The superior environmental performance and benefits of a plasma gasification facility include:
Beneficial use of byproducts and a reduction in the amount of material that ultimately must be landfilled
Lower greenhouse gas footprint
A plasma gasification combined cycle power plant or reciprocating engine plant is completely different than an incineration plant from an emissions perspective. Where incineration technology burns MSW to create energy, Alter NRG Plasma Gasifier uses extreme heat from its Westinghouse Plasma Torches, to break down the MSW to its molecular constituents including hydrogen and carbon monoxide, the two building blocks of syngas.
In a combined cycle or reciprocating engine application, syngas from a Alter NRG Plasma Gasifier is cleaned up to a specification similar to natural gas. It is this clean syngas that is burned in a gas turbine or reciprocating engine to make power. Emissions from this sort of plant will be similar to a natural gas fired power plant.
Syngas, after clean-up can meet the following specifications,
Lower Greenhouse Gas Footprint
Scientific Certification Systems (“SCS”), an independent consultancy, produced a report in 2010 that compared the lifecycle greenhouse gas emissions of a plasma gasification combined cycle power plant with the emissions from a state of the art incineration facility and a landfill with energy capture facility.
In their report SCS states:
“The results of this analysis show that the Plasma Gasification Combined Cycle (“PGCC”) system provides the lowest greenhouse gas emissions of the evaluated systems for waste disposal. The SCS study also concluded that the lifecycle greenhouse gas emissions were almost equivalent to the state of the art natural gas combined cycle power plant.
Reduced emissions, reduced amounts of solid wastes that need to be landfilled and reduced greenhouse emissions – plasma gasification has better environmental performance in all areas.”
Beneficial Byproducts vs. Bottom Ash and Flyash
Alter NRG Plasma Gasification facility produces vitrified slag as a byproduct that is inert and safe to use as aggregate or for use in other applications. Slag will not contaminate soil or drinking water. Slag from the Mihama Mikata plant has been tested against several standards including JLT-46, NEN-7341 and TCLP analysis. These tests were conducted by two independent laboratories Shimadzu Techno-Research Inc. and ALS Laboratory Group. The results show that the Mihama-Mikata slag components are below the test detection limits and the slag is considered non-leaching. On the right is a chart showing some of the results from the JLT-46 tests.
One hundred percent of the slag from the Mihama Mikata plant is used as aggregate for concrete products.
In a Alter NRG Plasma Gasifier, particulate is removed from the syngas downstream from the gasifier. However, the particulate can be recycled back into the gasifier for destruction (and also for further energy recovery) and therefore does not become a byproduct that requires disposal.
Instead of slag, incineration plants produce bottom ash and flyash. The flyash requires special disposal and in many jurisdictions is considered hazardous waste.
Assuming that particulate is recycled back into the gasifier, less than 2% of the material introduced needs to be sent to landfill. In comparison, about 20% to 30% of the waste processed in an incinerator must be sent to landfill.