Germany’s power grid stability and security of supply has been rising despite a huge expansion of intermittent green electricity production. Average power outages per consumer amounted to 12 minutes and 42 seconds in 2015, according to the Federal Network Agency (Bundesnetzagentur). In 2014, the average outage was 12 minutes and 17 seconds. “The slight increase in supply interruptions was mainly caused by weather events such as storms and heat waves,” the agency’s president Jochen Homann said in a press release. “The energy transition and the rising share of decentral generating capacity continues not to have any negative consequences for the quality of supply.”
When systematic monitoring started in 2006, average outage times were almost ten minutes longer. In the same period, the share of renewable electricity production in Germany rose from 11.2 to 29.0 percent, mostly from fluctuating sources such as wind and solar power stations.
The statistic is based on the international “System Average Interruption Duration Index” (SAIDI), which measures the total duration of electricity blackouts longer than three minutes for the average customer and does not include planned outages and disruptions caused by extreme weather. To include large and exceptional blackouts, for example after a strong storm, would make it more difficult to compare the technical performance of the grid over time.
Germany's security of supply is among the best in Europe, according to the Council of European Energy Regulators (CEER). In the CEER's 2015 comparison, the country’s SAIDI score including exceptional disruptions ranked fourth in the European Union. Only Luxembourg, Denmark and Switzerland fared better on a five-year averages basis. By contrast, the UK has around 80 minutes of disruptions per year, France, Spain and Italy around 100. Latvia and Romania find themselves at the bottom of the table with close to or over 600 minutes of blackouts every year.
Globally, Germany also fares very well. Blackouts in the US averaged 228 minutes per year across all networks (data not weighted according to the size of the regional grids), according to a calculation of Clean Energy Wire based on the preliminary regional data of the US Energy Information Administration (EIA). In Western Australia's three grids, the SAIDI score was 52, 350 and 389 minutes in 2014.
Generally, security of supply strongly correlates with the share of underground electricity cables. In Germany, 80 percent of its 1.8 million kilometres of cables are buried, whereas in the US – with around 40 percent – and Australia and many Southern European countries, this share tends to be lower. This makes the grid more vulnerable to being disrupted, for example by fallen tree branches.
The sources of energy generation so far have little impact on security of supply. But grid operators in Germany have to go to great lengths to balance asymmetric production of green electricity across their networks. The amount of so-called “re-dispatch measures” has risen strongly. Redispatch is when the grid operator forces a power station to lower production in a region with oversupply, and directs another plant in a low-production region to higher output. The cost is passed on to consumers. A fleet of costly backup power plants has also been put in place. Large disruptions or blackouts because of the rising green power share have so far been successfully avoided.
More short interruptions?
After the decision in 2011 to switch of Germany's eight oldest nuclear power plants immediately, some industry representatives started to complain that the SAIDI statistic misses short disruptions and rising oscillations in voltage, caused by the energy transition. The president of the Association of German Chambers of Commerce and Industry said in 2011 that “we hear from companies that the number of blackouts has risen significantly since the first nuclear power plants have been switched off”. The association for industrial energy industries (VIK) said however that the outages weren’t caused by the energy transition and nuclear phase-out but by the decreasing quality of the grid.
But there has so far been little evidence to back the claim that the quality of electricity supply is declining. Not only have SAIDI outages fallen by three minutes since 2010. A study by VDE, the German Association for Electrical, Electronic & Information Technologies, asserted in 2013 that fluctuations in voltage had been going down significantly between 2004 and 2011.
The German Chambers of Commerce and Industry monitors perceptions of security of supply by the industry. In 2016, eight percent of companies stated that their production had been impaired by blackouts, one percentage point down from 2012. This year, 15 percent reported outages of under three minutes – which are not covered by the SAIDI statistic – down from 17 percent in 2012.