Renewable power forecasting is one of key components to maintain the reliability of a power system with large-scale renewable integration and has been studied by use of a variety of approaches, such as area-wide numerical weather simulation, satellite image based forecasting and statistical model. In this paper, an approach to predict the area-wide total wind and photovoltaic power of one hour to one day ahead prior to the power delivery is presented, which makes use of multi regression technique and numerical weather prediction data distributed by the Japan Meteorological Agency. Tohoku area is taken as an example to show the prediction accuracy. The results show that, forecasting errors of the proposed models are a little higher than those of area-wide numerical weather simulation of earlier studies and further investigation in this approach is needed to improve the accuracy. According to the analysis of forecast error characteristics, both of the forecast error distributions of wind and photovoltaic power look well-fitted with Laplace distribution rather than Normal distribution.

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International grid interconnections have gained attention in Northeast Asia (NEA) as a means to promote variable renewables (VRE), such as wind power and solar PV. This paper quantitatively investigates the benefits of international power transmission for VRE deployment, employing a detailed temporal resolution power system model for NEA. The model determines the optimal hourly dispatch for a single year, which allows us to explicitly consider the power systems characteristics and intermittency of VRE. The simulation results suggest that international transmission may significantly affect VRE deployment in NEA, by promoting Mongolian wind power and replacing higher-cost solar PV and battery storage otherwise installed in a “no grid interconnection” case. However, strong CO₂ reduction policies, such as 80% reduction, are necessary for implementation, implying that international transmission of VRE would be an option for long-term deep de-carbonization in NEA; the relevant planning organizations need to consider the feasibility in the context of long-term CO₂ reductions strategies.

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There is a growing interest in utilization of unused materials for energy conversion to reduce CO₂ emission and to improve regional economy. There are several options regarding unused material utilization systems, from thermal utilization in the forms of wood stoves or wood chip boilers to biomass power generation. While public administrations have supported these systems by means of subsidy and feed-in tariff with added retail prices, the amount of comparative assessments of individual systems from the environmental and economic perspectives is not yet sufficient. In this research, we interviewed organizations that constructed these systems to obtained basic data. Next we constructed six typical systems based on the obtained data and assessed the respective systems. The results revealed characteristics of the respective systems, such as the high performance of wood stove systems in terms of CO₂ emission reduction per subsidy, and the high contribution of biomass power generation systems to regional employment.

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This paper presents the evaluation of kWh value of photovoltaic (PV) generation by application of simplified method using numerical factor of weather. The method is based on the statistical analysis of the relation between power generation and weather data for four years obtained in the 20kW PV system installed at the Tokyo City University Campus. We apply the method with above database as the first stage to verify by comparison with the field data of PV generation performance shown in the JSER paper, and we obtained rather good agreement with the actual generation value. Then we calculate kWh value, i.e. power energy value, of PV generation of every Prefectures of Japan by application of the proposed method based on both weather data provided by the Japan Meteorological Agency and PV installation data provided by the Agency for Natural Resources and Energy, and we clarify the regional and seasonal characteristics of the PV generation. As a result of the calculation, the PV generation energy is estimated 27.6TWh in 2015 by 30.1GW installed capacity, among them 5.0GW of residential systems below 10kW per system and 25.1GW for non-residential system above 10kW per system including mega-solar system. The main object of this research is to evaluate the kWh value in 2030 when the government supposes 63GW PV system installation, and the analysis shows estimated energy would be 68TWh, which is slightly below government estimation value of 76TWh.
The proposed system can be improved by applying more detailed weather data, for example every 30 minutes or one hour, which enables to get kW value step by step which is useful to control conventional generating plants and/or storage capacity and demand response control.

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