Page Top

Start Content

Utilization of Energy

Wastewater Heat (heating and cooling)

The wastewater temperature is lower in summer and higher in winter than the atmospheric temperature, which led the Sewerage Bureau to develop the "Urban Heat" system making use of the temperature difference of the wastewater. The system was introduced in Ochiai Water Reclamation Center in January 1987. At present, the system is used for cooling and heating in 11 sewerage facilities and in the district heating and cooling project in Koraku 1-chome area.
The adoption of the Urban Heat system reduces the use of fossil fuels (petroleum, gas, etc.) and contributes to the reduction of air pollutants and power consumption.

Facilities using Urban Heat system

Installation placeOperationAir-conditioning
floor area,
Ochiai Water Reclamation Center January 1987 2,270m3
Shingashi Water Reclamation Center April 1990 2,680m3
Morigasaki Water Reclamation Center April 1991 2,490m3
Kosuge Water Reclamation Center April 1993 5,910m3
Kita-Tama Ichigo Water Reclamation Center April 1994 513m3
Nakano Water Reclamation Center July 1995 5,600m3
Ariake Water Reclamation Center September 1995 4,410m3
Shibaura Water Reclamation Center April 1997 2,930m3
Nakagawa Water Reclamation Center February 2000 5,600m3
Ukima Water Reclamation Center April 2001 4,066m3
Miyagi Water Reclamation Center April 2005 2,421m3

Comparison between wastewater temperature and atmospheric temperature

Urban Heat system using wastewater heat (Ochiai Water Reclamation Center)

District Heating and Cooling Project in Bunkyo-ward Koraku 1-chome Area

In order to enhance environmental preservation through further reduction of air pollutants and to promote energy saving through the experiences obtained from implementation of the Urban Heat system, the facilities or areas using wastewater heat energy have been expanded beyond the sewerage facilities, to the surrounding buildings including the Koraku Pumping Station in Bunkyo-ku. In July 1994, the district heating and cooling project using the raw wastewater was kicked off for the first time in Japan.
Compared with the independent air-conditioning in each building, the district heating and cooling system has the emissions of carbon dioxide and nitrogen oxides reduced by half. The reduced carbon dioxide emission is equivalent approximately to the carbon dioxide absorbed by the forest covering an area 14 times as large as the Yoyogi Park (54 ha).

  • Service area: Koraku 1-chome area, Bunkyo-ku, Tokyo
  • Service area: 21.6ha
  • Main equipment: Electro-compression type cooling and heating machine
  • Supply temperature: Cold water 7℃/Hot water 47℃
  • Supply destination: Office buildings, hotels and commerce facilities
  • Supply started: July 1994

Koraku 1-chome area, Bunkyo-ku

Wastewater Heat Utilization Project of Shibaura Water Reclamation Center

This is a new heat recycling project where the treated wastewater from Shibaura Water Reclamation Center is supplied to the new Sony Corporation Building (Sony City) for cooling the air-conditioning equipment of the building. The waste heat from air-conditioning, absorbed by the treated wastewater through the heat exchanger, contributes to the reduction of the volume of cooling tower equipment. The environmental effect of the project is the annual reduction of CO2 amounting approximately to 22 t due to the reduction of the electric power and tap water required for operating the cooling tower. Further, compared with the conventional method of releasing all heat to the atmosphere, the heat in this project is released to the treated wastewater, contributing to the countermeasure against heat island phenomena.

  • Supply volume:60,000m3/day
  • Commencement of project: October 2006

The office building

Koraku 1-chome area, Bunkyo-ku

Sludge Incineration Waste Heat (heating and cooling)

The sewage sludge is subjected to incineration using sludge incinerator: The waste heat contained in the incineration exhaust gas is used for air-conditioning and hot-water supply for Water Reclamation Centers.

Water Reclamation CenterTamagawa Joryu Water
Reclamation Center
Asakawa Water
Reclamation Center
Kiyose Water
Reclamation Center
Tobu Sludge Plant
Heat obtained through the use of
incineration waste heat [kw]
651 366 1,163 1,279
Heating capacity [kw] 586 226 1.163 930
Cooling capacity [kw]
90 814 581
Area covered [m2] almost 1,480 almost 170 almost 3,590 almost 1,400
Places of utilization Offices Monitoring rooms Offices & monitoring rooms Offices & monitoring rooms
Operation started April/1990 April/1994 Janually/1999 April/2001

As of the end of FY2006

Regional Air-conditioning Project in Shinsuna 3-chome Area, Koto-ku

In this project the waste heat (scrubbing water) from sewage sludge incineration is used for heating water, and the treated water for cooling the gas-absorbing cooling machine, thus making the most effective use of the untapped energy in Water Reclamation Centers for air-conditioning and hot water supply.
Compared with the independent air-conditioning of each building, the project can cut down carbon dioxide by 60% and nitrogen oxides by 70%, with the carbon dioxide reduction being equivalent to the carbon dioxide absorbed by a forest almost 13 times as large in size as the Yoyogi Park. (54ha)

  • Service zone: Shinsuna 3-chome area, Koto-ku, Tokyo
  • Service area: 13.0ha
  • Main equipment: Gas-absorbing type cooling and heating machine and heat exchanger
  • Supply temperature: Cold water 7℃/Hot water 60℃
  • Supply destination: Facilities for elderly people's welfare, medical complex, etc.
  • Business commencement: April 2002

Supply from Sunamachi Water Reclamation Center

Sludge Incineration Waste Heat (power generation)

In the Tobu Sludge Plant, the waste heat from the sludge incinerator is recovered and used for power generation. The generated power is used inside the plant, covering almost 70% of the power required for running the incinerator.

Waste Heat Recovery and Steam Electric Generation Facility

  • Place of Installation: Inside Eastern Sludge Plant, Arasuna 3-8-1, Koto-ku
  • Operation commencement: April 1997
  • Sludge incineration facility: Fluidized bed incinerator (300 t/day) × 3 units
  • Waste heat recovery facility: Waste heat boiler and air preheater; introduction of an effective waste heat recovery system through parallel installation of waste heat boiler and air preheater
  • Steam power generation equipment: 2,500 kW (with 3 units of incinerator in operation)

Waste heat recovery steam power generation facility

Sludge Gasification (scheduled)

Organic parts of sludge are thermally decomposed, gasified (CO, H2), and used as fuel in the generation of energy. By processing sludge in this way, N2O emissions can be reduced 3% compared to conventional incineration. The generated energy is used to power sewerage facilities.

  • Place of Installation: Kiyose Water Reclamation Center
  • Operation commencement: FY2010 (scheduled)
  • Facility scale: 100 wt/day

Sludge gasification equipment

Power Generation using Biomass Energy※1

OMethane gas produced during digestion (the decomposition of organic materials by microorganisms in anaerobic condition) in the sludge treatment process is used as fuel of power generation. This power is then used at water reclamation centers. Through this, it is possible to use energy efficiently, reduce power costs, and reduce greenhouse gas emissions. Since 2004, Morigasaki Water Reclamation Center has implemented and has been using, as a sewerage activity, the first PFI system※2 and "Green Power※3 Certified" system※4 in Japan.

※1 Power generation using renewable energy created by living thing.
※2 Private Finance Initiative
Using private funding, technology, and management know-how, the PFI method aims for efficient development and promotion of public services.
※3 Power generated in environmentally friendly ways such as by wind, solar, and biomass energy.
※4 A system for promoting the environmental value added by using Green Power such as reduction of CO2 emissions.

Biomass Power Generating Facility

Place of installationOperationFacility scale
Morigasaki Water
Reclamation Center
Morigasaki Water Reclamation Center April 2004 Digestion gas mono-fuel combustion
type gas engine 3,200 kW × 1 unit

Supply from Sunamachi Water Reclamation Center

Utilization of Green Power Certification System

The Green Power Certification System is effectively used in the biomass power generation and Micro-hydro power generation project in Morigasaki Water Reclamation Center. This is a system of dealing on environmental added values such as green power, etc. The enterprises joining in with the green power program purchase the certification as an appeal to the society for environmental contribution.

Supply from Sunamachi Water Reclamation Center

Micro-hydro Power Generation

Clean power with no greenhouse gas emissions can be produced using the plentiful volumes of effluent in a water reclamation center and only a small amount of head.

Micro-hydro power generation facility

Installation placeOperation/font>Facility scale
Kasai Water Reclamation Center October 2004 11kW (average)
37kW (rating)
Morigasaki Water Reclamation Center June 2005 95kW (average)×2unit(110kW (rating))
4kW (average)×1unit(11kW (rating))

Micro-hydro Power Generation System

Morigasaki Water Reclamation Center

New-type Solar Photovoltaic Generation System

End Content

Start User Guide

End User Guide