Analysis Of How VRAS Thermal Plants Waste The Scarce Natural Gas Resource

The Gas Supply and Offtake Report of September 1, 2024 refers.

This gas supply and offtake report highlights gas flow rates and power generation loads for various power plants in Ghana. When examining the efficiency of gas use (in terms of power generated per unit of gas), it's clear that some plants are more effective at converting the gas resource into electricity than others.

Key Observations on Gas Resource Use:

1. VRA Takoradi (Simple Cycle)
Gas Flow Rate: 114 MMSCFD
Load (Power Generated): 508 MW
Units: 5

Efficiency: 4.46 MW per MMSCFD of gas

2. Karpowership (Takoradi)
 
Gas Flow Rate: 43 MMSCFD
Load (Power Generated): 241 MW
Units: 1

Efficiency: 5.60 MW per MMSCFD of gas

3. VRA Tema (Simple Cycle)

Gas Flow Rate: 26 MMSCFD
Load (Power Generated): 102 MW
Units: 1

Efficiency: 3.92 MW per MMSCFD of gas

4. SAPP (Tema)

Gas Flow Rate: 55 MMSCFD
Load (Power Generated): 302 MW
Units: 1

Efficiency: 5.49 MW per MMSCFD of gas

5. Cenit (Tema)

Gas Flow Rate: 8 MMSCFD
Load (Power Generated): 50 MW
Units: 1

Efficiency: 6.25 MW per MMSCFD of gas

6. ATPS (Kumasi)

Gas Flow Rate: 33 MMSCFD
Load (Power Generated): 143 MW
Units: 6

Efficiency: 4.33 MW per MMSCFD of gas


Comparative Efficiency of IPPs vs. VRA Simple Cycle Plants:

VRA Plants (Simple Cycle):
 
VRA Takoradi and VRA Tema have efficiency ratios of 4.46 MW/MMSCFD and 3.92 MW/MMSCFD, respectively. This shows that these simple cycle plants are less effective, generating fewer megawatts of electricity per unit of gas consumed.

IPP Plants (Independent Power Producers):
 
Plants like Karpowership, SAPP, Cenit, and Cenpower are much more effective. For instance, Cenit is producing 6.25 MW per MMSCFD, Cenpower is at 5.94 MW/MMSCFD, and Karpowership generates 5.60 MW/MMSCFD.

Expert Judgement 

The VRA simple cycle plants (Takoradi and Tema) are not maximizing the potential of the natural gas resource, as they generate lower power output per unit of gas compared to the more effective IPPs.

IPP plants like CenPower SAPP, and Karpowership demonstrate better gas optimization by producing more electricity per unit of gas consumed. This suggests that moving towards more combined-cycle or advanced gas turbine technologies used by IPPs could significantly improve the overall energy efficiency of the gas consumed in Ghana's power generation.

This efficiency gap demonstrates why a shift from simple cycle to combined cycle plants, especially for VRA operations, could be essential for better gas resource management.


Dr. Elikplim Kwabla Apetorgbor(Power Systems Economist)