Month: August 2017

The efficiency of a station has nothing to do with how many KWS of electricity it can generate a year. The efficiency of a station has everything to do with how much gas/coal….. is required to generate each KW of electricity.

A 1 MW power station of 100% efficiency or of 50% efficiency will both have the capacity to generate 8760 MWHs a year. The difference between the two is that the 50% power station will need twice as much gas to generate the same amount of electricity.

1 MMBTU of gas is equal 293 KWH under conditions of 100% efficiency.

When gas is sold, it is sold as Higher Heating Value by the gas producers (HHV) whilst the power stations calculate it as Lower Heating Value (LHV). The difference between the two is about 10% (ranges between 9%-11% depending on if the calculation is done from HHV down to LHV or other way round).

Thus, from 293 KWH one needs to deduct 10% and we reach 265 KWHs of electricity.

If the efficiency of the power station is 50%, one needs twice as much gas to generate the same amount of KWHs, or in other words each MMBtu of gas can only generate 132.5 KWHs of electricity.

So if one has a 1 MWs power station that could in principle operate 100% of the time, this station would have a capacity of 8760 MWHs a year, or namely, 8,760,000 KWHs. If the station is 50% efficiency it can still generate the same 8,760,000 KWHs. But to calculate how much gas it needs to do this, one has to divide the 8,760,000 by 132.5 = 66,113 MMBtus (namely this is the amount of gas that is needed to operate that power station).

If a steam unit of 9,000 MW has an efficiency of 53% and an HHV/LHV conversion rate of 9%, it would amount to 0.1413 MWH/MMBtu and would need 63,688 MMBtus of gas an hour to operate.