Hydrogen Management Strategy Research Articles

Methodology for multi-objective optimization of wind turbine/battery/electrolyzer system for decentralized clean hydrogen production using an adapted power management strategy for low wind speed conditions

In this study, the utilization of renewable energy sources (RESs) like wind energy for clean hydrogen production via water electrolysis in small-scale decentralized plant is addressed. This paper proposes an approach for multi-objective optimization of wind-hydrogen production system (WHPS) while satisfying multiple technical constraints based on a dynamic power and hydrogen management strategy (PHMS). WHPS consists of wind turbines (WTs), water electrolyzer, battery bank, power converters and hydrogen tank. Multi-objective optimization consists of minimizing the total hydrogen deficit (THD), energy dump possibility (EDP), levelized cost of hydrogen (LCOH) as well as CO2 emission avoided (CO2EA) and natural gas preserved (NGP). Battery assistance for electrolyzer is enhanced through a dynamic PHMS adapted to low wind speed conditions. PHMS based multi-objective optimization algorithm is developed to find Pareto-optimal solutions. The optimization results reveal that the adequate design of PHMS plays a crucial role in minimizing THD, LCOH and EDP, while ignoring the EDP objective may reduce potentially LCOH. Under the selected base case conditions, small-scale hydrogen production via WHPS consisting of 250 kW alkaline-electrolyzer, 857.5 kW WTs, 719 kW h battery bank and 2022 kg hydrogen tank, for supplying hydrogen demand at full reliability (THD = 0%), results in LCOH of 33.70 $/kg, CO2EA of 87.75 ton/year, NGP of 28.96 ton/year and EDP of 9.96%.

Heat and Hydrogen Management Strategies in an Integrated Autothermal Radial Flow Reactor for Enhancement of Olefin Production

Heat and Hydrogen Management Strategies in an Integrated Autothermal Radial Flow Reactor for Enhancement of Olefin Production

Comparative performance analysis of a grid connected PV system for hydrogen production using PEM water, methanol and hybrid sulfur electrolysis

This paper presents comparative performance analysis of photovoltaic (PV) hydrogen production using water, methanol and hybrid sulfur (SO2) electrolysis processes. Proton exchange membrane (PEM) electrolysers are powered by grid connected PV system. In this system design, electrical grid is considered as a virtual energy storage system (VESS) where the surplus of PV production can be injected and subsequently taken to support the electrolyser. Methanol (ME) and hybrid sulfur (HSE) electrolysis are compared to the conventional water electrolysis (WE) in term of operating cell voltage. Based on the experimental results reported in the literature, semi-empirical models describing the relationship between the hydrogen production rate and the electrolyser cell power input are proposed. Furthermore, power and hydrogen management strategy (PHMS) is developed. Case study is carried out to show the impact of each type of electrolysis on the system component sizes and evaluate the hydrogen production potentialities. Results show that the use of ME allows to produce 65% more hydrogen than with using WE. Moreover, the amount of hydrogen produced is almost double in the case of HSE. At Algiers city, based on a grid connected PV/Electrolyser system, it is possible to produce about 25 g/m2 d and 29 g/m2 d of hydrogen, respectively, through ME and HSE compared to 15 g/m2 d of hydrogen when using WE.

Off grid PV system for hydrogen production using PEM methanol electrolysis and an optimal management strategy

In this paper, we present a modelling and simulation study of an Off grid PV system for hydrogen production (PVHPS) using methanol electrolysis process. The system consists mainly on a PV array, lead-acid battery, methanol electrolyser and hydrogen tank. Mathematical models of each component of the system are presented. Using a semi-empirical relationship between hydrogen production rate and power consumption, hydrogen production at 80 °C and 4 M concentration is estimated. Optimal power and hydrogen management strategy (PHMS) is investigated to achieve high system efficiency. Case studies are carried out on two tilts of PV array: horizontal and tilted at 36°. Parametric sensitivity analysis is also carried out to illustrate the effect of the battery depth of discharge (DoD) on the system components sizes and overall system performance. In the simulation, data of solar irradiation and ambient temperature obtained from radiometric measurements at Algiers city are used. Simulation results show that the system with tilted PV array presents performances better than in horizontal PV array configuration and produce greater hydrogen amounts. In addition, reducing the DoD value in order to increase the lifetime of the accumulator induces some power losses which decreases the amount of hydrogen produced and consequently reduces the system efficiency.

Design, modelling and optimal power and hydrogen management strategy of an off grid PV system for hydrogen production using methanol electrolysis

Hydrogen used as an energy carrier and chemical element can be produced by several processes such as gasification of coal and biomass, steam reforming of fossil fuel and electrolysis of water. Each of these methods has its own advantage and disadvantage. Electrolysis process is seen as the best option for quick hydrogen production. Hydrogen generation by methanol electrolysis process (MEP) gained much attention since it guarantees high purity gas and can be compatible with renewable energies. Furthermore, due to its very low theoretical potential (0.02 V), MEP can save more than 65% of electrical energy required to produce 1 kg of hydrogen compared to water electrolysis process (WEP). Electrolytic hydrogen production using solar photovoltaic (PV) energy is positioned to become as one of the preferred options due to the harmful environmental impacts of widely used methane steam reforming process and also since the prices of PV modules are more competitive.In this paper, hydrogen production by MEP using PV energy is investigated. A design of an off grid PV/battery/MethElec system is proposed. Mathematical models of each component of the system are presented. Semi-empirical relationship between hydrogen production rate and power consumption at 80 °C and 4 M concentration is developed. Optimal power and hydrogen management strategy (PHMS) is designed to achieve high system efficiency and safe operation. Case studies are carried out on two tilts of PV array: horizontal and tilted at 36° using measured meteorological data of solar irradiation and ambient temperature of Algiers site. Simulation results reveal great opportunities of hydrogen production using MEP compared to the WEP with 22.36 g/m2 d and 24.38 g/m2 d of hydrogen when using system with horizontal and tilted PV array position, respectively.

Modeling of Hydrogen Networks in a Refinery Using a Stochastic Programming Appraoch

As hydrogen demand in the refineries is increasing, hydrogen management strategies are of great interest for the refiners. Hydrogen management deals with the optimal distribution, routing, and flow allocation of hydrogen gas within a refinery linking the hydrogen producing and consuming units. This is also known as the hydrogen network synthesis or design. Due to uncertainty in the crude feedstock or final product specification in a refinery, there exists variations or uncertainties in the operating conditions (parameters) required for hydrogen network design. Hence there is a need to incorporate these uncertainties while designing hydrogen networks. In this paper, we address the issue of optimal hydrogen network design under uncertainty or uncertain operating parameters. For this, we develop a nonconvex multiscenario Mixed Integer Nonlinear Programming (MINLP) model which is the deterministic equivalent of mathematical two stage stochastic model. The purpose is to develop a network design that is optimal...

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

Abstract 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 2 m + 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.

Improved optimization methods for refinery hydrogen network and their applications

Heavier market competition and tighter environmental legislation lead to the increasing demand for hydrogen in refinery. Hence it is necessary for refinery to seek effective hydrogen management strategies to satisfy the increasing hydrogen requirements. In this paper, two improved systematic mathematical methods are developed based on two-step approach and simultaneous optimization approach respectively to retrofit the hydrogen network in refinery. To make the proposed approaches more suitable for real systems, the flowrate and purity at the reactor inlet of hydrogen consumers and the hydrogen recovery of purification units are considered as variables, and the minimum pure hydrogen of hydrogen consumers must be satisfied. Then the corresponding optimization problem is mathematically transformed to a mixed-integer nonlinear programming (MINLP) problem. However, solving a MINLP model directly will result in inconsistency in solution quality and time. In this paper, the solving of the complex MINLP formulation is avoided by using a mixed-integer linear programming (MILP) linearization technique, resulting in better quality, stability, and efficiency than solving the MINLP model directly. The proposed approaches in this paper could make the best use of resources and consequently provide significant environmental and economic benefits for refinery. A real case study is presented to illustrate the applicability of the proposed approaches.

Integration of hydrogen management in refinery planning with rigorous process models and product quality specifications

New trends of increased heavy crude markets and clean-fuel legislation, to produce ultra low-sulphur (ULS) gasoline and diesel fuels, are forcing refineries to increase their consumption of hydrogen. This critical situation raises the need to have a tool for operating refineries with flexibility and profitability. This paper addresses the planning of refinery with consideration to hydrogen availability. A systematic method for integrating a hydrogen management strategy within a rigorous refinery planning model is undertaken. The presented model consists of two main building blocks: a set of non-linear processing units’ models and a hydrogen balance framework. The two blocks are integrated to produce a refinery-wide planning model with hydrogen management. The hydrogen management alternatives were determined by economic analysis. The proposed model improves the hidden hydrogen unavailability that prevents refineries from achieving their maximum production and profit. The model is illustrated on representative case studies and the results are discussed. It was found that an additional annual profit equivalent to $7 million could be achieved with a one-time investment of $13 million in a new purification unit.

Economics of hydrogen production and utilization strategies for the optimal operation of a grid-parallel PEM fuel cell power plant

This paper integrates the hydrogen production and utilization strategies with an economic model of a PEM fuel cell power plant (FCPP). The model includes the operational cost, thermal recovery, power trade with the local grid, and hydrogen management strategies. The model is used to determine the optimal operational strategy, which yields the minimum operating cost. The optimal operational strategy is achieved through estimation of the following: hourly generated power, thermal power recovered from the FCPP, power trade with the local grid, and hydrogen production. An evolutionary programming-based technique is used to solve for the optimal operational strategy. The model is tested using different seasonal load demands. The results illustrate the impact of hydrogen management strategies on the operational cost of the FCPP when subjected to seasonal load variation. Results are encouraging and indicate viability of the proposed model.