A classic method of measuring energy delivered is to use an orifice meter run and a circular chart recorder to obtain an integrated value for the flow. This flow measurement is combined with an average calorific value to obtain energy delivered. This method can be biased when changes in the calorific value correlate with changes in the flow. This classic method is next compared with two newer methods of measuring energy delivered. The first method uses a flow computer which has as inputs the pressure, temperature, and pressure differential from an orifice meter. This method also uses continuous measurements of relative density and calorific value. The output from the flow computer is the instantaneous energy flow. The second method uses a new energy flowmeter that is under development. It directly measures energy flow without measuring either calorific value or volumetric flow.