Sampling of CO2 for determining fossil proportion

The proportion of carbon dioxide of biogenic and fossil origin in flue gases can be determined by representative sampling of CO2 over a specified period of time and analysis of the proportion of 14C of the total amount of carbon in the sample taken.

Steps in fossil CO2 determination

• Representative sampling of emitted CO2 during a fixed period of time.
• Determination of the proportion of 14C in the sample taken.
• Calculation of the proportion of CO2 of biogenic origin during the testing period

Why determine the proportion of fossil CO2?

To investigate what proportion of the fuel has fossil or biogenic origin, this is primarily common as a basis for the trading of emissions rights. The method is primarily applicable to incineration plants fired with waste or recycled fuel, but can also be applied to various industrial processes.

How are fossil CO2 measurements performed?

1. A CO2 sampler is placed with the customer
2. Sample gas is taken out and conditioned with an extractive gas analysis system similar to the one in the figure. It is often good to use the existing set-up in the plant because the sample gas flow required for sampling is very low, approx. 5 ml/min.
3. The conditioned sample gas is led to the sampler where a partial flow of the flue gases is pushed through gas washing bottles with NaOH solution where the CO2 content of the flue gas is quantitatively absorbed.
4. Sampling usually takes place continuously throughout calendar months. At the end of the month, the sample is handled by Metlab and a new bottle with absorption solution is installed.
5. Report with percentage of biogenic and respectively fossil percentage presented in % is delivered to the customer after each sampling period.

Which absorption solution is used for CO2 sampling?

4 M NaOH solution free of carbonate is used as absorption solution. ATTENTION! The absorption solution is highly corrosive and should only be handled by Metlab or personnel with solid experience in chemical handling.

Contact us today if you are interested in getting started with determining the proportion of fossil and biogenic CO2.