The above diagram, which comes from The Electricity Operator in Ireland (SEMO), shows the increases in the different types of reserve or back up required by 2020 to keep the system stable with high penetrations of wind.
Some of these reserve increases will come from fast acting plant like open gas cycle turbines (OCGT) and interconnectors (both existing and new entrants according to the paper). OCGT are less efficient and higher emitting than their modern versions (CCGT). Likewise, SIR referred to above, refers to Synchronous Inertial Response which relates to the level of stability a generator can provide when operating at low outputs during periods of high wind. CCGT operating at these low loads are also less efficient and higher emitting.
Nobody, it seems, has bothered to do a study to see if this will offset any gains from higher wind penetrations.
So who or what is driving these changes to our electricity system ?
These changes are being driven in large part by European legal obligations outside the control of the SEM Committee.