Annual Energy Supply Research Articles

A two-stage decision-making approach for optimal design and operation of integrated energy systems considering multiple uncertainties and diverse resilience needs

The enhancement of energy system resilience from a planning perspective is crucial. In this study, a two-stage resilience optimization model is developed to determine the optimal additional configuration and scheduling plan for an integrated energy system, taking into account economic costs, loss of load, and various resilience indicators. Considering the uncertainty of disaster occurrence and component vulnerability, probabilities of multiple energy interruption scenarios are introduced, and a comprehensive system configuration optimization model targeting annual energy supply cost and loss of load is developed. Following which, accounting for the personalized energy demands of end-users, three resilience indicators, namely load importance, energy interruption duration, and the maximum degree of system damage, are proposed. According to the simulation results of an illustrative example, the proposed method effectively improve system resilience. Compared to the baseline solution from pure economic perspective, the total cost increases by 0.38 %, while the load loss decreases by 6.84 %. From the demand-side viewpoints, three resilience indicators are improved by 12.17 %, 11.8 %, and 20 %, respectively. Moreover, the capacity of renewable energy is recognized as the most critical factor determining the load loss over the planning period. Storage devices are more beneficial in reducing the duration of energy interruptions and lowering the maximum damage degree.

Collaborative modeling and optimization of energy hubs and multi-energy network considering hydrogen energy

To achieve the goal of carbon neutrality, integrated energy hubs (EHs) based on coupled energy sources such as electricity, gas and heat are gaining increasing attention due to their efficient and flexible energy supply characteristics. The introduction of integrated EHs may lead to the reconstruction of the existing superior energy network to accommodate the suitable flow of the new network. In this study, a multi-objective optimization model is proposed that synergistically considers the optimal configuration of EHs and the reconstruction of higher-level energy networks, with the objectives of minimizing total annual energy supply costs and CO2 emissions. First, an EH and multi-energy network (MEN) topology model considering hydrogen energy is developed. Secondly, the joint output of wind and solar power under typical scenarios is sampled and obtained by employing the Monte Carlo sampling method and the synchronous back-propagation scenario analysis method. To address the nonlinear constraint problem associated with multi-energy storage output, the Big-M method is introduced to improve the optimization capability of spatial-temporal coupling of energy storage. Moreover, the utilization potential of hydrogen and renewable energy is explored by considering constraints on the nonlinear dynamic pricing of hydrogen. Finally, a numerical analysis is conducted using an illustrative example. The Pareto frontier optimal results, derived from fuzzy theory membership functions, are achieved using both classical and heuristic algorithms. The classical mixed-integer linear programming algorithm yields relatively superior optimization outcomes in terms of annual energy costs and carbon emissions compared to the heuristic algorithm. However, it suffers from longer computation times.

Remote island renewable transition potential: Affordable, reliable and sustainable generation optimisation for Mornington island

Remote islands, comprising over one-sixth of the Earth's surface area and home to approximately 9% of the global population, face formidable challenges in securing affordable, sustainable, and reliable energy. This paper presents a pioneering investigation into Mornington Island's transition from diesel reliance to renewable energy predominance over the next four decades. By demonstrating the tangible benefits of renewable energy implementation on Mornington Island, this research provides compelling simulated evidence that blending traditional and renewable energy sources can revolutionize energy provision for small island communities. Employing hybrid Wind-Solar renewable energy systems bolstered by an effective battery storage system (ESS), this innovative approach ensures a seamless shift to renewable energy, resilient against seasonal variations and extreme weather events such as cyclones. Our analysis, conducted through a tech-economic model simulating each 5% increment of renewable energy penetration, reveals that renewable energy outperforms traditional diesel generation in terms of affordability over a 40-year operational span. Specifically, a 95% renewable energy penetration yields the lowest levelized energy cost ($162.2/MWh), resulting in a remarkable $8.54 million reduction in diesel costs. A 5% diesel component secures annual energy supply, bridging the gap during periods of seasonal renewable energy variability and extreme cyclonic weather. While achieving 100% renewable energy generation is financially feasible, challenges arise in scaling battery capacity to stabilize energy supply during cyclone seasons. Moreover, our carbon accounting model indicates that although the construction of renewable energy infrastructure entails some indirect (Scope 3) carbon emissions, a 95% renewable penetration mitigates emissions by 90% compared to traditional diesel generation, amounting to a reduction of 39.17 kilotons over the 40-year period. This comprehensive study provides policymakers with invaluable insights, fostering a holistic understanding of the financial, technical, environmental, and political dimensions inherent in island energy transitions.

Thermal performance and energy flow analysis of a PV/T coupled ground source heat pump system

Ground source heat pump (GSHP) system in cold regions will lead to a decrease in soil source temperature over the years after a long period of operation, and if no timely measures are taken, the system performance will get worse and worse, and even face the risk of shut down. The PV/T (photovoltaic/thermal) is an integrated energy supply system that can both improve the efficiency of solar energy utilization and weaken the soil temperature imbalance. In this paper, the thermal performance and year-round energy flow of the system are analyzed by the simulation model, and the effects of different soil thermal storage control strategies on the thermal storage performance in the transition season are explored. The results show that the coefficient of performance of the heat pump unit can reach 3.99 and 3.96 in the heating and cooling periods. The soil temperature only increases by 0.09 °C and 0.11 °C compared with the initial temperature after five and ten years of long-term system operation, respectively. In addition, after a comprehensive comparison of the thermal storage performance of different control strategies in the transition season, this study found that the temperature difference control strategy was superior to the time control strategy. Ultimately, the annual energy supply of the simulation system produces an additional 391.8 kWh of electricity in addition to meeting the energy demand for cooling, heating and power supply of the building, which realizes the zero-energy operation of the building.

Performance assessment of a solar-assisted absorption-compression system for both heating and cooling

Combining renewable energy with building energy supply is an effective way to pivot the building sector to carbon–neutral. This paper proposes a novel solar-assisted energy supply system which is applied in residential buildings for heating, cooling and domestic hot water. The heating/cooling output of the proposed system is mainly contributed by a vapor compression system to address the supply–demand mismatch of solar energy supply system, and the other part is assumed by a solar driven absorption system that is operating with lower generation temperature and higher evaporation temperature to assist the vapor compression system. Therefore, a solar-assisted absorption-compression system (SAACS) exploits the full potential of solar heat for annual energy supply by improving the contribution of per unit solar collection area, with considerable electricity-saving compared to air-source heat pumps. A thermodynamic model is established and validated by the results of the built experimental prototype which is testing. Solar-assisted heating mode and solar-assisted cooling mode are compared in comprehensive evaluation criteria to illustrate the performance differences caused by the assisted solar energy. The results indicate that solar heat at 60 °C is feasible for heating and cooling, revealing the great potential for efficient conversion from solar energy for heating and cooling. Due to the introduction of solar energy, the cooling and heating COPele increases by 10.3 % ∼ 17.6 % and 32.3 % ∼ 56.3 %, respectively. Despite the lower increase in COPele, electricity-saving ratio shows greater value at low hot water temperatures, varying from 24.3 % to 19.6 % for cooling and from 44.1 % to 39.7 % for heating as hot water temperature increases from 60 °C to 85 °C. The maximum SCOP is 0.63 for cooling, and 1.14 for heating. Yearly investigation shows that the SAACS combined with 20 m2 CPC collector has an annual average solar fraction of domestic hot water of 0.85 and a discounted payback period of 3.12 years. These results demonstrate the feasibility and flexibility of the SAACS applied to residential buildings toward decarbonization.

Discharging strategy of adiabatic compressed air energy storage system based on variable load and economic analysis

It is promising to match the variable loads of the supply objects in different seasons by adjusting the trigeneration of the adiabatic compressed air energy storage system (A-CAES).. In this paper, the thermodynamic model of the A-CAES system was developed to investigate the characteristics of the A-CAES system for trigeneration combined cooling, heating and electric supply. The cooling, heating, and electric load of a typical residential area in different seasons was analyzed. Then the load of residential area and trigeneration of system was matched to increase the efficiency of energy utilization. Finally, the new energy supply method by the A-CAES system for the residential area was compared with the traditional approach through economic analysis. The simulation results show that households' cooling, and heating load vary greatly in different seasons, but the difference in electric load is insignificant. For A-CAES, the mass flow rate of chilled water in the charging process has little effect on the cooling, heating, and electric output, so the minimum value is suggested to improve the thermal storage temperature of chilled water. The ratio of compression heat distributed for preheating the air in the discharging period can greatly change the cooling, heating, and electric output of the system. From the perspective of meeting the hot and cooling load as much as possible, the optimal heat distribution ratio for summer, spring/autumn, and winter were selected as 36.0%, 94.1%, and 36.0%. However, according to the economic analysis, the optimal heat distribution ratio was selected as 94.1%, 94.1%, and 67.5% to maximize daily profit. The economic analysis also found that the annual energy supply cost of the residential area with the A-CAES system is 24% lower than that of the traditional method. The annual energy supply cost decreases by 254.5 thousand dollars. Given the cost of devices, the static investment payback period of the system was calculated as 15.4 years.

Analyzing the impact of the aspect ratio of a building on concrete use in its structure

Buildings consume over half of annual energy supply as embodied and operating energy in their construction and operation releasing harmful emissions to the atmosphere. Over 90 % of the embodied energy is attributed to construction materials used in building structure, envelope, and interiors that must be reduced to minimize material use. Concrete is one of the major materials that contributes significantly to the energy and carbon footprint of buildings, as it is responsible for 5-9 % of global carbon emission. Because most of the concrete use in the building sector occurs in building structures, assessing how building design parameters influence its environmental sustainability is important. One of the design parameters that impact the sustainability of buildings is the aspect ratio, which is defined as the ratio of horizontal to vertical surface area of a building. A building with the same floor area can be designed horizontally or vertically with different aspect ratios, which will influence its structural design and eventually the amount of concrete used in the building. In this paper, we examine how aspect ratio may affect the environmental sustainability of a buildings foundation, structural framing, and slab. We model the structure of a generic building with different aspect ratio to analyze if aspect ratio can help reduce the energy and carbon embodied in reinforced concrete structures.

Rapid Identification of Economic Indicators of Integrated Energy Systems Based on Data Analysis

The construction of integrated energy systems has received widespread attention. In addition to system design and operating optimization, clarifying the internal relationship between the project’s own characteristics and its economic indicators is also important for high-value project selection and implementation. Based on various energy prices and the climatic characteristics of typical cities, 60 integrated energy supply projects in 4 typical cities were used as a case study, and the cold and heat source system solutions with the shortest investment payback period for each project were calculated through a system optimization model. We calculated the correlation coefficient between the initial investment of system equipment, annual energy supply, annual energy sales revenue, annual equivalent full-load energy supply hours, initial equipment investment indicators for annual unit energy supply, and the project’s static investment payback period. The key factors affecting the static investment payback period of the project were identified. The results show that, under the optimal system scheme, even for buildings of the same type in the same area, the economic indicators of different integrated energy projects are still quite different. Under the current design, operation, and operation conditions, load distribution is the decisive factor for the economic feasibility of the project. The static investment payback period of the project can be quickly calculated based on the equivalent full-load energy supply hours of the project throughout the year. Compared with the current numerical and system dynamics model for point-to-point single system optimizing modeling, the proposed statistical regression model can help reveal the main factors of integrated energy system’s economically feasible.

Predicting Dinitrogen Activation by Five-Electron Boron-Centered Radicals.

Due to the high bond dissociation energy (945 kJ mol-1) and the large highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap (10.8 eV), dinitrogen activation under mild conditions is extremely challenging. On the other hand, the conventional Haber-Bosch ammonia synthesis under harsh conditions consumes more than 1% of the world's annual energy supply. Thus, it is important and urgent to develop an alternative approach for dinitrogen activation under mild conditions. In comparison with transition metals, main group compounds are less explored for nitrogen activation. Here, we carry out density functional theory calculation to screen boron radicals for dinitrogen activation. As a result, the experimentally available seven-electron boron-centered radicals are found to be inactive to N2 activation, whereas some five-electron boron-centered radicals become favorable for dinitrogen activation, inviting experimental chemists' examination. The principal interacting spin-orbital analyses suggest that a five-electron boron-centered radical can mimic a transition metal on a synergic interaction with dinitrogen in the transition states.

Predicting Dinitrogen Coupling with a Series of Small Molecules Catalyzed by a Pincer Complex.

Due to consumption of more than 2% of the world's annual energy supply by Haber-Bosch process and the strongest triple bond (N≡N) in nature, directly coupling N2 with small molecules is particularly important and challenging, let alone in a catalytic fashion. Here we first demonstrate that a NNN-type pincer phosphorus complex could act as a catalyst to couple dinitrogen with a series of small molecules including carbon dioxide, formaldehyde, N-ethylidenemethylamine, and acetonitrile in the presence of diborane(4) under a mild condition by theoretical calculations. N2 fixation proceeds via a stepwise mechanism involving initial N2 activation by diborane(4), followed by intramolecular isomerization to a key intermediate (zwitterion). Such a zwitterion can be used to couple a series of small molecules with activation barriers of 23.5-25.2 kcal mol-1 . All these findings could be particularly useful for main group chemistry aimed at N2 activation.

Research on simulation of energy consumption of ground water-source heat pump air conditioning system in plant factory

The study of low-cost energy supply methods for large plant factories in China is of great significance to promote the healthy and steady development of large greenhouses. Aiming at the problems of high cost, poor stability, chaotic production management, and no indicator of long-term operation energy consumption in the operation of large plant factories, this paper analyzes long-term operation data by studying the heating situation of Chongming plant factory to improve plant factory regulation methods for the purpose of energy saving and cost reduction. A plant factory model was constructed using TRNSYS to simulate typical annual energy supply throughout the year to obtain cooling and heating energy consumption. The simulation results show that the annual peak heat load of the plant factory is 1502.6 kW and the peak cooling load is 913.8 kW. The annual energy consumption of the whole plant factory is 3799.12 GJ for cooling and 4468.34 GJ for heating, and the annual energy consumption of the whole plant factory is 8267.46 GJ. A8 and its three surrounding greenhouses A6, A7, and A10 can be used as a single zone for energy supply. This zone takes advantage of the structural characteristics of the building to reduce energy consumption. The simulation shows that the ground source heat pump system is sufficient to supply the energy consumption of these four greenhouses and even to achieve the optimal temperature conditions for growing vegetables inside them.

Evaluation of the ecoefficiency of greenhouse gases generation in the provision of complementary meals in a public hospital

The present study aimed to assess Ecoefficiency (EE) related to the emission of Greenhouse Gases (GHG) from the transport of the inputs used to provide complementary meals at a large university hospital in Brazil. For EE calculations, the annual energy supply in kilocalories of the inputs used and the estimated GHG emissions were considered, considering the distance in kilometers between the place of origin of each product and the destination city in southern Brazil. 31 products were used and selected for complementary meals distributed in the groups of: dairy products, cookies, drinks, supplements, and enteral diets for adults and pediatrics. The results showed that EE was directly related to the origin of the products, especially in enteral diets. The application of the Spearman correlation coefficient showed a strong negative correlation of -0.8119 [CI (95%) -0.9023; -0.6531] between the variables distance in kilometers and eco-efficiency and also when comparing GHG emissions with kilocalories. The health sector must play its role in relation to environmental impacts also in the assessment of GHG emissions in the context of nutritional therapy.

Life cycle embodied energy analysis of higher education buildings: A comparison between different LCI methodologies

Nearly half of the global annual energy supply is consumed by the building construction sector, indicating an enormous potential to minimize the carbon footprint. During its life cycle, a building consumes energy in the form of embodied and operational energy. Embodied energy (EE) is expended in processes during construction (ex: extraction of raw material, transportation, manufacturing, etc.). Operating energy (OE) is spent on operating and maintaining the building to ensure occupant comfort. Unlike OE, the methods used to calculate EE are complex, unstandardized, and time-consuming. Each EE calculation method utilizes different sources of data and system boundary definitions, therefore making it difficult to comprehensively evaluate building life cycle energy (LCE). Literature suggests that the disaggregated input-output based hybrid (IOH) approach is more accurate, complete, and reliable in comparison to the other EE calculation methods. In this study, we examine the EE-OE relationship by calculating EE factors for a newly constructed and renovated educational building. Next, we also compare the variation in EE factors across different life cycle inventory (LCI) methods (process-based, aggregated IOH, and disaggregated IOH). The results of this study indicate that using different LCI techniques to calculate EE causes massive variations in EE factors, which represent the EE expense of saving one unit of OE. The findings of our study and literature review show that the process-based approach underestimates EE, therefore the values of EE factors calculated using this approach need to be interpreted with caution. These results further elucidate the importance of standardizing the EE calculation method.

Rational Design of a Carbon-Boron Frustrated Lewis Pair for Metal-free Dinitrogen Activation.

Molecular nitrogen (N2 ) is abundant in the atmosphere and, found in many biomolecules, an essential element of life. The Haber-Bosch process, developed over 100 years ago, requires relatively harsh conditions to activate N2 on the iron surface and generate ammonia for use as fertilizer or to produce other chemicals, leading to consumption of more than 2 % of the world's annual energy supply. Thus, developing "green" approaches for N2 activation under mild conditions is particularly important and urgent. Here we demonstrate that a metal-free N2 activation could be favorable both thermodynamically and kinetically (with an activation energy as low as 9.1 kcal mol-1 ) by using a carbon-boron formal frustrated Lewis pair, which is supported by high-level coupled cluster calculations. Mechanistic studies reveal that aromaticity plays a crucial role in stabilizing both the transition state and the product. Our findings highlight the importance of a combination of an N-heterocyclic carbene with a methyleneborane unit in metal-free N2 activation, providing conceptual guidance for experimental realization.

Embodied energy analysis of building materials: An improved IO-based hybrid method using sectoral disaggregation

Buildings consume approximately half of the annual energy supply of the United States in their construction and operation. To effectively decrease this extensive energy footprint, both embodied and operating energy must be quantified and optimized. Although validated standard methods are available to compute operating energy, quantifying embodied energy is still complicated and inconsistent. Among the available embodied energy calculation methods, an input-output-based hybrid (IOH) method has the potential to offer a more complete calculation. However, its calculation lacks specificity and reliability, which can be improved using suggestions provided by literature. Studies across the globe have proposed techniques such as sectoral disaggregation to enhance not only the specificity and reliability, but also the completeness, of an IOH method.This study investigated and improved an IOH method of embodied energy calculation. Using the improved method, the embodied energy of commonly used building materials was calculated and evaluated. The results demonstrate a significant difference after disaggregating the relevant industry sectors. The study concludes that using embodied energy values without industry sectors being disaggregated can cause significant errors in a building’s embodied energy calculation.

Defining and operationalising the concept of an energy positive neighbourhood

The increase in distributed renewable energy supply offers new opportunities to improve the performance of local energy systems. In line with this, research and development has begun to broaden its scope from the building scale towards the neighbourhood and district scales. The formulation and comparison of potential energy solutions in different contexts at different scales of analysis demands well-defined concepts and robust decision support tools. This paper studies the concept of energy positive neighbourhoods, which it defines as areas “in which the annual energy demand is lower than annual energy supply from local renewable energy sources. … The aim is to support the integration of distributed renewable energy generation into wider energy networks and provide a functional, healthy, user friendly environment with as low energy demand and little environmental impact as possible.” Key performance indicators for energy positive neighbourhoods are proposed along with an ‘energy positivity label’. A decision support tool, called AtLas, designed to inform the long term planning of neighbourhood energy solutions is described and used to evaluate the energy positivity level of a Finnish residential neighbourhood and part of a French university campus.

Current and potential use of forest biomass for energy in Tasmania

Although Tasmania, Australia's southernmost state, has a large forest resource per capita there is no reliable information on the potential use of harvest residues, low quality logs or processing residues for energy production. In order to address the current knowledge gap we: i) quantified the current use and the potential sustainable supply of forest biomass in Tasmania, ii) compared those results with the use of forest biomass in Bavaria, a comparable state in Southeast Germany, and iii) analysed the low Tasmanian production of energy from forest biomass considering economic, legislative and social drivers. The current use of forest biomass for energy (400 kt y−1 of bone dry material) represents about 6% of Tasmania's total annual energy supply. The potential supply of forest biomass for energy production is estimated at 1800 kt y−1 of bone dry material equivalent to about 30% of Tasmania‘s current total annual energy supply. In contrast to Bavaria and other European countries, forest bioenergy production is small in Tasmania relative to the available resource and could be more than quadrupled from a resource availability perspective. A weak domestic market for energy wood leading to low prices, the lack of political stimuli and a low social acceptance are likely key factors. As a strong increase in market prices for forest biomass is unlikely, political incentives are necessary in order to increase the use of forest biomass. Addressing social acceptance will be a prerequisite for the success of initiatives or legislation to achieve this potential.

Tools to support sustainable entrepreneurship in energy positive neighbourhoods

In an Energy Positive Neighbourhood (EPN) the annual energy demand is lower than annual energy supply from local renewable energy sources. Short-term imbalances in energy supply and demand are corrected with national energy supplies. In this paper the early stages of the development - the specifications - of the tools for intelligent management of energy positive neighbourhoods are presented. These tools include an energy management tool for real-time management of the energy flows, user interfaces that support energy efficient behavior of the users in the neighbourhood and an urban planning decision support tool. The specifications and tools are the result of European co-operation, and are designed so that they can easily be adopted in different European countries with minimum changes.

Status and outlook of geothermal energy in Jordan

An updated assessment of geothermal energy sources in Jordan and the prospects for their future utilization are presented. Furthermore, a development strategy for geothermal energy in the country is proposed. The results show that Jordan has enormous underground energy resources in many parts of the country in the form of thermal underground hot water (wells and thermal springs), having a temperature ranging from 20 °C to 62 °C. It was also found that the installed capacity of geothermal energy is 153.3 MWt and the annual energy supply potential is 1540 TJ/year in the form of domestic hot water for bathing and swimming, giving an overall capacity factor of 0.42. Possible future applications of geothermal energy were found to be absorption refrigeration to preserve fruit and vegetables or freeze fish and meat, as well as fish farming and greenhouse heating.

Optimal energy management of an industrial consumer in liberalized markets

This paper presents an optimization model for mid-term management of a thermal and electricity supply system of an industrial consumer under liberalized energy markets. Electricity is supplied from the electric grid or from a gas engine, while thermal energy is satisfied through a boiler or the mentioned gas engine. The objective is to minimize the overall annual energy supply costs in order to make optimal contracting decisions. Mixed-integer linear programming is applied to solve the problem since binary decision and operation variables have been employed. A realistic case is presented to illustrate the model capabilities.