Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
ISO 27928:2025 — CO2 Capture Plant Performance: Evaluation Methods for CO2-Intensive Industries
Performance Evaluation for CO2 Capture in Industry
1. Scope and System Boundaries
ISO 27928:2025 provides a comprehensive framework for evaluating the performance of CO2 capture plants connected to large industrial emission sources. Unlike ISO 27927 which focuses on laboratory-scale absorbent screening, this standard addresses the full-scale capture plant system including boundary definitions, mass and energy balances, utility consumption accounting, and product CO2 stream quality specifications. It is applicable to chemical absorption, physical absorption, membrane separation, pressure-swing adsorption, and temperature-swing adsorption processes.
The standard defines a clear physical boundary between the host facility and the CO2 capture plant. All utilities (steam, power, cooling water, instrument air) crossing this boundary must be metered and allocated. The boundary definition is critical for fair performance comparisons between different capture technologies and plant configurations, as different boundary choices can change reported energy consumption by 10-30%.
ISO 27928 is the first international standard defining how to measure and report complete CO2 capture plant performance across all major technology types. It was developed through collaboration between ISO TC 265 and experts from 22 countries.
2. Key Performance Indicators
The standard establishes a comprehensive set of performance indicators organized into three categories: capture efficiency metrics, resource consumption metrics, and product quality metrics. These indicators enable plant operators, technology developers, and regulators to evaluate capture plant performance on a consistent basis.
| Performance Metric | Definition | Typical Range | Measurement Method |
|---|---|---|---|
| CO2 capture rate | Ratio of captured CO2 to total CO2 in feed gas | 85-99% | Mass balance on gas streams |
| Specific reboiler duty | Thermal energy per unit CO2 captured | 2.5-4.0 GJ/t CO2 | Steam flow and enthalpy |
| Electrical energy consumption | Power per unit CO2 captured | 0.1-0.4 kWh/kg CO2 | Power meter integration |
| Product CO2 purity | CO2 concentration in product stream | Greater than or equal to 95 mol% | Gas chromatography |
| Cooling water consumption | Cooling utility per unit CO2 captured | 20-100 m3/t CO2 | Flow meter and temperature |
| Solvent consumption | Chemical make-up rate | 0.5-3.0 kg/t CO2 | Tank level and purchase records |
The CO2 capture rate is the most important performance indicator. Most regulatory frameworks require a minimum capture rate of 90%. Designing for 95% capture versus 90% can increase specific energy consumption by 15-25%, making the 90-93% range the common economic optimum.
3. Utility Consumption and Integration
ISO 27928 provides detailed calculation methods for all utility flows including thermal energy (steam), cooling water, electrical energy, and chemical consumables. Steam quality is characterized by pressure, temperature, and condensate return conditions. The standard requires separate metering of major electrical loads: CO2 compressors (typically 50-65% of total power), solvent circulation pumps (15-25%), cooling water pumps (5-10%), and auxiliary systems (5-10%). This breakdown is essential for identifying efficiency improvement opportunities.
For heat integration, the standard specifies how to account for waste heat recovery within the capture plant and from the host facility. If low-grade steam (2-4 bar) from the host plant is used, the equivalent high-grade steam consumption must be calculated using exergy-based correction factors to ensure fair comparison between plants with different integration levels.
When designing a CO2 capture retrofit, pay special attention to steam quality requirements specified in Section 6. A 5-degree reduction in steam temperature can increase specific reboiler duty by 15-20% due to reduced driving force for solvent regeneration. Always verify host plant steam turndown capability.
4. Engineering Design Insights and Commissioning
Key engineering considerations include: integration of steam extraction points from the host plant steam cycle, optimization of lean/rich solvent cross-exchange to minimize reboiler duty, selection of compression train configuration (integrally geared vs. reciprocating), and management of solvent degradation products through filtration and reclaiming. The standard also addresses commissioning protocols, requiring a 72-hour continuous performance test at design conditions before acceptance.
Measurement uncertainty analysis is a critical requirement. All performance claims must be accompanied by uncertainty budgets covering instrument calibration, sampling frequency, and data processing methods. The standard specifies that overall CO2 capture rate uncertainty should be less than +/- 2 percentage points at 95% confidence.
Never accept performance guarantees without reviewing the uncertainty analysis methodology. A reported 90% capture rate with +/- 3% uncertainty is fundamentally different from one with +/- 0.5% uncertainty. Ensure the EPC contractor uses the same measurement approach specified in ISO 27928.
5. Frequently Asked Questions
Q: What capture technologies does ISO 27928 cover?
Chemical absorption (amines, chilled ammonia), physical absorption (Selexol, Rectisol), membrane separation, pressure-swing adsorption, and temperature-swing adsorption.
Chemical absorption (amines, chilled ammonia), physical absorption (Selexol, Rectisol), membrane separation, pressure-swing adsorption, and temperature-swing adsorption.
Q: How is the CO2 capture rate precisely defined?
The ratio of the mass flow of CO2 in the product stream to the mass flow of CO2 in the flue gas entering the capture plant boundary, expressed as a percentage.
The ratio of the mass flow of CO2 in the product stream to the mass flow of CO2 in the flue gas entering the capture plant boundary, expressed as a percentage.
Q: Can ISO 27928 be applied to direct air capture (DAC) facilities?
No. This standard is explicitly scoped for industrial point source CO2 capture. DAC is covered under a separate work item in ISO TC 265.
No. This standard is explicitly scoped for industrial point source CO2 capture. DAC is covered under a separate work item in ISO TC 265.
Q: What is the required continuous test duration for performance validation?
The standard requires a minimum 72-hour continuous operation at design conditions, with data recorded at intervals no longer than 15 minutes.
The standard requires a minimum 72-hour continuous operation at design conditions, with data recorded at intervals no longer than 15 minutes.
