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Transcripción del abstract original del autor: A new low cost energy meter was developed at Gasunie Research. The new energy meter is based on the measurement of suitable properties (e.g. physical or chemical properties or component concentrations) and an accurate correlation between these properties and the gas composition. Tests undertaken so far, indicate that the uncertainty (±0.3%) and reproducibility (±0.02%) of this new correlative energy meter are fully comparable with highly accurate field GC’s used in custody transfer applications, nowadays. Furthermore, the calibration frequency appears to be significantly lower compared to the current systems. The new correlative energy meter, based on velocity of sound measurements at 40 and 5 bar and a CO2 measurement, seems a promising instrument to determine the energy value of gas streams at production sites and custody transfer stations. It is also an ideal instrument to determine the energy value (Wobbe-Index) of natural gas streams for process control applications (e.g. at blending stations). Main advantages of the new instrument are: (i) it does not require an analyser housing, (ii) it can be positioned near the pipe, so there is a short sample line, (iii) a fast response time (5 seconds), (iiii) also density and CO2 are determined, therefore no instruments for these measurements are required anymore. The costs of ownership for the new system are considerably lower compared to current energy meters such as gas chromatographs and Wobbe meters.