The photo is sourced from electrek.co
Overall, there are four types of power generation facilities operating in the USA: the above-mentioned combined cycle gas turbine units belong to the first type using steam gas engines and gas-turbine engines; the second type includes gas turbine units, where the turbine is rotated by the gaseous products of fuel combustion; the third type includes steam turbines, where steam generated during heating water by gas burning is used as a working fluid (the term from the thermodynamics); finally, the internal combustion engines used mainly for industrial purposes belong to the fourth type.
The steam-gas units are most common of all the four types, and one of the efficiency criteria for them is the calorific energy volume required for generating 1 KW-h of electricity. The units of B, D and E classes introduced in the USA in 1990s needed on average 8,000 BTE of calorific energy for generating 1 KW-h of electricity. Then came the first generation of F class units (2000s) using on average 7,300 BTE of calorific energy for generating 1 KW-h of electricity, and the second-generation F class units (2010s) using 7,000 BTE per 1 KW-h. Finally, the same metric for steam-gas units of classes H and J (introduced starting from 2010s), makes 6,700 BTE per 1 KW-h.
The steam-gas units of these classes differ from the standpoint of average electric capacity. Thus, the units of B, D and E classes have the capacity from 80 MW to 110 MW, while as for the first-generation F class units this metric varies from 160 MW to 190 MW, and for the second generation of such units – from 200 MW to 225 MW. Finally, the capacity of H and J class units is in the range of 265 MW – 340 MW.
According to EIA, in 2022, the average utilisation rate of the steam-gas units commissioned during the period from 2010 to 2022 made 64%, while as for the units commissioned in 2000-2009 and 1990-1999 it was 55% and 35% respectively. The units accounting for more than half of the steam-gas units capacity mix were commissioned during the period from 2000 to 2006, as a response to frequent blackouts in the end of 1990s. This explains why the average utilisation rate of the steam-gas units in 2022 was close to the technical capabilities of the first-generation F units commissioned exactly in 2000s.
Then again, the above-mentioned availability of feedstock also significantly affects the utilisation rate of the steam-gas units. For example, the average price of gas at Henry Hub – the key gas hub of the USA decreased from USD 228 per kcm in 2022 down to USD 89 per kcm at the end of 9 months of 2023, while as the average utilisation rate of the steam-gas units during the same period grew from 57% up to 60%.
