In the field of alternative energy, hydrogen and alternative fuels such as sustainable aviation fuel (SAF) have received significant research attention and market growth due to their ability to meet the energy demands of key industrial sectors such as transportation, aviation, and heavy industry.
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Research into these alternative, green fuels requires powerful, robust, and efficient analytical techniques. This article will examine Raman spectroscopy and the advantages of real-time monitoring, including how this technique enhances product quality and facilitates innovative energy solutions.
What is Raman Spectroscopy?
Raman spectroscopy is a non-destructive analytical technique used in multiple industries. Detailed material information such as molecular interactions, molecular structure, crystallinity, and phase can be explained using this method.
A high-intensity laser light is used to provide information on a sample. When irradiated by the laser in a Raman spectrometer, it is scattered. Most of this scattered light is at the same wavelength as the source (Rayleigh scattering), but a small percentage is scattered at a different wavelength (Raman scattering), which provides information on the sample’s chemical and molecular composition.1
The wavelength position and intensity of the Raman scattered light are recorded in a number of peaks within the Raman spectrum, which correspond to specific vibrations. A Raman spectrum can determine single bonds in a sample and groups of bonds, such as polymer chains, providing important information on the material.
Hydrogen and Sustainable Aviation Fuels
Sustainable aviation fuel is a more ecologically friendly alternative to conventional aviation fuel. The difference between the two lies in their source: conventional aviation fuel is derived from fossil fuels, whereas sustainable aviation fuel is made from sustainable feedstocks such as biomass and waste cooking oil. Its chemistry is very similar to standard jet fuel but produces less carbon emissions.2
Hydrogen is a clean-burning fuel with virtually no emissions. It produces only heat, energy, and water vapor, making it a much more sustainable alternative to carbon dioxide-emitting petrochemical fuels such as gas or diesel. Hydrogen fuel cells are also very efficient, although there are still some key challenges with their use and commercialization.
Both of these alternative, sustainable fuels have the potential to revolutionize the transportation and aviation sectors, helping to bring about the green transition of industry and the economy.
Advantages of Raman Spectroscopy for Hydrogen
Raman spectroscopy is an effective non-destructive tool for the analysis and quality control of alternative fuels.
It is anticipated that hydrogen will be a major contributor to the future green transition, providing sustainable solutions for power generation and energy storage. Increasingly sophisticated and efficient fuel cells can power vehicles, computers, and medical equipment.
Raman spectroscopy can detect and monitor the conversion of hydrogen spin isomers in real time, ensuring more efficient energy storage and optimizing liquefaction processes. In recent years, its sensitivity has significantly improved, making it a sophisticated tool for the analysis of gaseous compounds.
The hydrogen industry has a pressing need for trace gas sensors to monitor inadvertent hydrogen loss. Hydrogen is difficult to detect at low concentrations (less than a few ppm), and conventional optical methods such as ICOS and QC-TILDAS cannot adequately detect these losses. More suitable instruments, such as gas chromatographs, are bulky and expensive, though they are trace-sensitive.3
Micro-electromechanical systems and metal oxide semiconductor devices are low-cost, rapid, and possess the benefits of miniaturization. However, they require regular recalibration and have poor chemical specificity.
Raman spectroscopy is economical, robust, and possesses suitable sensitivity for these purposes. The unique Raman spectra produced during analysis can detect extremely low concentrations of gas particles. Furthermore, potentially dozens of analytes can be detected simultaneously. Recent enhancement techniques have further improved the power of this analytical method.
Suitability of Raman Spectroscopy for Sustainable Aviation Fuel Analysis
Raman spectroscopy has also provided several benefits to the sustainable aviation fuel sector.
Feedstock quality is crucial for manufacturing high-quality green fuels, such as sustainable aviation fuel. Raman spectroscopy can detect even trace amounts of contaminants and impurities that may impact fuel manufacture, quality, performance, and regulatory compliance. This is vital for monitoring and quality control.
Aside from feedstocks, Raman spectroscopy can also detect contaminants in the fuels. Precise, in-line material identification improves production efficiency and ensures product safety and quality. Raman spectroscopy can be used for process optimization.
Another useful application of Raman spectroscopy in sustainable aviation fuel manufacture is carbon footprint analysis. This method can quantify carbon content in combination with other techniques and detect unwanted by-products and pollutants.
Raman spectroscopy boosts R&D efforts as part of a laboratory or production facility’s analytical toolkit. It can be used to investigate the composition of new feedstocks and evaluate new production processes amongst a plethora of potential applications.4
In Summary
Hydrogen and sustainable aviation fuels will likely become key pillars of the transportation and aviation sectors' sustainable, green fuel and energy storage transition. However, several technical challenges still exist, impacting their widespread adoption.
Raman spectroscopy is an analytical tool well-suited to the analysis and quality control of these alternative fuels. It provides real-time, robust, non-destructive analysis that can benefit laboratories and companies working in this emerging industrial sector. While some technical challenges will persist over the next few years, innovation aids this important technological transition.
References and Further Reading
- Horiba Scientific (2024) What is Raman Spectroscopy? [online] Available at: https://www.horiba.com/int/scientific/technologies/raman-imaging-and-spectroscopy/raman-spectroscopy/ (Accessed on 09 November 2024)
- BP (2022) What is sustainable aviation fuel (SAF)? [online] Available at: https://www.bp.com/en/global/air-bp/news-and-views/views/what-is-sustainable-aviation-fuel-saf-and-why-is-it-important.html (Accessed on 09 November 2024)
- Singh, J & Muller, A (2023) High-Precision Trace Hydrogen Sensing by Multipass Raman Scattering Sensors (Basel) 29:23(11):5171 [online] National Library of Medicine. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC10255963/ (Accessed on 09 November 2024)
- McHugh, M (2023) How Raman Spectroscopy Helps Create More Viable and Economical Sustainable Aviation Fuel [online] MarqMetrix. Available at: https://marqmetrix.com/raman-analysis-sustainable-aviation-fuel (Accessed on 09 November 2024)
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