG), P2G, and an electric boiler (EB) to provide new ideas for problem solving. Firstly, the structure of AIES is introduced and the mathematical model of the equipment of the system is described; then, an economic optimal dispatching model with the objective of minimizing the comprehensive operating costs of the system is established, and the output of each piece of energy conversion equipment is controlled to achieve the effect of improving the system’s operating performance and reducing the operating costs. The results show that the system with HES and multi-energy coupling equipment has a 20% lower overall cost, 23.2% lower environmental protection cost, and 51% higher energy efficiency than the original system; the stored power of energy storage equipment in the HES mode is primarily determined by the change in demand of the corresponding load, and the number of conversions between different energy sources is limited. The energy conversion loss is minimal. Full article

To efficiently utilize low-concentrate digestate nutrients, further treatment is needed to decrease their volume, recover process water, and increase nutrient concentrations. Membrane distillation (MD) is a thermally driven process that is advantageous due to its ability to harness low-grade waste heat to treat highly complex wastewater streams. This study assessed the techno-economic performance of integrating MD for two-fold concentrations of nutrients and the recovery of process water from digestate at a thermophilic biogas plant. Thermal assessment showed that the recovered waste heat from flue gas and digestate fully met the thermal energy demand of MD and saved 20% of boiler energy by heating incoming slurry. The permeate flux from MD was 3.5 L/(m²h) and 3.1 L/(m²h) at 66 °C and 61 °C digestate inlet temperatures during winter and summer, respectively. With internal heat recovery, the specific heat demand for MD was 80 kWh/m³ and 100 kWh/m³ in winter and summer, respectively. The unit cost of MD permeate was estimated to be 3.6 €/m³ and 4.1 €/m³ at a digestate feed temperature of 66 °C and 61 °C (with heat recovery), and 7.6 €/m³ and 9.1 €/m³ (without heat recovery) in winter and summer, respectively. However, cost sensitivity analyses showed that waste heat recovery and thermal energy cost variations had a significant impact on the MD permeate production cost. Nevertheless, the economic assessment indicated that the thermal integration of a biogas plant with industrial-scale MD digestate treatment capacity could be economically feasible, with winter being more economically favorable due to higher waste heat recovery. Full article

This paper presents the energy potential of biogas obtained from the anaerobic digestion (AD) of sewage sludge (SS) preceded by thermal hydrolysis (THP) using Cambi THP^® technology. The presented data are for the Tarnów (Poland) wastewater treatment plant for the year 2020. A detailed energy balance of biogas and its use in the cogeneration process and in the production of heat in the water boiler and the steam boiler is presented. The article contains data on the amount of processed SS and the content of dry matter and dry organic matter at different stages of the technological process. The annual plant operation resulted in the production of 3,276,497 Nm³ of biogas as a result of processing 8684 tonnes of dry solids (tDS) of municipal SS from the Tarnów wastewater treatment plant (WWTP) and regional WWTPs. The energy potential of the produced biogas was 75,347.06 GJ. The average calorific value of biogas was 23,021 kJ/Nm^3.. The obtained biogas production allowed us to cover the thermal energy demand of the THP 100%. The annual average specific biogas conversion rate during the study period was 0.761 Nm³/kg of dry organic matter reduced and the average organic matter content reduction in the sludge was 64.60%. Full article

The use of Stirling-cycle-based heat pumps in high-temperature applications and waste heat recovery at an industrial scale is of increasing interest due to the promising role in producing thermal energy with zero CO₂ emissions. This paper analyzes one such technology as developed by Olvondo Technology and installed at the pharmaceutical company AstraZeneca in Sweden. In this application, the heat pump used roughly equal amounts of waste heat and electricity and generated 500 kW of steam at 10 bar. To develop and widen the use of a high-performance high-temperature heat pump that is both economically and environmentally viable and attractive, various analysis tools such as exergy analysis and life cycle assessment (LCA) can be combined. The total cumulative exergy loss (TCExL) method used in this study determines total exergy losses caused throughout the life cycle of the heat pump. Moreover, an LCA study using SimaPro was conducted, which provides insight into the different emissions and the overall environmental footprint resulting from the construction, operation (for example, 1, 8, and 15 years), and decommissioning phases of the heat pump. The combined results were compared with those of a fossil fuel oil boiler (OB), a bio-oil boiler (BOB), a natural gas-fired boiler (NGB), and a biogas boiler (BGB). Full article