“Demand enough renewables and you might as well ban coal” cautions science writer Joanne Nova.
Source http://joannenova.com.au/16 June 2017
There’s a lesson Australia needs to learn from South Australia. When intermittent renewables reach a certain percentage of daily average supply they make baseload power unfeasible. The situation develops into an impossible dead end that can only be solved with container-ships of cash.
The intermittent supply of wind and solar is the immoveable problem. It eats into the daily chart of the cheapest stable electricity supply — which is coal fired. Coal can’t be ramped in and out in minutes. It is a creature that runs best non-stop, efficiently, smoothly, at a high capacity factor (meaning it works best when it is producing around 90% of it’s design limit continuously).
Tom Quirk points out that sometime after these intermittent renewables hit 30% of the average daily supply, as they have in South Australia — locally sourced coal power becomes uneconomic. There are times during the daily cycle when renewables are providing almost all the demand. There is little demand left for the massive coal turbines to supply, so they spin on pointlessly, but costs remain, and profits are zero.
In SA, the owner of the last coal fired station was still willing to pour in money, but even large cash injections didn’t change the daily bad news cycle, and the coal station was closed.
If the electricity markets were left to run free, and compete purely on price, coal would provide the baseload (unless we had nukes) and obviously, electricity would be cheaper. But no amount of word mangling can dress up the situation. The insistence on having a large slab of intermittent power forces coal out of the system, and that forces prices up.
Continue reading…. http://joannenova.com.au/16 June 2017