Carbon sensors are critical tools for emissions monitoring and climate reporting. Explore how NDIR, TDLAS, and CRDS technologies work, their strengths, and where they still face limitations.
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As global attention turns toward decarbonization and emissions transparency, the ability to measure carbon dioxide (CO₂) accurately and reliably has never been more important. From climate research to industrial monitoring and methane mitigation programs, carbon sensors have become foundational tools for understanding how carbon moves through our atmosphere and infrastructure.
But like any measurement technology, carbon dioxide sensing comes with both strengths and limitations. While the technology has advanced significantly in recent years, understanding what these sensors can, and cannot, do is critical for interpreting the data they produce.
In this post, we explore where carbon dioxide sensing technology stands today, what types of sensors are commonly used, and how they fit into the evolving landscape of emissions monitoring.
Why Carbon Measurement Matters
Carbon dioxide is the most widely tracked greenhouse gas and plays a central role in climate reporting frameworks, emissions inventories, and atmospheric research. Measuring CO₂ helps operators and researchers:
• Track emissions from industrial processes and energy production
• Validate reported emissions inventories
• Understand combustion efficiency and fuel use
• Improve atmospheric transport models
• Support regulatory and voluntary reporting frameworks
Because CO₂ is produced alongside methane in many industrial processes, measuring both gases together can provide important context when interpreting emissions data.
Common Types of Carbon Dioxide Sensors
Several sensor technologies are used to measure carbon dioxide, each with its own advantages depending on the application.
Non-Dispersive Infrared (NDIR) Sensors
NDIR sensors are among the most widely used CO₂ detection technologies. They work by measuring how infrared light is absorbed by CO₂ molecules within a sample cell. Their popularity comes from a combination of reliability, relatively low cost, and ease of deployment. NDIR sensors are commonly used in building ventilation systems, indoor air monitoring, and portable environmental sensors. However, while NDIR sensors are robust and versatile, they generally offer lower precision than more advanced spectroscopic methods and may require periodic calibration to maintain accuracy. Additionally, NDIR sensor can have reduced selectivity where some other species or instrumental signals can sometimes mimic the signal of CO₂.
Tunable Diode Laser Absorption Spectroscopy (TDLAS)
TDLAS technology uses a narrow-band laser tuned to a specific gas absorption line. This enables extremely precise detection of gas concentrations and is widely used in industrial and research environments. Because TDLAS sensors measure gas absorption directly at specific wavelengths, they offer excellent disambiguation from other gases and fast response times. Additionally, these sensors are characteristically lightweight and require low power, so they are well suited for mobile applications like on drones. The tradeoff is complexity and cost. Laser-based systems are typically more expensive than NDIR and may require careful optical alignment and calibration.
Cavity Ring-Down Spectroscopy (CRDS)
CRDS is one of the most precise techniques available for atmospheric gas measurement. It works by measuring how quickly a laser pulse decays inside a highly reflective optical cavity. Because the light travels thousands of times through the gas sample, CRDS systems can achieve extremely high sensitivity and accuracy. These systems are widely used in atmospheric research and high-end emissions monitoring. However, they also require longer sampling time which makes surveying large areas more time consuming and increases uncertainty due to atmospheric variability. An additional downside is that CRDS instruments are generally larger, more expensive, and highly sensitive to vibration, making them less suitable for lightweight mobile deployments compared to other sensor technologies.
The Strengths of Modern Carbon Dioxide Sensors
Over the past decade, carbon dioxide sensing technology has improved dramatically in several key ways. Sensors have become smaller and more ruggedized, enabling deployment on mobile platforms such as drones, aircraft, and autonomous monitoring systems. Advances in optics and electronics have also improved detection limits and stability, allowing for higher confidence measurements in dynamic environments. Another important development is the integration of environmental sensing. Many modern systems measure temperature, pressure, and wind conditions alongside gas concentrations, allowing measurements to be interpreted in a more physically meaningful way. SeekOps has a long heritage in leading such advancements in ruggedization, precision engineering, and scientific validation. Together, these improvements have expanded the range of applications for carbon sensors, from laboratory instruments to field-ready monitoring tools.
Where Carbon Sensors Still Struggle
Despite these advances, carbon sensing is not without challenges. One limitation is that CO₂ concentrations are naturally high in the atmosphere relative to methane. This means that detecting small incremental changes in CO₂ can be more difficult, particularly in open environments where background concentrations fluctuate. Environmental factors can also affect measurements. Temperature variations, humidity, and pressure changes can introduce measurement drift if not properly accounted for.
Another challenge lies in the fact that many carbon sensing technologies were originally developed for applications such as indoor air quality monitoring, industrial process control, or carbon capture, utilization, and storage (CCUS). These use cases often prioritize stable, high-concentration environments or point measurements, rather than detecting subtle concentration enhancements from combustion sources at a distance. As a result, applying these sensors to open-air emissions monitoring, especially in dynamic environments, can introduce additional limitations.
A further challenge lies in translating concentration measurements into actual emissions rates. Measuring gas concentration alone does not directly reveal how much gas is being emitted. To estimate emission rates, measurements must be combined with wind data and atmospheric transport models or data-driven measurement strategies designed to avoid such models. This is why many modern monitoring systems integrate gas sensors with meteorological instruments and modeling frameworks.
Carbon Dioxide Sensors in Emissions Monitoring
As methane monitoring programs evolve, CO₂ measurement is increasingly being used as a complementary tool. For example, CO₂ measurements can help evaluate combustion processes such as flaring, where carbon dioxide and methane ratios can indicate flare efficiency. They can also help validate bottom-up emissions inventories by providing an independent top-down perspective. Because methane and carbon dioxide often originate from related processes, measuring both gases together can improve source attribution and reduce uncertainty in emissions estimates.
The Road Ahead for Carbon Sensing
The next generation of carbon sensing technology is likely to focus on three areas: increased sensitivity, better environmental integration, and broader deployment. Miniaturization will continue to enable smaller, lighter sensors suitable for drones and autonomous platforms. Improved calibration techniques and sensor fusion will reduce measurement drift and improve reliability in field environments. At the same time, integration with atmospheric modeling tools will make it easier to translate concentration measurements into actionable emissions data. As emissions monitoring frameworks such as OGMP 2.0 and other measurement-based reporting programs mature, the demand for reliable, field-ready carbon sensing technologies will continue to grow.
SeekOps’ Carbon Dioxide Measurement Capabilities
While SeekOps is best known for its methane detection and quantification systems, our sensing platform is expanding to include the ability to measure carbon dioxide alongside methane. This evolution reflects a broader industry shift toward multi-gas measurement as a way to better understand emissions behavior in complex environments.
We are deploying this capability in the field, with our flagship application in combining methane (CH₄) and carbon dioxide (CO₂) measurements. These campaigns provide valuable insight into how simultaneous measurements can improve interpretation of combustion processes, emissions attribution, and overall site performance.
We expect to learn more about the practical benefits and limitations of measuring both gases together in real-world conditions. We’ll be sharing those insights in more detail in a future post focused specifically on simultaneous multi-gas measurement.
As carbon measurement technologies continue to evolve, integrating multiple gas measurements with in situ environmental data will play an increasingly important role in improving transparency and confidence in emissions data.
References
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