Decarbonisation Technology May 2026 Issue

The company offers a number of CO 2 removal (CDR) packages that enable individuals and organisations to make philanthropic donations and/or offset their carbon emissions. In addition, organisations participating in Carbon Trading can purchase CDR Credits directly from Octavia. The success of DAC depends on its ability to maximise process efficiency and to reliably and accurately quantify CO 2 capture. In common with all carbon capture processes, DAC requires continuous CO 2 measurement. Octavia’s team is utilising the performance characteristics of CO 2 sensors developed by the Finnish measurement technology company, Vaisala. CO 2 measurement challenge Conscious of the requirement to develop a DAC process that is as efficient as possible, Octavia’s optimisation team needed to be able to take accurate inline measurements at every stage of the process. In addition, verification of the company’s carbon capture process is only possible with accurate, reliable CO 2 measurements. Octavia evaluated several products from CO 2 sensor manufacturers before adopting Vaisala’s. It rigorously tested materials to assess their CO₂ capture efficiency. This demanded precise CO₂ monitoring across a broad concentration range, spanning from below 400 ppm during CO₂ capture, and from 0-100 vol% during CO₂ release phases. High levels of accuracy were required across all measurement ranges. Octavia found that some sensors were able to measure accurately at certain concentrations, but not all, and that reliability became an issue with these sensors. Following a number of trials, it was concluded that Vaisala’s sensors were the only ones capable of delivering the required accuracy across the measurement ranges. In addition to measurement accuracy, Octavia also required measurement stability. Its DAC is essentially a batch process, which means that sensor measurements vary from very low to very high over a short period of time, typically around one hour. Its team discovered that some of the initial (now discarded) generic sensors lost accuracy over a single cycle, which had two important consequences. Firstly, they had to conduct frequent, laborious, and time-consuming recalibrations. Secondly,

most importantly, they could not rely on the measurements to identify the point at which the sorbent was fully saturated. Vaisala’s solution for carbon capture Octavia’s process optimisation team evaluated Vaisala’s GMP343 CO 2 probe and found it to be ideal for their application. In addition to a wide range, they required high accuracy below 400 ppm, which was not possible with most of the sensors they tried. They were pleased to discover that the GMP343 could achieve this with ±3 ppm accuracy and long-term stability, eliminating the need for recalibration before every test. The GMP343 employs Vaisala’s Carbocap technology, a silicon-based non-dispersive infrared (NDIR) single-beam, dual-wavelength sensor with no moving parts. Carbocap sensors offer high levels of stability over time (see Figure 1 ) thanks to an exceptionally long lifetime infrared light source based on silicon micromechanics and a micromechanical optical filter (Fabry-Pérot Interferometer). This provides a reference measurement that compensates for any potential changes in light source intensity, as well as for contamination and dirt accumulation in the optical path. For Octavia, this stability represented an excellent ±2% of the reading per year. In addition to the GMP343, the company also employs the Vaisala MGP241, developed specifically for carbon capture processes, delivering reliable measurements in wet Figure 1 Vaisala GMP343 measures ppm level CO 2 at the inlet and outlet of the DAC plant with high accuracy and precision