The Plan for Mitigation of Global Warming by Tokyo Metropolitan Sewerage Bureau

- Earth Plan 2004 -

Kiyoshi INOUE*

Bureau of Sewerage, Tokyo Metropolitan Government 1. Introduction The sewerage works consume a huge amount of energy. Tokyo Metropolitan Sewerage Bureau consumed 1% of the total electric power consumed in Tokyo, and had the annual emission of greenhouse gas amounting to 1.026 million t-CO2 (record of fiscal year 2004), equivalent to approximately 40% of the total emission of greenhouse gas in Tokyo Metropolitan Government administrative works and projects. As such, Tokyo Metropolitan Sewerage Bureau drafted the “Earth Plan 2004” for mitigation of global warming in September 2004, ahead of the enforcement of Kyoto Protocol, and has steadily promoted the plan. Tokyo Metropolitan Government, on the other hand, launched “10-Year Project for a Carbon-Minus Tokyo” in 2007 in order to take initiative in preventing emission of greenhouse gas as a duty of the capital city of an advanced country. 2. Earth Plan 2004 2.1 Basic policy The Earth Plan 2004 sets a target of reducing greenhouse gas emission by more than 6% of the level of FY1990 by the fiscal year 2009 (See slide3, 4). With the measures taken until FY2006, we have already been successful in reducing the greenhouse gas emission approximately by 60% (105,000t-CO2) of the set designed reduction target for FY2009 (188,000t-CO2). 2.2 Reduction measures The Earth Plan 2004 calls for promotion of three major policies given below: (1) reduction of greenhouse gas emission in wastewater treatment, (2) switching to energy source with less greenhouse gas emission, and (3) coordination with various activities. (1) Reduction of greenhouse gas emission in wastewater treatment 1) Reduction of power consumption in wastewater treatment process Fine-bubble diffuser and energy-saving agitator are introduced in the reaction tank that consumes huge electric power. Compared with ordinary air diffuser, the fine-bubble diffuser produces fine bubbles to improve oxygen transfer efficiency, and eventually restrains air flow and reduces power consumption by 20% (slide7). The *2-8-1 Nishishinjuku, Shinjuku-ku, Tokyo 163-8001 Japan

-1-

energy-saving agitator, on the other hand, cuts down the power consumption by 40% of the power consumed by a conventional agitator (slide8). 2) Reduction of dinitrogen monoxide (N2O) produced in sludge treatment process (a) High-temperature incineration of sludge: It has been proved through the experimental study in Tokyo Metropolitan Sewerage Bureau that N2O (the greenhouse effect of N2O is 310 times higher than that of CO2) produced during incineration can be reduced by 70% by raising the sludge incinerating temperature (from 800 to 850 deg C). Hence, we are introducing high-temperature incinerators when improving the existing incinerator or renewing the aged one (slide10). (b) Sludge carbonization: The “Tobu Sludge Plant Sludge Carbonization Project” started in November 2007. Sludge carbonization is producing carbonized material from dried sludge by carbonization furnace (slide11). During the sludge carbonization process, the pyrolysis gas with nitrogen content is burned at a high temperature of 950 deg C to control N2O generation drastically, with the possible annual reduction being equivalent to 37,000t-CO2. Further, the produced carbonized material can be used in thermal power plants as an alternative fuel instead of coal. (2) Switching to energy source with less greenhouse gas emission (a) Micro-hydro Power Generation: For clean power generation, we have developed micro hydropower generator that makes an effective use of the slight effluent head of the steady and abundant effluent. In Morigasaki Water Reclamation Center, the largest sewerage treatment plant in Japan, the Micro-hydro Power Generation project with designed annual power generation 800,000 kWh started in 2005 (slide14). (b) Biomass Power Generation: We generate high-efficiency power by using the digester gas (methane gas) of sewerage sludge, a kind of biomass energy, and supply heat to reduce power and fuel consumption. A power generation project using digester gas started in Morigasaki Water Reclamation Center in 2004, introducing PFI (Private Finance Initiative) for the first time in sewerage works in Japan (slide15). (3) Coordination with various activities In order to reduce greenhouse gas emission, we take non-technological measures as cooperation in town building, introduction of private-sector activities, use of newly established system, etc. 3. 10-Year Project for a Carbon-Minus Tokyo 10-Year Project for a Carbon-Minus Tokyo aims at reducing, by the year 2020, the emission of greenhouse gas by 25% of the emission level of 2000. 3.1 Revision of Environment Securement Ordinance In order to ensure reduction of total greenhouse gas emission, Tokyo Metropolitan Government has revised the Environment Securement Ordinance, has imposed obligation on large corporations responsible for considerably high-level emission of greenhouse gas for reducing the total volume of the gas, and has introduced the

-2-

emission trading system. -Contents of obligation for reducing the total volume- The gas here refers to CO2 exhausted during the use of fuel, heat and electricity. The obligation is scheduled to start in FY2010 and temporarily last for about 5 years. The methods for reducing total volume are: 1) execution of in-house reduction measures by each individual corporation, such as energy saving, etc., and 2) procurement of reduction volume achieved by any other corporation (emissions trading). 3.2 Contribution of Tokyo Metropolitan Sewerage Bureau to the Project (1) Key point of greenhouse gas emission reduction Emission of greenhouse gas in sewerage works is attributed 40% to power consumption, 32% to N2O generated during sludge incineration (slide22). Hence, measures are taken mainly in the fields of power consumption and sludge incineration which have larger effect on the reduction of greenhouse emission. 1) Reduction of power consumption: As for the electric power consumed in treatment process, aeration system in wastewater treatment process and thickening and dewatering facilities in sludge treatment process cover almost 30% of the total power consumption. In order to reduce power consumption of the aeration system effectively, we are taking measures for energy saving of the main component, the blower, in addition to the measures for reducing power consumption of the entry system (slide23). Further, currently centrifugal type thickening and dewatering facilities with excellent maintainability are used. But these facilities consume a huge amount of electricity. Hence, new technologies for reducing power consumption of the system and of the peripheral facilities are under development, while achieving the set targets in thickening performance, etc. through reduction in size and weight of machines. 2) Reduction of N2O: Emission of N2O is particularly high in sludge incineration process. Therefore, in the future we are going to install sludge carbonizing and sludge gasification facilities capable of further suppressing the emission of N2O (slide24). The sludge gasification technology reforms the volatile solids contained in sludge into fuel gas at a low-oxygen state, with the N2O reduction rate exceeding that of sludge carbonization (slide25, 26). (2) Effective use of space of water reclamation center and introduction of new energy Since the wastewater treatment facilities have huge site, the space thereof is of extremely valuable for a city like Tokyo, which is crowded with a large number of people and industries. We have so far made an effective use of the above-ground space of the wastewater treatment facilities as parks, etc. open to public. In the future, in view of mitigating global warming we are keen on introducing new energy sources such as solar photovoltaic generation, making effective use of our huge space.

-3-

The Plan for Mitigation of Global Warming The Plan for Mitigation of Global Warming by Tokyo Metropolitan Sewerage Bureauby Tokyo Metropolitan Sewerage Bureau

-- Earth Plan 2004 Earth Plan 2004 --

Kiyoshi InoueKiyoshi InoueBureau of SewerageBureau of SewerageTokyo Metropolitan GovernmentTokyo Metropolitan Government

CO2 emission Approx. 6060 million tons

Tokyo Metropolitan GovernmentTokyo Metropolitan Government

CO2 emissionApprox. 2.2.33 million tons

Business & IndustryBusiness & Industry

TransportTransport

43%43%

Earth Plan 2004Earth Plan 2004

Target Reduction Rate 66 %

1010--Year ProjectYear Projectfor a Carbonfor a Carbon--Minus TokyoMinus Tokyo

Target Reduction Rate 2525 % with Emission TradingEmission Trading

SewerageSewerageBureauBureau

Tokyo Metropolitan AreaTokyo Metropolitan AreaFY2000

HouseholdHousehold

Business & IndustryBusiness & Industry

-4-

Tokyo Ward Area SewerageTokyo Ward Area Sewerage

Tokyo

• Projected area・・・・・・・・・・・・・・・・・・ 57,839ha • Projected population・・・・・・ 9,093,000 people• Total length of sewers・・・・・・・・・・・ 15,700km• Number of pumping stations・・・・・・・・・・・・ 82• Number of Water Reclamation Centers・・・ 13• Volume treated・・・・・・・・・・・4,800,000 m3/day• Annual power consumption・・800 million kWh

2

-Reference fiscal

year-

1990

1,018,000 t-

CO2

-Target fiscal

year-

2009

956,000 t-CO2

Reduction level

6% or above

Basic Policy of Basic Policy of ““Earth Plan 2004Earth Plan 2004””

3

-5-

1990FYReference Year

2009FYTarget Year

2004FYPlan drafted Year

Speculated volume without counter-measure implementation

Speculated volume with

counter-measure implementation

4

Estimation of greenhouse gas emission and Estimation of greenhouse gas emission and target of Earth Plan 2004target of Earth Plan 2004

5

Outline of Measures for Mitigation of Global Outline of Measures for Mitigation of Global Warming in Warming in ““Earth Plan 2004Earth Plan 2004””

Switching to energy source with less greenhouse gas emission

Reduction of greenhouse gas generated in wastewater treatment

Cooperation with various activities etc.

Global warming mitigation

1 2 3

-6-

Switching to energy sources

with less greenhouse gas

emission

Reduction of greenhouse gas emission due to

wastewater treatment

･Reduction of power consumption in wastewater treatment process ･Reduction of dinitrogen monoxide (N2O) generated in sludge treatment process ･Well-managed maintenance

･Utilization of renewable energy ･Introduction of new power source ･Promotion of fuel switching

6

Measures for Mitigation of Global Warming in Measures for Mitigation of Global Warming in ““Earth Plan 2004Earth Plan 2004””

7

Reduction of power consumption in wastewater Reduction of power consumption in wastewater treatment process (1/2)treatment process (1/2)

(a) Introduction of fine-bubble diffuser

Illustration of reduction by improvement of air diffuser

Blower BlowerPower consumption

20% reduction

Oxygen transfer efficiency

Low ⇒ High

Reaction tank Reaction tank

Fine-bubble air diffuser

Conventional diffuser

-7-

8

(b) Development and introduction of energy-saving agitator

Reduction of power consumption in wastewater Reduction of power consumption in wastewater treatment process (2/2)treatment process (2/2)

Anaerobictank

Anoxictank

AerobicTank

PP

Secondary sedimentation

tank

Diffuser

Primarysedimentation

tank

Circulating pumpAgitator

Reaction tank

Advanced treatment facilities A2/O process

9

(Ref.) Energy-saving agitator

-8-

790 810 820 830 840 860800 C

10

Reduction of NReduction of N22O generated in sludge O generated in sludge treatment process (1/2)treatment process (1/2)

(a) High-temperature sludge incineration

0

2

4

6

8

10

12

14

Incineration temperature and N2O emission

70% reduction

Incineration temperature (deg C)

N2O emissionkg/DS-t

850 C

Supplemental fuel

[city gas]

DryerCarbonization

furnace

IncineratorHeat

Recovery of gases generated during carbonization

(b) Sludge carbonization

Reduction of NReduction of N22O generated in sludge O generated in sludge treatment process (2/2)treatment process (2/2)

11

Dewatered sludge

Carbonized material

Illustration of carbonization process

Facilities capacity:100 w t/day x 3 lines

-9-

Thermal power plant

Batch consignment (Facility design, construction and operation plus carbonized

material sales)

Batch consignment (Facility design, construction and operation plus carbonized

material sales)

Dewatered sludge

Carbonization process

Carbonization process

Carbonized material

Tokyo Sewerage BureauTokyo Sewerage Bureau

SalesSales

Alternative fuel to coal

Selection of enterprise : Public proposalProject term: 20 years

Sludge carbonization project schemeSludge carbonization project scheme

EnterpriseEnterprise

12

CapacitySludge treatment capacity: 300 t/day [100 w t/day x 3 lines]Treated sludge volume : 99,000 t/yearCarbonized material fuel generation volume: 8,700 t/year

Sludge carbonization facilitySludge carbonization facility

Carbonizedmaterial

13

-10-

Adoption of siphon system

Utilization ofuniversal products

Cost reduction

Illustration of micro-hydro power generation

Realization ofcost down

工事の簡素化Simplified

construction

Discharge

Siphon system

14

Utilization of renewable energy (1/2)Utilization of renewable energy (1/2)(a) Micro-hydro power generation

Illustration of biomass power generation

15

(b) Biomass power generation

Digestion tank

Gas engine generator

Sludge

Wastewater treatment facilities

Sludge treatment

Methane gas

Heat

Electric power

Digestion

Utilization of renewable energy (2/2)Utilization of renewable energy (2/2)

Biomass energy

Methane gas

-11-

16

Coordination with various activitiesCoordination with various activities

Reduction of greenhouse

gas emission

Reduction of greenhouse

gas emission

Coordination for town building

Coordination for town building

Introduction of private-sector

activities

Introduction of private-sector

activities

Utilization of new system

Utilization of new system

Development and introduction of new

technology

Development and introduction of new

technology

Reclaimed water and wastewater

heatPFI project

Joint researchGreen electric

power

17

Contribution to Contribution to the 10the 10--Year Project for a Year Project for a CarbonCarbon--Minus TokyoMinus Tokyo

-12-

18

Outline of the 10Outline of the 10--Year Project for a Year Project for a CarbonCarbon--Minus TokyoMinus Tokyo

“The 10-Year Project for a Carbon-Minus Tokyo” is an approach aiming at realization of a leading-edge environmental city with the least environmental load in the world, looking toward an Olympic candidate city and reformed society

~ Aiming at handing down a rich environment to the next generation through world top countermeasures against global warming ~

It is an approach to grade up the city model to a top class level in the world, and to dispatch the information not only to Asia but also to the whole world.

Target of CO2 reduction

Reducing the emission by 25% of the level of 2000 by the year 2020.

What is the 10-Year Project for a Carbon-Minus Tokyo

Introduction of “obligation of reduction of total emission” to large-scale corporations

Support to energy-saving measures by small-and-medium scale corporations

Promotion of power-saving and energy-saving in household

Improvement in fuel consumption of automobiles and transportation

40% large-scale corporations (1300)

Household : 24%

Transport : 30%

60% small-and medium scale corporations (700,000)

Promotion of eco-drive in corporationsPromotion of bio-fuel utilization

Thorough saving powerPromotion of installation of high-efficiency hot water

supply units Utilization of 1-million kW Solar Power

Approximately 60 million ton (As of FY2000)

CO2 emission level in Tokyo

CityCity--wide Countermeasures against Global Warmingwide Countermeasures against Global Warming

To ensure 25% reduction of 2000 levelby the year 2020

Large scale promotion of renewal of cooling/heating facilities in factories, buildings, etc.

Obligation of reducing the total emission of greenhouse gas and introduction of emissions trading system

Business and industry : 44%

19

-13-

20

Gas requiring reduction in emissionEmission of CO2 while using fuel, heat, electricity, etc.

(ex.) Case of general corporations For instance, when 10% reduction is obliged

10,000 t-CO2/year 9,000 t-

CO2/year

Reference emission level

Reduction plan period

Obligation for reduction and means of executionObligation for reduction and means of execution

1 (Basic) Self reduction

2 (Complementary) Procurement of other party’s “reduced volume” (Emissions trade)○ The volume beyond the emission reduction level obliged to the party○ Purchase of green power certificate, etc.

○ The introduction of the latest high-efficiency equipment, etc.

21

The year 2000

The 10-Year Project for a Carbon-Minus Tokyo

25% reduction of the 2000 levelby the year 2020

The year 2020

Overall Tokyo: Approx. 61.8 million ton

Target emission levelApprox. 46.3 million ton

Tokyo Sewerage Bureau

Approx. 1 million ton-CO2(43% of the total emission for

administrative works and projects of Tokyo Metropolitan Government)

Target emission levelApprox. 750,000 t-CO2

Realization of a city model with the least environmental load in the world

Target Reduction Level in the 10Target Reduction Level in the 10--Year Project for a Year Project for a CarbonCarbon--Minus TokyoMinus Tokyo

21

-14-

22

Power consumption (370,000 t- CO2)

N2O etc. from sludge incineration (300,000 t-CO2)

N2O etc. from wastewater treatment (140,000 t-CO2)

Others (100,000 t-CO2)

Contents of greenhouse gas emission in FY2006 Contents of greenhouse gas emission in FY2006 in Tokyo Metropolitan Sewerage Bureauin Tokyo Metropolitan Sewerage Bureau

Total emission in FY2006 : 916,000 t-CO2

23

Power consumption

Development and introduction of low-power sludge thickening and dewatering facilities for realization of drastic energy saving

Development and introduction of energy-saving technology for aeration system that consumes huge power

Reduction of power consumptionReduction of power consumption

Approx. 370,000 t-CO2

Development andintroduction of energy-saving system of the

entire sewerage facilities in

coordination with private sectors

(Emission level for FY2006)

-15-

Reduction of NReduction of N22O generated in sludge O generated in sludge incineration processincineration process

24

Approx. 300,000 t-CO2

N2O emission due to sludge incineration

Gasification furnaceHere, the organic content of sludge is gasified (CO･H2) to generate electric power.

Woody biomass co-incineration facilityHere, wooden chips are used as auxiliary fuel for incinerator, etc.

Carbonizing furnaceHere, carbonized material is produced from sludge for use as an alternative fuel in coal-burned thermal power plants.

Switching to new technology from conventionalincineration

(Emission level for FY2006)

Gasification furnaceGasification furnace

Dewatered sludge

Heat recovery

Furnace of making to sludge gas

GeneratorReforming furnace

Fuel gas

Electric power

Gas engine

Sludge dryer

Image of Gasification furnace

25

-16-

26

Greenhouse gas emission from Greenhouse gas emission from sludge incineration processingsludge incineration processing

100

30

153

Sludge carbonization

Normal incineration of 800 deg C

High temperature incineration of 850 deg C

Sludge gasification

【Outline of the research】We conducted demonstration experiment of the “new photovoltaic generation

system” by combining “uniaxial tracking” type with thin-film solar battery, aiming at improving the power generation efficiency.

Interlocked with solar orientationExperimental facility above

wastewater treatment facility

Joint Research on New SolarJoint Research on New Solar--Photovoltaic Photovoltaic Generation SystemGeneration System

Experimental power generation scale: 1 kW

Uniaxial tracking type Fixed-mount type

27

-17-

Improvement in sludge recycling rate through installation of sludge carbonization facility

Power and fuel cost reduction by switching to energy-saving system (aeration, dewatering, gasification furnace, etc.)

Improvement in sewerage serviceImprovement in

sewerage service

High-efficiency of workHigh-efficiency of work

Creation of more safe and comfortable urban space for the next generation through mitigation of global warming and energy saving

Effect of Global Warming Mitigation Effect of Global Warming Mitigation and Energyand Energy--saving measuressaving measures

28

29

Thank YouThank You

http://www.gesui.metro.tokyo.jp/

“Earth-kun” is the Mascot of Tokyo Sewerage Bureau

-18-