As a clean alternative to landfills, waste is completely destroyed and limits the long-term risks from groundwater contamination, spread of disease, uncontrolled fires, and eliminates or greatly reduces the release of methane and other air emissions.
Incinerators
As a clean alternative to incinerators, plasma has much lower emissions. Plasma creates no volatile organic compounds (VOCs), such as dioxins and furans, which are particularly harmful to the general public. Incinerators also create large volumes of ash that must be handled as a hazardous material and ultimately sent to landfill.
Fossil fuel power plants
As a clean alternative to fossil fuel power plants, air emissions are much lower and using waste as a resource can lessen the dependence on non-renewable resources that harm the environment when extracted.
SUNBAY plasma facilities will assist communities to avoid the environmental and public health challenges of landfills, incinerators and fossil fuel power plants. Rather than the environment and public health being an afterthought, it is the primary focus for SUNBAY and the reason why plasma gasification is a best-fit for most communities.
As a clean alternative to landfills, waste is completely destroyed and limits the long-term risks from groundwater contamination, spread of disease, uncontrolled fires, and eliminates or greatly reduces the release of methane and other air emissions.
As a clean alternative to incinerators, plasma has much lower emissions. Plasma creates no volatile organic compounds, such as dioxins and furans, which are particularly harmful to the general public. Incinerators also create large volumes of ash that must be handled as a hazardous material and sent to landfill.
As a clean alternative to fossil fuel power plants, air emissions are much lower and using waste as a resource can lessen the dependence on non-renewable resources that harm the environment when extracted.
Despite both being thermal processes in a similar general and very broad category, gasification should not be confused with incineration.
The following table provides a comparison between plasma and typical incinerators:
Incineration
Plasma
Energy recovery
20%
40%
Visual impact
Large installation
Compact units
Ultimate residue
Large flue gas treatment,
fly ashes for 6% of input
Less flue gas per ton of
waste for <1% of input (no fly ash)
Plasma gasification also has the following advantages:
High efficiency: where incinerators are reaching a full chain efficiency of 20%, gasification plants are closer to 40%, double that of incinerators. Efficiency is measured from heating value of the fuel to electrical energy produced.
No harmful by-products: limited emissions create limited reactive residues for fumes treatment; inorganic waste are melted and are transformed into a slag that retains pollutants in a vitrified glass matrix. This material can be used as raw material for civil works and for other applications.
Compact size: gasification furnaces do not require a large volume as there is no need to mix a lot of air for combustion. These installations require a small footprint that can be designed for aesthetics (80m x 60m for a 400 TPD plant). Smaller cities that cannot support a large incinerator can be equipped with a gasifier, enlarging the market potential.
Reduced transport: gasification plants can be near cities, near the places where waste is produced, saving transport costs and pollution.
Low noise: Noise is kept 55dB at 1m, gas engines are enclosed.
No fly ash: Low volume of the gasifier and low speed of the gas results in very little ash in the gas. Heavy metals are trapped in the slag rather than the fly ashes, unlike incinerators with ash that must be treated as hazardous waste. Remaining dust is collected in the plasma reactor and added to slag for vitrification.
Slag vitrification: The bottom of the gasifier is around 850°C, some part of the slag will start to vitrify. The process connects the gasifier to a plasma vitrification unit ensuring full vitrification (above 1200°C) of the slag. The result is an inert material that retains pollutants in a very stable glass matrix that does not leach. The vitrification process has been operational at an industrial scale since 1997.
Less flue gas than incinerators: The flue gas results from the transformation of organic elements of the waste into syn-gas plus the plasma torch gas stream. The volume of the gas that must be treated remains limited to strict minimum (3100 Nm3 per ton of MSW, compared to 5400Nm3 for incinerators), making the scrubbing more efficient than incinerators.
Very low emissions: As there is no combustion and low oxygen, there is very low production of NOx and CO2, and the high temperature ensures no volatile organic compounds (dioxins and furans) are created. Flue gas volume is very limited and these low emissions are easily treated by industry-standard fumes treatment. Thanks to the efficiency of the flue gas treatment, Europlasma facilities operate well within the world's toughest emission standards in the European Union.
The following provides a few brief comments on the performance of the Europlasma plants on some of the most closely watched pollutants:
Carbon monoxide
The overall process works under suction, preventing CO from escaping in case a minor leak in the installation occurs.
Lightly volatile halogenated hydrocarbons (CxHy), COV
These components are completely destroyed and oxidized in the high level temperature plasma reactor.
Dioxins, furans
These components cannot exist at 1200°C, and cannot reform because of the rapid cooling of plasma gas.
Acids SO2, HCl, HF
Efficiently removed from the plasma gas in the scrubbing system.
Heavy metals
The reducing atmosphere of the gasifier means that heavy metals remain in metallic form and remain in the slag, retained in the glass matrix. A minor part will go through the flue gas and will be trapped by an active coke filter and re-injected in the process, avoiding ultimate waste generation.
Process water
The process uses a closed loop water system with low water loss. The contaminated process water is pH neutralized, vaporized and recycled.
Ultimate waste
Slag is vitrified and can be used beneficially for no ultimate waste. Active coke filter is reinjected in the process for no ultimate waste. The only ultimate waste results from the pH neutralization of the waste water and must be landfilled for 1% by mass of waste.
In October 2003, a committee of scientists in France analyzed the qualities of the vitrified slag originating from a Europlasma facility. They made the following findings:
the qualifying test results show a proportion of unmelted substances equal to 0.03%. This value which is identical to that of nuclear glass and ten times lower than that of natural basalt glass, is significantly lower than the qualifying threshold level prescribed by the Scientific Committee;
the ecotoxicity test results are significantly lower than the threshold levels defined in the ministerial proposal entitled "Criteria and methods for evaluating the ecotoxicity of waste", dated January 1998;
the long term behaviour of the vitrified end-product is satisfactory as determined with the Atomic Energy Authority model, based on the scenario of open-air storage. The conclusion of this long-term behaviour study report also points out that the highest concentrations of toxic elements that may be reached within the leached liquids remain at least 80 times lower than the threshold limits that define drinking water fitness (French governmental decision no. 89-3 dated 3rd January 1989)";
the leach analysis results were:
significantly lower than the threshold levels defined in the ministerial proposal entitled "Criteria and methods for evaluating the ecotoxicity of waste", dated January 1998;
significantly lower than the regulatory threshold levels concerning the "Minimal criteria applicable to liquid effluents in the natural environment" as per the French governmental decision dated 09/09/97;
significantly lower than the regulatory threshold levels concerning the "Quality limits for source water used for the production of water for human consumption" as per paragraph III of the French governmental decision dated 03/01/89;;
The Scientific Committee considered that:
the vitrified end-product turned out at the Cenon plant is not dangerous for the environment, according to the French governmental decision no. 97-517 dated 15th May 1997 relative to the classification of dangerous waste products;
the vitrified end-product changes very little over time physically, chemically as well as biologically. It may therefore be stored in class 3 type storage facilities.
