| Title | Geothermal Heat Pumps in Japan |
|---|---|
| Authors | Masakatsu Sasada |
| Year | 2012 |
| Conference | Japan International Geothermal Symposium |
| Keywords | geothermal heat pump, closed-loop, open-loop, ground heat exchanger |
| Abstract | Geothermal heat pumps are used for space heating, cooling, domestic hot water supply, and snow melting. They are classified into closed- and open-loop systems. The former system consists of a heat pump, fan coil unit or other domestic equipment, and ground heat exchangers in which brine (anti-freezing fluid) or water circulates. On the other hand, the latter does not have ground heat exchangers, but has water wells from which groundwater is supplied to extract heat. Installation of open-loop heat pump systems started in the 1960s, and many systems were installed in urban areas in the ’60s and ’70s. However, a new installation of an open-loop system was strictly restricted by regulations after the central and local government groundwater laws were in force to prevent land subsidence. Some of the old open-loop systems are still working in local cities where groundwater regulation is not applied. Installation of closed-loop systems has been started in Hokkaido since early 1980s after the oil crisis. Some domestic companies manufactured geothermal heat pumps. Other companies imported the geothermal heat pumps and drilling machines to make a borehole for a ground heat exchanger. The numbers of facilities installed were less than ten every year. Most Japanese people were not aware of energy efficiency of geothermal heat pump systems whereas the government conducted the “Sunshine Project” to promote renewable energies including research and development of geothermal resources mainly for power generation. The previous organization of the Geo-Heat Promotion Association of Japan was established in the year of 2000. Many companies joined the organization, and the numbers of geothermal heat pumps installed has increased gradually. The share of domestic geothermal heat pumps also increased. The geothermal heat pump course of Hokkaido University in 2004 to 2007 played an important role in establishing the technological base of geothermal heat pump systems. Several companies and universities monitored heat pump systems to evaluate their energy efficiency and reduction of CO2 emission in this decade. Ministry of the Environment took notice of geothermal heat pumps for accommodation of the “urban heat island phenomenon” around mega cities. The statistics of geothermal heat pump systems were published by Ministry of the Environment in 2010 (Fig. 1). It contains the data of closed- and open-loop systems from 1981 to 2009. The total number of facilities using geothermal heat pumps is 580 including 474 closed-loop, 102 open-loop, and 4 using both. More systems have been installed in the northern districts including Hokkaido, indicating the economical predominance of geothermal heat pumps when they replace an old oil boiler for a new geothermal heat pump system. The Japanese government had finally recognized geothermal heat pump as renewable energy by 2010, when they published the Basic Energy Plan and the New Growth Strategy. In 2011 the Ministry of Economy, Trade and Industry made a policy promoting the use of heat from renewable energy sources including granting subsidies to local municipalities and private companies. Thus an accelerated installation of geothermal heat pumps in Japan is expected in the coming years. |