Two-Stage Approach for the Assessment of Photovoltaic and Cogeneration Systems: Integration of Regional Distributed Energy Systems and Power-Expansion Planning

Abstract

Distributed energy systems such as solar power photovoltaics (PV) and cogeneration systems (CGS) are expected to play a main role in future energy systems. However, consumers employ these distributed energy systems based on individual decisions rather than top-down installation planning, so even if the expansion of PV and other renewable energy sources is a national energy policy, it remains uncertain how and when PV installation targets will be realized. Furthermore, when consumers extensively deploy distributed energy systems, the power-expansion planning of utilities will be affected by changes in daily load patterns. In this paper, the authors develop a two-stage model focusing on interactions between the energy system adoption behavior of customers and power-expansion planning of a utility. In the first stage, the authors disaggregate Japan’s Kanto region into 38 areas and then develop an optimum energy system model including PV and CGS for consumers. In the second stage, the demand for electric power from the utility is transferred to the power-expansion planning model of the Tokyo Electric Power Company. The authors observe how well the results for PV penetration agree with the cost and the market projection scenarios given by governmental plans. The effects of subsidy scenarios for PV are also evaluated. The authors find that PV penetration will not meet installation targets unless additional PV promotion policies are implemented. The power-expansion model in Stage 2 shows how consumer behavior affects long-term expansion. These findings suggest the need for an integrated energy policy promoting a low-carbon society.