CEM - Abstract

Abstract Information :

The need for accurate emission measurement is becoming more apparent to us all. Specifically, the determination of greenhouse gas (GHG) emissions is crucial. Public outcry is driving demand for the reduction of fossil CO2 emissions and the maximization of the production of so called “green energy”. However, when electricity or heat is produced from a mixed fuel stream it is hard to determine what’s ‘green’ and what’s not.

Refuse-derived fuels (RDF) processed from municipal solid waste (MSW) and/or hazardous waste (HW) are usually an unknown mixture of biogenic and fossil organic matter. Due to European regulations (e.g. the Directive on Electricity Production from Renewable Energy Sources 2001/77/EC) producers and operators of RDF plants need reliable and cost-effective methods for determining the biogenic and fossil organic material, energy, and carbon content of the RDF.

Common methods already exist for the determination of biogenic content of fuel by the analysis of a few grams of the fuel. Besides being time consuming, these methods have a greater uncertainty due to the random nature of the samples (analysis of a few grams – out of tons of material!) and to their systematic limitations.

However, with continuous sampling of a part of the flue gas on a CO2 adsorber material, it is possible to monitor and to determine the biogenic CO2 portion of the emitted flue gas in an easy and accurate way.

Functional Principle Mixed fuel as used in RDF or MWI plants consist of a mixture of biogenic and fossil carbon. Biogenic carbon is in the fuel’s recently-grown raw material, for instance: wood, food, plants, paper etc., and the contained CO2 is part of a natural cycle. The fossil fuel carbon is contained within the fuel material, which developed over millions of years, for example: coal and oil. These different materials can be identified by a marker of the carbon atoms, as fossil material consists of 12C and biogenic material of 14C.

When the fuel is burned, carbons are emitted into the atmosphere. Biogenic CO2 is thereby defined as CO2 neutral, as the CO2 which is released via the burning process, was bounded by the material only a short time before. The fossil fuel CO2 emissions are therefore defined as a GHG source, but not biogenic carbon emissions. A determination of the 14C fraction of the flue gas makes it possible to determine the biogenic content of the fuel.

For the determination of the biogenic fraction, the AMESA B system extracts a part of the flue gas under volume-proportional conditions and the CO2 is sampled in an adsorber cartridge filled with Ascarite or soda lime. After a sampling period ranging from several hours up to one month, the cartridge is sent to a carbon dating laboratory to apply the carbon-14 method and determine the proportion of the 14C and 12C isotopes within the CO2. With the analysis result, and the information of the 14C fraction, it is possible to calculate the emitted fraction of biogenic and fossil CO2 or the amount of green energy. The used principle is a standardized method and complies with EN ISO 13833 and EN 15440.

This paper will describe in detail the system, which was developed based on the knowledge gained from years of customer experiences and product development of ENVEA’s globally renown AMESA D system for continuous dioxin sampling and AMESA M for continuous mercury sampling. Experiences of more than 20 years of continuous sampling were implemented in this system to ensure accurate and reliable measurement results.

Results of applications in waste to energy plants and refused derived fuel plants will be displayed.