Search Results (13)

Direct lithium extraction (DLE) of brines after geothermal power production offers opportunities to produce environmentally benign “green” lithium; however, some environmental impact is inevitable. We examined solid waste production at geothermal power plants in southern California that are also locations for planned DLE facilities. Currently, the geothermal plants in this region produce approximately 79,800 metric tons (wet weight) per year of solid waste, which represents about 28 metric tons per GWh of net electricity production or approximately 500 mg solids per kg geothermal brine. Approximately 15% of this waste requires management as hazardous waste. Solids produced during power production represent about 0.2% of the total dissolved solids in the brine. Lithium production will require the removal of silica, iron, and other metals as part of the DLE process. Using a mass balance approach, we calculate that precipitation of silica and metals could produce up to an additional 6800 mg solids per kg brine. Calcium occurs at very high concentrations, and the amount of solids disposed in landfills will be dependent on the amount of calcium removed during lithium recovery. Our analysis shows that evaluation of brine chemistry in the context of the DLE process is useful for evaluating the potential solid waste impacts of producing lithium from brines. Full article

Many countries, including Indonesia, have abundant renewable energy sources (RES), but the share of RES in the current national energy supply is still insignificant. The study aimed to investigate and provide the most feasible combinations of RES that meet domestic electricity demand. For Java and Bali, Indonesia, initially, 35 scenarios, given 4 primary RES (solar, wind, hydropower, geothermal) and municipal solid waste, were assessed based on economic and environmental indicators. This explorative data-driven study found that the existing capacity could only meet 51% of the electricity demand. However, the proposed energy mixes could cover 100% of the electricity demand in 2020 with a required capacity of 8.32–19.10 GW, varying on each scenario. The feasible energy mixes can reduce CO₂ emissions by 90–94% compared to a fossil energy mix with gas-fired power plants. The installation, and operation and maintenance costs per life cycle can range from 29–50 and 4–16 billion dollars. The wind-based energy mix, with installed capacities of geothermal (1.16 GW), hydropower (2.87 GW), solar (0.003 GW) and municipal solid waste (0.18 GW) in 2020, showed the highest return on investment (139% ROI) and smallest CO₂ emission with highest CO₂ reduction (94%). This study provides a scientific method of selecting, projecting, and evaluating viable RES combinations for generating electricity without using fossil fuels. Full article

In this paper, an electrical generator is presented for the exploitation of alternating energy. Some renewable sources are directly available in such forms, such as the wave power obtainable from the sea, but most of them can be converted to alternative forms; therefore, the proposed generator can be applied to different kinds of renewable sources. In particular, the proposed system is thought to be coupled with a thermoacoustic engine, which converts heat into mechanical vibration without using solid moving parts. This opens the proposed system to the use of most thermal sources, such as solar radiation, waste recovery, geothermic, car exhaust, and others. The object of of this present work concerns the transformation of alternating mechanical energy into electricity by using a specific type of magnetohydrodynamic (MHD) disk generator. The functioning of this generator is based on the interaction between a DC magnetic field embedded in a disk structure and a conducting fluid held in an inner channel. A simplified model of the generator is presented here, and a sensitivity analysis is performed. It is shown that, under specific operating conditions, the efficiency of the system can reach 70% with a level of power of hundreds of watts. Full article

It is difficult for the commonly used Class G oil well cement to withstand the high-temperature environment of geothermal wells, and it is easy to deteriorate the mechanical properties and damage the integrity of the cement sheath. Industrial solid waste red mud can be used as supplementary cementing materials (SCMs) to improve its mechanical properties at high temperatures. In addition, compared to Class G oil well cement, high belite cement (HBC) has lower energy consumption and better mechanical properties at high temperatures. In this study, the mechanical properties of HBC as a gel material and quartz sand and red mud as SCMs were studied at high temperatures. The ratio of HBC to SCMs and the ratio of quartz sand to red mud in SCMs were optimized using the response surface method (RSM). The response surface was established using the three-level factorial design model, which fit well with the experimental data. The optimization results show that the best mass ratio of SCMs/HBC is 37.5% and that the best quality ratio of quartz sand/red mud is 9 under the curing conditions of 180 °C. However, the best mass ratio of SCMs/HBC is 49.3%, and the best quality ratio of quartz sand/red mud is 7 under 220 °C. With the addition of SCMs, the silicon-to-calcium ratio of HBC hydration products decreases, and high-temperature-stable xonotlite and tobermorite can be formed. After adding SCMs, the cement sample is denser without obvious cracks. Full article

Despite the considerable breakthrough in district heating systems (DHS) globally, there is not yet any policy on developing this technology in Iran. This country has a high range of energy demand, while renewable energies play a minor role in its energy supply chain. Furthermore, the world is going through a transition towards renewable resources, which currently consist of only 10% of the total energy mix. As the first contribution in this area, this paper aims to design a 100% renewable DHS integrated with radiant floor heating for a group of residential buildings in Sarein, Iran. Moreover, the literature proposes a novel approach for combining geothermal energy and Municipal Solid Waste (MSW) to achieve a 100% renewable energy system. Building Information Modeling (BIM) is used for thermal analysis by 3D designing the buildings in SketchUp and OpenStudio and simulating the heat load in EnergyPlus. Three scenarios are presented to better compare the DHS with the decentralized heating system regarding fuel consumption, as well as environmental and economic aspects. The town’s existing heating system that consumes natural gas for both space heating and hot water demand is referred to as the IHS-G scenario. The DHS-G scenario represents an 87% renewable DHS system, working with natural gas and geothermal energy, while the DHS-MSW scenario is a 100% renewable system, consuming both geothermal energy and Municipal Solid Waste (MSW). Finally, findings suggest that DHS-MSW and DHS-G scenarios reduce the annual energy consumption of buildings by about 595 and 33 toes, respectively. Hence, the greenhouse gas effect will alleviate by mitigating the emission of 1403 and 1339 tons of CO₂-eq./year, respectively. Moreover, exporting the extra natural gas through both LNG and pipeline provides about 26 million and 28 million USD/year revenue in DHS-G and DHS-MSW scenarios. Full article

Conventional cements and plugs are challenged by corrosion in CO₂-rich and extreme geothermal environments, due to the hostile chemistry and high temperatures. Thermite-based sealing and well intervention technologies are being applied in the oil and gas industry, combining the energy delivery capability of thermite materials with the sealing characteristics of low melt temperature alloys. The thermite reaction products (ceramics) and the sealing alloys used in these plugs both have very attractive corrosion properties, and their operating envelopes extend into geothermal conditions. Thermite plugs and platforms, without supplemental sealing materials, have been considered for nuclear waste isolation, carbon sequestration, and geothermal applications due to the geochemical stability of the ceramic product and its very high service temperature. This study addresses corrosion resistance of the thermite reaction products. A range of engineered thermite systems which yield thermite reaction products including pure aluminum oxide, feldspar, or aluminosilicate solid solutions (in addition to the iron produced in thermite reactions) was developed. These materials were evaluated for their strong acid resistance (pH 1), carbonate resistance (sodium carbonate) and thermal shock resistance (600 °C heating → cold water quenching repeated three times). Performance of different materials was evaluated based on the changes in mechanical properties, water-fillable porosity, phase changes under stress conditions. The aluminosilicate product exhibited very good corrosion resistance, both from material loss and strength perspectives, while the other products performed with varying degrees of stability. This paper presents the results of the thermite corrosion studies and describes the novel tools being deployed, and under development, to satisfy challenging barrier and intervention applications. Full article

Biofuels are becoming more important in the renewable energy sources mix. Liquid biofuels are products of agriculture. Bioethanol can be prepared from corn, beetroot and other plants. Biodiesel is mainly made from rapeseed. This paper presents information about biodiesel development in Poland, as well as some background information about its development in the European Union (EU). We analyzed the data about biofuels in the literature, and provide statistical data about liquid biofuel in Poland and other countries of the EU. The aim of the study is to assess the viability of liquid biofuel development in Poland. The base for biodiesel production in Poland and the EU is rapeseed. The production yields and sown area of rapeseed increased in Poland from 2005–2020. This was due to integration and European Union policies which aim to supply clean energy. The energy mix in Poland differs from that of the EU. Solid biofuels have made up the biggest share of renewable energy sources in Poland (73.4%) and the EU (40.1%). Poland has smaller share of wind energy, biogas, heat pump, water energy, solar anergy, municipal waste and geothermal energy in its renewable energy sources compared to the rest of the EU. Only with solid and liquid biofuels is the share of renewable energy sources larger in Poland compared to the EU averages. Poland has decreased its share of solid biofuels and water energy among its renewable energy sources, while other sources have increased. Poland is investing to increase its renewable energy sources. To analyze the opportunities for biodiesel production in Poland, we used the scenario method of analysis. We outlined three scenarios. The first is increasing the production of biodiesel by 3% each year for the next three years. The second is production remains unchanged, i.e., at the 2020 level. The last scenario is decreasing production by 3% each year. According to the first scenario, the total demand for rapeseed for energy and food purposes will be 375 thousand tons in 2025. Such a scenario is very likely to occur because of the growing demand for biodiesel and edible oil. The current situation with Ukraine and the Russian Federation will create an increase in demand for rapeseed, leading to higher prices. Full article

Energy security education explores various issues, such as a secure and competitive economy and nuclear safety. In the context of energy transition and sustainable development, it also addresses the world’s reliance on nonrenewable and renewable energy sources. The aim of this study was to identify research trends pertaining to energy security education, paying particular attention to renewable and nonrenewable sources. This was accomplished with the use of mixed-method research in two steps. The first step was a text-mining and content analysis of publications on energy security education published on the Web of Science platform between 2016 and 2021. From 660 publications on energy security education, titles, abstracts, and keywords were extracted and analysed with NVivo software to identify the most frequent concepts on energy sources in publications. The concepts were associated with nonrenewable energy sources (coal, natural gas, uranium, petroleum, and fossil fuels), nuclear power, and renewable energy sources (hydro, geothermal, solar, tide/wave/ocean, wind, solid biofuels, biogases, liquid biofuels, and renewable municipal waste). The second step was conducting detailed searches with Boolean operators, where “energy security education” was juxtaposed with the distinguished keywords. All searches on energy security education showed that publication activity tended to decrease, while citations increased. The most explored topics concerned: “fossil fuels”, “oil, petroleum”, “renewable” energy, and “solar” energy sources. An increasing trend was observed for all renewable energy sources as well as selected nonrenewable sources: “oil, petroleum”, “nonrenewable”, and “coal”. Additionally, R-squared values were calculated to indicate the fit of the trendline to the model. Due to the technologically enhanced energy transition and didactic innovations, education focussing on energy sources is expected to remain in demand. Curricula will need to be revised in the future to better reflect this reality. Full article

Ethiopia is one of the fastest-growing economies in the world despite immense challenges towards access to sustainable energy supplies and modern energy technologies. The country is undertaking great effort towards the development of renewable energy technologies and green legacy. However, the largest share of energy consumption (≈87%) in Ethiopia is dominated by traditional fuels (charcoal, fuel wood, dung cakes, and agricultural residues) which pose various health and environmental risks. The country has an enormous amount of renewable energy potentials (e.g., solar, hydro, wind and geothermal), but only 5% of its full hydropower potential is exploited and others are not fully harvested or not well developed to date. This review paper provides a comprehensive assessment on renewable energy availability, potential, opportunity, and challenges in Ethiopia. We believe the information provided in this review will enlighten the current and future prospects of renewable energy deployment in Ethiopia. Full article

Fly ash cement is used to solidify marine clay to prepare marine-clay-based cemented paste backfill (MCCPB) to fill the underground goaf of mines, which not only utilizes solid waste such as fly ash and marine clay, but also controls surface subsidence and protects the environment. To simulate the complex underground mine water environment of the filling body, a dry-wet cycle aquatic environment test under different material ratios and curing ages was designed. The water absorption and unconfined compression strength (UCS) of MCCPB with curing ages of 7 and 28 days under the action of 0, 1, 3, and 7 dry-wet cycles were investigated. The results indicate as the number of dry-wet cycles increases, the surface of MCCPB becomes significantly rougher, and the water content and the solid mass decrease accordingly. Different ratios and curing ages of MCCPB in dry-wet cycles of the UCS tend first to increase, then decrease. Meanwhile, the stress-strain curve of the specimen shows that the trend in the elastic modulus is consistent with that of UCS (first increasing, then decreasing), and that, the minimum UCS value of the specimen still meets the early strength requirements of cemented paste backfill in coal mine geothermal utilization. On the one hand, it proves the feasibility of fly ash cement-solidified marine clay for use as cemented paste backfill in coal mines; on the other hand, it also expands the available range of cemented paste backfill materials in coal mines. Full article

This study investigates the hybridization scenario of a single-flash geothermal power plant with a biomass-driven sCO₂-steam Rankine combined cycle, where a solid local biomass source, olive residue, is used as a fuel. The hybrid power plant is modeled using the simulation software EBSILON^®Professional. A topping sCO₂ cycle is chosen due to its potential for flexible electricity generation. A synergy between the topping sCO₂ and bottoming steam Rankine cycles is achieved by a good temperature match between the coupling heat exchanger, where the waste heat from the topping cycle is utilized in the bottoming cycle. The high-temperature heat addition problem, common in sCO₂ cycles, is also eliminated by utilizing the heat in the flue gas in the bottoming cycle. Combined cycle thermal efficiency and a biomass-to-electricity conversion efficiency of 24.9% and 22.4% are achieved, respectively. The corresponding fuel consumption of the hybridized plant is found to be 2.2 kg/s. Full article

Bamboo, a fast-growing plant from Asia, is used as building material with unique properties, while exhibiting fast degradation due to its hydrophobicity. Therefore, many attempts have been implemented using several technologies for bamboo modification to alter the hydrophobicity. Most previous studies producing superhydrophobic properties are conducted by using tetraethoxysilane (TEOS) as a precursor agent. However, this method, using TEOS with harmful properties and unaffordable compounds, requires many steps to accomplish the experimental method. Therefore, this paper employed geothermal solid waste as a silica source of the precursor. Thus, an effective and efficient method was applied to prepare superhydrophobic coating by using a precursor of geothermal silica and further modification using hexamethyldisilazane (HMDS) and trimethylchlorosilane (TMCS). The research was executed by the full factorial statistical method using two numerical variables (HMDS/TMCS concentration and silica concentration) and one categorical variable (solvent types). The uncoated material revealed higher weight gain in mass and moisture content than that of the coated bamboo after the soil burial test to assess the durability of the bamboo. However, the durability of superhydrophobic coating realized hydrophobic performance for both agents during sand abrasion for a total of 120 s at an angle of 45°. Statistical results showed the optimum contact angle (CA) achieved in superhydrophobic performance with lower silica concentration for HMDS concentration and the appropriate solvent of n-hexane for HMDS and iso-octane for TMCS. All results were supported using many instruments of analysis to confirm the step-by-step alteration of geothermal silica to be used as a superhydrophobic coating, such as XRF, XRD, FTIR, SEM, and SEM EDX. Full article

The production of biodiesel using zeolite catalysts from geothermal solid waste has been studied. This study aims to make zeolite catalysts as catalysts in biodiesel production, assessing the effect of catalyst concentration, and temperature in the esterification–transesterification process on the biodiesel yield produced. The results showed that the synthesized zeolite catalyst was an analcime zeolite catalyst (Al_1.9Na_1.86O₁₂Si₄). The biodiesel yield of 98.299% with 100% fatty acid alkyl ester (FAAE) content was achieved at a catalyst concentration of 5%wt and a reaction temperature of 300 °C for one-hour reaction time. The yield of biodiesel decreased with repeated catalysts, which experienced morphological changes before and after three usage times. Consequently, in this case, the catalyst cannot be regenerated. Full article