AIST FREA

産総研トップへ

H2 and Heat Utilization System Team

Hydrogen Energy System and Heat Utilization Technology

Over View

With the start of the Feed-In Tariff, particularly large-scale photovoltaic systems have been installed in recent years. However, due to inadequate adjustment of the balance of supply and demand and inadequate capacity of transmission lines, there have been many limitations. They include output restrictions, resulting in the generation of renewable energy that will not be used, and there is concern that this will further increase in the future. Also, in order to suppress CO₂ emissions, the reduction of CO₂ emissions from buildings to zero is important. These mismatches must be eliminated and it is necessary to make the best use of renewable energy.
Our team is now engaged in the research and development of energy systems that make the best use of hydrogen and heat totally from power generated from renewable energy to satisfy demand, in order to convert renewable energy that cannot be effectively utilized with conventional technology into hydrogen, and make the best use of the thermal energy generated.


Research Target

This team is developing an energy system that utilizes hydrogen as well as heat, and is capable of storing a large amount of energy in the long term.
This has been an issue that cannot be solved with power systems or existing energy storage technology, in order to introduce large amounts of renewable energy. With the surplus power from photovoltaic systems that will be increasingly introduced in the future, we will develop high-efficiency, low-cost hydrogen production technology. In order to reduce emissions from buildings, which account for 40% of Japan’s CO2 emissions, we will utilize CO2 -free hydrogen to develop safe hydrogen storage technology that can be used in urban areas. We are developing an energy system that makes full use of hydrogen and thermal energy in accordance with demand for heat as well as electricity. Further, in anticipation of the widespread use of fuel cell vehicles as a way of utilizing hydrogen, we are also working on safe hydrogen boosting and refining technology.


Research Outline

The team continue to develop high-efficiency hydrogen production technology by utilizing surplus power from solar power generation, which is expected to be introduced and used in large quantities in the future. We will aim to achieve both system interconnection and hydrogen production, which are expected to come when the Feed-In Tariff ends.
Specifically, we are aiming for high efficiency with proprietary technology that directs DC power from photovoltaic systems to the water electrolyzer by controlling the number of electrolysis cells.
As a technology for storing hydrogen, the team is developing hydrogen storage systems that use a metal hydride. In order to promote the use of hydrogen in urban areas, we are developing an inexpensive, safe, and large-scale hydrogen storage method that is not subject to the High Pressure Gas Safety Act and Fire Service Act, by using a metal hydride that has a pressure of 1 MPa or less and does not ignite.

  • The team is developing technology to meet the demand for electricity and heat with the use of energy systems that utilize hydrogen, aiming at zero emissions buildings. Here, we are demonstrating this technology using the newly developed hydrogen storage systems.
  • The team will develop new hydrogen compression technology and refining technology for wider utilization of hydrogen.
  • In order to further improve the functionality of these technologies, the team will develop and demonstrate thermal power generation and thermal storage technology for effectively using solar heat and unused waste heat.

Outline of energy system demonstration using BEMS


Appearance of metal hydride(Left: ingots, Right: powdered) 
Appearance of metal hydride
(Left: ingots, Right: powdered)

Solar heat collection apparatus

SEM image of hydrogen-permeable membrane under development

Main Research Facilities

Solar Power Generation Direct Electrolyzer Hydrogen storage technology using metal hydride
Water electrolyzer with directly connected solar cells equipped with capacitor smoothing device Hydrogen Storage Unit
A 20 kW solar cell is connected directly to the water electroly zer. The water electrolyzer is capable of switching the number of electrolysis cells and following the maximum power point of the solar cell. We are also attempting to smooth the fluctuation of solar radiation by connecting lithium ion capacitors (LiC). Eight tanks are installed, filled with a metal hydride of different type produced by research and development. The absorption/desorption operation can be performed at less than 80℃, the hydrogen storage capacity is approximately 100 Nm³ at 1 MPa or less, and hydrogen produced from renewable energy can be stored.
Various Analyzers High Pressure Hydrogen Facility
Field Emission Scanning Electron Microscope(FE-SEM) Appearance of the high-pressure hydrogen facility & 100 MPa Pressure Resistance/200℃ Heat Resistant Reaction Vessel
This team has the following various analyzers.
Examples: field emission scanning microscope, X-ray diffractometer, PCT characteristic evaluator , hydrogen-permeable membrane evaluator, surface tensiometer, thermal conductivity meter , thermal analysis device (TG-DTA/DSC).
The high-pressure hydrogen facility includes a high-pressure hydrogen supply booster (<90 MPa), accumulator (<90 MPa, 200 L), bundle of hydrogen cylinders (19.6 MPa, 1,250 L), high pressure/high temperature reaction vessel (<100 MPa, <200℃), and solar therma l panels, and we are conducting demonstration tests on hydrogen boosting with metal hydride. If the bundle of cylinders is filled with hydrogen made from renewable energy and is supplied to a station, the hydrogen can also be used for fuel-cell vehicles.

Activities and Achievements

1.Water Electrolysis Degradation Prevention Technology
The team has succeeded in converting approximately 15% of solar energy into hydrogen energy using 20 kW solar cells and a 5 Nm³/hour water electrolyzer. Electrolytic current that varies depending on the weather can be smoothed using lithium-ion capacitors, which makes it possible for the electrolyzers to have a longer lifespan.
capacitor

2.Safe Hydrogen Storage Technology(non-burnable metal hydride)
The team has developed an inexpensive metal hydride that does not use rare-earth elements. As shown in the photograph, even after repeated hydrogen absorption/desorption is performed, it does not ignite. It is therefore an alloy that is not designated as a hazardous material under the Fire Service Act (certified).


Hazardous material check of metallic powder (ignition test)

Team Member

Title Name
Leader Tetsuhiko Maeda
Senior Researcher Naruki Endo
Researcher Kiyotaka Goshoume