The incineration process in a waste incinerator produces two types of energy: heat and electricity, each with its own production process and level of energy efficiency, so how does the incinerator produce these two types of energy?
Heat production: this involves simply heating water through waste combustion. This process is energy efficient, with 70 to 80 percent of the heat of combustion recovered after incineration, or about 1,500 kWh per ton of waste. Of course, the heat generated must then be used somewhere near the waste incinerator.
Generating electricity: The heat exchanger must contain steam at the highest possible pressure. This steam is fed into a turbine that drives a generator. The electricity generated can be supplied to the grid throughout the year. The energy efficiency of this process is about 20 to 25 percent (300 to 400 kWh).
A better solution for generating heat or electricity through incineration is to simultaneously generate heat or thermal energy (CHP) through cogeneration. This involves utilizing the residual heat in the exhaust gases from the turbines that generate electricity. Through this process, energy efficiency is increased to 50 to 60 percent.
In a waste incinerator, five to seven tons of waste need to be generated to produce the equivalent of one ton of fuel oil.
In addition, the flue gases from incinerating waste are highly toxic. Therefore, the resulting gas must be scrubbed and neutralized (due to its acidic nature) before it is released. Otherwise the air around the waste incinerator is particularly polluted, so there is still room for improvement in the waste incinerator treatment process.