Biogas is a renewable energy source with many different production pathways and numerous excellent opportunities for use; for example, as vehicle fuel after upgrading (biomethane). Reliable analytical methodologies for assessing the quality of the gas are critical for ensuring that the gas can be used technically and safely. An essential part of any procedure aimed at determining the quality is the sampling and transfer to the laboratory. Sampling bags and sorbent tubes are widely used for collecting biogas. In this study, we have combined these two methods, i.e., sampling in a gas bag before subsequent sampling onto tubes in order to demonstrate that this alternative can help eliminate the disadvantages associated with the two methods whilst combining their advantages; with expected longer storage stability as well as easier sampling and transport. The results of the study show that two parameters need to be taken into account when transferring gas from a bag on to an adsorbent; the water content of the gas and the flow rate used during transfer of the gas on to the adsorbent.

If we want to keep the number of necessary characterisation measurements within acceptable limits, we need to be confident that a flow instrument design reacts in a predictable and straightforward way to systematic influences. In this paper, the important systematic influences for an ultrasonic flow meter (UFM) for feed water flow are identified to decide which characterisations have to be carried out in addition to a typical baseline calibration with water at 20 °C. In heat metering applications where there are temperatures up to 120 °C it is for example known that the temperature influence on the flow instrument is important and this also applies to higher temperatures such as in the feed water control of power plants. One of the critical systematic temperature influences that affects most flow instruments is the thermal expansion of the meter body. From June 2009 to March 2010, the “Heat and Vacuum” department of the Physikalisch-Technische Bundesanstalt conducted a measurement campaign to characterise the influence of thermal expansion of a meter body on the calibration of an 8 inch (DN 200) five chord UFM for feed water application in the temperature range from 4 °C to 85 °C and flow range from 50 m3 h−1 to 900 m3 h−1. An overview of the procedures and facility used for the calibration is given and the measurement conditions under which the calibrations were performed are detailed. It is shown that a linear model of the thermal expansion effect is appropriate for the investigated conditions

Standards ISO14687 and EN17124 set stringent limits for numerous gaseous impurities and particulates that may damage the fuel cell system in a hydrogen vehicle, as it is highly sensitive to the presence of even very low levels of impurities. However, performing the whole set of analyses is both technically challenging and time-consuming for any laboratory and will require a combination of several analytical techniques or instruments. In this study, we discussed the selection of analytical techniques for hydrogen purity testing in order to optimize the CAPEX (capital expenditure) and OPEX (operational expenditure), while ensuring the quality of the results and the compliance of the analytical methods with ISO21087. Among the individual impurities to be analysed in ISO14687, spectroscopy techniques are suitable for ammonia, carbon dioxide, carbon monoxide, formaldehyde, formic acid, oxygen and water. Spectroscopy techniques are even suitable for some impurities belonging to the three total species such as hydrogen sulphide, hydrogen chloride and methane. However, helium and argon, which are monoatomic, do not exhibit response in the infrared region. Therefore, any spectroscopic analysis method must be completed by another method in order to simultaneously analyse all individual gaseous impurities from ISO14687. In this study, we constructed and demonstrated the feasibility of an instrument composed of a gas chromatograph having three columns (two packed columns and a PLOT (Porous Layer Open Tubular) column and two detectors (FID and TCD) coupled in parallel to two OFCEAS instruments using reference gas mixtures. Finally, we also proposed an extended configuration that will allow performing the whole set of analyses for gaseous species from ISO14687.