Variable Renewables and Grid Reliability. Europe, US and Sask.
There is a view that more variable renewables (i.e. wind and solar) means a less reliable electricity network. In fact the opposite is true...
Europe is the world's leader in the use of variable renewables and it is therefore instructive to look to their experience. The Council of European Energy Regulators (CEER) annually publishes a report ('Continuity of Electricity Supply') which compares electricity system reliability across EU member countries. The standard metric for assessing reliability is the System Average Interruption Duration Index (SAIDI) which is, as the name implies, representative of the average interruption on low voltage (i.e. customer-connected rather than transmission) electricity networks.
A comparison of the SAIDI data by country (page 10 of the aforementioned CEER report) with the percentage of that country's electricity which is generated by wind and solar power, is revealing;
As the trendline indicates; the relationship between the two variables is negative however the Correlation Coefficient (R2) is so low that the relationship not statistically significant. Nonetheless the implication is that countries with MORE wind and solar power tend to have MORE reliable grids. Certainly there is no evidence here that would support the assertion that variable renewables reduces grid reliability.
Saskatchewan compared with US/Canada and Denmark
So much for Europe - but where does Saskatchewan fit in the picture? Saskatchewan's 2013 SAIDI is published in SaskPower's 2013 Annual Report (page 25) and was 354 minutes which is comparable with that of the Czech Republic (351 minutes).
It is interesting to compare this with Denmark which had a much higher proportion of wind & solar in their power mix (34 percent vs. 2.8 percent for Saskatchewan) yet which had an average outage duration of only 15 minutes. This was more than 23 times less than Saskatchewan's 354 minutes. This information is represented graphically below;
There are good reasons why Saskatchewan has poor grid reliability (very low population density and chronic under-investment for many years). SaskPower is currently trying to remedy this with significant and much needed, new investment in transmission and distribution assets.
However the point is that detractors should not seek to claim, as they often do, that wind and solar power reduces grid reliability. That is just plain wrong!
In fact a GE study released in August 2014 found that "when equipped with the appropriate modern plant controls, wind applications can substantially enhance grid resiliency".