We will continue to use the existing combustion turbines during extreme weather and dark calms.
We need new dispatchable thermal, aeroderivative combustion turbines to complement renewable generation on a minute to minute, hour to hour and day to day basis. They will be frequently starting, stopping, accelerating and decelerating as the output from wind and solar varies from instant to instant. We can illustrate this need with an example.
The following chart shows Platte River’s renewable generation and load on Oct. 1, 2023, measured every 5 minutes. The top black line shows a gradual increase in load while the green line shows total renewable generation. It can be seen that renewable generation changes very frequently. This chart shows renewable generation from 225 MW of wind and 52 MW of solar. By 2030, Platte River will add a lot more solar and wind. This means, for 2030, the absolute level of the green chart will be higher, but the weather pattern could be exactly the same. These variations will require new dispatchable, flexible and efficient aeroderivative combustion turbines to ensure customer load is met.
Platte River’s existing combustion turbines were not designed for this type of wildly varying duty cycle while aeroderivative turbines are designed for this purpose. Additionally, during dark calm periods, Platte River’s load could be as high as 600 – 700 MW. The existing 388 MW of combustion turbines along with about 70 MW of hydro will not be sufficient to meet our customer’s future load during the dark calm period. Therefore, we need additional turbines.