I think that recently built gas-fired plants are going to be around for a long time. But like marginal coal plants today, they may shut down for entire seasons and only go to standby-active during high demand seasons. It's possible to reduce emissions a lot without entirely retiring combustion plants if the plants don't burn any fuel for 8 or 9 months out of the year.

That kind of duty cycle changes the economics of those plants drastically. The capital efficiency becomes much lower - basically turbines are very mature, efficient, but high capital. Then to only operate them 25-30% of the time seasonally, they lose even more economic efficiency. But, if that seasonal load becomes the operating demand, then certain kinds of other technologies like flow batteries become more attractive to the degree they can decouple the power regeneration equipment costs from the capacity of storage. i.e. if you only need to size the power generation equipment to the fairly small instantaneous demand, but have to some degree a separate capacity storage cost for the next added unit of run time.

I agree that lower duty cycles increase the per-MWh generation costs; I just think that there's going to be room for recently built plants to operate even with those higher costs.

The sunk costs of already-built plants don't affect whether they will operate going forward. It's even possible that plants would be mothballed for some years and then revived when the economics support at least part-time operation, as I expect to happen with the currently idled Irsching units in Germany.

New combined cycle gas plants are not terribly capital-intensive. Overnight capital cost is about $1/watt:

https://atb.nrel.gov/electricity/2017/index.html?t=cg

Since they can also be built quickly, overnight capital costs are relatively representative of true capital costs for gas plants.

I wish that the LCOE chart in the link above had included a scenario for "Gas combined cycle - low capacity factor" in the LCOE chart, because I think that's going to be how a fair number of plants end up operating: high CF in the peak demand season, but low annualized CF.

For new builds, I think we're beginning to see accelerating encroachment of renewable + storage on the low capacity factor natural gas plants. For short timeframes it looks like the existing cost reduction curves for PV, wind, and Lithium storage seem likely to grow to completely knock out the competition for hours to days level of intermittent supply.

https://www.greentechmedia.com/articles/read/record-low-sola...

For longer time periods, and comparisons vs existing plants, I agree that the economic changeover point will be less clear except that turbine tech is basically on the matured portion of a manufacturing S-curve, while PV, wind, storage are riding the downslope.

Seriously. I plotted these data in Dec. 2017 of the entire Pacific Northwest's wind resources drop to zero for ten full days. Not overly uncommon.

https://partofthething.com/thoughts/wp-content/uploads/decem...

Maybe biomass could help. Already now we put apples etc into cold storage to get them out duringtimes where there are no apples growing on the trees. Same could be done for biomass. Put into the fridge and gotten out when we need it. Of course, cooling down the biomass does require energy, not sure whether it requires little enough.