Robert W. Wylde claims that the cost of operating destructors “is in a great measure offset and frequently quite overbalanced by the revenue” from the sale of steam and clinker. One hundred tons of refuse burned during 16 hours a day produces 800 engine H. P. Clinker from 100 tons might amount to 30 tons per day and would bring $1.00 a ton in many localities. Another expert says that one pound of refuse has been found to produce one-half to one and three-fourths pounds of steam. The value of refuse as a fuel is estimated by one expert to be 49 cents per ton.
The Chicago Waste Commission’s report points out, “that experience in connection with the development of power from refuse furnaces demonstrates that it is not easy to find an available use whereby the power can be utilized regularly as produced and the furnace operated continuously. In the majority of plants constructed, it has not been possible to utilize all the power available, and in most cases the use is limited to the operation of the plant. When power developed is used in lighting and power stations, the demand only comes during a part of the day. Supplementary coal-fired boilers are usually found in connection with destructor-electric lighting stations, or else the destructor is much larger than would be required to deal with the refuse alone. The power produced from refuse furnaces will be best utilized by some local industry, such as ice-making plants or electro-chemical plants, which require continuous operation. When power is used in connection with pumping plants, it is found good practise to operate the refuse plant only as an auxiliary to the power plant of the pumping station. The saving that results or credit that can be given the destructor plant will amount to the value of the fuel equal to that which it requires to produce the amount of steam developed and used. The fluctuating amount of power developed in most cases can be depended upon only for the average minimum production. In selecting a site for a refuse disposal plant from which power is developed it is not always profitable to utilize the power where the demand is not constant and where the demand would be constant, suitable sites are not always available.”
William M. Venable, sanitary engineer, believes that if a city has a steam power plant, it will pay, but it will not pay to build one for that purpose.
In a suburb of Montreal, the refuse destructor is constructed in connection with a municipal electric light power station and power is used in generating electricity for lighting purposes. The plant is operated only during the time when lighting load is in demand, and the material as delivered is stored during the day and burned at night. Only a part of the power is furnished by the refuse furnaces, the remainder being obtained from a coal-fired boiler plant.
In Savannah, Georgia, the water works boilers are kept in service, with banked fires, to use in case of shortage of garbage.
The following are some of the reports from cities which receive a revenue from by-products:
Minneapolis: The steam generated lights and heats hospital and workhouse buildings, also lights 31 miles of streets. Estimated annual revenue, heat $6,293.89; light $1,080.62; street lights ($60 per arc) $4,657.48; total, $12,031.99.
Borough of Richmond, New York City: West New Brighton incinerator uses clinker in manufacture of brick by mixing cement with ground clinker.
New Orleans, La.: Plans perfected to light streets and public buildings. Claimed that from 500 tons of garbage daily 30,000,000 K. W. can be generated a year.
Savannah, Georgia: Ninety-five per cent. of coal fuel previously used at pumping station is now saved by destructor. To operate water works pumping station it cost $81.90 per day. To operate the station and destructor it costs $46.50 per day, or a difference of $12,921 per year, this being 10 per cent. of the cost of the plant. This is expected to provide for repairs and amortization charges. Besides, the city has all of its refuse disposed of without cost at a central point and in a sanitary manner with freedom from nuisance. The clinker is used for road building and is estimated to have a value equal to the cost of hauling it from the plant.