Local Energy Sources Research Articles

Analysis of the Stirling engine in the Schmidt approximation

Exploration, oil and gas well development, and oil and gas production facilities are often located in remote, remote locations away from electrical networks and highways. Autonomous power supply of these facilities is currently carried out by means of diesel power plants, which is associated with the necessary supply of fuel and associated high overhead costs. In this regard, the use of renewable energy sources (RES) is of particular relevance. As such, wind energy, geothermal heat, solar radiation energy, associated petroleum gas energy are known. The same group should include local energy sources such as peat, wood, coal, coal shale, etc.with the exception of the first of these sources, the rest require the conversion of thermal energy into mechanical energy, and then, by means of an electric generator into electrical energy. The only known universal Converter is the Stirling generator-a machine in which the generator is combined with the Stirling engine. Stirling engine (DS) – refers to external combustion engines, more precisely external heat supply. For the operation of the DS, it is only required to bring the temperature difference to its heat exchangers, and both the increased temperature of the heater and the reduced temperature of the refrigerator are important. As a heater, you can use the heat of the burner, steam or water heated in geothermal or solar collectors. It is possible to supply directly solar energy from solar concentrators. For these cases, a special design of the DS with a quartz head is provided, through which concentrated solar radiation enters directly into the expansion chamber. Geothermal water supplied directly from the well or associated petroleum gas, which can be highly corrosive, can also be used for these engines. As a refrigerator, you can use the environment, chilled water, ice or snow. DS works in a closed cycle, which allows you to completely seal the body and use helium or hydrogen as a working fluid. This ensures high working fluid pressure, which increases the specific power (power per unit volume or weight of the engine). Currently, these engines have not received mass application, which is explained by both economic reasons (high cost of development, competition from the ice) and commercial (patent restrictions, trade secrets).

Odnawialne źródła energii jako szansa na stworzenie proekologicznego wizerunku jednostki samorządu terytorialnego

W artykule została poruszona kwestia obowiązku samorządu terytorialnego dbania o środowiska naturalne. W tym celu jednostki samorządu terytorialnego powinien wykorzystywać najlepsze dostępne techniki, a więc m.in. alternatywne źródła energii. Odnawialne źródła energii zostały ukazane w kontekście zasad ogólnych wspólnotowegoprawa ochrony środowiska. Zgodnie z zasadą integracji polityki ochrony sektorowej z polityką ochrony środowiska, sektor energetyczny nie powinien szkodzić środowisku naturalnemu. Zasada prewencji wymaga działań zapobiegających zanieczyszczeniom powietrza, z kolei zasada ,,zanieczyszczający płaci” wprowadza kary za szkodliwą emisję.Zgodnie z zasadą wysokiego poziomu ochrony w każdym działaniu należy mieć na uwadze ochronę przyrody, a zasada usuwania szkód u źródła promuje stosowanie technologii czystej produkcji. Omówione zostały też zasady zrównoważonego rozwoju oraz partycypacjipublicznej, stanowiące podstawę zarówno ochrony środowiska, jak i udziału obywateli w decydowaniu o nim. Kolejna część artykułu dotyczy związków odnawialnych źródeł energii z samorządem terytorialnym na gruncie prawa krajowego w oparciu o polskie akty prawne, znajduje się tam też opis energetyki obywatelskiej z jej zaletami, sposobamifinansowania, a także z przykładami zarówno z Polski, jak i z krajów UE.

Modelling urban energy requirements using open source data and models

The transition towards sustainable and self-sufficient cities requires extensive knowledge of the electricity requirements for diverse consumers that interact in a temporal and geospatial platform. Energy models contribute to the strategic planning of future urban energy systems by providing relevant insights and scientific recommendations. In this context, energy policy advice have to entail transparency of the tools and models used as well as their respective input datasets which are generally neither open nor publicly available. The aim of this contribution is, to model urban energy requirements, namely local electricity consumption and on-site renewable power generation, using solely open source data and models. A systematic approach for a bottom-up simulation of urban electricity supply and demand down to the building unit level is developed here. The methodology combines spatial parameters of urban geometries and settlements and links them to real-world data using Geographic Information Systems. The developed model is showcased and validated for the city of Oldenburg (Germany). Quarter-hourly time series of electricity demand and supply are extracted for each existing urban unit such as buildings and streets. A regression analysis has been performed to validate the model outputs against measured data. Accordingly, up to 94% of the variance of the simulated urban electricity demand and supply are predictable from the measured datasets. The resulting demand and supply profiles have been used to investigate storage needs in urban areas. Furthermore, the model presented here offers a detailed load representation of different urban consumers’ segmentation. It determines also the configurations of on-site urban renewable energy mixes at which the share of electricity from grid and/or storage are at its minimum. Preliminary results show that, high levels of urban energy autarky could be achieved for a specific combination of local renewable energy sources.

Urban energy futures: a comparative analysis

No contemporary major city is sustainable, with current population and levels of consumption, beyond the fossil fuels which have facilitated what has appropriately been called “high-energy modernity.” At present, there appears to be no realistic possibility in any major city of replacing most of the energy from fossil fuels with renewable energy. Even in cities which could get most of their electricity from renewables, there is still a heavy reliance on motorized transport of people, goods, and food into and around the city. There does not appear to be a way to power and reproduce these fleets of vehicles solely with renewable energy, and most cities are not sustainable at their current size and density without them. But cities and regions vary in sustainability depending on local renewable energy sources, hinterland food production, population, extent of urban sprawl, and access to water-borne transportation. This paper identifies the features of more sustainable versus less sustainable cities, with examples from Asia, the Americas, and Europe. Case studies of two cities—Hong Kong and Vancouver, B.C.—are used to illustrate the analysis.

Atomic and Ionized Microstructures in the Diffuse Interstellar Medium

It has been known for half a century that the interstellar medium (ISM) of our Galaxy is structured on scales as small as a few hundred kilometers, more than 10 orders of magnitude smaller than typical ISM structures and energy input scales. In this review we focus on neutral and ionized structures on spatial scales of a few to ∼104 AU, which appear to be highly overpressured, as these have the most important role in the dynamics and energy balance of interstellar gas: the tiny scale atomic structures (TSASs) and extreme scattering events (ESEs) as the most overpressured example of the tiny scale ionized structures (TSISs). We review observational results and highlight key physical processes at AU scales. We present evidence for and against microstructures as part of a universal turbulent cascade and as discrete structures, and we review their association with supernova remnants, the Local Bubble, and bright stars. We suggest a number of observational and theoretical programs that could clarify the nature of AU structures. TSAS and TSIS probe spatial scales in the range of what is expected for turbulent dissipation scales and are therefore of key importance for constraining exotic and not-well-understood physical processes that have implications for many areas of astrophysics. The emerging picture is one in which a magnetized, turbulent cascade, driven hard by a local energy source and acting jointly with phenomena such as thermal instability, is the source of these microstructures.

A geothermal energy system for wastewater sludge drying and electricity production in a small island

Waste management and energy production are becoming critical issues in geographically disadvantaged areas, like small islands. For waste disposal the most common strategy is shipping to the mainland, due to the scarcity of land and local suitable treatments. Electricity generation is based on the importation of fossil fuels for local production, due to the lack of connections with continental energy networks. Both, waste shipping and fuels importation determine strong dependence on the mainland, as well as high economic and environmental cost for small islands. Therefore, using local renewable energy sources is extremely attracting. In this work, geothermal energy is considered for thermal drying of wastewater sludge and electricity supply of the whole wastewater treatment. The system is analysed for the case study of Pantelleria, a small island in Southern Italy, where sludge is currently dewatered to a final water content of 70–80%, and then shipped to mainland. The proposed system decreases wastewater sludge to be transported and disposed by 73.3%. Its profitability is demonstrated by several economic indicators, showing a Simple Payback time equal to 8.34 years and a Net Present Value of 502 k€. In addition, a sensitivity analysis for the main parameters affecting plant operation is carried out.

Alternative energy as a tool for the development of small and medium-sized enterprises in Russia

Nowadays, the level of development of small and medium-sized enterprises (SMEs) in Russia lags behind that of the states with advanced economy. Problems with connection to the power supply attributed to prohibitive costs and time-consuming procedures can be distinguished among many other reasons. The aim of this paper is to consider feasibility of applying alternative energy sources to the needs of small and medium-sized enterprises through the study of the Sverdlovsk Region. While analyzing local energy sources of the region with due regard to its geographic and climatic peculiarities, we have identified the most promising sources of energy that require state support for their efficient use. Estimation of economic efficiency of the implemented project of alternative energy supply at a small enterprise proves feasibility of using a stand-alone solar panel based energy supply system.

Modelling autonomous hybrid photovoltaic-wind energy systems under a new reliability approach

Hybrid photovoltaic-wind energy systems are being designed and implemented as stand-alone or grid connected generation systems, due to the need to use local, environmental friendly and low cost energy sources. In this study, a novel methodology to optimize the size of an autonomous hybrid photovoltaic-wind power system with battery storage is presented. A multi-objective optimization problem is considered with two objective functions, the total net present cost and a new reliability indicator called maximum expected energy not supplied, which is calculated using a probabilistic approach. The non-dominated sorting genetic algorithm-II was utilized to find the model solution. The results obtained with the presented methodology were compared with those from traditional methodologies, with the proposed methodology generating a set of feasible solutions, with respect to the system economy and reliability, which maximizes the use of renewable sources and reduces the size of the system backup.

Energy payback time and Greenhouse Gas emissions: Studying the international energy agency guidelines architecture

Abstract The International Energy Agency (IEA) in collaboration with an international panel of experts has published three editions of the Methodology Guidelines on Life Cycle Assessment of Photovoltaic Electricity (2009, 2011 and 2016) with the growing purpose of making increasingly precise assessments. This reference implies the estimation of major environmental indicators reported in literature, such as Energy PayBack Time (EPBT) and Greenhouse Gas (GHG) emissions in order to determine their benefits in terms of energy compared to conventional alternatives. However, in most cases this framework provides simplified calculations at the expense of accuracy. This study strengthens the monocrystalline (mono-Si) and polycrystalline (poly-Si) energy production estimation proposed by the IEA guidelines with formulas and calculation models of highest accuracy and contrast the resultant EPBT and GHG emissions in a case study. Likewise, a detailed analysis has been carried out to observe the range of orientations with the optimum performance while on the other hand; emphasis was placed on the need to compare the results directly with those corresponding to local energy sources, instead of regional or national ones. Results indicated that EPBT was 17%–19% and GHG emissions were 14–16% lower with the proposed method compared to the IEA guidelines respectively. Moreover, a range of orientations with near-optimal performance is also detailed. Finally, despite having clear environmental benefits compared to the local electric mix, its benefit is lower than if compared to the national electric mix in the case studied. Therefore, conclusions expressed herein contribute to reliability consolidation of PV technologies

Policy discussion for sustainable integrated electricity expansion in South Africa

Emerging reports have shown that despite Eskom's continued investment in increasing electricity supply capacity to grid connected and off-grid households, there has been a steady decline in electricity consumption (kWh/month/individual) and household income (ZAR/month). This paper presents an integrated electricity expansion model (IEEM) for South Africa that seeks to incorporate demand side management (DSM) in providing a roadmap for improving and increasing energy (electricity) access that is sustainable, viable, ethically compliant and cost effective. In modelling IEEM, a modified genetic algorithm (MGA) would be utilized in simulating the dispatch of DSM loads (residential houses only) across the country. This paper advances traditional grid expansion planning by presenting smart policy discussions on the usefulness of IEEM in reducing associated network losses, enhancing utilization of local energy sources and minimizing expansion and plant operations costs. This paper also discusses the impact of the IEEM on the quality of life (QoL) of households and quality of service (QoS) of the utility. Electricity consumption data have been adopted from the existing literature and appropriately modified.

Hybrid renewable energy systems for renewable integration in microgrids: Influence of sizing on performance

Hybrid Power System (HPS) are effective means for the increase of the exploitation of local renewable energy sources in the Distributed Generation (DG) paradigm concept. This work aims at analyzing thoroughly the effects mentioned for two different energy demand profiles: an industrial facility and a residential complex of 75 apartments. A parametric analysis with different components sizing is proposed to evaluate the optimal solution in terms of deployment of renewable energies, resilience of the system and environmental impact, considering the economic convenience as a sustainability constraint. Results show that the two main drivers for the convenience of such systems are the load profile and the PV power plant power sizing. The former shows greater effectiveness of the microgrid management for the residential load rather than the industrial one. The latter shows that the correct sizing of the PV powerplant allows for a smarter use of the battery and gives lesser dependence on the energy exchanged with the grid.

The Energy Cost Analysis of Hybrid Systems and Diesel Generators in Powering Selected Base Transceiver Station Locations in Nigeria

As more locations gain access to telecommunication, there is a growing demand to provide energy in a reliable, efficient and environmentally friendly manner while effectively addressing growing energy needs. Erratic power supply and rising operation costs (OPEX) in Nigeria have increased the need to harness local renewable energy sources. Thus, identifying the right generator schedule with the renewable system to reduce OPEX is a priority for operators and vendors. This study evaluates the energy costs of hybrid systems with different generator schedules in powering base transceiver stations in Nigeria using the Hybrid Optimization Model for Electric Renewable (HOMER). A load range of 4 kW to 8 kW was considered using: (i) an optimised generator schedule; (ii) forced-on generator schedule and (iii) the generator-only schedule. The results showed an optimal LCOE range between averages of USD 0.156/kWh to 0.172/kWh for the 8 kW load. The percent energy contribution by generator ranges from 52.80% to 60.90%, and by the solar PV system, 39.10% to 47.20%. Excess energy ranges from 0.03% to 14.98%. The optimised generator schedule has the highest solar PV penetration of 56.8%. The OPEX savings on fuel ranges from 41.68% to 47% for the different load schedules and carbon emission savings of 4222 kg to 31,428.36 kg. The simulation results shows that powering base stations using the optimised hybrid system schedule would be a better option for the telecom industry.

Nowcasting solar irradiance using an analog method and geostationary satellite images

Accurate forecasting of Global Horizontal Irradiance (GHI) is essential for the integration of the solar resource in an electrical grid. We present a novel data-driven method aimed at delivering up to 6 h hourly probabilistic forecasts of GHI on top of a localized solar energy source. The method does not require calibration to adapt to regional differences in cloud dynamics, and uses only one type of data, covering Europe and Africa. It is thus suited for applications that require a GHI forecast for solar energy sources at different locations with few ground measurements. Cloud dynamics are emulated using an analog method based on 5 years of hourly images of geostationary satellite-derived irradiance, without using any numerical prediction model. This database contains both the images to be compared to the current atmospheric observation and their successors at one or more hours of interval. The physics of the system is emulated statistically, and no numerical prediction model is used. The method is tested on one year of data and five locations in Europe with different climatic conditions. It is compared to persistence (keeping the last observation frozen), ensemble persistence (generating a probabilistic forecast using the last observations) and an adaptive first order vector autoregressive model. As an application, the model is downscaled using ground measurements. In both cases, the analog method outperforms the classical statistical approaches. Results demonstrate the skill of the method in emulating cloud dynamics, and its potential to be coupled with a forecasting algorithm using ground measurements for operational applications.

Integrating a hydrogen fuel cell electric vehicle with vehicle-to-grid technology, photovoltaic power and a residential building

This paper presents the results of a demonstration project, including building-integrated photovoltaic (BIPV) solar panels, a residential building and a hydrogen fuel cell electric vehicle (FCEV) for combined mobility and power generation, aiming to achieve a net zero-energy residential building target. The experiment was conducted as part of the Car as Power Plant project at The Green Village in the Netherlands. The main objective was to assess the end-user’s potential of implementing FCEVs in vehicle-to-grid operation (FCEV2G) to act as a local energy source. FCEV2G field test performance with a Hyundai ix35 FCEV are presented. The car was adapted using a power output socket capable of delivering up to 10 kW direct current (DC) to the alternating current (AC) national grid when parked, via an off-board (grid-tie) inverter. A Tank-To-AC-Grid efficiency (analogous to Tank-To-Wheel efficiency when driving) of 44% (measured on a Higher Heating Value basis) was obtained when the car was operating in vehicle-to-grid (V2G) mode at the maximum power output. By collecting and analysing real data on the FCEV power production in V2G mode, and on BIPV production and household consumption, two different operating modes for the FCEV offering balanced services to a residential microgrid were identified, namely fixed power output and load following.Based on the data collected, one-year simulations of a microgrid consisting of 10 all-electric dwellings and 5 cars with the different FCEV2G modes of operation were performed. Simulation results were evaluated on the factors of autonomy, self-consumption of locally produced energy and net-energy consumption by implementing different energy indicators. The results show that utilizing an FCEV working in V2G mode can reduce the annual imported electricity from the grid by approximately 71% over one year, and aiding the buildings in the microgrid to achieve a net zero-energy building target. Furthermore, the simulation results show that utilizing the FCEV2G setup in both modes analysed, could be economically beneficial for the end-user if hydrogen prices at the pump fall below 8.24 €/kg.

A network approach to decentralized coordination of energy production-consumption grids.

Energy grids are facing a relatively new paradigm consisting in the formation of local distributed energy sources and loads that can operate in parallel independently from the main power grid (usually called microgrids). One of the main challenges in microgrid-like networks management is that of self-adapting to the production and demands in a decentralized coordinated way. Here, we propose a stylized model that allows to analytically predict the coordination of the elements in the network, depending on the network topology. Surprisingly, almost global coordination is attained when users interact locally, with a small neighborhood, instead of the obvious but more costly all-to-all coordination. We compute analytically the optimal value of coordinated users in random homogeneous networks. The methodology proposed opens a new way of confronting the analysis of energy demand-side management in networked systems.

Implementation of talis and dc house system for rural areas in indonesia

In 2017, the aggregate electrification ratio in Indonesia has been achieving 92.8%. However, some rural areas such as in Maluku and Papua Islands still have low electrification ratio (~70%). One of the main problems in supplying electricity to rural areas in Indonesia is the geographical concern which consisted of islands leading to the difficulty of electricity grid development. In some areas, diesel power plant has been being built to supply the electricity. However, it causes another problem to transport the primary energy source to the targeted area which would increase the cost of electricity supply. Besides, it also needs investment cost to build transmission and distribution systems, as well as the maintenance expenses. To resolve this issue, a new scheme of battery-based Tabung Listrik or TaLis (DC-based power bank) and DC house system is proposed to be the solution to provide electricity to rural areas. The potential of local renewable energy sources such as biomass, hydro, wind, and solar could be utilized to be charging sources of batteries (TaLis). This study presents the TaLis prototype, DC house installation, supply chain process and charging scheme of TaLis, and cost comparison between the proposed system with other existing power systems such as communal PV farm and diesel power plant. We found that TaLis and DC house system provided the least cost of electricity production compared to other power systems, i.e. $0.88/kWh for TaLis and DC house system, $1.65/kWh for diesel power plant, and $1.47/kWh for communal PV farm. Implementation of this approach is expected to improve the welfare and quality of life of rural communities immediately.

Peak-Aware Online Economic Dispatching for Microgrids

By employing local renewable energy sources and power generation units while connected to the central grid, microgrid can usher in great benefits in terms of cost efficiency, power reliability, and environmental awareness. Economic dispatching is a central problem in microgrid operation, which aims at effectively scheduling various energy sources to minimize the operating cost while satisfying the electricity demand. Designing intelligent economic dispatching strategies for microgrids, however, is drastically different from that for conventional central grids, due to two unique challenges. First, the erratic renewable energy emphasizes the need for online algorithms. Second, the widely-adopted peak-based pricing scheme brings out the need for new peak-aware strategy design. In this paper, we tackle these critical challenges and devise peak-aware online economic dispatching algorithms. For microgrids with fast-responding generators, we prove that our deterministic and randomized algorithms achieve the best possible competitive ratios $2-\beta$ and $e/(e-1+\beta)$, respectively, where $\beta\in[0,1]$ is the ratio between the minimum grid spot price and the local-generation price. Our results characterize the fundamental \emph{price of uncertainty} of the problem. For microgrids with slow-responding generators, we first show that a large competitive ratio is inevitable. Then we leverage limited prediction of electricity demand and renewable generation to improve the competitiveness of the algorithms. By extensive empirical evaluations using real-world traces, we show that our online algorithms achieve near offline-optimal performance. In a representative scenario, our algorithm achieves $17.5\%$ and $9.24\%$ cost reduction as compared to the case without local generation units and the case using peak-oblivious algorithms, respectively.

Micro Hydropower: An Adaptive Technology in the Changing Context, a Case Study from Trans Himalayan District of Mustang, Nepal

Situated at an altitude of about 3,000 meters above sea level, Trans Himalayan district of Mustang categorized as water deficit arid desert has growing demand for electricity just like in rest of Nepal. As access to grid has become a major development agenda, National grid is penetrating remote districts like Mustang. In the face of grid expansion, the Micro Hydro systems installed 20-30 years to lighten the villages could be at risk of being nonfunctional if proper energy planning is not done. The study was conducted in the villages in phase of grid connection and having micro hydro commissioned 20-30 years ago. This study assesses the community perception on extending grid and their perception on preexisting micro hydro. The paper illustrates the role of MHP in the changing context of emerging renewable energy technologies and expansion of grid penetration across the Himalayas. Underscoring the relevance of local resource utilization and energy source diversification paper highlight the needs for proper planning of energy mix for promoting sustainable energy supply.

Making the World More Sustainable: Enabling Localized Energy Generation and Distribution on Decentralized Smart Grid Systems

Smart grid is an idea of upgradation of the traditional electric grid infrastructure. The efficiency of the existing electrical grid can be automated by integrating with innovative technical equipment such as: high-tech forecasting system, digital sensors, advanced two-way communication and two-way power flow systems. Smart grid establishes an interface between utility and consumer which helps to use energy, based on the preferences of price, eco-friendly and without technical system issues. It empowers the grid to be more secure, reliable and efficient. The peer-reviewed articles and published government reports have been reviewed, based on the analysis of technical characteristics of power generation systems, eco-friendly sources of power generations, cost reduction, functionality and design of traditional grid versus smart grid. Furthermore, the innovative technologies that enable the grid to integrate with decentralized power generation system efficiently have been considered. This paper claims that in this modern era, it is arduous for traditional grid to fulfill the rising demand of electricity, along with sustainable, eco-friendly and stable power supply, as it cannot be efficiently integrated with decentralized and localized power generation systems and renewable energy sources. The result of this paper shows that decentralized and localized power generation systems are located close to end-users which decrease the transmission and supply cost of electricity. Innovative technologies allow the decentralized and localized power generation systems to be integrated with renewable energy sources which help to reduce the cost of utility services and provide clean energy. Moreover, technological advancement played a decisive role in enabling the electrical system to be more efficient. Electrical reliability can be improved, greenhouse gas emissions can be reduced, renewable energy sources can efficiently be integrated, and rising demand for electricity can be met by embedding advanced applications and technological equipment in the electrical grid.

Overcurrent Protections in MV Grid with Local Energy Sources

The article presents typical methods of connecting various types of local power sources to a medium voltage network. Describes the advantages and disadvantages of individual solutions. The authors focus particularly on the issues of power system protection, with particular emphasis on overcurrent protection (ANSI 50 and 67). The key part of the article is the presentation of the selection methodology, along with examples, of setting this type of protection for a frequently encountered case - connecting local energy sources with busbars with a line with receipts.