Measurement method for determination of the ratio of biogenic and fossil-derived CO2 in stack gas

ABSTRACT
In this paper, we present a measurement method for sampling and analysis of the ratio of biogenic and fossil-derived CO2 in stack gases from the combustion of mixed fossil and biogenic fuels. The measurement method was developed as a part of a project performed for Energinet.dk and the association of waste incineration and treatment plants in Denmark. The methodology for sampling and analysis is described, and preliminary measurement results from a field test at a Danish waste incineration plant are presented.

The method follows the guidelines of the prEN ISO 13833 standard that is currently being developed. After a number of laboratory and full scale tests, the measurement method was used in a field test at a Danish waste incineration plant, where the composition of waste was varied in 5 full scale experiments. The ratio of biogenic and fossil carbon in the waste was varied as much as possible through mixing known amounts of commercial and industrial waste, biomass and plastics with household waste. 

Preliminary results showed that during the field test, diurnal emissions of biogenic CO2 varied between 53% and 67% out of the total CO2 emission from the waste incineration plant. Based on the preliminary field test results, it is concluded that the reproducibility of the measurement method is 1%-6% RSD, including uncertainties from both sampling and analysis. Compared to the uncertainties generally deriving from similar measurements of gases in stack emissions, this is found to be fully acceptable.