Probabilistic hydrogen,thermal and electrical management of PEM-fuel cell power plants in distribution networks

This paper presents a Stochastic Multi-objective Optimal Operation Management (SMOOM) framework of distribution networks in presence of PEM-Fuel Cell Power Plants (FCPPs) and boilers. Operational costs, thermal recovery, power trade with grid and hydrogen management strategies are considered in this model. Furthermore, four objective functions has been considered as criteria for SMOOM, i.e. electrical energy losses, voltages deviations from their nominal values, total emissions emitted by CHP systems and grids, and total operational costs of CHP systems, as well as electrical energy cost of grids. A 2m + 1 Point Estimated Method is used to cope with the uncertain variables i.e. electrical and thermal loads, gas price of FCPPs consumption, fuel cost of residential loads, purchasing and selling tariff of electricity, hydrogen price, operation temperature of fuel cell stack, and the pressures of hydrogen and oxygen of anode and cathode, respectively. A new multi-objective Modified Firefly Algorithm (MFA) is implemented for minimizing the objective functions while the operational constraints are satisfied. Finally, a 69-bus distribution network is utilized to examine the performance of the proposed strategy regarding the rest.     

Techno-economic analysis of hydrogen energy for renewable energy power smoothing

With the increasing proportion of renewable energy (mainly wind power and photovoltaic) connected to the grid, the fluctuation of renewable energy power brings great challenges to the safe and reliable operation of power grid. As a clean, low-carbon secondary energy, hydrogen energy is applied in renewable energy (mainly wind power and photovoltaic) grid-connected power smoothing, which opens up a new way of coupling hydrogen storage energy with renewable energy. This paper focuses on the optimization of capacity of electrolyzers and fuel cells and the analysis of system economy in the process of power output smoothing of wind/photovoltaic coupled hydrogen energy grid-connected system. Based on the complementary characteristics of particle swarm optimization (PSO) and chemical reaction optimization algorithm (CROA), a particle swarm optimization-chemical reaction optimization algorithm (PSO-CROA) are proposed. Aiming at maximizing system profit, the capacity of electrolyzers and fuel cells are constrained by wind power fluctuation, and considering environmental benefits, government subsidies and time value of funds, the objective function and its constraints are established. According to the simulation analysis, by comparing the calculated results with PSO and CROA, it shows that PSO-CROA effectively evaluates the economy of the system, and optimizes the optimal capacity of the electrolyzers and fuel cells. The conclusion of this paper is of great significance for the application of hydrogen energy storage in the evaluation of power smoothness and economy of renewable energy grid connection and the calculation of economic allocation of hydrogen energy storage capacity.     

Energy and economic evaluation of cooling,heating, and power systems based on primary energy

Cooling, Heating, and Power (CHP) systems have the potential to make better use of fuels than other technologies because of their ability to increase the overall thermal energy efficiency. Feasibility of CHP systems is generally driven by economic savings. In addition, economic evaluation of CHP systems is based on site energy use and cost, which could lead to misleading conclusions about energy savings. Since energy savings from CHP systems only occurs in primary energy, the objective of this investigation is to demonstrate that feasibility of CHP systems should be performed based on primary energy savings followed by economic considerations. This paper also evaluates the effect of the power generation unit (PGU) efficiency over the primary energy reduction when a CHP system is utilized. The advantages of operating CHP systems under a primary energy operational strategy, such as the proposed Building Primary Energy Ratio (BPER) strategy, are also discussed. Results show that for some cases economic savings are attained without the corresponding primary energy savings. However, the use of the BPER operational strategy guarantees better energy performance regardless of economic savings. Regarding to the PGU efficiency, an increase of the efficiency reduces the primary energy use more than proportionally. For example, increasing the PGU efficiency from 0.25 to 0.35 (increase of 40%) can reduce the primary energy use from 5.4% to 16% (increase of 200%).     

Performance improvement in direct methanol fuel cells using a highly porous corrosion-resisting stainless steel flow field

Power generation with direct methanol fuel cell (DMFC) systems requires only simple equipment, and has the important advantage of using a liquid fuel with higher energy density and easier handling characteristics than hydrogen. However, the power output of DMFC is lower than hydrogen fuel cells. To improve the power output of DMFC it is very important to reduce diffusion polarization at higher current density conditions. This research used a corrosion-resisting type porous stainless steel developed based on the technology for metal–hydride battery electrodes in the separator flow fields for reactants and products in a single cell DMFC and analyzed its influence on performance characteristics.     

Performance analysis of a 5 kW PEMFC with a natural gas reformer

Power systems based on fuel cells have been considered for residential and commercial applications in energy Distributed Generation (DG) markets. In this work we present an experimental analysis of a power generation system formed by a 5 kW proton exchange membrane fuel cell (PEMFC) unit and a natural gas reformer (fuel processor) for hydrogen production. The performance analysis developed simultaneously the energy and economic viewpoints and enabled the determination of the best technical and economic conditions of this energy generation power plant, and the best operating strategies, enabling the optimization of the overall performance of the stationary cogeneration fuel cell unit. It was determined the electrical performance of the cogeneration system in function of the design and operational power plant parameters. Additionally, it was verified the influence of the activation conditions of the fuel cell electrocatalytic system on the system performance. It also appeared that the use of hydrogen produced from the natural gas catalytic reforming provided the system operation in excellent electrothermal stability conditions resulting in increase of the energy conversion efficiency and of the economicity of the cogeneration power plant.     

A review of technical and regulatory limits for hydrogen blending in natural gas pipelines

There is rising interest globally in the use of hydrogen for the provision of electricity or heat to industry, transport, and other applications in low-carbon energy systems. While there is attention to build out dedicated hydrogen infrastructure in the long-term, blending hydrogen into the existing natural gas pipeline network is also thought to be a promising strategy for incorporating hydrogen in the near-term. However, hydrogen injection into the existing gas grid poses additional challenges and considerations related to the ability of current gas infrastructure to operate with blended hydrogen levels. This review paper focuses on analyzing the current understanding of how much hydrogen can be integrated into the gas grid from an operational perspective and identifies areas where more research is needed. The review discusses the technical limits in hydrogen blending for both transmission and distribution networks; facilities in both systems are analyzed with respect to critical operational parameters, such as decrease in energy density, increased flow speed and pressure losses. Safety related challenges such as, embrittlement, leakage and combustion are also discussed. The review also summarizes current regulatory limits to hydrogen blending in different countries, including ongoing or proposed pilot hydrogen blending projects.     

成品油管道能源管理系统的研究

成品油在管道输送过程中,沿线泵机组在管道运行中要消耗电力。结合成品油管道能源管理的国内、外现状,对成品油管道能源管理过程中存在的问题进行了分析总结,并根据能源管理工作的总体目标和成品油管道的运营特点,设计了成品油管道的能源管理系统,并阐述了其主要研究内容。     

Investigation of hydrogen and power co-generation based on direct coal chemical looping systems

This paper evaluates hydrogen and power co-generation based on direct coal chemical looping systems with total decarbonization of the fossil fuel. As an illustrative example, an iron-based chemical looping system was assessed in various plant configurations. The designs generate 300–450 MW net electricity with flexible hydrogen output in the range of 0–200 MW_th (LHV). The capacity of evaluated plant concepts to have a flexible hydrogen output is an important aspect for integration in modern energy conversion systems. The carbon capture rate of evaluated concepts is almost total (>99%). The paper presents in details evaluated plant configurations, operational aspects as well as mass and energy integration issues. For comparison reason, a syngas-based chemical looping concept and Selexol^®-based pre-combustion capture configuration were also presented. Direct coal chemical looping configuration has significant advantages compared with syngas-based looping systems as well as solvent-based carbon capture configurations, the more important being higher energy efficiency, lower (or even zero) oxygen consumption and lower plant complexity. The results showed a clear increase of overall energy efficiency in comparison to the benchmark cases.     

Augmenting rooftop solar energy penetration ratio with secondary distribution network using smart inverter for maximum power transfer capacity for subordinate grid- A review

A rooftop photovoltaic power station, or rooftop PV system, is a photovoltaic system that has its electricity-generating solar panels mounted on the rooftop of a residential or commercial building or structure. The various components of such a system include photovoltaic modules, mounting systems, cables, solar inverters, and other electrical accessories. Rooftop mounted systems are small compared to ground-mounted photovoltaic power stations with capacities in the MW (megawatt) range. With the significant improvement of Rooftop Solar Photovoltaic Energy System (RSPES) among various Renewable Energy Systems, the major issues, effects, and several operational characteristics of the rooftop solar PVs in the Distribution System (DS) with Low Power Utility Network are actively being studied and investigated by global researchers and operation engineers. The most important objective of various researches about RSPES is to design a Power System with Optimal Maximum Power Transfer Capacity (MPTC). These review papers analyze the performance of Secondary Distribution System integrated to grid with Smart Inverter with or without the presence of Distribution Generation (DG) units. The effects caused by the penetration of Rooftop Solar Photovoltaic (PV) units in the Distribution Equipment (DE) are detailed in this paper with various research techniques. With the consideration of different objective constraints, Optimization techniques are utilized for solving minimization problems of objectives such as Size, Area, Operational Characteristics, Energy Loss, Cost of Installation, Generation Cost, Peak Load, Reverse Power Flow, and maximization problems of objectives such as PV power generation, Energy Saving Capability, Electricity Energy Mix, etc.. The various optimization techniques and frameworks for improving the performance of Power System and their corresponding results are demonstrated in this paper. This paper reviews totally 42 related researches done on the different phases of Optimization based Rooftop Solar PV system in the period between 2015 and 2017. This review summarizes the evaluation of the i) Solar rooftop energy with effects of increase in penetration; ii) The performance of efficient secondary distribution system with grid integrated smart inverter; iii) Algorithms based on optimization for solving the objectives in rooftop solar PV system are investigated.     

The impact of renewable energy intermittency on the operational characteristics of a stand-alone hydrogen generation system with on-site water production

In renewably powered remote hydrogen generation systems, on-site water production is essential so as to service electrolysis in hydrogen systems which may not have recourse to shipments of de-ionised water. Whilst the inclusion of small Reverse Osmosis (RO) units may function as a (useful) dump load, it also directly impacts the power management of remote hydrogen generation systems affecting operational characteristics.     

Miniaturization of spacecraft electrical power systems with solar-hydrogen power supply system

The concept of solar-hydrogen systems for spacecraft, orbital stations, lunar and Martian bases is currently receiving a new impetus. The supply of solar energy to energy receivers aboard space vehicles is limited. The number of everyday tasks and energy-intensive experiments on board space objects is growing with the development of astronautics. To perform energy-intensive work and experiments, energy consumption exceeds the incoming solar fluxes. The modern solar-hydrogen system ensures the reception, conversion and accumulation of excess incoming energy in the form of chemical energy - hydrogen. Cryogenics makes it possible to miniaturize the solar-hydrogen system. The safety of the cryogenic solar-hydrogen energy system is ensured by hydrogen concentration and leakage sensors.The article proposes a comprehensive solution for miniaturization of Power Conversion Unit (PCU) of Energy Power System (EPS) of spacecrafts (SC), which consists in a joint solution of four key problems of miniaturization of power devices: energy, structural, design and technological, system. Miniaturization of the solar-hydrogen energy system (SHES) is achieved by installing onboard hydrogen and oxygen microcryogenic refrigerators, as well as hydrogen and oxygen cryogenic tanks, water tank, electrolyzer and hydrogen fuel cells (FC). The accumulation of chemical hydrogen energy on board the orbiting spacecraft ensures reliable operation when entering the shadow. Storage of hydrogen in cryogenic form significantly reduces the volume required. A cryocooler based on the Stirling cycle provides the process of liquefying hydrogen after the electrolysis of distilled water. In addition, cryogenic temperatures of 20.2 K can be used to thermostat precision instruments placed on board the spacecraft, For example, to ensure the operation of the SQUID. A 3D - model of a voltage stabilization module (VSM), on the basis of which EEC can be produced with different output power and redundancy depth. We give an example of a complete structural scheme of the EEC, which allows implementing all the fulfillment of all the tasks, assigned to the EEC of the PCU SC.     

Modelling and simulation of a heaving wave energy converter based PEM hydrogen generation and storage system

The research on wave energy systems has been ongoing for decades. However, there are not many operational wave energy converters in use. The hydrogen energy systems also have a great potential. The proposed solution is to combine wave energy system with hydrogen energy system. The study provides details of simulation models and related simulation results. It is environmentally friendly, safe, feasible and effective. The results indicate that the proposed system model has a very high potential. With the use of low to medium energy density sea states, it is appears to be possible to generate (for DS1, DS2 and DS3, m_H2 = 350.8 kg, 623.9 kg and 2124 kg, respectively) a considerable amount of hydrogen in 20-min. The presented results include WEC motion properties, instantaneous and moving average value of other system parameters. The future promising simulations results indicate that next generation wave energy converter systems could be accompanied by hydrogen generation and storage systems.     

Multi-operation management of a typical micro-grids using Particle Swarm Optimization: A comparative study

Nowadays, it becomes the head of concern for many modern power girds and energy management systems to derive an optimal operational planning with regard to energy costs minimization, pollutant emissions reduction and better utilization of renewable resources of energy such as wind and solar. Considering all the above objectives in a unified problem provides the desired optimal solution. In this paper, a Fuzzy Self Adaptive Particle Swarm Optimization (FSAPSO) algorithm is proposed and implemented to dispatch the generations in a typical micro-grid considering economy and emission as competitive objectives. The problem is formulated as a nonlinear constraint multi-objective optimization problem with different equality and inequality constraints to minimize the total operating cost of the micro-grid considering environmental issues at the same time. The superior performance of the proposed algorithm is shown in comparison with those of other evolutionary optimization methods such as conventional PSO and genetic algorithm (GA) and its efficiency is verified over the test cases consequently.     

Optimal power allocation for a FCHV based on linear programming and PID controller

Hybrid electric vehicles positively influence the transportation industry with regards to reducing the use of fossil fuels and minimizing polluting emissions. A class of such vehicles incorporates fuel cells and energy storage systems as alternatives to internal combustion engines. This paper develops a dynamically efficient energy management system for fuel cell hybrid vehicles for the purpose of achieving an optimal power allocation between the energy sources while adhering to component requirements and maintaining the essential operational performance. The paper addresses a two stage control methodologies, pre-driving optimization using linear programming algorithms and on-line optimization using PID controllers and component mechanisms. The performance criteria are based on the overall operational cost as well as the hydrogen consumption per trip. Comparison against a state control algorithm shows improvements in hydrogen consumption.     

Operational strategy and marginal costs in simple trigeneration systems

As a direct result of economic pressures to cut expenses, as well as the legal obligation to reduce emissions, companies and businesses are seeking ways to use energy more efficiently. Trigeneration systems (CHCP: Combined Heating, Cooling and Power generation) allow greater operational flexibility at sites with a variable demand for energy in the form of heating and cooling. This is particularly relevant in buildings where the need for heating is restricted to a few winter months. In summer, the absorption chillers make use of the cogenerated heat to produce chilled water, avoiding waste heat discharge. The operation of a simple trigeneration system is analyzed in this paper. The system is interconnected to the electric utility grid, both to receive electricity and to deliver surplus electricity. For any given demand required by the users, a great number of operating conditions are possible. A linear programming model provides the operational mode with the lowest variable cost. A thermoeconomic analysis, based on marginal production costs, is used to obtain unit costs for internal energy flows and final products as well as to explain the best operational strategy as a function of the demand for energy services and the prices of the resources consumed.     

Field experience study and evaluation for hydrogen production through a photovoltaic system in Ouargla region,Algeria

An experimental study on small-scale for solar hydrogen production system via a Proton Exchange Membrane electrolysis under a desert climatic condition in Ouargla region (South-East of Algeria) has been carried out, the target of this study has been first to evaluate hydrogen production by water analysis and to store the solar energy which has had the form of a hydride-metal hydrogen, after that, to investigate the performance of sophisticated commercial electrolyser (HG-60)powered by photovoltaic panels via the Power Management Unit (PMU) as a power conditioner, this paper has also a mathematical models based on real-time experiments were used to simulate both the photovoltaic system and PEM electrolyser work, along with attempting to direct linking strategy with the same experimental components of photovoltaic panels and commercial electrolyser, it was found through this study, the addition of the number of commercial electrolyser with the bank of four HG-60 stacks in series. More effective considering the improving voltage matching, with power transfer efficiency reach to 99%, also another factor is the photovoltaic panels slope on panel output power and hydrogen productivity are theoretically examined, where the proper selection of optimal tilt angle has an importance for collecting the maximum hydrogen amount, eventually, over the experiment span, the real-amount of hydrogen vented over experiment course is around 92.54l.     

Transient performances of the gas turbine recuperating waste heat through hydrogen rich fuels

Operational rules and control strategies of the chemically recuperated gas turbine (CRGT) in the marine propulsion are investigated in this paper. The Minimization of Gibbs free energy method is used to calculate the diesel-steam reforming reaction which products synthetic hydrogen rich fuels, and a universal model of the chemical regenerator which is easily applied to different application environments is created. The hydrogen production and hydrogen molar fraction are investigated to verify that the CRGT improve the combustion performances under low working conditions. Off-design calculations are performed to derive proper operational rules, and transient calculations are performed to investigate the best control strategies for the systems. The modelling approach of the chemical regenerator can be generally used in the chemically recuperated gas turbine. The elaborate operational rules can greatly improve the thermal efficiencies under every working condition. The system using synchronous control strategies have better regulation speed and operation stability than that using asynchronous control strategies.     

Off-grid solar powered charging station for electric and hydrogen vehicles including fuel cell and hydrogen storage

This paper designs an off-grid charging station for electric and hydrogen vehicles. Both the electric and hydrogen vehicles are charged at the same time. They appear as two electrical and hydrogen load demand on the charging station and the charging station is powered by solar panels. The output power of solar system is separated into two parts. On part of solar power is used to supply the electrical load demand (to charge the electric vehicles) and rest runs water electrolyzer and it will be converted to the hydrogen. The hydrogen is stored and it supplies the hydrogen load demand (to charge the hydrogen-burning vehicles). The uncertainty of parameters (solar energy, consumed power by electrical vehicles, and consumed power by hydrogen vehicles) is included and modeled. The fuel cell is added to the charging station to deal with such uncertainty. The fuel cell runs on hydrogen and produces electrical energy to supply electrical loading under uncertainties. The diesel generator is also added to the charging station as a supplementary generation. The problem is modeled as stochastic optimization programming and minimizes the investment and operational costs of solar and diesel systems. The introduced planning finds optimal rated powers of solar system and diesel generator, operation pattern for diesel generator and fuel cell, and the stored hydrogen. The results confirm that the cost of changing station is covered by investment cost of solar system (95%), operational cost of diesel generator (4.5%), and investment cost of diesel generator (0.5%). The fuel cell and diesel generator supply the load demand when the solar energy is zero. About 97% of solar energy will be converted to hydrogen and stored. The optimal operation of diesel generator reduces the cost approximately 15%.     

Hydrogen production for energy: An overview

Power to hydrogen is a promising solution for storing variable Renewable Energy (RE) to achieve a 100% renewable and sustainable hydrogen economy. The hydrogen-based energy system (energy to hydrogen to energy) comprises four main stages; production, storage, safety and utilisation. The hydrogen-based energy system is presented as four corners (stages) of a square shaped integrated whole to demonstrate the interconnection and interdependency of these main stages. The hydrogen production pathway and specific technology selection are dependent on the type of energy and feedstock available as well as the end-use purity required. Hence, purification technologies are included in the production pathways for system integration, energy storage, utilisation or RE export. Hydrogen production pathways and associated technologies are reviewed in this paper for their interconnection and interdependence on the other corners of the hydrogen square.Despite hydrogen being zero-carbon-emission energy at the end-use point, it depends on the cleanness of the production pathway and the energy used to produce it. Thus, the guarantee of hydrogen origin is essential to consider hydrogen as clean energy. An innovative model is introduced as a hydrogen cleanness index coding for further investigation and development.     

Long-term optimization based on PSO of a grid-connected renewable energy/battery/hydrogen hybrid system

This paper presents and evaluates three energy management systems (EMSs) based on Particle Swarm Optimization (PSO) for long-term operation optimization of a grid-connected hybrid system. It is composed of wind turbine (WT) and photovoltaic (PV) panels as primary energy sources, and hydrogen system (fuel cell –FC–, electrolyzer and hydrogen storage tank) and battery as energy storage system (ESS). The EMSs are responsible for making the hybrid system produce the demanded power, deciding on the energy dispatch among the ESS devices. The first PSO-based EMS tries to minimize the ESS utilization costs, the second one to maximize the ESS efficiency, and the third one to optimize the lifetime of the ESS devices. Long-term simulations of 25 years (expected lifetime of the hybrid system) are shown in order to demonstrate the right performance of the three EMSs and their differences. The simulations show that: 1) each EMS outperforms the others in the designed target; and 2) the third EMS is considered the best EMS, because it needs the least ESS devices, and presents the lowest total acquisition cost of hybrid system, whereas the rest of parameters are similar to the best values obtained by the other EMSs.