Why WtE sites are relying on CO2 measurements to meet standards.
Carbon dioxide (CO2) produced by Waste-to-Energy (WtE) sites is a growing source of planet-warming emissions. With many national and international governmental frameworks mandating the achievement of net-zero targets within decades, the rules surrounding WtE operation are changing: both the European Union and United Kingdom will have to cap emissions from 2028, with operators in the UK required to monitor their CO2 emissions from 1 January 2026.
Almost half non-recyclable waste – such as food, plants and paper – contains CO2 which was naturally absorbed in their original state and released back into the atmosphere when incinerated. This biogenic CO2 is classified as climate-neutral, so no purchases are required from EU ETS allowances or local emissions trading systems for this emitted CO2.
Consequently, the accurate measurement of biogenic CO2 is of interest to all plant operators who burn fossil and organic fuels and who are or will be required to participate in an emissions trading system. By accurately measuring and accounting for biogenic CO2, operators can pay less under any carbon tax schemes that are applicable in their country of operation, and by reporting lower emissions, can capitalize on carbon credits when WtE falls under the Emissions Trading Scheme in 2028. Allowances can be sold or saved for later use.
Given the need for carbon accounting and financial incentives at stake, the accuracy of measurement data is critical. Guiding the process is ISO standard 13833 and EN ISO 13833, established in July 2013 to standardize the procedure for determining the proportion of biogenic CO2 in the total CO2 content produced in an emission stream. The standard specifies a process for capturing accurate, trustworthy data for biogenic CO2 emissions so the data can be used for emissions trading schemes and greenhouse gas inventories. See how much you could save with accurate biogenic CO2 reporting with our calculator.
The monitoring of biogenic CO2 emissions needs to enable measurement of both percentage shares of fossil and biogenic CO2 released by the process, as well as calculate the quantity of fossil CO2 emissions (tons/year). EN ISO 13833 specifies this be achieved by the capture of a sample from the incineration emissions stream, from which the measurement of biogenic content is determined by radiocarbon (14C) dating.
The sampling of waste post-combustion delivers a more accurate determination than a pre-combustion milled sample of waste matter, with the emitted waste stream a homogeneous gas comprising carbon dioxide, oxygen, nitrogen and some moisture. There are two methods for sampling waste gases: firstly, a periodic ‘grab’ sampling and continuous sampling. Grab sampling involves taking isolated samples at specific moments, which may not fully capture fluctuations in waste composition. In contrast, continuous sampling—conducted over a period ranging from one hour to one month—provides a more reliable average measurement. Because it is flow-proportional, it ensures a more representative sample of the emitted gas stream.
Having established that continuous flue sampling helps mitigate the potential for errors and irregularities that pre-combustion and grab sampling techniques can introduce, the process of continuous flue sampling with automated sampling systems reduces variability and enhances data reliability. Managed variables such as temperature, humidity, and flow rates help stabilize measurements and prevents deviations due to external factors. To achieve a consistent, stable sample capture that ensures the highly reliable measurement needed for an accurate and repeatable CO2 measurement, operators should ideally install a complete turnkey system solution for the sampling process, such as that provided by ENVEA’s AMESA-B smart sampling system.
In the AMESA-B monitoring process, the sampling principle for capturing CO2 specified by EN ISO 13833 is achieved by continuously sampling a volume-proportional extraction of part of the flue gas via a heated sampling probe. The sample is captured in an adsorption cartridge filled with either Ascarite® sodium hydroxide-coated silica or soda lime.
The sample stream must be extracted and captured under consistent sampling conditions throughout the sampling period, which can range from one hour to four weeks in duration. Once the sampling period is completed the adsorber cartridge (which only needs to be changed only once every 30 days) is exchanged and sent to an accredited laboratory to determine the ratio of biogenic and fossil-derived CO2 by 14C analysis.
Measurement stability, which ensures accuracy, is achieved by preventing data drift and errors that compromise compliance and reporting data. This stability is critical in WtE plants, where combustion processes and waste composition vary.
Leaks in the sampling system can potentially result in underreporting analyte concentrations relative to actual flue gas concentrations. To counter this, the AMESA-B provides pre- and post-sampling checks to ensure and confirm a precise sample flow rate. The first sensor confirms the extracted CO2 stack gas is passing the adsorber cartridge; the second breakthrough sensor notifies when the cartridge needs to be exchanged to avoid saturation. This ensures the reliability of the supplied sample for testing, fulfilling EN ISO 13833 requirements by not only ensuring high accuracy, but also by providing full sample traceability.
In the laboratory, the fine accuracy of the measurement is determined by the three alternative methods specified for determining the 14 C content in the sample: Accelerated mass spectrometry (AMS), beta-ionization (BI), and liquid scintillation (LS). This process will be mandatory not only to meet ISO 13833 standards but also to qualify for incentives and subsidies: for example, in the UK’s Waste Industrial carbon capture model, 14 C process is the only permitted method for assessing the split of biogenic-fossil CO2 emissions. It uses only the sample collection method provided by the AMESA-B, with analysis again provided at an accredited laboratory.
Some operators identify potential concerns around the loss of flue gas samples due to sampling or systems failures, with consequent impacts on the accuracy of the captured sample and the data produced. Consequently, they are choosing to install two sampling systems per process, which not only ensures emission data remains continuous but also provides an extra degree of measurement verification between two captured samples.
However, using the combination of continuous sample monitoring using a credible, reliable sampling system such as the AMESA-B, with results analyzed using an accredited laboratory to perform the 14 C analysis, provides the most accurate method currently possible of producing reliable, trustworthy biogenic CO2 data.
With coal undergoing a gradual phaseout as a power feedstock in Europe and the UK, attention is now shifting to the emissions footprint of the sources of power generation seeking to replace it.
Understanding and, most importantly, accurately measuring your business’s Biogenic CO2 emissions can offer many business opportunities.
