As you may know from reading this blog, in plasma arc, plasma gasification, waste is broken down at temperatures around 1,500°C. While this form of gasification can be energy intensive, it ensures that the plasma gasification syngas produced is cleaned of residue tar, which makes it a higher value product. Another major benefit of plasma arc, plasma gasification is that it creates little to no emissions. This blog entry attempts to take a quick look at some of the other waste to energy technologies available.

Conventional gasification slightly differs from plasma arc, plasma gasification in that the temperatures inside its primary reactor are lower and the fuel source may be natural gas. However conventional gasification is similar to plasma arc, plasma gasification in that both are thermo-chemical processes in which waste is heated in an oxygen deficient environment to produce syngas which contains hydrogen, carbon monoxide and sometimes methane. This gas can be used as fuel for electricity generation or to produce chemicals or biofuels.

Pyrolysis is sometimes linked to plasma arc, plasma gasification. Pyrolysis is also a thermo-chemical process, however here the waste is heated in the complete absence of oxygen. The products are olefin liquid, syngas-type product, and char. The liquid fuel can be used as an input to produce gasoline, while the char can be recovered or passed along to a gasification process.

Other waste to energy alternatives include landfill gas recovery that convert methane gas from decomposing trash in to power. Methane is collected through a series of pipes and compressed for electricity generation. There are also waste to biofuels and waste to chemical processes. These are similar to aforementioned waste to energy technologies as they may utilize gasification or other thermo-chemical processes. Appropriate waste feedstocks include soybean straw, wood waste and used oils/fats.

Finally, there is anaerobic digestion (AD). This differs greatly from the other waste to energy technologies mentioned here in that AD uses microorganisms to convert organic waste into a biogas (primarily methane) and digestate. This biogas can be used to generate electricity, while the digestate has applications as a fertilizer. Anaerobic digestion is limited to wet organic wastes (including manure and sewage) or food waste. As such it requires that these materials to be separated from regular waste.