A new method for gas quality tracking in distribution grids

The article presents a new method for tracking the superior calorific value (SCV) of gas in regional and local distribution grids. The method uses standard load profiles in combination with a new correction algorithm to determine the volumes taken at exit points. Including further input information it is possible to determine an SCV for each grid node which can be traced to verified SCVs measured at entry points. The method will allow accurate and selective invoicing of customers in supply areas with several natural gas and/or biomethane entry points. Cost-intensive conditioning of biomethane to be injected into the grid will then no longer be necessary, thus improving the economics of biogas plants. Moreover, the article presents the results of a field test made for validation of the method. Under the field test the SCV of gas was measured on a regional group-H gas distribution grid of E.ON Avacon over a period of nine months at several points along the grid using a mobile process gas chromatograph (PGC). Two different gas qualities (group-H gas and biomethane) are injected into the grid. Referred to monthly average values the deviations of measured SCVs from calculated SVCs are within ± 0.1 %. The method was approved for use billing on 9 August 2012.