Evaluating the carbon emission reduction effect of distributed energy system in 20 years: Experience from Kitakyushu Science and Research Park, Japan

Abstract

Distributed Energy Systems (DES) are widely recognized for their high energy efficiency and low environmental impact, attracting significant attention in the building sector. Among them, the combined cooling, heat, and power (CCHP) system is a key model. However, existing research predominantly relies on software simulations, lacking empirical analysis of long-term operational performance, which, to some extent limits the accuracy of carbon reduction benefit assessments for DES. This study analyzes 20 years of operational data from the Kitakyushu Science and Research Park (KSRP), focusing on the dynamic changes in carbon emissions of the CCHP system, aiming to fill the gap in empirical research on long-term performance evaluation of DES. The result shows that (1) KSRP has achieved environmental benefits through the CCHP system. In 20 years, the heat recovery has reduced emissions by 3,254 tCO₂/year, accounting for 98 % of the total emission reduction benefits. (2) The use of CCHP technology in the DES reduces KSRP’s carbon emissions by 5,445 tCO₂/year compared to using the urban power grid. However, with the fuel cell shutdown, this dropped to 2,432 tCO₂/year, and further declined to just 9 tCO₂/year with the shutdown of the gas engine and termination of heat recovery. (3) As the key piece of heat recovery equipment, absorption chiller-heaters contribute 53 % of the total carbon reduction achieved by the DES over the 20 years. (4) The DES at KSRP showed the most significant energy-saving and emission-reduction benefits in the first 10 years, followed by a decline every five years. This study not only provides essential empirical data support for the long-term performance evaluation of DES but also offers scientific insights for optimizing system operation strategies and enhancing carbon reduction benefits.