Daisuke Mikawa

Contribution of a hydrogen storage-transportation system to the frequency regulation of a microgrid

This work addresses the dynamical contribution of a hydrogen storage-transportation system to the frequency quality of a microgrid containing large amounts of variable-output wind and solar generation which make the task of energy balance more demanding. Hydrogen has recently emerged as a promising energy carrier and in this respect the method of organic chemical hydride (OCH) offers advantages in the transportability and handling, over the traditional methods of compression and storage of hydrogen. This study is regarded as necessary for a clear understanding of how this type of storage system can contribute to the effective energy demand-supply balance, since the power absorption and injection processes are performed by different devices with different time constants. Two broad scenarios are considered: first, the dynamics is evaluated for a step increase of the solar radiation, which imposes a need for rapid power absorption by the water electrolyzer, and secondly, a step decrease in the wind speed, which requires that the loss in power generation be compensated by the injection of power by the fuel cell. The study is performed by modelling and simulation of a microgrid located in a cold region, in the northern part of Japan. The injection and absorption of energy by these two devices can contribute to improve the frequency profile under variable load and generation conditions. However, the maximum possible variations should be carefully taken into account in order to, if necessary, properly set other faster storage devices to provide support in the task of keeping the frequency variation within prescribed values.

Development of the control system for gas-hydrate power generation systems

When CO2 hydrate of 273 K is heated by 283 K, the pressure difference of nearly 3 MPa can be obtained by expansion of dissociated gas. Moreover, the heat cycle of generation of CO2 gas-hydrate and gas dissociation can use low temperature exhaust heat and the outdoor air temperature in a cold district. When an actuator is operated using the pressure difference of this heat cycle, the power generation system with a low environmental impact can be obtained. However, there is no example of examination until now regarding the control method of the gas-hydrate power generation system. Therefore, the gas-hydrate power generation system is modeled. The optimal control system is examined taking notice of the electric-power quality of the model described in the top. The proposed system which consists of various loads is assumed, the details of the control method which the stable supply of electric power can realize were clarified.