Ryoji Hiwatari

Economic Value of PV Energy Storage Using Batteries of Battery-Switch Stations

The Japanese government has set a power sector goal for photovoltaic (PV) power usage to reach 53 million kW by 2030. To achieve the large-scale introduction of PV, a large storage capacity, in the form of pumped storage systems or batteries, is needed to store surplus electricity from PV plants. At the same time, in the transport sector, the electric vehicle (EV) is being developed as an environmentally friendly vehicle. To promote the diffusion of EVs, we need infrastructure that can charge EVs in a short time; a battery-switch station is one solution to this problem. This study 1) proposes the use of the station batteries as a countermeasure for surplus electricity from PVs and 2) conducts two relevant analyses. In the first analysis, we calculate the marginal value of a battery and an inverter using the Optimal Generation Mix Model (OPTIGEN). In the second analysis, we set the annual lease fee for the inverter and the battery, and calculate the optimum installed capacity of these devices. The results showed that the marginal value of the inverter/battery decreases with increasing inverter/battery capacity. The optimum installed capacity of the inverter/battery is derived from the intersection of the line of marginal value with the line of the annual lease fee. The stations gain an additional profit by leasing batteries to utilities.

Energy storage of PV using batteries of battery-switch stations

In the power sector, the Japanese government has set the goal of that the introduction of PV will reach 53 million kW by 2030. However, large-scale introduction of PV will cause several problems in power systems such as surplus electricity. We need large capacity of pumped storages or batteries for the surplus electricity, but the construction costs of these plants are very high. On the other hand, in the transport sector, Electric Vehicle (EV) is being developed as an environmentally friendly vehicle. To promote the diffusion of EV, it is necessary to build infrastructures that can charge EV in a short time; a battery switch station is one of the solutions to this problem. At a station, the automated switch platform will replace the depleted battery with a fully-charged battery. The depleted battery is placed in a storage room and recharged to be available to other drivers. This means switch stations always have the constant capacity of battery. We propose the use of stations batteries as a countermeasure for surplus electricity of PV and evaluate the economic value of the proposed system. We assumed that 53 million kW of PV is introduced in the nationwide power system and considered two countermeasures for surplus electricity: (1) Pumped storage; (2) Battery of station. The difference in total annual cost between Pumped case and Battery case results in 695.7 billion yen. Hence, if a utility leases batteries from stations fewer than 695.7 billion yen, the utility will get a cost advantage in Battery case.

A road traffic simulator to analyze layout and effectiveness of rapid charging infrastructure for electric vehicle

We have developed the road traffic simulator to analyze the location of EV running out of electricity and the number of charging EV at each charging station(ST). We also have proposed the search algorithm for the effective layout of charging STs based on the location of EV running out of electricity by the road traffic simulator. That algorithm has been installed into the traffic simulator. The layout of charging STs is successfully determined to reduce the number of EV running out of electricity, and it does not depend on the initial input of the location of the charging ST and the complexity of the road network.

Design Strategy and Recent Design Activity on Japan’s DEMO

Abstract The Joint Special Design Team for Fusion DEMO was organized in 2015 to enhance Japan’s DEMO design activity and coordinate relevant research and development (R&D) toward DEMO. This paper presents the fundamental concept of DEMO and its key components with main arguments on DEMO design strategy. Superconducting magnet technology on toroidal field coils is based on the ITER scheme where a cable-in-conduit Nb3Sn conductor is inserted in the groove of a radial plate. Development of cryogenic steel with higher strength is a major challenge on the magnet. Divertor study has led to a baseline concept based on water-cooled single-null divertor assuming plasma detachment. Regarding breeding blanket, fundamental design study has been continued with focuses on tritium self-sufficiency, pressure tightness in case of in-box LOCA (loss of coolant accident) and material compatibility. An important finding on tritium permeation to the cooling water is also reported, indicating that the permeation to the cooling water is manageable with existing technology.

Electricity pricing for PHEV bottom charge in daily load curve based on variation method

For fuel economy of power system, Plug-in Hybrid Electric Vehicle (PHEV) should be charged late at night to level a load curve. This paper proposes an electricity pricing algorithm for load leveling, using variation method. Variation method is a mathematical technique that can bring a value of integral functional to the extreme value. We formulate a cost minimization problem of PHEV owners, regarding the integral functional as an electric bill. By solving the problem, we get the electricity price curve that can realize the ideal bottom charge while PHEV owners minimize their electric bill. We analyze the difference in results between the proposal and the target case, where PHEVs are ideally charged to raise bottom demand. The ratio of the reduction of the proposal case to the target case resulted in 99.8%. It is verified that the proposed algorithm is effective in bottom-up of daily load curve.

Preliminary consideration on maintenance approach for a fast ignition ICF reactor with a dry wall chamber and a high repetition laser

Abstract The fast ignition method enables a reduction of the laser power required to achieve a large energy gain. This suggests consideration of a new inertial confinement fusion power plant concept, which has a small fusion pulse and a high repetition laser with a dry wall chamber. To establish the potential of the fast ignition method and to make clear the critical issues, a Fast Ignition ICF reactor concept with a Dry Wall chamber and a High Repetition Laser (FI-DWHRL concept) was previously proposed. The maintenance approach for this Fast Ignition ICF reactor concept is preliminary considered and its critical issues are described in this paper. The large cask and the large maintenance port for replacing the blanket sectors are applied to this Fast Ignition ICF reactor concept. The first wall and blanket system is divided into 20 sectors and all beam lines go between blanket sectors. The vacuum vessel is located outside the blanket system and this vacuum vessel also serves as the tritium boundary. To replace the final optical device, 6 access corridors are placed along the reactor room. Finally, critical issues on this maintenance approach are listed.

Design study of dry wall fast ignition laser fusion reactor with high repetition laser

Abstract The design of a laser fusion reactor with a dry wall chamber has been carried out. According to a simple point model calculation, sufficient pellet gain (G > 100) can be achieved with the injection energy of 400kJ under relatively conservative parameters (α = 2, ηc = 0.05, ηh = 0.2). Assuming the pulse heat load limit of a dry wall to be 2J/cm2, chamber radius of R = 5.64m is achievable. 1-D thermal analysis also supports the feasibility of this design. Then a medium scale plant (400MWe electric output) can be designed with moderate construction cost, which suits for the first-step reactor, if the laser repetition rate can be increased to 30 Hz. Since laser fusion reactors have flexibility in changing its output, this design enables them to be in flexible use according to the time-varying electric demand as the present fossil fuel power plants. This design is remarkable because it gives a new property to the fusion reactors.

Evaluation of EV charging load contributing to stabilize PV output with consideration for rapid charge

There are growing concerns around the world about global warming issues, and the various countermeasures to reduce global warming by greenhouse gas are proposal. In the transport sector, Electric Vehicle (EV) is mentioned as one of the solutions to reduce CO2 emissions and heavy dependence on oil. In order to promote the introduction of EV, it is necessary to build charging infrastructures that EV can be charged rapidly. The purpose of this research is to evaluate EV charging that includes rapid charge in charging station (ST). In order to calculate EV charging load, the traffic simulator utilizing the multi-agent method is employed. In this paper, the EV charging load in a day is calculated by the traffic simulation and evaluated in order to assess the influence of EV charging on the grid system and the applicability of EV in the smart-grid system.

Numerical investigation of threshold power by using the Shaing L-H transition model

We carry out transport simulations of the L-H transition by the Shaing L-H transition model based on ion orbit losses, and find that the time scale of the L-H transition and the time scale for development of the H-mode pedestal are consistent with experimental observations. We also compare the power threshold derived from the Shaing L-H transition model with L-H transition threshold power scaling laws. We find that the magnetic field, Bt, plasma density, ne, and plasma current, Ip, scaling can be reproduced.

A compact reversed shear tokamak reactor sustained by beam driven currents

A concept of cost competitive fusion reactor (CREST-1), based on a beam generated reversed shear equilibrium, is described. The driver optimization study shows that an NBI system with assistance of an RF system results in high flexibility in the operation, while the fully beam driven operation (without RF) is also possible. The flexibility in the operation parameters makes a partial load operation possible, which will be an important feature as a commercial reactor.