Novel method for setting up the relay protection of power systems containing renewable energy sources and hydrogen energy storage systems

Integration of renewable energy sources (RES) together with energy storage systems (ESS) changes processes in electric power systems (EPS) significantly. Specifically, rate of change and the lowest values of operating conditions during the emergencies are got influenced. Such changes can cause incorrect actions of relay protection (RP) as it was designed and adjusted with no regard for influence of RES and ESS. Detailed research on processes during the different normal and abnormal modes in both EPS and primary transducers and also in RP devices should be done to take preventive actions. To do this research mathematical modeling based on detailed and authentic models of all elements including RP should be used. HRTSim (which was developed by authors) software for simulating EPS provides the opportunity to create such models of EPS of any size without simplifications and limits. Using of this instrument together with detailed mathematical models of RP which were developed before provided the opportunity to investigate them rigorously in RES-integrated EPS. Settings providing adequate action of RP in certain conditions were performed as a result of this investigation. Fragments of these investigations are performed in this paper. Results of these investigations would be useful for designing new methods and tools of RP adjustment.     

Transition to renewable energy systems with hydrogen as an energy carrier

Unlike the present energy system based on fossil fuels, an energy system based on renewable energy sources with hydrogen and electricity as energy carriers would be sustainable. However, the renewable energy sources in general have less emergy than the fossil fuels, and their carriers have lower net emergy. Because of that they would not be able to support continuous economic growth, and would eventually result in some kind of a steady-state economy. An early transition to renewable energy sources may prove to be beneficial in the long term, i.e., it may result in a steady state at a higher level than in the case of a transition that starts later. Once the economy starts declining it will not be able to afford transition to a more expensive energy system, and transition would only accelerate the decline. Similarly, if a transition is too fast it may weaken and drain economy too much and may result in a lower steady state. If a transition is too slow, global economy may be weakened by the problems related to utilization of fossil fuels (such as global warming and its consequences) before transition is completed and the result again would be a lower steady state. Therefore, there must be an optimal transition rate; however, its determination would require very complex models and constant monitoring and adjustment of parameters.     

Economic aspects of nuclear and hydrogen energy in the world and Russia

Hydrogen, when used as a fuel, has the most minimal impact on the environment and is a viable, promising, but insufficiently studied alternative fuel. World demand for its production may increase by tens and hundreds of times, and alternative energy sources - renewable and non-renewable, including nuclear ones - are needed to meet it.The paper discusses the characteristics of these sources, shows the important role of nuclear energy.The development of hydrogen production stimulates the development of the symbiosis of nuclear and hydrogen energy in conjunction with renewable energy and allows the formation of a new sustainable global energy system - alternative energy.     

Trends in design of distributed energy systems using hydrogen as energy vector: A systematic literature review

Currently, a significant transformation for energy systems has emerged as a result of the trend to develop an energy framework without fossil fuel reliance, the concerns about climate change and air quality, and the need to provide electricity to around of 17% of world population who lacks the service. Accordingly, the deployment of power plants located close to end-users and including multiple energy sources and carriers, along with the growing share of renewable energies, have suggested changes in the energy sector. Despite their potential capabilities, the design of distributed energy systems (DES) is a complex problem due to the simultaneous goals and constraints that need to be considered, as well as to the high context dependence of this kind of projects. For these reasons, in this work a systematic literature review of DES including hydrogen as energy vector, was made analyzing 106 research papers published between the years 2000–2018, and extracted from Scopus^® and Web of Science databases. The aim was to identify how hydrogen is employed (technologies, uses) and the criteria that are evaluated (economic, technical, social and environmental) when these systems are designed, planned and/or operated. The results constitute a baseline information covering the type of technologies, equipment sizes and hydrogen applications, that could be valuable for the preliminary stages of research or project planning of DES involving hydrogen. Furthermore, other factors have also been identified, such as the focus on techno-economic issues, and the lack of considering socio/political aspects and the uncertainty about input data like weather conditions, energy prices and demands. Additionally, a more integrated approach is needed including all the hydrogen supply chain stages and project stakeholders, to tackle issues like safety of the energy systems that could produce consumer rejections.     

Toward a hydrogen society: Hydrogen and smart grid integration

Hydrogen has an important role as a smart solution for Smart Grid, as it can play as an energy vector, a storage medium, and a clean fuel cell. The integration of Hydrogen and Smart Grid can minimize the impact on the environment while maximizing sustainability, which indicates that we are developing toward a hydrogen society. There have been already many studies on different aspects of this topic. For a better understanding of the related work, this paper proposed a comprehensive overview of the related work on the integration of Hydrogen and Smart Grid. Related literature is organized and analyzed from four categories, including Hydrogen energy in smart grids, Hydrogen fuel cell electric vehicles, Hydrogen economy in smart grids, and Models for energy system in smart grids. And each subject has been introduced more carefully. What's more, for a clear understanding for readers, we provide overall scenario views for the organization of the related work.     

Renewable energy sources in the Mexican electricity sector

This paper analyzes the role of renewable energy sources (RES) in the Mexican electricity sector in the context of the proposed renewable energy bill currently under consideration in the Mexican Congress. This paper was divided into three parts. The first part presents a chronology of institutional background related to the RES. This is followed by an analysis of the coordination and management system of the Mexican electricity sector, which can facilitate the promotion and integration of the RES without significant structural changes. Finally, the pros and cons of the renewable energy bill are analyzed in order to demonstrate the need for greater coherence between the bill and the coordination system of the sector. It is concluded that when inconsistency is eliminated, RES would strongly be promoted in Mexico.     

Potential of renewable hydrogen production for energy supply in Hong Kong

Hong Kong is highly vulnerable to energy and economic security due to the heavy dependence on imported fossil fuels. The combustion of fossil fuels also causes serious environmental pollution. Therefore, it is important to explore the opportunities for clean renewable energy for long-term energy supply. Hong Kong has the potential to develop clean renewable hydrogen energy to improve the environmental performance. This paper reviews the recent development of hydrogen production technologies, followed by an overview of the renewable energy sources and a discussion about potential applications for renewable hydrogen production in Hong Kong. The results show that although renewable energy resources cannot entirely satisfy the energy demand in Hong Kong, solar energy, wind power, and biomass are available renewable sources for significant hydrogen production. A system consisting of wind turbines and photovoltaic (PV) panels coupled with electrolyzers is a promising design to produce hydrogen. Biomass, especially organic waste, offers an economical, environmental-friendly way for renewable hydrogen production. The achievable hydrogen energy output would be as much as 40% of the total energy consumption in transportation.     

Analyses of hydrogen energy system as a grid management tool for the Hawaiian Isles

One of the objectives of the research project at Hawaii Natural Energy Institute (HNEI) is to demonstrate long-term durability of the electrolyzer when operated under cyclic operation for frequency regulation on an Island grid system. In this paper, a Hydrogen Energy System with an electrolyzer is analyzed as a potential grid management tool. A simulation tool developed with a validated model of the hydrogen energy system and Island of Hawaii grid model is presented and employed for this investigation. The simulation study uses realistic measured solar and wind power profiles to understand what optimal electrolyzer size would be required to achieve the maximum level of grid frequency stabilization. The simulation results give insight into critical information when designing a hydrogen energy system for grid management applications and the economic impact it has when operated as a pure grid management scheme or as a limitless hydrogen production system.     

Feasibility study of renewable energy sources for developing the hydrogen economy in Pakistan

Hydrogen energy can play a pivotal part in enhancing energy security and decreasing hazardous emissions in Pakistan. However, hydrogen energy can be sustainable and clean only if it is produced from renewable energy sources (RES). Therefore, this study conducts feasibility of six RES for the generation of hydrogen in Pakistan. RES evaluated in this study include wind, solar, biomass, municipal solid waste (MSW), geothermal, and micro-hydro. RES have been evaluated using Fuzzy Delphi, fuzzy analytical hierarchy process (FAHP), and environmental data envelopment analysis (DEA). Fuzzy Delphi finalizes criteria and sub-criteria. FAHP obtains relative weights of criteria considered for choosing the optimal RES. Environmental DEA measures relative efficiency of each RES using criteria weights as outputs, and RES-based electricity generation cost as input. The results revealed wind as the most efficient source of hydrogen production in Pakistan. Micro-hydro and Solar energy can also be used for hydrogen production. Biomass, MSW, and geothermal achieved less efficiency scores and therefore are not suggested at present.     

How the hydrogen production from RES could change energy and fuel markets: A review of recent literature

The goal that the international community has set itself is to reduce greenhouse gas (GHG) emissions in the short/medium-term, especially in Europe that committed itself to reducing GHG emissions to 80–95% below 1990 levels by 2050. Renewable energies play a fundamental role in achieving this objective. In this context, the policies of the main industrialized countries of the world are being oriented towards increasing the shares of electricity produced from renewable energy sources (RES).In recent years, the production of renewable energy has increased considerably, but given the availability of these sources, there is a mismatch between production and demand. This raises some issues as balancing the electricity grid and, in particular, the use of surplus energy, as well as the need to strengthen the electricity network.Among the various new solutions that are being evaluated, there are: the accumulation in batteries, the use of compressed air energy storage (CAES) and the production of hydrogen that appears to be the most suitable to associate with the water storage (pumped hydro). Concerning hydrogen, a recent study highlights that the efficiencies of hydrogen storage technologies are lower compared to advanced lead acid batteries on a DC-to-DC basis, but “in contrast […] the cost of hydrogen storage is competitive with batteries and could be competitive with CAES and pumped hydro in locations that are not favourable for these technologies” (Moliner et al., 2016) [1].This shows that, once the optimal efficiency rate is reached, the technologies concerning the production of hydrogen from renewable sources will be a viable and competitive solution. But, what will be the impact on the energy and fuel markets? The production of hydrogen through electrolysis will certainly have an important economic impact, especially in the transport sector, leading to the creation of a new market and a new supply chain that will change the physiognomy of the entire energy market.     

PEM electrolysis for production of hydrogen from renewable energy sources

PEM electrolysis is a viable alternative for generation of hydrogen from renewable energy sources. Several possible applications are discussed, including grid independent and grid assisted hydrogen generation, use of an electrolyzer for peak shaving, and integrated systems both grid connected and grid independent where electrolytically generated hydrogen is stored and then via fuel cell converted back to electricity when needed. Specific issues regarding the use of PEM electrolyzer in the renewable energy systems are addressed, such as sizing of electrolyzer, intermittent operation, output pressure, oxygen generation, water consumption and efficiency.     

Renewable and hydrogen energy integrated house

The residential sector accounts for about a third of the total world energy consumption. Energy efficiency, Renewable Energy Sources and Hydrogen can play an important role in reducing the consumptions and the emissions and improving the energy security if integrated (Efficiency, Res, Hydrogen) systems are developed and experimented. The paper analyzes a real residential 100 square meters house, where energy efficiency measures and RES technologies have been applied, sizing a hydrogen system (electrolyzer, metal hydrides and fuel cell) for power backup, taking into consideration its dynamic behavior, experimentally determined. The technologies used are already available in the market and, except hydrogen technologies, sufficiently mature. Through energy efficiency technologies (insulation, absorbers, etc), the maximum electrical and thermal power needed decreases from 4.4 kW_e to 1.7 kW_e (annual consumption from 5000 kWh to 1200 kWh) and from 5.2 kW_t to 1.6 kW_t (annual consumption from 14,600 kWh to 4500 kWh) respectively. With these reduced values it has been possible to supply the consumptions entirely by small photovoltaic and solar thermal plants (less than 10 m² each). The hydrogen backup even if remains the most expensive (versus traditional batteries and gasoline generator), satisfying all the electric needs for one day, increases the security and allows net metering. Moreover the low-pressure hydrogen storage system through metal hydrides guarantees system safety too. Finally the system modularity can also satisfy higher energy production.     

Optimizing the exchange of active power of the main and distribution network,which includes hydrogen energy accumulators,taking into account the price indicators

The paper considers the task of creating an instrumental system for optimizing the exchange of active power of the trunk and distribution networks, taking into account the price indicators of electricity in a joint and separate mode of operation. As part of the development of a simulation model of the automated control system of the local intelligent power system MicroGrid, the results of modeling the exchange of active power of the power connection from the main network of the main South of Russia main electrical networks and the distribution network of the university campus (in which classical sources of generation are combined with solar, wind and hydrogen energy) are presented.In a single model, the electrical mode of operation of networks is simulated in the voltage range of 0.4–500 kV. Simulation is carried out in steady state and transient mode. Slow, real and fast time modes are available. Simulation of emergency control systems has been implemented. The modes of synchronization of the main and distribution networks in normal and emergency circuits are considered. Reliability control and monitoring of the main operating parameters are carried out.The active power exchange module created on the basis of the results of the simulation as part of the software package « RETREN » will make it possible to use this complex to automate the management of local power system. The energy system, in addition to power from the grid, includes gas generation, solar panels installed on the roofs of campus buildings, wind turbines and stationary hydrogen power plants operating on hydrogen fuel cells. The complex of designers allows organizing human-machine interfaces of any complexity on completely domestic software products.     

Evaluation of hydrogen storage technology in risk-constrained stochastic scheduling of multi-carrier energy systems considering power,gas and heating network constraints

The operation of energy systems considering a multi-carrier scheme takes several advantages of economical, environmental, and technical aspects by utilizing alternative options is supplying different kinds of loads such as heat, gas, and power. This study aims to evaluate the influence of power to hydrogen conversion capability and hydrogen storage technology in energy systems with gas, power, and heat carriers concerning risk analysis. Accordingly, conditional value at risk (CVaR)-based stochastic method is adopted for investigating the uncertainty associated with wind power production. Hydrogen storage system, which can convert power to hydrogen in off-peak hours and to feed generators to produce power at on-peak time intervals, is studied as an effective solution to mitigate the wind power curtailment because of high penetration of wind turbines in electricity networks. Besides, the effect constraints associated with gas and district heating network on the operation of the multi-carrier energy systems has been investigated. A gas-fired combined heat and power (CHP) plant and hydrogen storage are considered as the interconnections among power, gas and heat systems. The proposed framework is implemented on a system to verify the effectiveness of the model. The obtained results show the effectiveness of the model in terms of handling the risks associated with multi-carrier system parameters as well as dealing with the penetration of renewable resources.     

A regional decision support system for onsite renewable hydrogen production from solar and wind energy sources

Hydrogen technologies driven by renewable energy sources (RES) represent an attractive energy solution to ensure environmental sustainability. In this paper, a decision support system for the hydrogen exploitation is presented, focusing on some specific planning aspects. In particular, the planning aspects regard the selection of locations with high hydrogen production mainly based on the use of solar and wind energy sources. Four modules were considered namely, the evaluation of the wind and solar potentials, the analysis of the hydrogen potential, the development of a regional decision support module and a last module that regards the modelling of a hybrid onsite hydrogen production system. The overall approach was applied to a specific case study in Liguria region, in the north of Italy.     

Key challenges to expanding renewable energy

The key advantage of renewables is that they are free of direct pollution and carbon emissions. Given concern over global warming caused by carbon emissions, there are substantial policy efforts to increase renewable penetrations. The purpose of this paper is to outline and evaluate the challenges presented by increasing penetrations of renewable electricity generation. These generation sources primarily include solar and wind which are growing rapidly and are new enough to the grid that the impact of high penetrations is not fully understood. The intrinsic nature of solar and wind power is very likely to present greater system challenges than “conventional” sources. Within limits, those challenges can be overcome, but at a cost. Later sections of the paper will draw on a variety of sources to identify a range of such costs, at least as they are foreseen by researchers helping prepare ambitious plans for grids to obtain high shares (30–50%) of their megawatt hours from primarily solar and wind generation. Energy poverty issues are outlined and related to renewable costs issues.     

Hydrogen fuel as an important element of the energy storage needs for future smart cities

A considerable amount of non-dispatchable photovoltaic and wind power have always been planned in smart cities, however, the problem of massive energy storage has not yet been solved which limits the use of green energy on larger scale. At present the only battery energy storage is available, and it is effective only for storing modest quantities of energy for short periods of time. The other storage technology options are not often commercially available items; rather, they are just good concepts that need to be tested for viability. Currently, the only alternative options for turning an urban development into one that exclusively uses green energy is to use that energy to generate hydrogen through electrolyzers, then use this fuel to generate the required electricity in order to stabilize the grid. Even more appealing is the idea of using wind and photovoltaic energy to transform smart communities into a centre for producing hydrogen in addition to a city that solely uses renewable energy. The most likely solution, absent an urgent debate inside the science establishment, will be to import electricity from the burning of hydrocarbons while continuing to pay carbon offsets, which is incompatible with the goal of using only renewables. The smart city has not officially accepted this issue, just like the science establishment.     

Multi-agent direct current systems using renewable energy sources and hydrogen fuel cells

Direct current provides accumulation of electricity and is therefore necessary when using renewable energy sources. Hydrogen energy storage devices in the form of fuel cells are the most effective and environmentally friendly way of energy storage and conservation. Shortcomings of electric power networks compared with DC networks in terms of stability, controllability, reliability and redundancy are noted. The necessity of transition from digitalization in the form of automated process control systems to smart grids, and subsequently to multi-agent DC networks with a high degree of redundancy, is revealed. Besides, the paper deals with application of distributed generation consisting of traditional and renewable energy sources, as well as accumulators and static converters. Characteristics of the above mentioned elements are given for simulating the modes in order to select the structure and control algorithms that provide increased power supply reliability.     

Development of an ambient temperature alkaline electrolyser for dynamic operation with renewable energy sources

A comparison is made between the ambient and conventional temperature alkaline electrolysers in terms of operational system, voltage efficiency and corrosion rates. The capital, operational and maintenance costs are reduced by reducing auxiliary equipment as well as auxiliary utilities in the ambient temperature alkaline electrolyser. Also, since auxiliary electricity consumption is reduced, the alkaline electrolyser is capable for dynamic, continuous and fast-response operation with renewable energy sources. The ambient temperature alkaline electrolyser is capable for wider operational range and faster response time when powered by wind energy sources. Although the voltage efficiency for hydrogen production is increased by about 12% at the conventional operating temperature, corrosion rate of the electrode is increased by a factor of about 6.3. The voltage efficiency for hydrogen production, however, is increased by about 12% by employing electrocatalyst in the ambient temperature alkaline electrolyser, and there is benefit of enhancing lifetime durability of the electrode as well as cell components at relatively lower operating temperature.     

Power management strategies for a stand-alone power system using renewable energy sources and hydrogen storage

A stand-alone power system based on a photovoltaic array and wind generators that stores the excessive energy from renewable energy sources (RES) in the form of hydrogen via water electrolysis for future use in a polymer electrolyte membrane (PEM) fuel cell is currently in operation at Neo Olvio of Xanthi, Greece. Efficient power management strategies (PMSs) for the system have been developed. The PMSs have been assessed on their capacity to meet the power load requirements through effective utilization of the electrolyzer and fuel cell under variable energy generation from RES (solar and wind). The evaluation of the PMS has been performed through simulated experiments with anticipated conditions over a typical four-month time period for the region of installation. The key decision factors for the PMSs are the level of the power provided by the RES and the state of charge (SOC) of the accumulator. Therefore, the operating policies for the hydrogen production via water electrolysis and the hydrogen consumption at the fuel cell depend on the excess or shortage of power from the RES and the level of SOC. A parametric sensitivity analysis investigates the influence of major operating variables for the PMSs such as the minimum SOC level and the operating characteristics of the electrolyzer and the fuel cell in the performance of the integrated system.