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Carbon dioxide (CO2) is the main contributor to greenhouse gases that affect global warming. The industrial sector is the third largest producer of CO2 and the cement industry is one of the industries that consistently produces the most significant CO2 emissions. The cement industry produces 5–8% of global CO2 emissions. Several methods for reducing specific CO2 emissions have been reported in the cement industry, including calcium looping, which uses the reversible reaction between calcination [calcium carbonate (CaCO3) decomposition] and carbonation [CO2 capture by calcium oxide (CaO)]. This work investigates calcium looping employing limestone obtained directly from several cement factories in Indonesia to observe the carbon-absorption characteristics of limestone from different mining locations. The experiment was carried out using a tube furnace equipped with a controlled atmospheric condition that functions as a calciner and a carbonator. X-ray diffraction and scanning electron microscopy with energy-dispersive x-ray spectroscopy characterization were conducted to analyse the changes in the experimental samples. The results demonstrated that the reactor configuration was capable of performing the calcination process, which converted CaCO3 to calcium hydroxide [Ca(OH)2], as well as the carbonation process, which captured carbon and converted it back to CaCO3. Parametric analysis was performed on both reactions, including pressure, temperature, duration, particle size and reaction atmosphere. The results show that the limestone obtained from all sites can be used as the sorbents for the calcium-looping process with an average reactivity of 59.01%. Limestone from cement plants in various parts of Indonesia has the potential to be used as carbon sorbents in calcium-looping technology. With a similar CO2 concentration as the flue gas of 16.67%, the experimental results show that Bayah limestone has the maximum reactivity, as shown by the highest carbon-content addition of 12.15 wt% and has the highest CO2-capture capability up to >75% per mole of Ca(OH)2 as a sorbent. Similar levels of the ability to capture CO2 per mole of Ca(OH)2 can be found in other limestones, ranging from 14.85% to 34.07%. The results show a promising performance of raw limestones from different mining sites, allowing further study and observation of the possibility of CO2 emission reduction in the sustainable cement-production process.

Biomass and organic solid waste are considered as very potential alternative energy sources in the future, leading to the realization of a clean and CO2-free energy system. Therefore, the effective conversion of biomass and organic solid waste to a secondary energy source is urgently demanded. In addition, hydrogen is considered very promising among the secondary energy sources due to its advantages of cleanliness, wide range of conversion and utilization technologies, high energy efficiency, and high gravimetric energy density. This paper reviews several possible routes and key conversion technologies of biomass and organic solid waste to hydrogen. Recent progress related to biological and thermochemical conversion technologies is described. Thermochemical route includes gasification, pyrolysis, steam reforming, partial oxidation, and thermochemical cycle; while biological route covers fermentation (dark and photo), biophotolysis (direct and indirect), enzymatic, and microbial electrolysis. In addition, several challenges regarding the conversion and utilization of biomass and organic solid waste to hydrogen are also discussed in order to clarify the feasibility of biomass and the organic solid waste-based hydrogen economy.

Hydrogen (H2) is a secondary energy source (energy carrier) which has advantages of high cleanliness and efficiency, leading to its potential utilization in the future energy system. However, H2 suffers a great challenge in its storage because of low volumetric energy density. Among the available technologies and media for H2 storage, ammonia (NH3) is considered very promising due to its characteristics of high hydrogen density, excellent storage, high stability, and matured technology and infrastructure. Currently, NH3 is massively produced through Haber-Bosch process conducted at high pressure and temperature. Therefore, large energy is consumed to synthesize NH3. There are several other alternative technologies for NH3 synthesis, including thermochemical, electrochemical, photochemical, and plasma-assisted processes. This paper reviews mainly both thermochemical and electrochemical NH3 production technologies, including their updates and challenges, and also by considering both technological feasibility and applicability. In addition, several projects and efforts carried out by several countries to utilize NH3 as potential fuel in the energy system are also overviewed. Furthermore, technological analysis, challenges, and recommendations are also provided with the objective of evaluating the potential adoption of NH3 in the future energy system.

This paper exhibits a method to predict the remaining service lifetime of inflatable rubber dam by considering the appearance of deep hole damage. The material used for the rubber dam is a composite comprising three layers of woven fabric as fiber and EPDM/SBR 64 474 rubber as a matrix. The service lifetime is predicted by calculating the degradation of rubber dam’s material properties. Simple Rate Law model and Time-Temperature Superposition model are employed to calculate the rubber properties degradation. A finite element analysis is then conducted to investigate stress and strain distributions which occur in the rubber dam membrane during operational loading. Furthermore, the effect of deep hole damage in the rubber dam, which is caused by improper maintenance, is modeled as well. The results show that a 7 mm depth of the hole can accelerate rubber degradation, which causes catastrophic failure. This can happen because two layers of the woven fabric in the rubber dam have been broken. Suggestion to hold up the degradation is also discussed.

Materials flow values are instrumental in many industries for controlling and simulating processes, designing new equipment as well as modifying existing plants. They are sometimes impossible to determine by direct measurement in an operating plant due to the very high temperatures. This study attempted to overcome the difficulties associated with this measurement by proposing a new method to calculate materials flow of a double-string suspension preheater type of cement plant with separate line and in-line calciners (SLC-I), with heat balance error less than 1%. This study was divided into two sequential parts, with the first part presented in this paper. The methodology of the first part was to solve the conservation law of the main clinker plant equipment, supported by Bogue’s equation, the heat of calcination, and the thermodynamic properties of the related materials. The least-square method was employed for solving the overdetermined system equations obtained in the second part. The results of the first part were: the ratio of heat formation to specific heat consumption was 52.13% (> 50%), and the gas exhausted from the plant yielded more than 117 MW heat equivalent, which can potentially be recovered for electricity production.

For Indonesia's renewable energy mix target in the electricity generation sector, biomass co-firing in existing Coal Fired Power Plant (CFPP) is one of the applicable methods in the context of Indonesia's electricity generation industry. Among the various applicable power plant, Circulating Fluidized Bed (CFB) boiler-type CFPP is one of the power plant types applicable for co-firing. As various CFB manufacturers claim, CFB boilers can consume substantial biomass fraction, up to 30% of the original fuel mass flow rate. However, biomass co-firing will increase the load factor of the boiler equipment, such as coal feeders and combustion air supply draft fans. This paper shows that up to 30% of biomass co-firing can increase coal feeder working-level until 100.68% with typical coal and 108.76% with design coal. Primary Air (PA) and Secondary Air (SA) fan load also increased to 100.86% compared to typical coal and 100.99% compared to design coal. As for Induced Draft (ID) fan loading can reach up to 101.10% with typical coal and 102.25% with design coal. Also, 30% biomass co-firing results in higher auxiliary power consumption. Draft fan power consumption increases by 31.43 kW with typical coal and 43.29 kW with design coal. This study recommends that power plant engineers conduct such analysis to compare the baseline power profile and equipment capacity to the off-design basis of high fraction biomass co-firing. The purpose of the analysis is to identify the various limiting factors that may arise from high fraction co-firing, such as limitation of draft fan capacity and/or reduction of efficiency that arise due to the increase in auxiliary power consumption.

Ammonia (NH3) is one of the most valuable chemicals due to its multipurpose utilization in many applications. Beside major application as fertilizer in agriculture, NH3 is a promising hydrogen (H2) carrier because it has a high content of H2 and technically available storage and transportation systems. At present, most of NH3 is synthesized from a series of steam reforming process to the feedstock of H2 and nitrogen (N2) production, followed with the catalytic Haber-Bosch reaction. In this study, an integrated system of N2 production system, NH3 synthesis system and a power generation process is proposed to produce NH3 efficiently. Thermochemical cyclic process of an endothermic reaction of Al2O3 reduction by carbon in N2 atmosphere, is coupled with oxidation/steam-hydrolysis of aluminum nitride (AlN) back to Al2O3, producing NH3 without catalyst and the need of H2 production system. The thermal energy required for reduction reaction is covered by the heat generated during exothermic reaction and combustion process, and the remaining heat is utilized in power generation. Heat circulation optimization is carried out by applying the enhanced process integration, resulting in a highly efficient system. The proposed system is analyzed through an adjustment of the main parameters: oxidation temperature, steam turbine inlet pressure, and temperature, to observe their effect on system performance and efficiency. The proposed system can reach a very high system efficiency of 69.3%. The oxidation reaction temperature is observed to play major role in determining the system performance due to temperature dependent NH3 yield.

A dry steam power plant utilizes geofluid, which is the saturated or superheated vapor generated in the Earth’s interior as the working fluid. Compared to the other cycles of a geothermal power plant, the dry steam cycle has an advantage of lower capital costs due to a simpler configuration and higher enthalpy, which results in a higher output capacity. However, in order to achieve a vapor state, higher temperatures and specific pressure are basically required. In this chapter, the system configuration of the dry steam cycle is initially explained, especially in terms of thermodynamics analysis. In addition, recent developments related to the dry steam cycle in order to enhance the system as well as improve the total energy efficiency are also discussed. Several case studies are also provided in order to give a more detailed description related to the dry steam cycle.

In many industries, energy auditing is important as the basis for controlling processes and designing additional equipment or modifying an existing plant. However, it requires detailed data of the materials flow, which often cannot be determined easily by direct measurement due to high-temperature limitations. This paper presents the second part of an integrated study to perform energy auditing in a separate line and in-line calciners (SLC-I) type cement plant. The second part of this study, as presented in this paper, focused on the materials flow calculation for eight separate cyclones and two calciners. The least square method was employed for solving the obtained overdetermined system equations. Using the operation data from Part 1 of the study, calculation of the detailed materials flow in each cyclone was executed. The results showed that the separation efficiency of cyclones 1A, 2A, 3A, 4A and 1B, 2B, 3B, 4B was 93.86%, 89.80%, 84.41%, 81.98% and 93.96%, 88.70%, 88.53%, 80.72% respectively and the estimated calcination percentage of kiln feed coming out of the ILC and the SLC was 85.3% and 56.3%, respectively. These values are impossible to be measured directly in the cyclones and calciners during plant operation.

Floating solar still is a suitable technology for remote or rural coastal area applications. The device should be made of low-cost materials available locally to provide more access to the broader community. However, the low-cost materials usually do not have the best physical properties, decreasing the overall solar still performance. This work demonstrated a low-cost floating solar still prototype entirely made of locally available materials. To further understand the influence of different parameters on the solar still performance and guide the prototyping process, we also performed the system's heat and mass transfer analysis. Our experimental results indicate a high absorber temperature (59.5 °C), even on a cloudy day. Our model also fits the temperature measurement reasonably. However, the recorded overall efficiency still suffers mainly due to the collection system, which decreases the overall performance; an example of a practical challenge, which is often overlooked but plays a crucial role in increasing the readiness level of the prototype.

Silicon nanocrystals (SiNCs) featuring size-dependent novel optical and electrical properties have been widely employed for various functional devices. We have demonstrated SiNC-based hybrid photovoltaics (SiNC-HPVs) and proposed several approaches for performance promotion. Recently, owing to the superiorities such as low power operation, high portability, and designability, organic photovoltaics (OPVs) have been extensively studied for their potential indoor applications as power sources. SiNCs exhibit strong light absorption below 450 nm, which is capable of sufficient photocurrent generation under UV irradiation. Therefore, SiNC-HPVs are expected to be preferably used for energy harvesting systems in indoor applications because an indoor light source consists of a shorter wavelength component below 500 nm than solar light. We successfully demonstrated SiNC-HPVs with a PCE as high as 9.7%, corresponding to the output power density of 34.0 μW cm−2 under standard indoor light irradiation (1000 lx). In addition, we have found that SiNC defects working as electron traps influence the electrical properties of SiNCs substantially, a thermal annealing process was conducted towards the suppression of defects and the improvement of the SiNC-HPVs performance.

The rapid development of renewable energy generation and electric vehicle utilization has effect on increasing demand of battery performance as the energy storage, including lithium-ion and well-developed and commercially available type of battery. In order to increase energy density, silicon is employed as anode electrodes due to its high specific capacity. However, silicon electrode has a limited cycle due to expansion and shrinkage during operation cycle, which leads to the mechanical failure. Nanostructured silicon has been reported to enhance the life cycle with various combination with other materials, including polymer. In this paper, silicon nanoparticles (SiNPs) are produced plasma chemical vapor deposition with controllable particle size. SiNPs with different particle size were produced while maintaining the crystallinity and narrow size distribution. Nanocomposite of SiNPs and polymer were produced by solution processing at low temperature, enabling a low cost of fabrication and preserves the unique properties of SiNPs. Material characterization on nanocomposite provides a potential application of SiNPs as anode material in li-ion batteries.

Hydrogen (H2) has been widely studied as a promising energy carrier. However, H2 has a challenging technology in the storage and transportation. Since, it is a critical technology for H2 energy system implementation, the H2 storage and transportation is remain to be solved. This work proposes an integrated system of energy utilization of ammonia (NH3), which has been known as one of the promising methods of H2 storage. The system includes the decomposition of ammonia (NH3) through thermo-catalytic process and also power generation process using H2 as fuel. The heat generated from oxy-fuel combustion of H2 is utilized to supply the thermal energy required for the endothermic process of NH3 decomposition, and the remaining heat is converted to electricity by a combined cycle. A portion of exhaust gas is recirculated to the combustion chamber, and the heat circulation of the system is designed and optimized based on enhanced process integration (EPI), resulting in a highly efficient system. The result shows an optimum configuration of the integrated system with a recirculation fraction of 0.5-0.55, which is resulting in high system efficiency of 51.4%. The proposed work demonstrated an integrated system of H2-based energy utilization of NH3 with CO2-free while maintaining a highly efficient system.

A novel type silicon nanocrystal-based hybrid solar cell is demonstrated here, where two individual junctions are designed carefully and arranged in parallel with each other. It is found that complementary absorption can be realized by double parallel junctions, and more photons in a wide energy range can be absorbed. As a result, device efficiency has been enhanced more than twice compared to single junction reference device. In addition, its working principles are also studied extensively.

Despite the potential of hydrogen (H2) as an energy carrier, its storage and transportation are challenging and become two of the keys in the successful adoption of H2. Among various methods of H2 storage, ammonia (NH3) shows very promising characteristics of high gravimetric and volumetric H2 densities, possibility for direct utilization, and established infrastructure. This work proposes an integrated system consisting of NH3 decomposition through a thermo-catalytic process and H2-based power generation. The thermal energy demanded for the endothermic reaction of thermo-catalytic NH3 decomposition is supplied from the combustion reaction of H2. The remaining heat is used to generate the electricity using a combined cycle, and the overall heat circulation is optimized based on enhanced process integration (EPI) to achieve a highly efficient system. Four types of catalyst (ruthenium, molybdenum nitride, nickel oxide, and lithium nitrohydride), having different reaction temperature and conversion rate, are employed in the system and their performance are then evaluated. The results show that both parameters have an influence in determining the system efficiency and power generation efficiency with different behavior. The conversion rate has a strong effect on the system efficiency as it determines the amount of H2 produced from the NH3 decomposition process. Meanwhile, the reaction temperature has a major effect on the power generation efficiency. The proposed system with lithium nitrohydride shows the highest power generation efficiency of 43.7%, while the highest overall system efficiency of 48.3% can be achieved when ruthenium catalyst is employed.

Silicon nanocrystals (SiNCs) have been observed to have size dependent thermal properties, other than well-known optical and electrical properties, which has been widely studied and applied to the various application of optoelectronic devices. However, the effect of nano scale particles in nanostructured materials remains unclear with unspecified determining factors of thermal transport. In this work, well crystalline SiNCs and amorphous silicon nanoparticles (a-SiNPs) with a mean diameter of 6 nm and narrow particle size distribution were synthesized and dispersed in polystyrene (PS) matrix by solution procession to produce nanocomposite material. The thermal conductivity of SiNCs/PS nanocomposite sample were measured base on thermal diffusivity, specific heat, and density that were measured by Temperature Wave Analysis (TWA), Differential Scanning Calorimeter (DSC), and Hydrostatic Densimeter, respectively. Thermal conductivity measurement result of SiNCs/PS shown decreasing value when particle fraction increased, although SiNCs has higher thermal conductivity than PS. Furthermore, the comparison with amorphous filler (a-SiNPs) shown insignificant discrepancy, indicating the phonon scattering at material’s interface boundary played a dominant factor in determining the thermal transport in nanocomposite materials. Also, thermal conductivity models that include thermal boundary resistance (TBR) were calculated and compared with the measurement result. Thermal conductivity models showed good agreement, and minimum deviation with estimated TBR of ca. 4×10−7 m2K/W. Moreover, the fabrication and measurement processes were carried out at low temperature, which allows preservation of unique size dependent properties of nano scale particles and silicon ink utilization that opens the possibility of a broad range of inexpensive application.

Current researches on silicon nanoparticles (Si NPs) are mainly focusing on the crystallized one, while some basic optical and electrical properties of particles with different crystallinities are still unclear. Hence, in this work, Si NPs with different crystallinities were easily fabricated with non-thermal plasma by changing the input power, and the crystallinity effects on the optical, electrical, and photovoltaic properties of particles were extensively studied. It is found that amorphous particles have strong light absorption, especially in short wavelength region; however, the carrier mobility is relatively poor. This is mainly because of numerous dangling bonds and defects that exist in Si NPs with poor crystallinity, which work as carrier trapping centers. As a result, the efficiency of Si NPs-based hybrid solar cells increases monotonously with particle crystallinity. This indicates that highly crystallized Si nanocrystals with less defects are desirable for high efficiency solar cells.