Sampling and measurements

🇪🇺 CRCF requirement: Measurements of CO₂ stream

In addition to following the requirements set out in this section, CRCF projects shall ensure measurements of the CO₂ stream are taken in accordance with Articles 40-46 and Article 49 of the European Commission's Implementing Regulation 2018/2066.

Measurement standards

All measurements of the CO₂ stream shall be carried out using methods based on

• EN 14181: stationary source emissions - quality assurance of automated measuring systems

• EN 15259: air quality - measurement for stationary emission sources - requirements for measurement sections and sites and for the measurement objective, plan and report

• other relevant EN standards, in particular EN ISO 16811-2: stationary source emissions - manual and automatic determination of velocity and volume flow rate in ducts

Where none of the above is available, methods shall be based on suitable ISO standards, national standards, industry best practice guidelines or scientifically proven methodologies.

Laboratories carrying out measurements, calibration and equipment assessment for the measurement system shall have at least one quality assurance accreditation for the relevant analytical methods or calibration activities, such as:

• ISO/IEC 17025

• CEN/TS 17225-1

• ISO 10694

Calibration requirements

Measurement systems shall be:

• Calibrated, adjusted, and checked at regular intervals, including prior to entering service, at an accredited calibration facility or laboratory traceable to recognized international or national measurement standards.

• Installed in accordance with international or national standards or the manufacturer's specifications.

• Recalibrated periodically, at least annually, meeting or exceeding international or national standards (e.g. EN 14181 in the EU) or manufacturer's specifications, including parallel measurements against standard reference methods carried out by competent staff.

Where a component of a measurement system cannot be calibrated, Project Developers shall identify this in the monitoring plan and propose an alternative control method.

Where equipment is found to be non-compliant with performance requirements, Project Developers shall take corrective action without undue delay.

Determination of the amount of CO₂

The amount of CO₂ at each measurement point shall be determined using direct measurements (i.e. physical measurement equipment) rather than a calculation-based approach. Measurements shall meet a maximum measurement uncertainty of ±2.5%, meaning the uncertainty across all measured parameters.

The amount of CO₂ shall be calculated by continuously measuring the CO₂ concentration and the mass or volume flow rate, and multiplying them. For each measured parameter listed below, hourly averages shall be calculated using all data points available within that hour. Raw measurements data shall be made available upon request by Rainbow or the VVB.

Where equipment is temporarily out of operation during part of an hour, the hourly average may still be calculated from the remaining data points, provided at least 80% of the expected readings for that hour are available. If fewer than 80% are available, the requirements in the Handling missing data section below apply.

The following requirements for the measurement of the CO₂ stream parameters apply:

Mass or volumetric flow of the stream, $m_{stream}$ or $V_{stream}$

The mass or volumetric flow of the CO₂ stream shall be measured

• continuously, at least every 15 minutes, and aggregated over one day.

• before leaving the capture site, when being transferred to a new transport segment, before entering the storage site, and/or at the last monitoring point before entering permanent storage, depending on whether the segregated or the non-segregated stream approach applies.

• using a mass or volumetric flow meter. Project Developer shall prioritize metering technologies that are widely used in CCS measurements, such as differential pressure meters (orifice plate meters), turbine meters and coriolis meter.

Flow meters shall be chosen according to the conditions and ranges under which it will operate.

Density of the stream, $\rho_{stream}$

The amount of CO₂ is reported in tonnes of CO₂, a mass unit. To convert volume to mass flow, the stream's density is required.

The density shall be measured either by using an in-line densitometer or similar devices, or modeled using an equation of state (EoS). To model density from the EoS, the selection of an appropriate model, knowledge of the stream composition and reference pressure and temperature measurements are crucial. Various approaches for density determination using EoS can be found in the literature.

Measurements of the density shall be conducted

• continuously, and at the same frequency as the flow metering,

• as close to the metering point as possible.

Densitometers shall be calibrated with relevant reference fluids.

Pressure and temperature of the stream, $p,T$

Volumetric flow and density measurements are recorded at operational pressure and temperature but shall be converted to standard temperature and pressure conditions, STP.

Measurements of the operational pressure and temperature shall be conducted

• continuously, at the same frequency as the flow metering. Raw measurements data shall be made available upon request by Rainbow or the VVB.

• as close to the metering point as possible

• using pressure and temperature meters (e.g., pressure transducers, thermocouples, thermistors)

Concentration of CO₂ in the stream, $F_{mass,\ CO2}$

​The CO₂ concentration is measured either by direct measurement of the CO₂ concentration in the stream, or by indirect measurement of the chemical composition (i.e. CO₂ and impurities) of the stream. The CO₂ concentration using either of the two methods shall be measured

• continuously, at the same frequency as the flow metering. (raw measurements data shall be made available upon request by Rainbow or the VVB), and

• as close to the metering point as possible and prior to mixing with another stream, and

• using in-line or on-line analyzer.

Typical analytical technologies are based on gas chromatography, non-dispersive infrared spectroscopy (NDIR), and ultraviolet-visible (UV-Vis) spectroscopy. Concentration measurement systems shall be

• chosen according to the expected and actual composition of the stream, covering the detection range required by local/national standards or operational requirements, and

• on-site calibration at commissioning shall be performed against traceable calibration gases

Determination of biogenic fraction of CO₂

Project Developers shall determine $F_B$ according to Article 39 of the EU ETS monitoring and reporting, using either

• a mass balance approach of material inputs by type for every monitoring period, or

• continuous C14 testing over a representative period of time, following ISO 13833 or ASTM D6866 standard test methods, or

• other standards and analytical methods, subject to approval by Rainbow and the VVB.

Handling missing data

Where a valid hourly reading cannot be obtained because equipment is out of control, out of range, or out of operation, a substitute value shall be determined for each missing hour:

• For missing concentration data: the substitute value shall be calculated as the average concentration over the monitoring period plus twice the standard deviation.

• For data other than concentration: the substitute value shall be derived from a mass balance or energy balance model of the process, and validated against the remaining measured parameters for a period of the same length as the data gap.

If measurement equipment is down for more than 5 consecutive days, the Project Developer shall notify Rainbow without delay and propose corrective measures. Where the Project Developer is not the operator of the transport or storage infrastructure, a formal agreement shall be in place ensuring that all relevant measurement data and gap-filling records are communicated to the Project Developer in a timely manner.