Electric Power & Utilities/Natural gas consumption


Dear Stevens,
Can we convert net heat rate or net electrical efficiency to gas consumption in gas engine power plant? I've got limited data, Power plant with net output of 53 MWe, net electrical eff 43.1% and net heat rate 8271 KJ/KWHe consumming 511 m3 LNG a day (engine wartsila 6 x 20V34SG)

Secondly, there will be Wartsila 18V50DF (12 units for 200 MW) with data; fuel gas consumption at 50% load 8153 KJ/KWh and energy consumption at 50% load 8260 KJ/KWh. Can I simply convert fuel has consumption to LNG by multiplying gas consumption by 200 MW? or shiuld it be 100 MW as it is in 50% load.

I thank you for your kind explanation.


Hi Priyo -
For your first question you may need two more pieces of information. One is the heating value of LNG from the table at this site:
The other will have to come from Wartsila: Is the net heat rate  based on the "higher" or "lower" heating value of LNG? (see notes at bottom of the table)

For your second question, is there perhaps a typo in your question? Is the lowest heat rate (the 8153 value) actually at 100% load?
For a 12-engine plant at 50% load, I'd probably assume that 6 engines would stay at 100% load (lowest heat rate) and the remaining 6 would be shut down. But you seem to have have two heat rates for the particular engine used in this 12-engine plant, so you might be able to calculate total fuel use at 24 different load points.
Good luck!

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W.A. (Bill) Stevens


I can explain the technical and economic tradeoffs of making electricity from natural gas, coal, nuclear, wind, solar, and biomass energy sources. I'm familiar with air pollution control technologies, including CO2 capture and sequestration. I have a good understanding of the science on global warming and can explain how energy use inefficiencies and various fuels and technologies contribute to that process. I can tell you why we have to build more new gas, nuclear, wind, and solar power plants, but will still have to keep using coal for a few decades to make elctricity. I can explain energy conversion efficiency and power plant operations. However ... I'm not an electrician, so probably cannot help with questions on motors or wiring. ;-)


Forty years as a registered professional mechanical engineer.

Graduate of Purdue University, School of Mechanical Engineering.

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