Biogas usually contains volatile organic compounds such as terpenes, siloxanes, halogenated hydrocarbons, ketones, alcohols, furans and esters whose presence in the biogas is highly dependent on the feedstock. These trace components can affect the integrity of the materials they come into contact with, e.g., equipment, pipelines and engines, and their presence in the gas may pose health, safety and environmental risks. Understanding the composition of gases is a prerequisite to ensure the correct function of gas infrastructure, appliances and vehicles. This study examined how volatile organic compound (VOC) content in biogas varies depending on the feedstock and evaluated the efficiency of different upgrading processes in removing VOCs. The data, primarily collected in Sweden, include biogases produced in digesters and landfills. The selection of VOCs included in this study was based on extensive analysis of samples collected from numerous biogas and biomethane industrial facilities over an extended period, providing a comprehensive overview of VOC composition. The conducted research is intended to serve as a basis for more systematic studies on the influence of process parameters and feedstock composition on the formation of VOCs. The data have multiple potential uses, including predicting which VOCs would be found in biomethane for a given feedstock and upgrading techniques. Additionally, these data can also be used in standardization discussions to assess the plausibility of the proposed limit values and the need to regulate additional compounds. 

This study presents a validation protocol for the atomic emission spectroscopy (AES) method for determining total silicon in biomethane, developed in alignment with ISO 2613-1:2023. The work serves as a practical demonstration, contributing to the forthcoming ISO validation guide for analytical methods assessing impurities in biomethane, prepared within ISO/TC 193 WG 25: Biomethane. The protocol describes the complete analytical process: absorption of volatile siloxane compounds in mineral acid, chemical derivatization into a suitable form for spectroscopy, and measurement of the resulting liquid sample using an optical plasma emission instrument. Method development included optimisation of sampling, derivatization, sample preparation, and quality control procedures. Validation was carried out through rigorous evaluation of linearity, stability, robustness, selectivity, sensitivity, precision, bias, and measurement uncertainty. Results confirmed the method’s reliability for detecting very low mass fractions of silicon (μg/kg range) originating from siloxane species, such as L2, L3, D4, and D5, in biomethane. By demonstrating both methodological robustness and practical applicability, this study provides a model example for ISO’s upcoming guidance on validation of analytical methods, supporting the harmonisation of impurity testing in renewable gases

Biomethane is expected to be important in meeting Europe’s greenhouse gas reduction target. The composition of biomethane varies, therefore, depending on the feedstock and process parameters. The European standards EN 16723 specify requirements for injecting biomethane into natural gas networks and its use as vehicle fuel. Ensuring that biomethane composition complies with the requirements set in the standards requires rigorous quality control processes and validated analytical methods. Method validation for parties lacking practical experience or training can be a complex process involving numerous steps and requires adequate guidelines, which were lacking for biomethane. The BiometCAP project has, therefore, developed a standardized protocol for evaluating gas analyzers in biomethane applications with detailed procedures for assessing instrument performance and ensuring accurate and reliable measurements. This article describes how to use the validation protocol with practical applications for evaluating the limit of detection and limit of quantification, the working range and linearity, the precision, the bias and finally to calculate the measurement uncertainties using the analytical method described in ISO 2620:2024 as an example. This method based on TD-CG/MS-FID can therefore be considered fit-for-purpose, providing reliable, precise and sensitive measurements for the analysis of VOCs as demonstrated for 3-carene, dichloromethane and hexamethyldisiloxane. Finally, the article also summarizes the measurement uncertainties obtained during an extensive evaluation exercise organized between seven NMIs across Europe. For any future validation work, measurement uncertainties of 1 to 10% relative for any regulated compounds can be used as reference.

The capture, use and storage of biogenic CO2 from the biogas sector contributes to environmental benefits by reducing the overall greenhouse gas emissions. In several plants, CO2 separated in the biogas upgrading process is captured and processed. Depending on the composition, some level of purification is needed before the biogenic CO2 can be used, for example, in the food industry. In this article, we first present novel or adapted analytical methods which are both cost-effective and reliable to assess the purity of CO2 streams. These methods concern not only species that are currently regulated in different standards but also allows for an extensive overview of the overall gas composition. The methods are then applied to samples of CO2 stream collected from different biogas plants located in Sweden. Results from this campaign are presented together with some conclusions regarding the need to further purify the stream so the CO2 even fulfill the most stringent requirements such as those set by the food industry. The need for purification concerns only a few species: water, methane, oxygen, nitrogen (for all samples), and hydrogen sulfide (in two cases). VOCs found specifically when the plants digest food wastes may also require a purification step, however, only some of these compounds are currently regulated.

The quality of the hydrogen delivered by refuelling stations is critical for end-users and society. The purity of the hydrogen dispensed at hydrogen refuelling points should comply with the technical specifications included in the ISO 14687:2019 and EN 17124:2022 standards. Once laboratories have set up methods, they need to verify their performances, for example through participation in interlaboratory comparisons. Due to the challenge associated with the production of stable reference materials and transport of these which are produced in hydrogen at high pressure (>10 bar), interlaboratory comparisons have been organized in different steps, with increasing extent. This study describes an inter-laboratory comparison exercise for hydrogen fuel involving a large number of participants (13 laboratories), completed in less than a year and included eight key contaminants of hydrogen fuel at level close to the ISO14687 threshold. These compounds were selected based on their high probability of occurrence or because they have been found in hydrogen fuel samples. For the results of the intercomparison, it appeared that fully complying with ISO 21087:2019 is still challenging for many participants and highlighted the importance of organising these types of exercises. Many laboratories performed corrective actions based on their results, which in turn significantly improved their performances. © 2024 The Author(s)

To meet the new regulation for the deployment of alternative fuels infrastructure which sets targets for electric recharging and hydrogen refuelling infrastructure by 2025 or 2030, a large infrastructure comprising truck-suitable hydrogen refuelling stations will soon be required. However, further standardisation is required to support the uptake of hydrogen for heavy-duty transport for Europe’s green energy future. Hydrogen-powered vehicles require pure hydrogen as some contaminants can reduce the performance of the fuel cell even at very low levels. Even if previous projects have paved the way for the development of the European quality infrastructure for hydrogen conformity assessment, sampling systems and methods have yet to be developed for heavy-duty hydrogen refuelling stations (HD-HRS). This study reviews different aspects of the sampling of hydrogen at heavy-duty hydrogen refuelling stations for purity assessment, with a focus on the current and future specifications and operations at HD-HRS. This study describes the state-of-the art of sampling systems currently under development for use at HD-HRS and highlights a number of aspects which must be taken into consideration to ensure safe and accurate sampling: risk assessment for the whole sampling exercise, selection of cylinders, methods to prepare cylinders before the sampling, filling pressure, and venting of the sampling systems. 

Biomethane may contain trace components that can have adverse effects on gas vehicles performances and on the pipelines when injected in the gas grid. Biomethane quality assurance against specifications is therefore crucial for the integrity of the end-users’ appliances. Analytical methods used to assess biomethane conformity assessment must be validated properly and possibly, new methods specifically for biomethane should be developed. This paper provides an overview of the biomethane quality assurance infrastructure and the challenges faced with focus on sampling, analysis methods, reference gas mixtures, and performance evaluation. Currently, requirements for analytical method validation and fit-for-purpose assessments do not exist for biomethane. The industry is in urgent need of a protocol to evaluate the fit-for-purpose of methods in a harmonized manner. Reference gas mixtures to check the accuracy of the instrument and to determine the traceability of the measurement are also urgently required. 

It is foreseen that hydrogen heavy-duty (HD) vehicles will be used to a large extent to support the transition to zero emission transport in Europe by 2050. Ensuring the quality of hydrogen is crucial to guarantee a smooth transition. To demonstrate the quality of hydrogen, sampling systems adapted to HD conditions are being developed and tested as part of the EU-funded project MetHyTrucks (Metrology to support standardisation of hydrogen fuel sampling for heavy duty hydrogen transport). Poor sampling can lead to damage to fleets of HD vehicles, making standardization crucial for the shared HD Hydrogen Refuelling Station (HRS) network. Reliable, specific sampling systems for HD-HRS, designed for both gaseous and particulate phases, are currently being developed in the European Partnership on Metrology project MetHyTrucks. The dynamic nature of a HD-HRS, with changes in pressure, flow and temperature during refuelling, can affect the reliability of sampling. Moreover, the hydrogen fuel sampling at the HD-HRS is an operation performed in a potentially explosive atmosphere area involving safety risks. This paper discusses the parameters that can affect sampling when assessing hydrogen purity at a HD-HRS. 

The European Partnership on Metrology project BiometCAP (Protocol for SI-traceable validation of methods for biomethane conformity assessment) has developed a comprehensive performance assessment protocol tailored to benchmark and characterise analytical systems such as gas analysers. The outcomes, including practical tests, will contribute to the development of standards. This article highlights some of the findings obtained so far in the BiometCAP project, showing the applicability of this protocol to assess the performance of analysis techniques used for quantifying terpenes, siloxanes and halogenated volatile organic compounds in biomethane. 

The global impact of anthropogenic greenhouse gas emissions on climate change is undeniable, with carbon dioxide (CO2) identified as the primary contributor to global warming. Urgent action is required to mitigate global warming by reducing anthropogenic CO2 emissions to achieve net-zero levels. Carbon capture and storage (CCS) stands as a proven technology to curtail CO2 emissions from various sources by capturing and sequestering CO2 in geological formations. To address the challenge of deploying CCS on a global scale, it is crucial to accurately quantify the captured, transported, and stored CO2 since quantification underpins regulations and commercial contracts. However, the lack of standardization in CCS projects and measurement methodologies poses a significant challenge, necessitating a common measurement framework to ensure the transparency and reliability of these efforts. This article provides a comprehensive review, with 211 references, of the latest results and operating conditions for current measurement technologies covering the entire measuring system and not just a single instrument. As such, it is a first-of-its-kind effort at establishing a comprehensive framework for CCS measurement. This article serves as a source of references and as a step toward developing an international documentary standard for the transferred CO2 measurement. By addressing measurement challenges and providing comprehensive recommendations for future research, it contributes to the ongoing efforts to mitigate global warming through the widespread deployment of CCS technology.