low compared to the 40% efficiency of thermal power plants.

“Super waste power generation” is a technique for improving the efficiency of waste power generation. This is a system where natural gas-turbine power generation equipment is constructed in a waste incineration plant. Water vapor produced in the waste incineration boiler is heated to high temperatures with the heat discharged from the gas turbine and used by a vapor turbine for power generation. This system improves power generation efficacy by 20%-25%.

Additionally, the use of gasification and melting furnaces are being increasingly used as incineration equipment. These furnaces thermally decompose waste to produce combustible gases and carbides, and burns them at high temperatures of $ 1200^{\circ} $ C and higher. The heat discharged is used for power generation. (Fig. 2-43)

## b) Biomass power generation

Power generation using biomass such as wood chips or bagasse (residual pulp of sugar cane after the juice is extracted), among industrial wastes, has also been introduced. The biomass of such industrial waste can be acquired in large homogenous quantities. This type of power generation involves burning wood chips or bagasse in a stoker furnace or a fluidized bed furnace, absorbing burning heat in a boiler, and using it to power a steam turbine. It can supply heat at the same time. The issue of treating chlorine contained in biomass when water vapor is in a high temperature, high pressure state, and the issue of optimizing a series of processes including storage, pretreatment, transportation, supply, and burning of biomass to ensure stable power generation, had to be solved in order to put this technology into practical use.

## c) RDF (refuse derived fuel)

Small-scale garbage incineration plants cannot economically implement heat recovery individually. Thus, some small-scale garbage treatment plants process garbage into burnable solid fuel, and the fuel is collected at a dedicated power generation plant. This solid fuel is called RDF (refuse derived fuel). It is produced by crushing and drying burnable garbage, removing the non-burnable, iron, and aluminum portion, adding a preservative to it, and then compressing and forming it. (Fig. 2-44)

RDF has a heat capacity of about 4,000-5,000 kcal per kg, twice that of ordinary non-industrial waste. Moreover, harmful substances can be extracted in the processing stage, so discharge gases are easy to treat. Furthermore, it is easy to handle because it is a solid and can be transported by ordinary trucks. Additionally, this fuel is easy to make odor free and store because it is dry.

In August 2003, a storage tank exploded at an RDF power generation plant in Mie Prefecture. It was assumed that the RDF may have ignited due to heat generated by fermentation, or that the storage tank might have produced combustible gas. As a result, in December 2003 the Ministry of the Environment (MOE) reviewed RDF production, storage, and property control methods and developed guidelines for the safe production and use of RDF. In September 2004, the MOE revised the Regulations for Enforcement of the Wastes Disposal and Public Cleansing Law in terms of the safe production and use of RDF based on those guidelines in order to reinforce the regulation.

The Fire and Disaster Management Agency, Ministry of Internal Affairs and Communications, studied the actual state of RDF facilities, conducted demonstration tests for possible accidents, and developed safety measures in December 2003. Based on those

Fig. 2-44 Flow of RPF production