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 place | Operation | Air-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 |
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
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
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 Center | Tamagawa 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
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)
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
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 installation | Operation | Facility scale | |
|---|---|---|---|
| Morigasaki Water Reclamation Center |
Morigasaki Water Reclamation Center | April 2004 | Digestion gas mono-fuel combustion type gas engine 3,200 kW × 1 unit |
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.
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 place | Operation/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)) |
