Under the mandate M/475, issued by the European Commission to CEN, the European Organization of Standardization, specifications for biomethane have been developed for injection into the natural gas grid and for use as vehicle fuel (prEN 16723). In response to this specification, a European consortium has developed novel and metrologically traceable standards and methods in support of the conformity assessment of biomethane for a series of regulated properties. These properties include the contents of silicon and siloxanes, hydrogen chloride, ammonia, halogenated volatile organic compounds (VOCs), carbon monoxide, sulphur-containing compounds, particulates, as well as calorific value, moisture content and density. The project has provided traceable measurement standards and related calibration methods for the contents of carbon monoxide, particulate content, moisture content, ammonia content, calorific value, density of biomethane and biogas. In many cases, these novel measurement standards come with similar uncertainties as their counterparts developed for use in air quality measurements. The methods and standards developed for calorific value, moisture content and density have calibration and measurement capabilities close to those developed in the past for natural gas. Key challenges in the developed measurement standards are the methane matrix, which makes that most of the existing metrological infrastructure for air quality is unable to deliver unbiased calibration results for biomethane and biogas. The presence of high levels of carbon dioxide, especially in biogas, required extending and validating existing models for the calculation of, e.g., moisture content, calorific value, and density. The experimental issues associated with the levels of methane and carbon dioxide in the development of analytical reference methods are briefly described, as well as how these were successfully addressed.
Adriaan van der Veen is working as senior scientist at VSL. He is responsible for the maintenance and development of the national measurement standards for chemistry. VSL is the national metrology institute of the Netherlands.
In the past years, he has been coordinating the European R&D project “Metrology for Bias”, aimed at developing measurement standards and related methods for the contents of key impurities, particulates, water and thermophysical properties of biomethane and biogas.
Adriaan van der Veen is an active member of ISO/TC158 Analysis of gases (chairman), ISO/TC193 Natural gas, and JCGM WG1 “Guide to the expression of Uncertainty in Measurement”.