New Raman Spectroscopy Method Boosts Natural Gas Leak Detection Sensitivity

This video was created with the help of NotebookLM.

Recently, a team of researchers from Chongqing University (China) developed a new Raman spectroscopy technique that could significantly improve natural gas monitoring and leak detection systems. The study’s findings were published in the journal Analytica Chimica Acta (1).

Why is natural gas important?

Natural gas is an important resource for energy security. Also known as fossil gas, natural gas is highly flammable and colorless, consisting of methane and ethane, andis considered one of the cleanest energy sources we have access to (2). Natural gas is found in the soil; as part of the process to acquire it, oil extraction processes are used to remove it from the soil, and this can take place offshore or on land (2). According to the MET Group, natural gas consumption in various sectors is as follows: 15% residential, 11% commercial, 38% for electric power, 4% for transportation, and 32% for industrial use (2).

Currently, one of the challenges of using natural gas is ensuring its safe transport, storage, and utilization, which depend on the accurate and real-time monitoring of its components (1). Normally, Raman spectroscopy has been used for this purpose, but the technique does have limitations that prevent it from being fully effective in monitoring natural gas components, including low sensitivity because of the inherently weak Raman scattering effect (1). This limitation has long posed challenges for practical applications, particularly for detecting trace concentrations of multiple hydrocarbons in natural gas mixtures.

How did the researchers tackle this issue?

The researchers sought to overcome the abovementioned challenge by designing a high-sensitivity multi-cavity enhanced Raman spectroscopy (MPC-CERS) system featuring an innovative folded Z-shaped multi-pass cavity (1). This design amplifies the interaction length between the laser and the gas sample, leading to a 1000-fold increase in Raman signal intensity. As a result, the system achieved detection limits as low as 0.12 ppm for methane (CH₄), 0.53 ppm for ethane (C₂H₆), 0.55 ppm for propane (C₃H₈), and similarly low thresholds for butanes, pentanes, and hexanes (1).

As part of the experimental procedure, the research team also further developed a quantitative analysis model using the least-squares fitting method, establishing precise relationships between spectral peak heights and gas concentrations. This approach achieved a remarkable goodness-of-fit exceeding 0.9999, underscoring the system’s accuracy and repeatability in both single-component and mixed-gas environments (1).

What were the advantages of this new technique?

Compared to other enhancement techniques, such as surface-enhanced Raman scattering (SERS) and fiber-enhanced Raman scattering (FERS), the MPC-CERS system demonstrated clear advantages. Although SERS offers high sensitivity, its low quantitative accuracy limits its utility, and FERS suffers from weak signal enhancement (1). In contrast, the improved multi-pass cavity approach combines simplicity, robustness, and strong anti-interference performance, making it highly suitable for distributed energy natural gas monitoring (1).

According to the authors, the new method provides low detection limits, high reproducibility, and strong stability, all essential for real-time applications in energy systems (1). This innovation could enhance safety by enabling early leak detection, while also supporting efficient utilization of natural gas resources (1).

References

1. Wang, M.; Wang, J.; Wang, P.; et al. Multi-pass Cavity-enhanced Raman Spectroscopy of Complex Natural Gas Components. Anal. Chimica Acta. 2025, 1336, 343463. DOI: 10.1016/j.aca.2024.343463
2. MET Group, Importance of Natural Gas: Fueling Progress. Met.com. Available at: https://group.met.com/en/media/energy-insight/importance-of-natural-gas/#:~:text=Natural%20gas%20has%20the%20potential,smoother%20and%20easier%20energy%20transition. (accessed 2025-09-30).