Assessment of drastic peak demand reduction by gas cooling in Japan

Yozo Okamoto, Atsushi Sakakura, and Takao Kashiwagi, Tokyo University of Agriculture and Technology

Keywords

peak demand, gas cooling, CO2 reduction, load diversity factor, gas fired absorption chiller-heater (GACH), part load efficiency, gas engine heat-pump (GHP), air-source heat pump (ASHP), cooling load diversity factor (CLDF), building peak electricity density (BPED), building electricity load factor (BELF), grid peak electricity density (GPED)

Abstract

Electricity peak demand reduction by gas cooling has been successfully implemented for 40 years in Japan and more than ten million RT (refrigeration ton) (3.5 million kW) gas cooling was introduced by the end of FY 2002 . This big amount of gas cooling contributes not only to reduce electricity peak demand but also to conserve energy, to reduce CO2, CFCs , first and running cost .

In this paper, we first evaluated the contribution of gas cooling for peak demand reduction. In the first place, we surveyed peak electricity demand which were either air-conditioned by electricity or gas and showed the effect of gas cooling on buildings peak demand reduction in summer. P eak demand reduction for electric grid was also estimated by taking cooling load diversity factor (CLDF) into consideration and finally the rate of reduction was assessed .

Secondly, we evaluated the contribution of gas cooling to energy conservation for many types of buildings by developing a customized software PEACS to estimate annual energy consumption of various kinds of air-conditioning systems. Owing to continuous technical developments of gas cooling, it showed the advantage over alternative systems in many cases. CO2 reduction was estimated by the difference of aforementioned annual energy consumption.

Thirdly, we carried out the economic comparison among various kind s of air-conditioning systems and showed the cost-effectiveness of gas cooling .

The result of these analys e s suggest s that gas cooling is a good solution for many other countries who are suffering electricity shortage in kW as well as kWh.