wastes at the end of fiscal 2006 is 162.86 million m $ ^{3} $ , a decrease of 23.39 million m $ ^{3} $ . In addition, the national average residual number of years is 7.5, which indicates the situation has gradually improved. However, the residual number of years in the Greater Tokyo Metropolitan area is 4.4, and, in greater metropolitan areas in particular, their residual number of years has been decreasing (Figure 2-45).

Basically, final disposal sites of industrial wastes should be developed by private business operators. However, based on the development situation, the final disposal volume regarded as necessary needs to be secured with the development of facilities by the public sector.

### (2) Efforts at Thermal Recycling in Waste Incinerators A. Use of Residual Heat from Waste Incineration

About 70% of all facilities around the country make effective use of residual heat from waste incinerators for hot water, steam, electric power generation, etc (Figure 2-46). More specifically, the residual heat is used for various purposes, such as waste power generation described later, heating and hot water supply in waste incinerators. The heat is also used in places other than waste incinerators for heated pools, supply of hot water and heat to social welfare organizations, such as welfare facilities for the elderly, regional heating, etc.

Saving of natural resources and energy used in waste disposal facilities and contribution to regional communities account for the majority of reasons for using residual heat.

In addition to the promotion of such use of residual heat in waste incinerators, a system for further promoting the supply of heat, etc. to places other than waste incinerators needs to be created. In order to develop such a system, technical problems, such as dealing with changes in the volume and quality of wastes, cost comparison with heat supplied by gas and petroleum, coordination with relevant laws and regulations, such as the Electricity Enterprises Law, and so

Figure 2-45 Changes to residual volume and remaining years of final disposal sites (industrial waste)

forth need to be fully examined.

### B. Waste Power Generation

In waste power generation, the thermal energy of high temperature exhaust gas generated when wastes are incinerated is collected by a boiler, which generates steam to rotate a turbine for electric power generation. Waste power generation is one of the effective ways of using residual heat from waste incinerators.

At the end of fiscal 2008, among waste incinerators in operation or under construction, 300 incinerators are generating electrical power or scheduled to do so (Table 2-5). In addition, larger-scale waste incinerators tend to conduct waste power generation. Therefore, while such incinerators account for 23.6% of all incinerators, their waste treatment capability accounts for about 58.5% of that of all waste incinerators. The total amount of generated electricity of the waste incinerators conducting waste power generation is about 6.9 billion kWh. If annual electric power consumption per household is 3,600 kWh, the total amount equals to the annual electric power consumption of about two million households. In addition, 193 waste incinerators use electric power generated with waste power generation in places other than their facilities.

Power generation efficiency with waste power generation is about 11.2%, but it varies from a few percent to about 20%, depending on the incinerator. Recently, more efficient power generating facilities have been introduced.

Source: Ministry of the Environment

Table 2-5 Number of waste power generation facilities and generating capacity (fiscal year 2008)

Number of power generation facilities	300 (298)
Power generating capacity (thousand kW)	1,615 (1,604)
Power generation efficiency (%)	11.19 (11.14)
Total power generation (GWh)	6,935 (7,132)

Data in the brackets are for fiscal year 2007.

Source: Ministry of the Environment

Note 1: The facilities shown above are established by municipalities or affairs associations, and include facilities for which construction work had already started and facilities out of service, but exclude closed facilities.

Note 2: Power generation efficiency was calculated using the following formula.

Power generation efficiency [%] =

860 [kcal/kWh] × Total power generation [kWh/year]

1,000[kg/t] × Volume of waste incinerated [t/year] × 100

× Volume of waste heat generation [kcal/kg]

Note 3: Figures in the brackets are figures for the previous fiscal year.