An incinerator is a component and tool of the waste-to-energy industry. The primary objectives of an incineration plant are:

• To combust organic waste in order to combat the growing presence of human created waste.
• To divert and thus destroy the growing amount of garbage incoming into landfills worldwide.
• Whereby this diverstion will help keep existing landfills open longer, and thus postone the creation of new landfills.
• To provide electricity via the combustion of organic solids into energy for the local population
• And lastly, to combust and thus destroy medical waste and items that are thereby composed of organic toxins in order to safeguard humans from contamination, infection and possible death.
  

In short, incinerators are large furnaces that transfer organic solids into energy via combustion. There are four primary types of incinerators:

Moving Grate / Municipal Solid Waste Incinerators: This method utilizes a large conveyor system to move burning items through the furnace. As the organic compounds are combusted, the gases emitted (known as flue gases) are utilized to heat steam and thus power turbines present on site (these turbines are what creates the electricity).

Fixed Grate Incinerators: Most older and aging incinerators operate with a fixed grate system, and it is exactly what it sounds like--organic compounds are combusted on a grate that does not move. This is the primary difference between moving & fixed grate incinerators.

Rotary Kiln Incinerators: This system of incineration utilizes two seperate kilns (or chambers), one for combusting and turning the waste into flue gases, and the other processes the gases for post-combustion.

Fluidized Bed Incinerators: A strong airflow is introduced into a compartment whereby sand is added. The strong airflow and sand together break down the solid waste introduced, thus creating a product for the furnace to process more easily.

Note:  A grate is a system of iron bars in an incinerator's furnace that organic solids are placed on top of; therefore they also assist in seperating ash that can disposed of later.

Before the technological innovations of industrial air filters, particle filtration systems and electrostatic air cleaners--incineration was a dirty job. Heavy metals (such as lead and mercury), oil, sulfur, plastics, chemicals and basically everything used to be burned in an incinerator. In present time, industrial air filters, particle filtration systems and electrostatic air cleaners help purify the used-to-be dirty process of burning waste (note: plastics, oil, chemicals, acids and heavy metals are no longer burned in developed countries--only processed organic waste may be combusted.  The primary exception to this rule is the age of the incinerator).

Instances of modern technology present in incinerators today:

• Processed charcoal is utilized to "soak up" any remaining heavy metals that may be found via particle filtration systems.
• Nitrogen Oxides (NO_x) are reduced heavily by catalytic converters present (1975 onward in the United States).
• Wet Scrubbers are utilized to remove any remaining acids present when the organic waste is combusted.
• In 1990, 33% of dioxins, furans and carcinogenic dust emited in Germany was from incinerators (66 were operational in 1990), in 2007, 1% of dioxins, furans and carcinogenic dust emited in Germany was from incinerators (72 were operational in 2007).
• In 1990, 1200 'toxic units' were emitted by German incinerators--this number has been reduced to less than 70 in 2007. (the sources for these last two bullets are provided by Columbia University and can be located at the bottom of the article).
• There are dozens more of these examples provided in the source previously stated.
• Airflow is often rerouted through the boiler of an incinerator to remove odor pollution from the soon-to-be emissions. Although this is is not universal, and is a newer technology.
  

Incinerators are commonly seen as polluters and the antithesis to renewable energy. Older incinerators are monolithic, smelly and dirty. Though as times have changed, it is important to review the technologic innovations associated with this controversial method of renewable energy. To my critics--I hope this read has changed your mind, or has at least got you thinking about incineration as a modern renewable energy resource. For a last stab at those of you who still do not agree with me, swallow these facts:

• 4.8% of electricity and 13.7% of heating energy produced in Denmark was from incinerators present in the country.
• 96% of organic waste in Denmark goes through an incinerator first (the ashes are sent to a landfill afterwards).
• Several countries in Europe bar organic waste from entering a landfill prior to being treated at an incinerator.
• Private operators of incinerators in the European Union can apply for Renewable Energy Source (RES) tax credit.
• Incinerators are the primary alternative to landfills in countries where land availability is an issue. Examples include Japan, Luxembourg, Denmark, the United Kingdom and Austria.
  
• In 2008, The United Kingdom mapped out one hundred potential sites for thirty new incinerators to be built around the country.