Cogeneration Of Electricity Research Articles

Synergistic solar electricity-water generation through an integration of semitransparent solar cells and multistage interfacial desalination

Energy shortage and freshwater scarcity are critical challenges for the sustainable development of the society. The photovoltaic-thermal (PVT) hybrid system offers a promising strategy by harnessing solar energy for electricity and water cogeneration. However, existing systems suffer from relatively low efficiency due to incomplete solar spectrum utilization. To address this, we propose a novel PVT integrated system that combines semi-transparent solar cells and multistage interfacial stills to maximize solar spectrum utilization, allowing for efficient electricity and freshwater co-production. Experimental results demonstrate a record-high solar-to-vapor efficiency of 210% with a production rate of 3.17 L m-2 h-1 under one-sun, while maintaining an uncompromised electrical efficiency of 19.57%. Furthermore, we employ a verified theoretical framework to provide optimized strategies for concurrent enhancement of electricity-water production, by improving internal heat and mass transfer and effectively reducing the thickness of the interstage air gap. Moreover, we introduce a non-contact model for system structure optimization proposed to match the high transmittance of solar cells. This work realizes full solar spectrum utilization to cogenerate electricity and freshwater, offering optimized strategies from the thermal perspective for future research.

Heat energy utilization of a double-flash geothermal source efficiently for heating/electricity supply through particle swarm optimization method

The principal aim of this article is to optimize the thermal and electrical efficiency of a geothermal combined heat and power system through metaheuristic particle swarm optimization (PSO) method. The objective of this research is to conduct a thorough analysis of the incorporation of metaheuristic PSO technique, with a specific emphasis on the potential advantages and obstacles associated with the utilization of metaheuristic approaches in improving the effectiveness of geothermal energy systems. The utilization of a double-flash geothermal system in conjunction with a transcritical carbon dioxide Rankine cycle is utilized for the co-generation of electricity and thermal energy. The research utilized a PSO method to enhance power generation, heating capacity, and overall system efficiency. The PSO algorithm was employed to determine the optimum operational parameters for a pressure level of 820 kPa and a pressure ratio of 1.59, leading to the maximization of power output to 2591.4 kW The PSO algorithm effectively identified the optimal operational parameters as a pressure of 820 kPa and a pressure ratio of 1.59, resulting in the achievement of a peak power output of 2591.4 kW. The methodology has determined that a pressure of 916.4 kPa and a pressure ratio of 1.5 represent the optimal parameters for achieving a maximum heating capacity of 12329.1 kW.

Green conversion of waste polyester into few-layer graphene for interfacial solar-driven evaporation and hydroelectric electricity generation

The coupling of solar-driven interfacial evaporation with hydrovoltaic technology is emerged as a hopeful approach to alleviate energy crisis and freshwater shortage. However, constructing low-cost evaporators with high-performance freshwater and electricity co-generation and unveiling the co-generation mechanism remain a grand challenge. Herein, we report the green transformation of waste poly(ε-caprolactone) into graphene through a salt-assisted carbonization strategy and build a flexible bi-functional graphene-based evaporator for freshwater and electricity co-generation. The graphene exhibits a typical wrinkled structure with curved edges and is composed of 7–8 discontinuous layers with rich oxygen-containing groups. The graphene-based evaporator exhibits excellent sunlight absorption (98%), photo-to-thermal conversion property, good water transport ability, low water evaporation enthalpy, and low thermal conductivity of 0.06 W m−1 K−1. The evaporator not only exhibits a notable water evaporation rate (2.92 kg m−2 h−1), but also achieves the maximum output voltage of 310 mV, surpassing many previously reported evaporators/generators. The result of molecular dynamics simulation proves the diffusion difference between H+ and OH− in water and graphene, which eventually leads to the voltage generation. Not only will this work help to improve the upcycling of waste plastics and achieve carbon neutrality, but it will also open an avenue for co-generation of freshwater and electricity.

Hierarchical TiO2-coated metal-organic framework-derived carbon material for efficient co-generation of drinkable water and electricity

Co-generation of drinkable water and electricity through interface solar steam generation process is gradually becoming the preferred strategy to solve the current energy shortage and freshwater resources crisis. Inspired by the biological channel structures, flexible carbonized TiO2@Co-MOF nickel foam (CTCNF) based photothermal material with hierarchical nano-arrays structure is successfully fabricated on nickel foam surfaces by atomic layer deposition combined with an ingenious carbonization scheme, which endows CTCNF with combined excellent abilities including seawater desalination, evaporation-induced electricity generation, and wastewater purification, that is a three-in-one photothermal configuration. With the synergistic photothermal effect and hierarchical structure, CTCNF achieves a solar absorption efficiency of 93.65 %. Moreover, benefiting from its abundant oxygen- and nitrogen- containing functional groups, CTCNF not only possesses excellent hydrophilicity and salt resistance, but also reduces the water evaporation enthalpy (from 2453.3 J g−1 to 1378.6 J g−1). Importantly, combined with ingenious design of the evaporation device, CTCNF not only capture energy from environment during the evaporation process, with an evaporation rate of 3.60 kg m−2 h−1 and an evaporation efficiency of 109.9 % under 1 sun, but also obtains an open-circuit voltage (Voc) of 151.15 mV. This enriches the design ideas of high-performance photothermal materials for efficient co-generation of drinkable water and electricity.

Opportunities and challenges for direct electrification of chemical processes with protonic ceramic membrane reactors

Abstract The necessity of developing sustainable energy storage and process electrification technologies has built an unprecedented momentum for protonic ceramic membrane reactors (PCMRs). PCMRs are practically electrolytic cells (or even fuel cells in case of cogeneration) that extend beyond the classical approach of electrolysis towards producing a variety of value-added chemicals or fuels. The use of a ceramic electrolyte membrane to electrochemically supply or remove hydrogen offers unique advantages, such as process intensification, cogeneration of chemicals and electricity, as well as the shift of the chemical equilibrium to the desired products. During the last few years, rapid progress has not only been made in the cell components, but also for upscaling, which reveals their high potential in terms of efficiency and flexibility. Herein, we discuss recent innovations and breakthroughs in the PCMR concepts and components for different processes, while we attempt to identify challenges that may hinder their wide deployment. Closer to commercialization is the production of pressurized hydrogen from sustainable sources, i.e. biogas and ammonia, while significant advancements have been made in reversible H2O electrolysis systems. CO2/H2O co-electrolysis, hydrocarbon conversion and ammonia synthesis have been also successfully demonstrated, albeit with different obstacles related to the product selectivity and stability of the cell reactors. We conclude that future projects should target beyond the experimental discovery of materials, such as, multiscale modeling that would aid optimization of the involved surfaces, interfaces, and the operating parameters towards enhancing the viability of electrosynthesis in PCMRs.

Three birds with one stone: Constructing Janus multilayer carbon fabric to boost solar-driven interfacial evaporation, electrical power generation and inhibit VOCs volatilization

Solar-driven interfacial evaporation technology has great potential to address both the freshwater and energy crises in a low-cost, environmentally friendly, and sustainable method. How to achieve highly efficient freshwater and energy harvesting simultaneously is still challenging. Here, a Janus-structured multilayer carbon fabric (JMCF) solar evaporator is proposed to effectively overcome the bottleneck in the cogeneration of fresh water and electricity. The Janus structure of the multilayer fabric effectively controls water supply upwards, improves light absorption and photothermal conversion, increases evaporation surface area, facilitates water vapor escape and inhibits VOCs volatilization. Accordingly, the optimized JMCF solar evaporator can achieve a high evaporation rate of 3.12 kg m-2h−1 and an output voltage of 0.577 V in 3.5 wt% seawater under 1 sun irradiation. In addition, the JMCF evaporation system also demonstrates good working stability, self-cleaning capacity, environmental adaptability, and economic feasibility. This work provides new ideas and inspiration for the design of high efficiency solar-driven interfacial evaporation system to address the freshwater scarcity, energy crisis, global change problem, etc.

Berlin Green-Coated Cellulose Paper for Hydrovoltaic Electricity and Solar Steam Cogeneration

Berlin Green-Coated Cellulose Paper for Hydrovoltaic Electricity and Solar Steam Cogeneration

Effect of temperature on water evaporation coefficient (E) in a thermobalance: A solar-driven steam generation approach

During this investigation, the variation of the water evaporation phenomenon with the defined drying temperature and mass of water was analyzed, five levels were studied (50, 60, 70, 80 and 90 ℃), finally a correlation between temperature and evaporation rate was generated. With the study carried out, it was defined that the water evaporation velocity can be calculated with an initial mass of 35 g at 90 ℃, while the necessary time for the determination was 120 min. In addition, it was determined that the evaporation velocity follows a quadratic behavior with temperature, according to the experiments carried out with the Sartorius MA-100 balance, while the maximum deviation recorded was 0.349 mmol/m2s for a temperature of 80 ℃. It is concluded that the determination of the water evaporation velocity is highly dependent on the temperature and mass of water. Furthermore, this study can be used as a basis for future studies aimed at improving the efficiency of processes such as steam and electricity cogeneration.

Economic Analyses of a New Power and Cooling System at Low Temperature Applications

Recent research suggests that the implementation of more efficient combined cooling and power systems, which enable the cogeneration of electricity and cooling, can enhance the efficiency of hybrid plants. The present investigation is motivated by finding that, in the literature review on combined power and cooling systems, there is very limited information on the coupling of the organic Rankine cycle (ORC) and the ejector refrigeration cycle (ERC) with low sink temperatures. A suggested approach to do this involves using hot exhaust gas and waste heat engines to power an ORC hybrid system. To enhance the ORC–ERC system's performance, three heater configurations use waste heat from the ORC turbine exhaust, ejector, and engine waste heat to heat the working fluid. Renewable energy sources are the primary focus of most current research initiatives. The present research focuses on unique ORC and ERC systems, considered as combined power and cooling systems, with the goal of improving exergy performance at low temperatures. The suggested ORC–ERC can generate energy destruction of 69.85 kW at a source temperature of 155 °C, with an exergetic efficiency of 76.9% at the turbine. Setting the entrainment ratio at 0.5 results in a total sum unit cost of products (SUCP) of 465 $/kW‐h for the ORC–ERC. Furthermore, the 37.83% exergy destruction ratio introduces heat exchanger 2 (HE2) as the primary cause of the suggested ORC–ERC's irreversibility. A detailed parametric study reveals that altering the hot source temperature and entrainment ratio improves the system's SUCP. The current examination at high sink temperatures may be expanded to an advanced exergoenvironmental investigation.

Biomass microcrystalline cellulose based solar evaporator with aligned channels for clean water and electricity co-generation

Solar-driven interfacial evaporation co-generation (SDIE-CG) technology can effectively solve problems such as low latent heat utilization in the evaporation process, which provides a reliable solution to the problem of hydropower shortage in remote areas. Herein, we report a tea residue microcrystalline cellulose (TMCC) aerogel (abbreviated as TCA), in which TMCC is regenerated by dissolution through the co-solvent method, and microcrystalline cellulose is rearranged by the directional slow freezing technique to get a TCA with a directional aligned pore structure, resulting in a good mechanical and salt-resistant property. Due to the internal doping of carbon black particles, the TCA has an average ultra-high absorbance of 97.46 %. The evaporation rate of TCA is up to 3.066 kg m−2h−1 under 3 kW m−2 illuminations. The maximum output voltage of the TCA is 44.801 mV under 2 kW m−2 illuminations through the introduction of a suitable wind-assisted hydropower generation device. In addition, the TCA can effectively purify the wastewater containing traditional Chinese medicine, and the chemical oxygen demand (COD) value in wastewater shows a significant decrease after treatment. It is worth noting that TCA can maintain structural integrity and stable evaporation performance in saltwater under extreme pH conditions (2<pH<11), and has potential application value in water treatment and cogeneration.

Inclined interfacial solar evaporator using polypyrrole/polydopamine composites for efficient desalination and salinity-driven electricity generation

Water-electricity cogeneration using solar energy is an innovative technology to address global freshwater shortages and energy demands. Here, we designed an inclined evaporator based on polypyrrole/polydopamine photothermal materials for efficient water evaporation and electricity cogeneration. Due to the ingenious inclined structure of the evaporator, the water transport was highly promoted by gravity and siphon effect. This process not only improves the evaporation flux of water, but also create a salinity gradient that can be used for further electricity generation. The designed inclined PPy/PDA@MF evaporator exhibits an evaporation flux of 3.02 kg m−2 h−1 under one sun irradiance and achieves an open-circuit voltage of 56 mV during the electricity generation.

A system for efficient and sustainable cogeneration of water and electricity: Temperature difference induced by photothermal conversion and evaporative cooling

Solar energy, with its sustainable properties, has garnered considerable attention for its potential to produce green electricity and clean water. This paper proposes a multistage energy transfer co-generation system (MWCNTs-covered thermoelectric module with aerogel and cooler, AC-CTEM) combining power generation and evaporative cooling. On the light-absorbing surface, the hot side of a thermoelectric module is covered with a hydrophobic coating made of PDMS and MWCNT. The cold side transfers heat to the evaporation zone using a heat sink. Aerogel evaporators are cross-linked with chitosan and polyurethane, which reduces the enthalpy of evaporation and facilitates efficient interfacial evaporation to remove heat and return it to refrigeration. Additionally, with the addition of Fresnel lenses and wind energy to the enhancement device, the system achieved an evaporation rate of 3.445 kg m−2 h−1 and an open-circuit voltage of 201.12 mV under 1 kW m−2 solar irradiation. The AC-CTEM system also demonstrated long-term stability and effectiveness in treating various types of non-potable water. Furthermore, we demonstrated the practical utility of the system by successfully cultivating grass seeds and powering electronic equipment. The AC-CTEM system exemplifies a practical energy-saving approach for the development of highly efficient co-generation systems.

Hybrid thermochemical cycle for cold and electricity cogeneration: Experimental and numerical analyses of the process behavior and expander-reactor coupling

The valorization of waste heat to respond to the increase demand on electricity and cooling is an important energetic challenge. For this purpose, a hybrid thermochemical cycle is proposed. This discontinuous sorption cycle is based on reversible endothermic/exothermic solid–gas reactions, and it is able to recover medium grade waste heat (between 150 and 250 °C) to valorize it in a second step by providing cold production at its endothermic component and mechanical work thanks to the integration of an expander on the gas line. Moreover, the two-step operation leads to a storage functionality. This paper presents an experimental study of this new hybrid cycle prototype in different operating conditions, and a sensitivity study of the design parameters of the prototype performed through a steady state model. The experimentation shows the influence of the electrical load applied to the generator on the coupling between the expander and reactor, by affecting the rotational speed, the torque of the expander and the pressure of the reactor. The analysis of the experimental results highlighted the effect of two main limitations in the prototype: the internal leaks on the expander side (unlubricated scroll expander) and the heat transfer on the reactor side. A numerical parametric study is done on these two parameters, showing the possibility of cogenerating 125 W of mechanical power and 2.3 kW of cold for defined enhanced parameters of the prototype. These promising results prompt the next step of conducting a detailed exergetic analysis of the cycle. This analysis will aim to identify the primary sources of exergy destruction and to explore ways for reducing them by minimizing main irreversibilities in the cycle.

Performance and Stability of Pt-Based Alloy Catalysts for High-Temperature PEM Fuel Cell Application

Ever increasing energy demands and push for low-carbon imprint technologies require at least partial replacement of internal combustion engines. For many stationary and heavy-duty applications, high-temperature fuel cells with proton-exchange membrane (HTPEMFC) represent a feasible solution for electric energy and heat co-generation. HTPEMFC operates with hydrogen as a fuel and atmospheric oxygen as an oxidant. The core of the technology is membrane (PEM), based on polymer doped with phosphoric acid, enabling operating temperature between 120 and 200 °C. Elevated temperature is necessary for heat cogeneration and enables use of hydrogen produced from fossil fuels and other sources without additional demanding purification. On the other hand, in synergy with phosphoric acid, it also accelerates degradation processes in HTPEMFC, making relatively high loadings of Pt on the electrodes necessary.The basic catalyst used in HTPEMFC comprises Pt nanoparticles on carbon black graphitized support, exhibiting reasonable activity and stability. Phosphoric acid is an adsorbing electrolyte, decreasing Pt catalyst activity by blocking the active Pt surface with phosphate anions and products of phosphoric acid reduction on the anode. Additionally, dissolution of Pt in phosphoric acid at elevated temperature is relatively high, leading to pronounced Ostwald ripening process on the cathode resulting in the progressive loss of Pt surface area. Both these effects can be, to a certain degree, mitigated by the introduction of highly active, Pt-based alloy catalysts on stable, carbon-based supports. Nanoparticles with Pt-rich shell and intermetallic Pt-X core can have activity superior to Pt, lower susceptibility to phosphate adsorption and, possibly, different kinetics of degradation. Introduction of novel, oxidation-resistant supports can further improve catalyst durability by nanoparticle-support interaction and minimize nanoparticle sintering due to support corrosion.Accordingly, this study investigates possibility of introduction of Pt-Co and Pt-Ni nanoparticular catalysts on supports including Ketjenblack and reduced graphene oxide to HTPEMFC. The study is divided to stages, including the investigation of alloying metal dissolution in phosphoric acid at elevated temperatures, determination of catalyst activity at conditions relevant to HTPEMFC operation using thin film-modified rotating rod disc electrode and finally, single cell testing. Leaching of Pt alloy catalysts proved that during relatively short time, majority of alloying metal is lost in case of Ketjenblack support. However, supporting of Pt alloys on reduced graphene oxide significantly improved alloy stability. The activity towards oxygen reduction reaction of Pt alloy catalysts was in majority of cases superior to commercial Pt catalyst, underlining the positive effect of alloying metal presence. Single cell experiments with Pt-Co and commercial Pt catalyst proved feasibility of alloy catalyst application. When used on the cathode and commercial Pt catalyst on the anode, Pt-Co catalysts led to superior cell performance in comparison with cell utilizing commercial Pt catalyst on both electrodes. Moreover, the performance of cells with Pt-Co on the cathode progressively improved during 300 hours of operation, pointing out to the combination of dealloying and restructuring of nanoparticle. In line with these results, it is evident that Pt alloy catalysts are an interesting alternative to Pt catalysts and, after optimization of alloy nanoparticle-support combination, can lead to improved performance and stability of HTPEMFC, making the technology even more attractive for market.The study was funded by the Czech Science Foundation (GAČR), project No. 22-23668K.This work was supported by the project "The Energy Conversion and Storage", funded as project No. CZ.02.01.01/00/22_008/0004617 by Programme Johannes Amos Commenius, call Excellent Research.

PVA/cellulose hydrogel with asymmetric distribution of MoS2 for highly efficient solar-driven interfacial evaporation and electricity generation

Population growth and economic globalization have exacerbated freshwater shortages and energy crises, and solar-driven interfacial evaporation (SDIE) offers a promising solution due to its environmental friendliness, accessibility, and sustainability. However, the highly efficient cogeneration of freshwater and electricity using the SDIE process is a challenge. Herein, a PVA/cellulose hydrogel with asymmetric distribution of MoS2 is proposed as a highly efficient SDIE system to overcome the bottleneck in the cogeneration of freshwater and electricity. By applying material genome engineering and microstructure regulation to improve light harvesting, energy efficiency, evaporation performance, and vapor escape. The evaporation rate of the PVA/cellulose evaporator could reach 3.23 kg m−2 h−1 when desalinating 3.5 wt% seawater under 1 sun and remained basically stable during the long-term continuous evaporation. In addition to desalination, the prepared evaporator also has a potential application in the cyclic utilization of the industrial and domestic wastewater. The synergistic effect of the electron double layer effect and the seawater battery principle produces a high output voltage of 0.714 V. Meanwhile, the optimized solar evaporator demonstrates good mechanical properties, salt resistance, environmental adaptability, and carbon emission economy. This work provides new insights into efficient seawater desalination and power generation, and inspires further research on multifunctional solar-driven interfacial evaporation systems to effectively address water scarcity and energy crises.

Boosting nitrate electroreduction to ammonia on atomic Ru-Co pair sites in hollow spinels

Electrocatalytic nitrate reduction reaction (NO3RR) to ammonia (NH3) provides a promising way to simultaneously remove widespread nitrogen pollution and electrify NH3 manufacturing. However, developing suitable electrocatalysts to efficiently convert NO3--to-NH3 remains a great challenge because of the slow kinetics of NO3RR and competitive hydrogen evolution reaction (HER). Herein, we reported a novel method to incorporating Ru single atom into hollow Co3O4 to construct atomically dispersed Ru-Co pair sites (Ru1-Co/HCO) for efficient NO3- electroreduction to NH3, with a maximal NH3 Faradaic efficiency of ∼100 % and a yield rate as high as 7.02 mg h−1 cm−2 (11.0 mg h−1 mgcat−1). The NO3RR activity can be explained by the synergistic tandem effect of Ru1-Co pair sites, where Ru sites are responsible for activating NO3- and stabilizing the intermediates, and neighboring Co site promotes water dissociation to generate active hydrogen (*H) for accelerating intermediate hydrogenation on Ru sites, alleviating the site competition between NO3RR and HER. A Zn–NO3- battery coupled with in-situ NH3 recovery device was also assembled to achieve the co-generation of high-purity NH4Cl fertilizer and electricity. Our work paves a new way for boosting NO3RR activity via constructing dual active sites.

Thermodynamic analysis of two very-high-temperature gas-cooled reactor-driven hydrogen and electricity cogeneration systems under off-design operating conditions

This study conducts a thermodynamic analysis for two very-high-temperature gas-cooled reactor-driven hydrogen and electricity cogeneration systems integrating an iodine-sulfur cycle and a helium turbine direct cycle under off-design operating conditions. Control strategies are proposed based on inventory control. The calculation model is established for the main components of the system under off-design conditions. Two operation modes are proposed, one is to maintain the split ratio at the reactor outlet at the rated value, and the other is to maintain the hydrogen generation rate at the rated value. The off-design performance of the two systems under partial load in two modes is analyzed. For Systems 1 and 2, the suggested lower limits of reactor thermal power are 68.80 % and 69.00 % of the rated value in mode 1, and 72.04 % and 64.98 % in mode 2. As the reactor thermal power decreases from the rated value to the suggested lower limit, in modes 1 and 2, the hydrogen-electricity efficiency of System 1 decreases from 37.46 % to 36.20 % and 31.81 %, and that of System 2 decreases from 42.40 % to 41.45 % and 35.21 %. The decrease in overall efficiency is more significant in mode 2.

Excess energy recovery from a stand-alone PV system for freshwater production using RO unit: Techno-economic analysis

A techno-economic assessment of electricity and freshwater cogeneration system powered by a standalone solar PV system is investigated under weather conditions of Al-Khobar City, Kingdom of Saudi Arabia. The excess electricity generated by the PV system is used to operate Reverse Osmosis (RO) desalination unit using three alternative storage types: Battery, Water-Tank, and hybrid Battery/Water-Tank storage system. The RO desalination plant is mathematically modeled, and its hourly specific energy consumption is predicted by taking into consideration variations in pressure and temperature for one full year using Engineering Equation Solver (EES) software. Then, a MATLAB code is developed and used to optimize the PV array with the three alternative storage options. A novel indicator called the Shortage of Water Supply Probability (SWSP) is introduced and used to optimize the storage size and to ensure satisfying water demand. Results showed that the lowest levelized cost of water (LCW = 1.874 $/m3) is obtained when operating the RO desalination plant with a hybrid Battery/Water-Tank storage system. However, LCW is 2.892 and 2.647 $/m3 when battery or water-tank storage systems are used, respectively. From an environmental point of view, utilizing renewable energy to run the cogeneration system saved 131 tons/year of CO2 emissions.

Greenhouse gas emission implications of small-scale sugarcane farmers’ trash management practices: A case for bioenergy production in South Africa

Sugarcane trash is a source of biomass available for energy generation. However, this potential has not been explored in the South African small-scale sugarcane sector. The current trash management practices of farmers, especially, pre-harvest burning, have huge negative environmental implications. Sustainable management of sugarcane trash could help address several challenges in the sugarcane industry including the high cost of irrigation. Therefore, this study is meant to assess small-scale growers’ trash management practices and their implications on greenhouse gas emissions. It also ascertains the potential for using sugarcane trash in the co-generation of electricity. The study was conducted in two communities in KwaZulu-Natal and Mpumalanga provinces with 330 small-scale farmers. A probit regression was used to determine factors that influence farmers’ trash management practices. Other analyses such as estimations of the amount of available trash, burning emissions and potential energy from sugarcane were informed by previous studies. The findings showed that pre-burning of sugarcane is a common practice among smallholder producers in South Africa. However, some farmers have attempted to move away from this practice opting to leave their sugarcane in the field or use it for compost. The farmers’ burning of sugarcane releases an estimated 0.08 tCO2-e per ha into the atmosphere. In total, the estimated greenhouse gas emissions from sugarcane burning of all small-scale growers in the two provinces are 725 tCO2-e per annum. The findings also revealed that having more land, poor endowment with psychological capital, lack of access to extension, limited resources, and working in silos compound the practice of burning sugarcane. The estimated energy potential from small-scale sugarcane producers in the country, using a 50 % recovery efficiency and 36 % energy conversion efficiency is 150,323.3 MWh. The study proposes several recommendations for improving trash management practices and initiating the co-generation of electricity from trash in the small-scale sugarcane industry.

Electricity Cogeneration Potential in Minas Gerais Cement Industry with Thermodynamic Cycles

To assess the electricity cogeneration potential in the Minas Gerais cement industry with thermodynamic cycles is the main purpose of this study. The potential was estimated based on Minas Gerais cement sector data. The Kalina cycle, the organic Rankine cycle, and the conventional Rankine cycle were technically and economically assessed. The technical evaluation considered the thermodynamic modeling with optimization including the mass, energy, entropy, and exergy balances and the heat transfer calculations for heat exchangers. The economic evaluation considered the economic modeling including the calculation of electric power generated specific cost, the total investment, cash flow, and payback. The result shows that the greatest irreversibilities are concentrated in the turbines and evaporators. The Kalina cycle confirmed more generated power and exergetic efficiency, but in terms of thermal efficiency, the values were very similar between the cycles. The three cycles can cover more than 35% of the energy demand, which means a considerable reduction in cement manufacturing costs. All cycles reveal a payback value lower than 3 years, a considerable value of cash flow, and high competitiveness in the current tariff scenario. The electricity cogeneration potential in the Minas Gerais cement industry is near 100 MW, and it is in the south-central region of Minas Gerais, where there is a greater population and energy demand concentration. This potential could save emissions of around 282,913 tCO2/year.