Local Energy Demand Research Articles

An evolutionary approach to modeling and control of space heating and thermal storage systems

Home Energy Management systems are in a rapid development curve, supported by the advancements in computational intelligence, smart appliances, and new smart-grid frameworks. These systems are a fundamental part to implement demand-side management strategies and to shift local energy demand to periods of lower consumption effectively. In this paper, we explore the application of distributed co-evolutionary optimization algorithms and an agent-based architecture to reduce the consumption profile signature of the heating system during the critical peak demand periods, by reducing costs and respecting the comfort constraints of the occupants. The proposed control architecture targets the typical baseboard space heating systems and electrical thermal storage systems, as these represent a large portion of the energy usage in Nordic countries and are commonly controlled by room independent thermostats, which could be easily replaced by smart devices running an algorithm as the one presented in this work. Results prove the strategy proposed getting a cost reduction of up to 23% and a peak-to-average ratio decrease of up to 25% for reference scenarios. Also, an emulation Simulink model is developed to recreate a house and the different heating loads studied in this paper and an experimental test bed is built to model a real ETS system, two different complexity degree RC models are proposed to describe such systems.

Biomass energy as a possibility for innovative agriculture initiatives

In searching for sustainable solutions for humans’ necessities, clean and safe energy possibilities have been pursued. The objective of this research is to develop a procedure that improves the integration of renewable technologies into local planning processes. The methodology should be suitable for different contexts. The objective of this paper is to evaluate the potential of energy production through agricultural waste, ensuring the sustainability and development of clean technologies, the ideal allocation of the energy production unit, and the costs involved in the enterprise. The research hypothesis is that the potential for sustainable use of biomass can be identified and evaluated, thus showing the way for an improved energy plan for Brazil. The study area is within the Doce River Basin in Brazil. The methods developed in the study could be relevant for municipalities to record their potentials for energy production and pursue investments and local arrangements, promoting sustainable biomass energy generation. The results show that with proper investment, the energy generation through biomass residues could be viable and pay itself in a short amount of time, moreover in a scenario where the agricultural area is increased, growing the power generation capacity of a biomass power plant. The current agricultural production would cover 20% of the local energy demand.

The Drosophila midgut and the systemic coordination of lipid-dependent energy homeostasis.

The evolution of complex organ systems in metazoans has dictated that the maintenance of energy homeostasis requires coordinating local and systemic energy demands between organs with specialized functions. The gastrointestinal tract is one of many organs that is indispensable for the systemic coordination of energy substrate uptake, storage, and usage, and the spatial organization of this organ (i.e. proximity to other metabolic organs) within a complex body plan underlies its role in organ crosstalk. Studies of various arthropod intestines, and in particular insects, have shed light on the evolution and function of the gastrointestinal tract in the maintenance of energy homeostasis. This brief review focuses on studies and theories derived from the insect intestine (particularly the midgut) of adult Drosophila melanogaster to inform on the how, what, and why of the gastrointestinal tract in the systemic regulation of lipids, the most common form of stored energy in insects.

Anaerobic Digestion of Floral Waste and Methane Enrichment: A Sustainable Approach for Waste to Energy Conversion

Disposal of floral waste into water or landfill because of religious beliefs causes water and soil pollution. The purpose of present experimental work is to find an energy proficient solution for the disposal of floral waste. The method used in the present work includes anaerobic digestion of floral waste for biogas generation. The proposed method aims to follow waste-to-energy approach, for meeting the local energy demands. The techniques for getting enhanced biogas production from floral waste include novel alkaline chemical pretreatment of floral waste, and co-digestion of floral waste along with food waste. Alkaline chemical pretreatment of floral waste using sodium carbonate showed improved biogas production up to 106%, as compared to the traditional sodium hydroxide chemical pretreatment. Also, a reduction in the cost of chemical pretreatment up to 90% was possible. Co-digestion of floral waste along with food waste was also found effective for getting enhanced biogas output. A feedstock mixture of 70% of floral waste and 30% food waste could produce 32.6% more biogas than the singular feedstock in the form of floral waste. Alkaline pretreatment of floral waste using sodium carbonate and co-digestion with food waste seem to be the novelty of the work. Application of chemical absorption technique for biogas quality improvement could enrich the methane content of biogas up to 96%. Large-scale application of the proposed techniques of solid waste management can meet the energy demands at potential locations. The biogas with enriched methane content can suitable for widespread applications, such as vehicular applications and electricity generation for the benefit of the end users.

Integrated and dynamic energy modelling of a regional system: A cost-optimized approach in the deep decarbonisation of the Province of Trento (Italy)

Since the Kyoto Protocol (1997), the European Union has fought against climate change adopting European, national and regional policies to decarbonise the economy. Moreover, the Paris Agreement (2015) calls 2050 solutions between -80% and -100% of greenhouse gas emissions compared with 1990. Regions have an important role in curbing CO2 emissions, and tailor-made strategies considering local energy demands, savings potentials and renewables must be elaborated factoring in the social and economic context. An “optimized smart energy system” approach is proposed, considering: (I) integration of electricity, thermal and transport sectors, (II) hourly variability of productions and demands, (III) coupling the EnergyPLAN software, to develop integrated and dynamic scenarios, with a multi-objective evolutionary algorithm, to identify solutions optimized both in terms of CO2 emissions and costs, including decision variables for all the three energy sectors simultaneously. The methodology is tested at the regional scale for the Province of Trento (Italy) analyzing a total of 30,000 scenarios. Compared to the Baseline 2016, it is identified: (I) the strategic role of sector coupling among large hydroelectric production and electrification of thermal and transport demands (heat pumps, electric mobility), (II) slight increases in total annual cost, +14% for a -90% of CO2 emissions in 2050.

Evaluation of Using the Ceiling and Wall Spots Ventilation System on Indoor Thermal Environment

The aim of this paper is to enhance the local comfortable zone for the occupants in a small office room. The ceiling spot ventilation (CSV) system and the wall spot ventilation (WSV) system are proposed and investigated numerically to show the influence of these systems on the local thermal comfort and energy demand. Three different amounts of airflow rate are used in this investigation. A CFD model is employed to explain the behavior of indoor airflow and temperature distribution in each case study. The results show that, when using these systems as a main ventilation system will reduced the demand on fresh air and this will reduce the required load on cooling coil and saving more energy. Also, the results revealed that the wall spot ventilation (WSV) was provided a required local indoor thermal environment air for the occupant zone. Therefore, using this system will provide a comfortable local environment and enhance the air velocity distribution as well as saving more energy.

Sustainability assessment of a novel micro solar thermal: Biomass heat and power plant in Morocco

AbstractNovel renewable energy technologies in the Middle East and North Africa region can be developed through microgeneration systems aiming to supply local energy demands in a sustainable way. In this study, we carried out a sustainability assessment combining two reputable methodologies which have been applied to a facility comprising a hybrid solar/biomass micro‐cogeneration organic ranking cycle system located in Morocco. We first applied a multiregional input–output analysis where economic issues such as the production of goods and services generated in all project's phases, as well as the added value and employment created, are estimated. Then, environmental impacts were assessed through a life cycle assessment (LCA). In terms of socioeconomic analysis, the total production of goods and services shows a value of 1.18 €2015/kWh. The added value and employment creation were 0.56 €2015/kWh and 0.05 full‐time employees/MWh, respectively. The levelized cost of electricity results in 0.218 €2015/kWh and the multiplier effect amounts to 2.26. The largest increase in sectorial output is produced in the Moroccan electricity sector and the largest job creation takes place in the agriculture sector from the biomass supply. Regarding environmental results, LCA shows a climate change potential of 11.8 g CO2 eq/kWhel, of which more than 70% comes from the boiler operation and specifically from the emissions due to biomass transportation. These results can help in promoting micro solar‐biomass systems in Morocco as they identify the socioeconomic and environmental benefits that can counterbalance the higher costs of such systems compared to fossil technologies.

Operational performance of on-grid solar photovoltaic system integrated into pre-fabricated portable cabin buildings in warm and temperate climates

Depreciating costs of solar photovoltaic (PV) electricity, increasing government support and initiatives, and rising prices of grid electricity have spurred the production of electricity through solar PV systems. The Chandigarh government in India has installed a 200 kWp on-grid PV system on the roofs of pre-fabricated portable cabins (PPC) to fulfil their local energy demand at the Indian Reserve Battalion (IRB) complex. In this paper, the operational performance of this system in warm and temperate climates is characterized based on on-field recorded data. Results for annual reference yield are 5.21 kWh/kWp/day, the array yield is 4.15 kWh/kWp/day, and the system-wide final yield is noted as 3.70 kWh/kWp/day. The annual array efficiency, the inverter efficiency, and the system efficiency were recorded at 12.24%, 89.27%, and 10.93%, respectively. The performance ratio is 71.30%, and the capacity utilization factor is 15.21%. We also noted the capture losses for the plant to be at 20.12%, out of which thermal capture losses was 6.97%. Based on this empirical assessment, the annual electricity produced by the system was 2,66,460.0 kWh. Based on the electricity production from this plant, we estimate that PPC building based PV systems may have the potential to mitigate the CO2 emissions for the base year by 421.1 tCO2eq. in comparison with present-day conventional thermal power plants in India.

Application of CCHPs in a centralized domestic heating, cooling and power network—Thermodynamic and economic implications

The main objective of the present study is to utilize the waste heat and low-medium temperature geothermal heat sources in a centralized domestic heating, cooling and electricity network. Both geothermal and waste heat (from cement industry) are utilized to run domestic-scale combined cooling, heating and power (CCHP) units to meet the thermal and electrical demands of a residential area as the case study. Energy and exergy principles are applied to the designed CCHPs and the employed components, while exergoeconomic analysis is developed to show the economic feasibility of the proposed distributed energy systems. It is observed that the designed CCHPs not only meet the local energy demand in a sustainable way, but also deliver surplus thermal and electrical energy to the main grids. The thermodynamic analysis shows that under the base condition, the geothermal and waste heat driven CCHPs operate with sustainability index of 1.985 and 2.747, respectively. The economic evaluations demonstrated that, by using the proposed local CCHPs instead of the main grids to supply energy demand of the case study, it is possible to gain a benefit of 15687 € per year. This results in a lower energy payment of the end-users.

Optimization of Hydrogen Supply Chain: A Case Study in Malaysia

Hydrogen is regarded as the fuel of future by having greater heating value than the conventional fuels and with zero carbon emission. Most of the previous supply chain studies only consider the application of hydrogen as transportation fuel. Taking Johor as a case study, this paper aims to develop a holistic optimization model that exploits the use of hydrogen for vehicle fueling and electricity generation. Oil palm biomass and solar energy are used as the energy sources to produce hydrogen and electricity to satisfy the local energy demand. Through this study, the optimal configuration of hydrogen supply chain in Johor has been identified and the associated cost is found to be 3,644,800 USD/d.

Rooftop photovoltaics potential assessment：A framework to integrate technological, economic, environmental and social benefit

Buildings have a significant impact on global and local energy demand and climate change. Consequently, the issue of photovoltaic (PV) potential assessment of building roofs have been extensively studied. Although studies have adopted different methods to predict the various potentials of rooftop PVs, as yet there is no understanding of a comprehensive framework for evaluating the potential of rooftop PVs. This study aims to develop a new framework to evaluate the technical, economic, environmental, and social benefits of rooftop PVs in old communities in Nanjing. The study found that the total annual electricity generation of rooftop PVs in the two districts of Nanjing was 431,136,314 KWh, which can meet about 20% of the residential electricity demand in the study area; the total electricity generation in the life cycle of 25 years was 5327909814 KWh; The economic benefit was 4.06 yuan/wp; the CO2 emission efficiency was 20.02%; the social benefit was 11.224 yuan/KWh. The results of this study will potential provide valuable reference suggestions for urban planners from the perspective of the benefits brought by rooftop PV in the two districts.

Muscle-derived Dpp regulates feeding initiation via endocrine modulation of brain dopamine biosynthesis.

In animals, the brain regulates feeding behavior in response to local energy demands of peripheral tissues, which secrete orexigenic and anorexigenic hormones. Although skeletal muscle is a key peripheral tissue, it remains unknown whether muscle-secreted hormones regulate feeding. In Drosophila, we found that decapentaplegic (dpp), the homolog of human bone morphogenetic proteins BMP2 and BMP4, is a muscle-secreted factor (a myokine) that is induced by nutrient sensing and that circulates and signals to the brain. Muscle-restricted dpp RNAi promotes foraging and feeding initiation, whereas dpp overexpression reduces it. This regulation of feeding by muscle-derived Dpp stems from modulation of brain tyrosine hydroxylase (TH) expression and dopamine biosynthesis. Consistently, Dpp receptor signaling in dopaminergic neurons regulates TH expression and feeding initiation via the downstream transcriptional repressor Schnurri. Moreover, pharmacologic modulation of TH activity rescues the changes in feeding initiation due to modulation of dpp expression in muscle. These findings indicate that muscle-to-brain endocrine signaling mediated by the myokine Dpp regulates feeding behavior.

Intrafibrillar and perinuclear mitochondrial heterogeneity in adult cardiac myocytes

Mitochondria are involved in multiple cellular functions, in addition to their core role in energy metabolism. Mitochondria localized in different cellular locations may have different morphology, Ca2+ handling and biochemical properties and may interact differently with other intracellular structures, causing functional specificity. However, most prior studies have utilized isolated mitochondria, removed from their intracellular environment. Mitochondria in cardiac ventricular myocytes are highly organized, with a majority squeezed between the myofilaments in longitudinal chains (intrafibrillar mitochondria, IFM). There is another population of perinuclear mitochondria (PNM) around and between the two nuclei typical in myocytes. Here, we take advantage of live myocyte imaging to test for quantitative morphological and functional differences between IFM and PNM with respect to calcium fluxes, membrane potential, sensitivity to oxidative stress, shape and dynamics. Our findings show higher mitochondrial Ca2+ uptake and oxidative stress sensitivity for IFM vs. PNM, which may relate to higher local energy demand supporting the contractile machinery. In contrast to IFM which are remarkably static, PNM are relatively mobile, appear to participate readily in fission/fusion dynamics and appear to play a central role in mitochondrial genesis and turnover. We conclude that while IFM may be physiologically tuned to support local myofilament energy demands, PNM may be more critical in mitochondrial turnover and regulation of nuclear function and import/export. Thus, important functional differences are present in intrafibrillar vs. perinuclear mitochondrial subpopulations.

Optimisation and economic modeling of micro hydropower plant integrated in water distribution system

As one of the key renewable energy source, hydropower is experiencing a growing development throughout the world. Micro hydropower plant is emerging as a decentralized source used particularly for meeting local energy demand. It is, therefore, of great significance to propose some effective methodologies in order to guarantee the whole production benefits of hydropower system. This paper evaluates the potential for installing micro hydropower within water distribution networks. Methodologies for assessing the feasibility of such installation are presented. The proper sizing for micro-hydropower plant (MHP) is identified using an optimization algorithm which considers both the dimensioning of the main components and the assessment of the energy production. Technical and economic studies are performed to investigate the practicability and the profitability of this system. The proposed algorithm was applied as a case study to analyze the feasibility of installing a MHP in water supply system in Morocco. The environmental aspects of this installation are also considered in this work. The obtained results demonstrate that the cost of this installation is strongly decreased through the use of already existing infrastructures. Simulation results have shown that the economic gain is doubled with the proposed optimization algorithm. Additionally, the environmental analysis has revealed that an annual average of 282 tones can be reduced by generating energy using this environmentally friendly solution. The findings of the energetic, economic, and environmental analysis confirm the potential of integrating micro hydropower in water supply system.

The potential of solar photovoltaic systems for residential homes in Lagos city of Nigeria

The development and use of solar photovoltaic (PV) technologies worldwide is considered crucial towards fulfilling an increasing global energy demand and mitigating climate change. However, the potential of a solar PV-system is location specific, influenced by the local solar resource, energy demand and cost among other factors. The main aim of this study is to conduct a detailed assessment of the potential of solar PV-systems in residential buildings in Lagos Metropolitan Area, Nigeria. Nigeria has enormous solar energy potential, it is the most populous country in Africa and occupies a significant place in the development of Africa. Yet, it is a country with one of the lowest per capita electricity consumption in the world – at 149 kWh per capita for a population of about 170 million, about 7% of Brazil's and 3% of South Africa's. To achieve this goal, this study employed the survey of 150 residential buildings in three local government areas (LGAs) in Lagos State, Nigeria to obtain electric load data. HOMER Pro was used to size the PV-systems and to determine the levelized cost of electricity (LCOE). The computed energy results of the study for the base case scenario revealed the PV array, lead acid battery and the converter (inverter) of the PV-systems to be in the following range: 0.3–76 kW; 2 to 176 kWh; and 0.1–13.2 kW respectively. Economic analysis revealed a LCOE of the systems in the range of 0.398 USD/kWh to 0.743 USD/kWh. The use of PV-system generated electricity in the dwellings has potential for an annual reduction of greenhouse gas emissions in the range of 31.24 kgCO2eq to 7456.44 kgCO2eq. Clearly, the use of solar PV systems in residential buildings possesses potentials for enabling Nigeria to attain its climate change mitigation targets indicated in her Nationally Determined Contributions (NDCs).

Bi-level optimization of design, operation, and subsidies for standalone solar/diesel multi-generation energy systems

Unlike grid–tied energy systems, wherein uniform renewable energy subsidies can be applied directly, the standalone multi-generation energy systems integrated with renewable energy in remote areas deserve to be subsidized specifically according to the local natural resources and energy demands. To establish an effective subsidy policy, the impacts of electrical and thermal subsidies for renewable energy on the system performance need to be investigated effectively, from the perspective of various stakeholders. In this study, a bi–level optimization model is proposed to obtain optimal design, operation, and subsidies for a standalone multi-generation energy system situated on a remote island; the system incorporates solar energy, fossil energy, and storage. Herein, the social cost to the society is set as the upper-level objective, and the private cost to the residents is set as the lower-level objective. The results indicate that production-based incentives of solar electrical energy and solar thermal energy jointly impact the design and operation of the energy system to minimize the social and private costs simultaneously; moreover, the demand response could further increase the flexibility of system operation, thus decreasing the system cost to a larger extent.

How the Nanoarchitecture of Cardiac Muscle Mitochondria Affects Function: Lessons from Computer Simulations

Mitochondria share a fundamental design: an outer membrane (OM) surrounding a topologically complex inner membrane (IM) that in turn encloses a dense matrix. Folds in the IM define compartments (cristae) that are connected to the peripheral IM (adjacent to OM) by narrow junctions. Cristae can vary greatly in number and shape, sometimes between mitochondria within the same cell. For example, in cardiac myocytes interfibrillar mitochondria contain closely packed lamellar cristae, while most mitochondria on the cell periphery have tubular cristae. Whether this structural heterogeneity has a functional basis (adaptation of the IM to stimuli such as local energy demand or oxidative stress) is unknown, as is whether the extreme topologies are related by remodeling or formed de novo. We are using electron microscopic tomography to create a database of mouse cardiac mitochondria, to parameterize IM structure for use in computer simulations of mitochondrial activities, and to look for clues about the nature of IM heterogeneity. Concurrently, we also are developing computational tools to expedite the extraction from tomograms of 3D membrane surfaces to use in the simulations. We have discovered that lamellar cristae contain numerous roughly circular fenestrations (diameters ∼20-70 nm) that may facilitate matrix diffusion between adjacent cristae. In a few tomograms, swollen lamellar and tubular cristae coexist, with fenestrations aligned in a way suggesting their involvement in a transition between the two topologies. (Crista swelling is associated with oxidative stress in some cells.) Computer simulations employing idealized and extracted IM surfaces suggest that cristae may function to sequester or buffer key metabolites such as ADP and affect the rate of uptake of calcium released from nearby internal stores. (Supported by NIH grant U01HLI16321.)

Dendritic shrinkage after injury: a cellular killer or a necessity for axonal regeneration?

Dendrites form an essential component of the neuronal circuit have been largely overlooked in regenerative research. Nevertheless, subtle changes in the dendritic arbors of neurons are one of the first stages of various neurodegenerative diseases, leading to dysfunctional neuronal networks and ultimately cellular death. Maintaining dendrites is therefore considered an essential neuroprotective strategy. This mini-review aims to discuss an intriguing hypothesis, which postulates that dendritic shrinkage is an important stimulant to boost axonal regeneration, and thus that preserving dendrites might not be the ideal therapeutic method to regain a full functional network upon central nervous system damage. Indeed, our study in zebrafish, a versatile animal model with robust regenerative capacity recently unraveled that dendritic retraction is evoked prior to axonal regrowth after optic nerve injury. Strikingly, inhibiting dendritic pruning upon damage perturbed axonal regeneration. This constraining effect of dendrites on axonal regrowth has sporadically been proposed in literature, as summarized in this short narrative. In addition, the review discusses a plausible underlying mechanism for the observed antagonistic axon-dendrite interplay, which is based on energy restriction inside neurons. Axonal injury indeed leads to a high local energy demand in which efficient axonal energy supply is fundamental to ensure regrowth. At the same time, axonal lesion is known to induce mitochondrial depolarization, causing energy depletion in the axonal compartment of damaged neurons. Mitochondria, however, become mostly stationary after development, which has been proposed as a potential underlying reason for the low regenerative capacity of adult mammals. Per contra, upon reduced neuronal activity, mitochondrial mobility enhances. In this view, dendritic shrinkage after axonal injury in zebrafish could result in less synaptic input and hence, a release of mitochondria within the soma-dendrite compartment that then translocate to the axonal growth cone to stimulate axonal regeneration. If this hypothesis proofs to be correct, i.e. dendritic remodeling serving as fuel for axonal regeneration, we envision a major shift in the research focus within the neuroregenerative field and in the potential uncovering of various novel therapeutic targets.

Impact of the Uncertainty of Distributed Renewable Generation on Deregulated Electricity Supply Chain

Active districts are districts that have a system in place to coordinate distributed energy generation and external grid to meet the local energy demand. They are now widely recognized as a clear opportunity toward distributed renewable integration. Despite apparent benefits of incorporating renewable sources in an active district, uncertainty in renewable generation can impose unprecedented challenges in efficient operation of the existing deregulated electricity supply chain, which is designed to operate with no or little uncertainty in both supply and demand. While most previous studies focused on the impact of renewables on the supply side of the supply chain, we investigate the impact of distributed renewable generation on the demand side. In particular, we study how the uncertainty from distributed renewable generation in an active district affects the average buying cost of utilities and the cost-saving of the active district. Our analysis shows that the renewable uncertainty in an active district can: 1) increase the average buying cost of the utility serving the active district, termed as local impact and 2) somewhat surprisingly, reduce the average buying cost of other utilities participating in the same electricity market, termed as global impact . Moreover, the local impact will lead to an increase in the electricity retail price of active district, resulting in a cost-saving less than the case without renewable uncertainty. These observations reveal an inherent economic incentive for utilities to improve their load forecasting accuracy, in order to avoid economy loss and even extract economic benefit in the electricity market. We verify our theoretical results by extensive experiments using real-world traces. Our experimental results show that a 9% increase in load forecasting error (modeled by the standard deviation of the mismatch between real-time actual demand and day-ahead purchased supply) will increase the average buying cost of the utility by 10%.

Heat mapping for district heating

If the UK wishes to decarbonise its energy supply, it should consider a wider uptake of district heating. Currently, district heating only accounts for 2% of the country’s total heat supply. This paper considers the initial stages of designing a district heating network, the energy mapping in the local area, using a case study of Darley Dale, England. Energy mapping techniques are used to estimate the local area energy demand, a basis on which the district heating network design will rely on. The areas in the case study that are found to be profitable for possible district heating and where the rest of the district heating design work should focus on are Matlock, Bakewell and Darley Dale. The results of the mapping technique presented in this paper are found to agree with heat mapping work carried out by the UK Government. The agreement between the two mapping techniques shows that the mapping technique outlined in this paper is accurate enough for use.