Challenging Technologies or Challenged Technologies?

If it sounds too good to be true – it probably is!
Some technologies that fit this criteria are:
Gasification
Pyrolysis,
Plasma Arc
“Water Wash Systems”
Etc…

The idea is to stop land filling and not to continue expensive experiments!

Outdated Concept:
Worst of the “pack”: Landfilling:

Today the number one competition to WTE is land filling. WTE and land filling compete in different areas and on different levels. One can differentiate between region, governmental regulations, political and public perception, and economic perception all on a local, state and/or nationwide level.

Today’s landfill practices incorporate “state of the art” landfill technology – however, when compared to WRSI’s Advanced Thermal Recycling (ATR) technology it is completely outdated.

Environmental activists dislike landfills not only because of the potential for pollution, but because they permanently remove various raw materials from economic use. All of the energy and natural resources that went into the manufacturing process of a disposed of item are "wasted" and not conserved. This is said to contribute to damage of forests, and agricultural areas, including in less-developed countries that derive a majority of their export revenues from raw material.

Methane is 21x more potent than CO2

One million tons of Municipal Solid Waste (MSW) treated in a modern WTE facility and not land filled will release 500,000 tons less CO2 into the atmosphere.

Alternative Technologies for Dealing with MSW:

In addition to landfilling and ATR and conventional WTE there are two other technologies available for dealing with MSW: Pyrolysis and Gasification. Approximately 200 plants and test facilities have been built in the last twenty years. Very few plants remain in operation today. These technologies have proven uneconomic and undependable in dealing with quantities of any consequence. Industry may find solutions for these technical shortcomings over the next couple of decades, however at this time their commercial use is limited.

Pyrolysis:

Technical Description: Pyrolysis is used for the conversion of MSW biomass into liquids. This process burns wet MSW in an oxygen and water free environment. It generates substantial amounts of condensable hydrocarbons which make operating the plant difficult and inefficient. The solids resulting from the Pyrolysis process are highly contaminated and are high in carbon thus making the solids unsuitable for land filling without further treatment. Additional processing required consumes more energy than the Pyrolysis produces, thus negating commercial viability.

The use of the Pyrolysis condensate from waste Pyrolysis for upgrading and production of special oils etc. was tested in many different ways. All failed because inefficient technical performance could not guarantee the pureness of the product. This resulted in poor economic performance with the outcome that the operational costs were several times higher than the gain.

The use of Pyrolysis gas and condensate for thermal use with combustion needs an additional reactor which adds to the price tag significantly.

Direct combustion is far more efficient than Pyrolysis.
Remnants still have to be land filled!

Gasification:

Technology Description: Gasification is a process that uses heat, pressure and steam to convert materials directly into a gas composed primarily of carbon monoxide and hydrogen. Typical raw materials used in gasification are coal, petroleum-based materials and organic materials. The feedstock is prepared and fed, in either dry or slurried form, into a sealed reactor chamber called a gasifier. Most commercial gasification technologies do not use oxygen. All require an energy source to generate heat and begin processing.

Hydrocarbon build up in the flue gas of these plants is a significant technical problem. This has been the main contributor to plant failures. Theoretically the power production of a gasification plant can be higher than that of a combustion plant although this has never been achieved. This process requires heterogeneous waste input which means that a great deal of sorting must be done at the front end. The combined cost of the requirements to operate gasification has made it commercially unviable.

Unless significant higher fees are paid for the treatment of waste such as in Japan ($300 to $1000) neither gasification nor Pyrolysis are economically viable.

Direct combustion is far more efficient than gasification.
Remnants still have to be land filled!

There are many other technologies that tried and failed which are discussed in the PowerPoint presentations. These can be found in numerous places on the website.

Plasma Arc:

Technology Description: Two high voltage probes create an electrical arc in a field of low pressure gas which causes the gas molecules to lose an electron and become ionized; the resulting hot, ionized gas is referred to as a "plasma." When a combination of organic and inorganic waste is introduced into the plasma field, the intense heat breaks the waste products’ molecules into simpler compounds. These gaseous products are then scrubbed to remove contaminants, and burned or used directly in a gas turbine to produce electricity. The resulting products from the gas combustion are carbon monoxides, hydrogen and carbon dioxides from the organic waste and a glassy slag residue from the inorganic waste. The plasma arc itself operates at a temperature of 7000° F. The reaction chamber heated by the plasma will reach between 1700 and 2200° F. The slag is typically around 3000° F when discharged from the Pyrolysis chamber.

Technical Pitfalls

• The electrodes which create the arc and generate the plasma must be in contact with the solid waste. The physical characteristics of the waste, as well as the corrosive gases created as Pyrolysis proceeds leads to a very short operating life for the electrodes. Thus, reactors must frequently be removed from service to permit replacement electrodes to be installed.

• A tremendous amount of external, electrical energy is required to operate the arc which reduces the net positive quantity of electrical output from the plant.

• Pre-processing (shredding) is also a requirement of the plasma arc method with greater homogeneity and smaller size of the feed to the plasma reactor decreasing the possibility of fouling or damage of the electrodes that are inserted into the waste mass to achieve the decomposition reactions in the waste feed.

• The high temperature gases produced from the garbage feed stock can also include vaporized metals such as cadmium, mercury, and lead. These can be emitted into the atmosphere following the combustion chamber, internal combustion engines or gas turbine stage. Rapidly cooling the gas either before it enters the gas reactor of afterward is the only method of capturing the metals and converting them back into solid form. Cooling is difficult given the high temperatures generated by the plasma arc and, thus plants utilizing this technology face air pollution control issues. Quick cooling of the flue gases (exit gases) is also necessary to prohibit the reformulation of dioxins and furans that are destroyed during the incineration process. The flue gases must be cooled below 300 degrees F within seconds to prevent dioxins and furans from forming. The plasma arc system does not have a boiler which can easily facilitate this rapid cooling and current designs employ a liquid scrubbing step. There is currently no data with respect to air quality available for the plasma arc facilities in operation worldwide.

The bottom line is that none of these technologies have a proven concept that works with MSW. These technologies are not laid out to deal with the heterogeneous challenges of MSW but rather to deal with single a homogenized stream like coal (and even here many have failed).