Totalized Hydrogen Energy Utilization System Research Articles

建築設備用の統合型水素利用システムの開発 : 第1報-水素吸蔵合金タンクの最適設計

建築設備用の統合型水素利用システムの開発 : 第1報-水素吸蔵合金タンクの最適設計

Experimental study on laboratory scale Totalized Hydrogen Energy Utilization System using wind power data

The renewable energy source like wind energy generates electric power with intermittent nature. Hydrogen energy system can help to solve the fluctuation problem of the wind power. Totalized Hydrogen Energy Utilization System (THEUS) consists of a Unitized Reversible Fuel Cell (URFC), a hydrogen storage tank, and other auxiliary components. Wind power is inherently variable; the URFC will be subjected to a dynamic input power profile in water electrolyzer mode operation. This paper describes the THEUS operation and performance at different variations in intermittent wind power. The performance of the THEUS was evaluated in water electrolyzer and fuel cell mode operation. The stack efficiency, system efficiency, and system efficiency including heat output from the URFC were presented at each operation. The total efficiency of the URFC and THEUS were also investigated. The maximum total efficiency of the URFC and THEUS were 53% and 66%, respectively.

Experimental study on a laboratory scale Totalized Hydrogen Energy Utilization System for solar photovoltaic application

Most of the countries have increased the production of renewable energy to reduce pollution and their dependency on oil and natural gas. In case of Japan, solar power is increased rapidly, especially after the Fukushima Nuclear Accident. The load leveling and fluctuation absorption are the main bottlenecks to the integration of solar PV power into the future electricity system. Hydrogen is considered as an energy carrier in a future energy system based on renewable resources. Totalized Hydrogen Energy Utilization System (THEUS) consists of a unitized reversible fuel cell and a hydrogen storage tank. The main objective of this paper is to evaluate the THEUS operation and performance at different variations in solar photovoltaic (PV) power during a sunny day and a partly cloudy day and to characterize its dynamic response. Energy efficiency of the THEUS was evaluated in water electrolyzer and fuel cell mode operation.

Research and development of a laboratory scale Totalized Hydrogen Energy Utilization System

Hydrogen is accepted as the energy carrier for future. Hydrogen based energy storage system represents an important option to store the fluctuating power generated from the renewable sources. A laboratory scale Totalized Hydrogen Energy Utilization System (THEUS) has been developed. THEUS consists of the Unitized Reversible Fuel Cell (URFC), which has both fuel cell and water electrolysis functions in one component, and hydrogen storage tank. THEUS was tested separately in water electrolyzer mode operation and fuel cell mode operation. THEUS was also tested continuously for three days to evaluate the energy efficiency. The URFC and hydrogen storage tank performance were characterized. In particular the overall system efficiency, stability upon cycling, and the reaction heat recovery rates of the metal hydride tank were discussed.

Research and development for a metal hydride tank with double coil type heat exchanger below 1.0 MPa (G) operation

A metal hydride tank has been developed with the aim of recovering the reaction heat of a metal hydride for the Totalized Hydrogen Energy Utilization System application. The metal hydride tank, which had the same geometrical configuration as one previously evaluated at SRNL, was fabricate with a different composition of the metal hydride alloy for operation below 1.0 MPa (Gauge). The hydrogen mass flow data from hydrogen production by renewable energy (solar power) and the fuel cell operation, which were obtained at SRNL, were used for the testing at AIST. The relatively large heat leak from the tank support of the metal hydride tank at SRNL was confirmed, and thus the tank support was replaced in this work. Furthermore, a vacuum thermal insulator was developed and applied to the metal hydride tank. This resulted in overall tank size reduction without reducing the thermal insulation performance.

Cyclic stability test of AB2 type (Ti, Zr)(Ni, Mn, V, Fe)2.18 for stationary hydrogen storage in water contaminated hydrogen

Abstract Totalized Hydrogen Energy Utilization System (THEUS), which consists of fuel cells, water electrolyzers, hydrogen storage and their auxiliary components, is proposed for the stationary application. In the previous researches, mischmetal-based MmNi 5 compound was used for the stationary hydrogen storage in THEUS. However, the cost of mischmetal is so expensive that can be an obstacle to the practical use of THEUS. In addition, since THEUS utilizes hydrogen produced by water electrolysis, it is necessary to confirm the influence of the water contamination on the metal hydride reactivity. The samples were Ti 0.24 Zr 0.76 Ni 1.2 Mn 0.64 V 0.14 Fe 0.18 (Sample A) and the sample with 1 at.%-La addition (Sample B). Using hydrogen including 40 ppm-water, hydrogen absorption and desorption was carried out 30 times. The degradation of hydrogen storage capacity was observed for Sample A while not observed for La-added Sample B. The results revealed that the addition of La improved cyclic stability against the water contamination.

Effect of the Metal Hydride Tank Structure on the Reaction Heat Recovery for the Totalized Hydrogen Energy Utilization System

A Totalized Hydrogen Energy Utilization System (THEUS) is proposed for load leveling and stabilizing the grid. The THEUS is a novel unitized regenerative fuel cell system that achieves high overall efficiency through optimized heat utilization. In this paper, a metal hydride tank (MHT) is chosen as hydrogen storage. In the MHT, the heating and cooling from adsorption/desorption processes is used to produced heated and chilled water for building ventilation systems. A new horizontal type MHT was developed to enhance the recovery rate of the reaction heat. This tank has a double coil heat exchanger and contained 50kg of AB5 metal hydride. The experimental results were compared with the results which were developed previously at AIST. The new tank results showed an improvement for the heat recovery rate which is the ratio of recovered energy to the entire reaction heat of the metal hydride. The reaction heat recovery was improved due to the decrease of the thermal capacity of the tank.

Study on a metal hydride tank to support energy storage for renewable energy

AIST and SRNL have engaged in a joint research project on a Totalized Hydrogen Energy Utilization System (THEUS) under the clean energy partnership technology program between METI and DOE. THEUS makes use of a novel unitized reversible fuel cell and metal hydride tanks. A horizontal metal hydride tank with a double coil type heat exchanger was developed and connected to the hydrogen system, which was comprised of solar panels, a water electrolyzer, and a fuel cell, etc. in SRNL. The absorption characteristic of the metal hydride tank with the intermittent hydrogen production rate from the electrolyzer, and the desorption characteristic of the tank with the fuel cell were experimentally investigated. It was confirmed that the reaction heat recovery rates of the metal hydride tank was almost 100% in case of absorption, and it was 96% in case of desorption.

Improvement of Numerical Simulation Model of the Metal Hydride Tank for the Totalized Hydrogen Energy Utilization System

Authors have proposed the Totalized Hydrogen Energy Utilization System(THEUS) for load leveling and stabilizing the grid system. THEUS consists of fuel cells, water electrolyzers, hydrogen storage and their auxiliary machinery. The basic operation for load leveling is as follows: In the nighttime, it produces hydrogen through water electrolysis by using low-cost electric power and stores the hydrogen. In the daytime, it conducts fuel cell generation using the stored hydrogen to meet the demand. Hydrogen storage equipment is the core of THEUS. In this paper, the metal hydride tank was chosen as hydrogen storage. The hydrogen desorption process is endothermic reaction. It is possible to use the cool heat for air conditioning. It is necessary to develop a useful numerical simulation code for not only the operation method but also the optimization of the structure of the tank. We developed the simulation code. The validity of the code has been improved by comparing with experimental results. Concretely, the following points were considered. (1)The thermal capacity of the tank. (2)Heat loss to the outside. (3)The copper plate effect. The simulation results become in good agreement with experimental results. And to achieve hydrogen high flow rate, new design tank performance was investigated.

Experimental Study on a Metal Hydride Tank for the Totalized Hydrogen Energy Utilization System

We have been performing research on a Totalized Hydrogen Energy Utilization System (THEUS) which is composed of a Unitized Reversible Fuel Cell (URFC) and metal hydride tanks. THEUS is very similar to the regenerative fuel cell system located at the Savannah River National Laboratory (SRNL) but it utilizes the thermal energy from the system to improve the total system efficiency. AIST and SRNL started a collaborative research program on THEUS in 2010 under the Clean Energy Partnership Technology Program between METI and DOE. To initiate the project, a horizontal type metal hydride tank was developed. It had a double coil type heat exchanger and contained 50kg of AB5 type metal hydride alloy. Absorption and desorption of 6,350 NL of hydrogen was successfully attained at an absorption rate of 11.8 NL/min and a desorption rate of 8.1 NL/min. The experimental results of the heat exchanging performance were compared with the results of a vertical type metal hydride tank which was developed in AIST in 2008. This paper introduces the experimental results of the metal hydride tank which is tested in SRNL.

Study on absorption/desorption characteristics of a metal hydride tank for boil-off gas from liquid hydrogen

We have been performing research on the Totalized Hydrogen Energy Utilization System (THEUS) which has applications to commercial buildings and a planned added function of supplying energy to stations for hydrogen and electric vehicles. In that case we will utilize liquid hydrogen transported from a hydrogen station and all Boil-Off Gas (BOG) will be recovered in THEUS’s metal hydride tanks. It is known that BOG is chiefly composed of para-hydrogen, which has different thermo-physical properties from normal hydrogen. It has been reported that some metal hydride alloys work as a catalyst to accelerate the para-ortho conversion and the conversion proceeds relatively fast in the case of La–Ni5. The conversion is considered to be an endothermic reaction. A misch metal (Mm)-Ni5 metal hydride alloy, which contained La and Ni, was used in our THEUS metal hydride tank. To examine the effect of the para-ortho conversion on the THEUS operation, we investigated the absorption/desorption characteristics of the metal hydride tank with BOG. We confirmed that the effect of the heat of conversion was very small and BOG could be treated as normal hydrogen for practical application.

Experimental study of hydrogen storage with reaction heat recovery using metal hydride in a totalized hydrogen energy utilization system

Experimental results for hydrogen storage tanks with metal hydrides used for load leveling of electricity in commercial buildings are described. Variability in electricity demand due to air conditioning of commercial buildings necessitates installation of on-site energy storage. Here, we propose a totalized hydrogen energy utilization system (THEUS) as an on-site energy storage system, present feasibility test results for this system with a metal hydride tank, and discuss the energy efficiency of the system. This system uses a water electrolyzer to store electricity energy via hydrogen at night and uses fuel cells to generate power during the day. The system also utilizes the cold heat of reaction heat during the hydrogen desorption process for air conditioning. The storage tank has a shell-like structure and tube heat exchangers and contains 50 kg of metal hydride. Experimental conditions were specifically designed to regulate the pressure and temperature range. Absorption and desorption of 5,400 NL of hydrogen was successfully attained when the absorption rate was 10 NL/min and desorption rate was 6.9 NL/min. A 24-h cycle experiment emulating hydrogen generation at night and power generation during the day revealed that the system achieved a ratio of recovered thermal energy to the entire reaction heat of the hydrogen storage system of 43.2% without heat loss.

Numerical simulation of the hydrogen storage with reaction heat recovery using metal hydride in the totalized hydrogen energy utilization system

Numerical simulation of a hydrogen storage tank of a Totalized Hydrogen Energy Utilization System (THEUS) for application to commercial buildings was done to verify the practicality of THEUS. THEUS consists of a fuel cell, water electrolyzer, hydrogen storage tank and their auxiliary machinery. The hydrogen storage tanks with metal hydrides for load leveling have been previously experimentally investigated as an important element of THEUS. A hydrogen storage tank with 50 kg AB5 type metal hydride was assembled to investigate the hydrogen-absorbing/desorbing process, which is exothermic/endothermic process. The goal of this tank is to recover the cold heat of the endothermic process for air conditioning, and thus improve the efficiency of THEUS. To verify the practical effectiveness of this improved system, we developed a numerical simulation code of hydrogen storage tank with metal hydride. The code was validated by comparing its results with experimental results. In this code the specific heat value of the upper and lower flanges of the hydrogen storage tank was adjusted to be equal to the thermal capacity of the entire tank. The simulation results reproduce well the experimental results.

The Development of the Totalized Hydrogen Energy Utilization System for Commercial Buildings

We have proposed the Totalized Hydrogen Energy Utilization System(THEUS) for applying to commercial buildings. THEUS consists of fuel cells, water electrolyzers, metal hydride tanks and their auxiliaries. We evaluated the energy saving of the basic THEUS in view of an actual operation using thermal demand data of actual buildings. The THEUS have ability for achieving energy saving, in comparison with an ice storage system for cooling demand. We have developed the hydrogen storage system using metal hydride and unitized reversible cell (URC) combine the functionality of a fuel cell and an electrolyzer in a single device, these are important components of THEUS. The metal hydride tank designed and manufactured to evaluate that we assumed actual operation in the experiments. We developed the numerical simulation code, and simulation results are in good agreement with experimental data. The simulation about two tanks system was done by using this code. The heat utilization can be improved greatly. To achieve URC commercial use, improvement of durability was examined. It confirmed that our URC had durability for several thousand hours.

Development of Totalized Hydrogen Energy Utilization System for Commercial Buildings : Part 2-Operation Control Method of the Multiple Hydrogen Storage Tanks

Development of Totalized Hydrogen Energy Utilization System for Commercial Buildings : Part 2-Operation Control Method of the Multiple Hydrogen Storage Tanks

Development of Totalized Hydrogen Energy Utilization System for Commercial Buildings : Part 3-Utilization of Hydrogen Desorption Reaction Heat by the Multiple Hydrogen Storage Tanks

Development of Totalized Hydrogen Energy Utilization System for Commercial Buildings : Part 3-Utilization of Hydrogen Desorption Reaction Heat by the Multiple Hydrogen Storage Tanks

441 建築設備用水素利用システムの実運用を想定したシステム評価(蓄熱・電力貯蔵技術)

We proposed the Totalized Hydrogen Energy Utilization System (THEUS) for applying to commercial buildings. By introducing this system in actual fields, we have realized the simultaneously effective uses of electricity, hydrogen and heat, hi this paper, we reported energy efficiency evaluation of the system by the calculation. Data as heat demand for seven type buildings were used, including buildings with different scales, applications, and characteristics of heat load. In comparison with an ice storage system, it has been proved that the hydrogen system has the advantage of 9-17% in terms of effective energy use. Moreover, the flexible operation of metal hydride tanks for fluctuating heat demand of the building was evaluated.

D134 建築設備用水素利用システムにおける水素吸蔵合金タンクに関する研究 : システムの運用評価と設計検討(多孔質中の熱・物質輸送現象I)

We proposed the totalized hydrogen energy utilization system that consists of a fuel cell device, a water electrolysis device and metal hydride tanks, and developed the mathematical model of hydrogen storage system that composes of several metal hydride tanks. The discharging hydrogen performance was investigated experimentally and numerically. As a results, it was shown that if the circulating water piping that flows in metal hydride tanks was connected with the series, and control method that increased the number of operating tanks are adopted when the outlet pressure of hydrogen decreases, hydrogen in each tank could be efficiently used.