jaue2019-042: Retrofitting in HAKOZAKI DHC Utilizing Renewable River-Sourced Heat

Abstract

In 2009, hydrothermal, aerothermal, and geothermal energies, which are used as heat pump heat sources, were defined as renewable energy in the EU and Japan. The use of river heat is therefore important not only for energy saving but also for expanding the use of renewable energy.
In this report, we outline the Hakozaki district heating and cooling （DHC） plant, which was the first plant to use river heat for DHC in Japan in 1989, and describe the items examined and implemented to address issues specific to the use of river heat at the time of new construction and renovation. This report covers the following issues: reducing the impact on river ecosystems at the time of new construction, solving the excessive temperature difference between intake and discharge river water and the clogging of heat pump tubes at the time of renovation.
The coefficient of performance （COP） of the Hakozaki DHC plant has been improved after the renovation to 1.24, which is 68% greater than the average COP of 0.74 for DHC plants in Japan. Moreover,CO2emissions have been reduced to 0.042 t-CO2/GJ, an improvement of about 30% compared with the low-carbon DHC standard of the Tokyo Metropolitan Government.