Ryoichi Komiyama

World energy outlook in 2020 focusing on China's energy impacts on the world and Northeast Asia

This paper presents a consistent international energy projection developed by an integrated econometric model for the purpose of analysing Chinas energy impacts on the energy markets in the world and Northeast Asia to 2020. Vigorous economic growth, soaring electricity demand and progressive motorisation are going to expand the primary energy demand in China, which accounts for a large part of the world primary energy increase, eventually positioning China as an important player in the world energy market and in terms of CO2 emissions. Focusing on Northeast Asia, considerable oil demand growth in China, which has only a limited oil production, would increase the regional reliance on Middle Eastern oil, thereby underlining a serious energy security problem of oil importing countries in this region. It is becoming increasingly important for the energy issue to be addressed as one where all Northeast Asian countries have a common stake and can commit themselves.

Analysis for large-scale integration of PV system in Japan with a high time-resolution optimal power generation mix model

This paper assesses the possible integration of a massive PV resource into the power generation mix in Japan using a high time-resolution optimal power generation mix model. The feature of the model allows us to explicitly consider actual PV and wind output variability in 10-minute resolution on 365 days. Simulation results reveal that both the suppression control of PV output and rechargeable battery installation show a significant increase when PV installs at more than the similar scale of the peak demand or PV fraction in total power generation exceeds the level of around 20 percent. The calculated results imply as well that a large-scale integration of PV potentially decreases the usage ratio of LNG combined cycle (LNGCC) in specific seasons, which suggests the challenge for utility companies to assure LNGCC serving as a profitable ramp generator for treating the PV variability.

Evaluation of Optimal Power Generation Mix Considering Nuclear Power Plants’ Shut-Down Risk

After Fukushima nuclear power plant accident, resilience engineering has emerged as a new paradigm of risk management, and the design of resilient energy system is getting more and more important. Energy model analysis based on mathematical programming contributes to discussing how to implement resilience into energy system by identifying quantitative suggestions. In this paper, as an example of such analysis, the authors try to derive possible appropriate measures to enhance electricity supply system resilience to successive nuclear power plants’ shut-down risk. The model developed in this paper is a dynamic power generation planning model, which considers nuclear power plants’ shut-down risk stochastically and identifies resilient capacity expansion in Japan from 2012 to 2030 under the uncertainty of the risk from a quantitative perspective. This resilient capacity expansion includes the necessity of alternative power resources and demand response compensating for supply capacity loss due to nuclear power plants’ shut-down, considering economic constraints. Simulation results successfully show the need for these measures in the capacity expansion. Importantly, the suggestion is not like a future prediction but a normative image of the system through the comprehensive incorporation of forecasted future parameters and scenarios. The more detailed the parameters and the scenarios are, the better image can be obtained. Learning from past accidents and updating our scientific knowledge base will detail the parameters and the scenarios and make energy model analysis very effective. It will tell us how to make resilient energy system.

Considering Nuclear Accident in Energy Modeling Analysis

After Fukushima nuclear accident, alternative energy sources show a dramatic growth such as natural gas, petroleum and solar photovoltaic to compensate the loss of nuclear energy supply in Japan, and in the latest national energy policy, the government plans to promote renewable energy at a scale larger than the one aimed in the previous policy. Hence, the Fukushima accident can be regarded as the tipping point for the country to pursue alternative energy and environmental policy adjusting into the social circumstance after the Fukushima. So far, energy model has been developed to discuss long-term energy scenario in a consistent way and to analyze the effectiveness of energy policy. However, the most of the model developed until now does not explicitly consider the impact of nuclear accident on the long-term pathway of energy portfolio, in spite of the fact that the Fukushima accident is actually observed to dramatically change the situation of energy demand and supply in Japan. This manuscript aims to overview the transition of energy supply and demand in Japan after the Fukushima and to discuss the possibility of considering nuclear accident in energy modeling analysis by applying stochastic dynamic programming.

CO2 Emission Reduction Effect of Cogeneration System in Commercial and Residential Sectors Considering Long-Term Power Generation Mix in Japan

Publisher Summary Cogeneration system (CGS) is expected to be installed increasingly into commercial and residential sectors in Japan, due to its high potential of energy conservation characteristics, resultant high economic performance and CO2 emission reduction effect through its recent research and development. This chapter proposes a comprehensive model to examine future CO2 emission reductions through the installation of cogeneration system (CGS) in commercial and residential sectors of Japan, considering its long-term power generation mix. With the development of the CGS model and long-term generation mix model on a cost minimizing basis, Japans prospective power generation structure is figured out and CO2 emission reduction potential by CGS in Japan is evaluated. While considerable uncertainties remain regarding the various assumptions made for the model analysis, some results have been identified. In the standard fuel price scenario, the installation of CGS in commercial and residential sector accomplishes the reduction of both CO2 emission and primary energy consumption. In the low fuel price scenario, in which case the current fuel price continues into the future, the CO2 reduction effect decreases compared to the standard fuel scenario because of the dominant generation share of LNG-fired plant and LNG combined cycle in the future generation mix of Japan. In the case where nuclear power plant obtains economic advantage and increases its share in the future generation mix, CO2 emission from the energy system, conversely, increases by installing CGS (in comparison with prior to installing) as electric power generation of CGS gradually replaces the nuclear power plants. These results suggest that the effect of CO2 reduction potential by the introduction of CGS is cautiously evaluated, taking into account future power plant construction program in Japan.