Page Top

Start Content

Are You Fully Prepared for a Flood? -June Is Flood Measure Strengthening Month-


Are You Fully Prepared for a Flood? -June Is Flood Measure Strengthening Month-

June marks the start of rainy season, and each year the Bureau of Sewerage carries out the following public relations activities as part of its efforts to promote understanding of the role of sewers in creating a safe community.

Major Activities during Flood Measure Strengthening Month(June)

  1. Give tours of pumping stations and projects under construction, and explain the bureau's flood measures. Normally, such facilities are not open to the public.
  2. At supermarkets, distribute informational pamphlets on flood preparation. Bureau staff also visit homes with basements or sub-basements to deliver a leaflet describing preventative measures for such buildings and encourage residents to be prepared for floods.
  3. Participate in community floodfighting drills and exhibit influent models to encourage residents to take flood prevention measures.

Photo:The Inside of the Wada Yayoi Trunk Sewer

The Inside of the Wada Yayoi Trunk Sewer

poster for Flood Measure Strengthening Month

Promotional poster for Flood Measure Strengthening Month

Coincineration Plant for Sewage Sludge and Wood Biomass Starts Operations

A collaboration that benefits both sewage works and efforts to reduce pollen allergies

This Plant now receives a stable supply of wood chips made from leftover cedar wood and branches from cedar trees that have been pruned to reduce allergy-causing pollen. These chips are used as a supplemental fuel to sewage sludge.
Coincineration not only reduces the greenhouse gases but also makes effective use of materials from pollen countermeasures that would otherwise go unused, and also contributes to forest maintenance in Tokyo's Tama District, where the chip materials originate.


Wood biomass input: 9.6 tonnes per day(3,160 tonnes annually)of branches, roots, bark and prunings(The new No. 1 incinerator has an overall capacity of 150 tonnes per day.)

Photo:The new No.1 incinerator

The new No.1 incinerator

Photo:Wood Biomass

Wood Biomass

2.Coordination Among Bureaus

Illustration:Coordination Among Bureaus


  • Greenhouse gas reduction: approx. 1000 tonnes of CO2 per year
  • This amount is equal to the amount of CO2 that 4.7 hectares of forest(equivalent to 59 Tokyo Domes)would absorb annually.
  • Reduction in natural gas use: approx. 543,000 cubic meters per year
  • This is the amount of natural gas that 1,610 regular households would use over the course of one year.

Development of a Solar Photovoltaics System using Thin-Film Solar Modules

1.Solar Photovoltaics System to Address Global Warming

The United Nations Climate Change Conference(COP15)will be held in Copenhagen, Denmark in December 2009 as part of the growing global fight against global warming. Tokyo Metropolitan Government(TMG)is promoting "10-Year Project for a Carbon-Minus Tokyo" targeting a 25% reduction in CO2 emissions by 2020 against a base of year 2000 emissions. As the largest generator of CO2 emissions resulted from the administrative activity of TMG, the Bureau of Sewerage is formulating and implementing its own program, Earth Plan, to deal with global warming. Our efforts include a joint research project on a new solar photovoltaics system to lower greenhouse gas emissions due to reduction of the electric power generated from fossil fuels at the Water Reclamation Centers.

2.Outline of Joint Research Project

The system features thin-film solar cell modules mounted on a uniaxial tracking type pedestal. The system is shown in the picture.
We installed and tested a solar photovoltaics system during the 2008 fiscal year(from Apr. 2008 to Mar. 2009)in cooperation with Sharp Corporation.
Two systems were installed on the rooftop of south facility for primary sedimentation tank at Kasai Water Reclamation Center experimentally: one system mounted on a uniaxial tracking type pedestal.
For comparison, another system mounted on a pedestal without a tracking device. Both feature 1kW of thin-film solar modules. The uniaxial tracking type system takes up a total of 20 square meters.

A photograph of a thin-film solar cell modules mounted on a uniaxial tracking type pedestal

thin-film solar cell modules mounted on a uniaxial tracking type pedestal

Thin-film solar modules use only 1/100th of the silicon needed for traditional solar cells, which contributes to lower costs. Moreover, the use of a uniaxial tracking device will translate to greater energy output since the panels can be oriented to take optimal advantage of the sun's rays.

The target items for joint research were as follows.

  1. Performance: match or exceed the performance of standard crystalline silicon solar cells(for a 1kW system, an output of 900kWH or more per year).
  2. Life rating: Retain at least 80% of the rated output after a durable life of 15 years.
  3. Output characteristics: Coordinate with facility power sources to cut peak demand and ensure there are no problems due to power load fluctuations or weather.
  4. Economic efficiency: A 15% cost savings over standard crystalline silicon solar cells on a per kW basis.

All of these targets were met during the research period, and it can be concluded from this small-scale experiment that solar power generation can be one of the new technologies introduced to sewerage systems.

3.The Next Steps

During fiscal 2009, we will install and test an expanded 500kW solar photovoltaics system at Water Reclamation Centers, researching any issues with the high voltages that couldn't be verified with the smaller system. Water Reclamation Centers in the metropolis also employ other types of common power generation systems such as NaS batteries, microhydroelectric power and biomass power that supplement grid power purchases, so it will also be necessary to verify interactions and control systems among these different power generation systems. Additionally, the effects of strong winds, salt damage and other environmental factors must be inspected so that we can choose suitable pedestal materials.

Technological innovations will result in solar photovoltaics systems with improved performance and reduced costs. The bureau is moving toward implementing solar photovoltaics at Water Reclamation Centers as one of its main sources of power, so it will be necessary to examine trends in the relevant technologies and carefully investigate how solar photovoltaics can be put to practical use.

Get Adobe Acrobat Reader

You need Adobe Acrobat Reader to view PDF files.
You can download it for free from the Adobe Systems website, so please use make use of it.

End Content

Start User Guide

End User Guide