The main aspect of gasification, whether it is plasma-arc plasma gasification or “traditional” gasification is to raise carbon–rich materials or waste to a high temperature in an oxygen–deficient reactor, where the materials break down thermochemically versus combustion.

This process is more efficient than incineration, has a significantly lower environmental footprint, while the syngas can be transformed into a number of end products (liquid fuels, power, chemicals, etc.).

The feedstocks for traditional gasification processes range from coal, the organic components of municipal waste and biomass while the range is even greater for plasma-arc plasma gasification processes, which can handle just about any waste stream with the exception of radioactive materials.

Due to the fact that gasification occurs pre-combustion (assuming the syngas would be burned to generate electricity), it supports easier carbon capture than incineration where the chemistry can be more complex.

Plasma-arc plasma gasification is just one type of gasification. Other common forms include (1) updraft, (2) downdraft, (3) fixed bed and (4) fluidized bed. The first two are quick similar with exception of the gas flow. More on the differences in the next posting.

Plasma arc plasma gasification reactors do not require moving grates and the smaller volume of gases generated means that the plasma arc plasma gasification reactors can accommodate the required minimum residence times in a smaller volume. (Residence time – sometimes referred to as removal time – is the average amount of time that a particle spends in a particular system, which is important in hazardous waste or industrial waste processing to ensure that any toxic nature in the feedstock was exposed to the high temperatures generated within the plasma arc plasma gasification for a certain period of time).

Additionally, the smaller gas production and reducing environment (condition in which oxidation is prevented) within the plasma arc plasma gasification reactor does facilitate smaller sized air pollution control systems as a smaller volume of gas is required to be cleaned as compared to a combustion process.

There are a number of perceptions within the marketplace regarding plasma arc treatment and plasma arc gasification processes. Two weeks ago, this blog addressed the smaller physical footprint with regards to plasma arc gasification waste-to-energy systems.

This week we discuss the idea/claim regarding the plasma arc technology’s ability to generate significant useable recyclable end-products and energy with no residual waste.

Certainly this depends on the waste feedstock; however it is worth noting that if metals and glass are processed simultaneously in a plasma arc system, additional processing would be required to separate out these products for any re-use potential. The re-use of the vitrified slag product generated from to plasma arc systems has been demonstrated commercially in France and Japan.

Depending on the feedstock and moisture content and plasma utilization (combustion vs. plasma gasification/ plasma pyrolysis), to plasma arc gasification waste-to-energy systems can require significant amounts of energy to operate as such the net energy claims made by some within the industry may be overly optimistic in theory and largely unproven at this point in time in commercial operations. Criticizing the electrical loads associated with processing municipal solid waste in a plasma gasification waste-to-energy system may be valid as the primary goal would be net energy production, however when it comes to industrial, hazardous and universal waste treatment, the primary goal is destruction efficiency and thus the electrical consumption/generation should be considered secondary. Energy balances associated with to plasma-arc gasification waste-to-energy systems should to be reviewed on a project-by-project basis, rather than at a macro level within the industry.

Through PEAT’s India subsidiary, a Special Purpose Vehicle has been formed to support a PTDR-1000 plasma gasification waste-to-energy project within the Ankleshwar Industries Association to process a range of industrial waste and hazardous waste. A project site has been set aside by the local industrial development corporation and the official application to secure the land is expected later this year for the plasma gasification waste-to-energy project.

Further, the Environmental Clearance (EC) for the plasma gasification waste-to-energy project was granted in November 2009 and now the focus is on the process of securing the No Objection Certificate (NOC) from the Government of Gujarat.

The plasma gasification waste-to-energy project includes the utilization of a portion of the syngas produced to dewater an additional 15 metric tons of aqueous organic wastes (brining gate capacity to 45 metric tons per day).