Cleaner Energy Systems最新文献

Fuel wood is the most important source of cooking energy for households in developing countries such as Ethiopia, particularly in rural areas where alternative sources are either unavailable or simply unaffordable. Even if the country is using different electricity generation methods, it has not been enough to meet the surplus need of society. In this research, a thermoelectric generator integrated biomass rocket stove was designed and a prototype of the stove was manufactured. The performance evaluation was conducted using laboratory-based measurement ISO 19,867–1. The overall thermal efficiency of the stove was around 29 %. The TEG rocket stove was able to run a fan directly. To get a uniform output voltage a DC-DC boost converter was used. After being connected to the DC-DC converter it was able to generate an output voltage of 5 V and output power of 3.5W- 5 W depending on the current produced. At an average temperature difference of 90 °C, the stove was able to generate an output power of 5 W with a conversion efficiency of 4.3 %. The TEG rocket stove was able to light LED lamps that require a USB input of 2.5 W, charge mobile phones, tablets, and a Bluetooth radio that requires an input power of 5 W. The estimated cost of thermoelectric generating rocket stove is 92 USD with a lifetime of at least five years. The stove can further be designed for mass manufacturing so that it is disseminated to the rural community in developing worlds such as Ethiopia.

Increasing energy demand and greenhouse gas emissions are major concerns in India. Building energy use in India accounts for 33 % of total energy consumption and is growing at an annual rate of 8 %. In order to save energy, energy conservation in buildings should be given primary importance. Energy conservation practices can reduce energy use in buildings while maintaining thermal comfort. This can be achieved by optimising existing energy use or lowering consumption. One such initiative was undertaken by Siksha 'O' Anusandhan Deemed to be University. It analysed the energy consumption pattern and possible energy conservation opportunities (ECOs) to lower energy usage in its buildings at campus 1 in Bhubaneswar. The Energy Conservation Building Code Odisha (OECBC) was followed to reduce energy use by replacing all the damaged windows with efficient glazing. By following OECBC guidelines, we can save up to 30 % of the energy consumed by an existing building. Besides, energy conservation measures were performed by replacing ceiling fans with brushless direct current (BLDC) fans, existing lights with LED bulbs, and using variable speed drives instead of induction motors. This study will help to define the most efficient energy conservation measures for existing buildings in terms of cost and energy savings. Retrofitting the present building with energy-saving devices will cost INR 21, 32, 90,152 with an overall annual energy savings of 47, 28,177 kWh and a yearly cost saving of INR 319,66,703.

Local Energy Markets (LEMs) allow direct citizen involvement in energy production and trading. A study surveyed 636 Swiss electricity consumers using choice-based conjoint analysis to explore preferences for various LEM characteristics. Three consumer segments emerged: 'Renewable energy enthusiasts' (42 %), interested in energy mix and community PV investment; 'Price sensitives' (30 %), driven mainly by costs; and 'Uninvolved' (28 %), focused on energy mix but hesitant about PV investment. Demographic and psychological variables helped characterize these segments, suggesting tailored communication strategies to boost participation in future energy markets. Communication strategies should focus on ‘Renewable energy enthusiasts’ segment and should emphasize environmental benefits and community engagement to leverage their high motivation for involvement.

Despite extensive investment in energy efficiency efforts, the energy footprint of the building sector still contains over 40 % of the world's annual consumption of energy. Although most of a building's life cycle energy use comes from operational activities, a portion of it stems from embodied energy (EE), which is directly expended in a building's construction and indirectly consumed using materials. Because each material consumes not only different amounts but also different types of energy sources, studying embodied carbon (EC) is equally important. The building construction sector also consumes nearly 1/5th of global fresh water, which is becoming a grave concern, given the increasing frequency of droughts and wildfires. The fact that material manufacturing and construction processes also consume water makes it essential to not just assess energy and carbon but also embodied water (EW). The literature recommends evaluating total EW including direct and indirect EW as well as any EW associated with EE use. In this paper, macroeconomic models are utilized to compute and analyze the energy, carbon emission, and water embodied in four university buildings. The results show that the total EE, EC, and EW values for the four case study buildings vary from 13.1 to 51.1 GJ/m², 1.4–10.0 kgCO₂/m², and 2,820–12,900 gal./m², respectively. The EE values also show a near perfect positive correlation with EW values. However, the share of EREW in the total EW ranges from 13 % to 16 %, indicating that a decrease in EE use may not help decrease a majority of EW.

Compression ignition CI engine are versatile engines required for both industrial and domestic purposes. CI finds application in household mill, transportation and as components in energy plants. Operating the CI engine with biodiesel and its combination with fossil-based diesel is being encouraged to combat environmental menace of using only fossil diesel. This current work seeks to probe into comparison between the use of biodiesel and its emulsion to improve the performance CI engine. Methyl esters was synthesized from blends of three nonedible oils; Tevetia Peruviana, Honne and Neem (THN) using catalyst made from three bio wastes mixture. The production process was optimized using Taguchi tool. The THN methyl esters (THNME) obtained was assessed for fuel properties. Box Behnken tool was adopted to generate 17 investigational steps to explore the effect of THNME 100 and parts containing 20% and 60% of THNME on the fuel efficiency and safety of the CI engine. These fuel mixes were used as fuel in an unmodified single cylinder CI engine. The engine was operated on three engine loads (EL) 25%, 50% and 75% as well as engine speeds (ES) 1500, 2500 and 3500 rpm (rpm). The result obtained showed that blend of THNME with fossil diesel has the minimum exhaust gas temperature EGT. ANOVA of the performance result shows that the model developed is suitable to predict the behaviour of brake power and exhaust gas temperature only. This work conclude that B20 is moderately fuel efficient and safer for the unmodified engine in terms of EGT and BSFC.

Novelty: Emulsion of THNME B20 is a preferred fuel for the safety of the unmodified CI engine because of low EGT

Internal short circuit of cells is one of the main causes of thermal runaway in electric vehicle battery systems. Therefore, one of the most effective ways to prevent thermal runaway is to detect and identify internal short-circuit lithium-ion batteries before thermal runaway using a battery management system. This paper investigates the detection and identification of internal short circuits in batteries by proposing a multi-variable stepwise analysis (MSA) method. The MSA method is proposed for detecting and identifying faulty batteries by combining horizontal and vertical comparison methods and aging cells' ohmic internal resistance variation characteristics. A less consistent pack containing aging cells was designed to perform internal short-circuit experiments. Based on setting the appropriate threshold and moving the window frame horizontally, comparing the deviation degree of the ohmic internal resistance of each cell in the battery pack and the average ohmic internal resistance of the normal battery, the aging battery in the battery pack can be effectively identified. State of health (SOH) is the percentage remaining of the battery's actual maximum capacity value. The deviation degree of ohmic internal resistance of aging batteries with SOH of 92% and 80% is maintained at more than 15% and 45%. For early internal shorts with an equivalent internal short-circuit resistance of 100 Ω, the internal short-circuit detection time is 3896 s. For the short circuit in the middle and later periods (<10$\Omega$), the MSA algorithm can achieve rapid internal short-circuit detection within the 50 s window, reducing the risk of thermal runaway. The results verified that the method could effectively identify aging cells within the battery pack and detect internal short circuits for other cells, reducing false positives and effectively preventing thermal runaway.

Achieving local sustainable development often depends on consumers' incentives to efficiently utilize energy and resources. In this paper, Local sustainable communities (LSC) are introduced as a combination of sustainable communities and local energy communities to promote local energy and resource utilization. Business models on technology and service provision and those on promoting sustainable resource utilization are developed, which are then applied to a community in Austria. A modeling framework on sector coupling in community operations, that also considers resource utilization is developed to assess the impact of the business models. LSC business models promote participation and sustainable operation in an LSC as 31% of electricity and 34% of heat can be covered by LSC purchase. The implementation of energy recovery business models and the availability of sufficient decentralized technologies have the greatest impact on LSC operations, reducing external electricity grid coverage to 58%. The consideration of resource business models can positively contribute to a local resource utilization efficiency, reducing the water pipeline coverage by 43%. The introduction of an LSC has a positive impact on the United Nations Sustainable Development Goals and can therefore efficiently contribute to the development of a cleaner energy system.

Although the role of nuclear power in the energy mix is being discussed from various aspects, studies on nuclear power in the energy security narrative are still limited. In this context, the role of nuclear energy in energy security is examined from a vulnerability-based approach. First, causal linkages between various terms of energy security, including vulnerability, threat, hazard, and resilience were conceptualized. Amongst these terms, we further focused on resilience and explored it from the viewpoint of its robustness, flexibility, redundancy, diversification, adaptability, and interdependency. Finally, considering these six components of resilience, nuclear power as a part of the energy supply system was analyzed in the context of energy security. This reiterated the necessity to balance the positive effect of strengthening the resilience and the negative effect of generating hazards and threats associated with nuclear power. This study is the first to discuss pros and cons of nuclear power from the perspective of its interaction with energy system in energy security. This approach differs from existing approaches in which nuclear-specified issues are alone considered in the narrative of nuclear safety. Since energy security has become an important driver of energy policy in recent years, the developed concept of nuclear power in energy security shall act as an essential stepping stone in determining its future use.

The increasing demand for electrical and electronic equipment (EEE), particularly air conditioning (ACs), has caused a significant increase in energy demand. Improvements in energy efficiency increase material and carbon footprints under the production stage owing to the additional use of resources. Higher energy-efficiency models need to compensate for this rise before EEE reaches the end of its lifespan. Thus, the timing of offsetting, named breakeven point (BEP), was analyzed between two models of ACs manufactured in Japan with different energy efficiencies in this study, considering material and carbon footprints based on different lifestyles. Through the analysis, a contradictory relationship between energy efficiency and renewable energy was quantitatively identified; that is, the improvement of energy efficiency leads to a lower BEP, while the increase in renewable energy leads to a higher BEP. When the share of renewable energy in the energy mix reaches more than 40 % in the case of material footprint, the choice of low-efficiency appliances would be even preferable considering the lifespan of EEE and lifestyle. The developed concept contributes to optimal selection among different EEE efficiency from an environmental perspective.

Heat pumps will play a key role in the future provision of low carbon domestic heating and the re-use of industrial waste heat. Adsorption cycle heat pumps are advantageous in that they can use the existing natural gas network to avoid electricity supply limitations across the UK. A 2 kW domestic-scale ammonia/salt heat pump demonstrator is currently being tested at the University of Warwick as a replacement for a conventional condensing gas boiler. This paper describes analysis work in support of this testing which will lead to design refinements in follow-on developments.

A Matlab-based 2D transient simulation package was developed to study heat transfer and reaction rate within a pair of linked reactors. Heat conduction and sorption rate are modelled together with inter-reactor gas flows and parasitic heat loss. Novel features include the use of Matlab's linked ODE solvers for convergence (ODE15S was found to be fastest) and the script file input configuration which combines clear visibility of parameters with the ability to run multiple simulations to show the effect of parametric variations. The code facilitates rapid design optimisation.

Eleven cycle parameters have been investigated, including filling pressure, heat transfer coefficients, salt ratio, source temperatures, void space and heat capacity. The choice of cycle period involves a compromise between coefficient of performance and power output. A water/glycol heat transfer fluid gives better COP and output power than thermal oil. Insulation within the reactor shell has the potential to limit shell transient heat exchange but void space effects are likely to be more significant. The heat capacity of fluid in pipes and manifolds should be minimised.

COP = 1.31 is achieved at 45 °C delivery; 60 °C for hot water is possible but with lower COP. The best results for space heating are obtained with source temperatures above -5 °C.