Gas Quality

Harmonised gas quality standards for biomethane injected into natural gas grids, accepted all over Europe are pre-condition to open a European wide market. Acutally the European Commission has given a mandate to CEN for CEN/TC 408, the "Project Committee – Biomethane for the use in transport and injection in natural gas pipelines". The target of this mandate is to come up with harmonised European standards for fuel use and for injection of biogas into natural gas grids. Before the mandate for CEN/TC 408 was given another project CEN committee - CEN/TC 234 WG 9 worked on the issue of biogas injection into the natural gas grid.
You can find the comprehensive draft technical report of the former CEN/TC 234 WG 9 on biomethane below.

Within the GreenGasGrids project Table 5, Table Table 7 and Table 8 of that draft report were updated with recent information from the GreenGasGrids project partner countries. Table 5 was supplemented with information from CH, HU, HR, PL, SW and SLO, Table 7 was supplemented with information from HU, HR, PL, SLO and SE and Table 8 with information from AT, HU, HR, ESP, IT, PL, SLO and UK.

Download
Report TC 234  [pdf]

The following information gives an overview on the most important gas quality parameters and gas components and the bandwiths which are allowed for biomethane, which is allowed to be injected into natural gas grids in the countries compared.

The Wobbe number - the range of the first parameter which is pictured in the chart - is an indicator of the interchangeability of fuel gases, and is a crucial in order to assess/analyse  the impact of usage of substitute fuels for natural gas such as propane-air mixtures and others. Although the range of the Wobbe number allowes to feed in gas which is  in the range, the Wobbe number is relatively constant in reality since just minor variations (on a regular basis below 5%) are allowed in order not to be noticeable to the consumer. These facts might be regarded to a certain extend as an obstacle for cross border trade - if accompanied by physical transport. Thus harmonisation of the Wobbe number might be supportiv for cross border trade but at the same time the specifics of the EU-MS have to be taken into account.

The graph below indicates the applicable range for the gross caloric value of gas in the respective country. If in a particular Member State two gas qualities are used/applicable, this fact is indidated in the graph as well. Although the range of the gas quality allowes to feed in gas which is in the range, the feed in quality is relatively constant in reality. One can see that an attempted harmonisation of the biomethan quality does not mean unification but dealing with factual circumstances. In case of cross border trade - along with physical transport - the different requirements in relation to the gross caloric value might hinder such approaches to a certain extend.

The methane (CH4) content in gas is the main determinant of the gross and net caloric value as well as of the Wobbe number (impacts see above). Therefore the chart depictures more or less the admitted lower value of methane in biomethane. The higher the lower level is the more upgrading of biogas is required to be allowed to feed into the gas grids as biomethane. Thus the thereby generated costs are high and these circumstances make it difficult for biomethane to become competitive in comparison to natural gas, LPG, oil products etc.

As depictured in the chart, the CO2 content differs significantly among the countries, thus make harmonisation more difficult when taking cross border trade and transport into consideration.

Taking the intention of further harmonisation of the biomethane quality into consideration, it is obvious that the different levels of oxygen allowed in the countries are not supportive to further harmonisation, hence also not advantegous for physical cross border transport.

Hydrogen sulphide is a colorless, very poisonous, flammable gas. It smells like foul odor of rotten eggs. In addition hydrogen sulphide causes corrosion. Having said this, it is obvious that the allowed amount of hydrogen sulphide in the gas must not exceed a very small amount.  The ranges indicate that the allowed number does not differ that much among the provisions of the Member States - except in Spain - thus should not be regarde as a hurdle for further harmonisation of the biomethan quality.