After sitting through two days of power outages in Saskatoon, we decided to take a look at the oft-repeated claim that variable renewables make the grid less reliable. Turns out - as with so many urban legends - that the opposite is actually true.
The standard international metric for measuring grid reliability is the System Average Interruption Duration Index (SAIDI) which is typically measured in minutes. At the distribution (i.e. low voltage) level this is average interruption time per customer. At the transmission (i.e. high voltage) level it is the total outage duration per circuit-year.
In Saskathewan, SaskPower reports SAIDI in its Annual Report. In Europe SAIDI is compiled annually by the Council of European Energy Regulators (CEER) (Benchmarking Report on the Continuity of Electricity Supply - 12-Feb-2015). The most recent European data from CEER is from 2013 and this is compared with SaskPower's 2013 SAIDI as per page 25 & 26 of their 2014 Annual Report. Note that SaskPower did not report actual 2013 transmission SAIDI and as a result we have used SaskPower's target 2014 transmission SAIDI.
The graph takes all European countries, for which the BP Statistical Review includes either wind or solar generation data, and plots total 2013 SAIDI on the Y- axis and total 2013 wind and solar generation, as a percentage of total generation, on the X-axis. SaskPower is also shown for comparison - and its not a pretty comparison.
While the correlation (as shown by R2, the Correlation Coefficient) is weak - the data nonetheless indicates that countries with MORE variable wind and solar have MORE reliable electricity systems.
Another myth busted! Onwards!