What are system effects?
Electricity generating power plants do not exist in isolation. They interact within a larger system, or grid, to ensure that our lights stay on in a continuous stream of power. Electricity is a unique commodity because it is extremely difficult to store. We cannot stockpile power for use on another day (unless we use it to pump water uphill and then release it when we need it). Battery storage can manage a few hours worth, but batteries large enough to store meaningful amounts of power at the society level are still a long way off.
Fossil fuel electricity generation is known as dispatchable: this means it can be switched on and off at the flick of a switch. This makes it easier for grid operators to balance supply with demand, instantaneously, at the flick of a switch, through a variety of generating sources.
One of the challenges we face in countries around the world as we begin to transition from fossil fuel electricity generation is to understand how clean technologies interact with each other and impact the whole system. This executive summary is a great introduction to the topic, and explores how wind, nuclear and solar interact with each other in a clean electricity system.