There have been a lot of big energy stories over the past several months: the continuing price decline in oil, new rules for fracking on federal lands and the latest U.N. climate change summit. But the biggest and most underreported story of 2015, so far, was the near collapse of major energy networks across the globe as a result of last week’s solar eclipse. While no power system actually failed, several of them came very close. Not surprisingly, those national power grids that edged closest to a shutdown were the ones that had invested the most in solar power generation. More significant, the experience suggests that the only way to provide assured power to the seven billion citizens of the world is by carefully balancing the use of traditional and new sources of energy.
Europe, in particular, may have dodged a bullet. Germany, the leader in installed solar power, saw the flow of solar energy into its electric power grid drop by more than 70 percent, from 21.7 gigawatts to a measly 6.2 at the start of the eclipse. According to reports by Reuters, German energy distributors were able to keep the lights on and buildings heated by falling back on a mixture of coal, gas, nuclear, hydroelectric energy and biogas. Even then, industry had to cut back on its demands for power. Europe overall saw a drop in available electric power of nearly half, or 17 gigawatts.
The large scale fluctuations in the supply of energy as solar power dropped off the grid and then as massive amounts of energy from alternative sources were rapidly pumped back into the system risked major disruptions. Italy chose to deal with this potential threat by shutting down 30 percent of its solar power generation capability at the start of the eclipse. German power companies took a different approach, carefully managing their output-controllable power plants, including gas-turbine and pumped-hydro power plants to balance the grid’s load. In pursuing this strategy they were helped by the fact that it wasn’t a windy day, meaning that the country’s massive wind farms were generating only 15 percent of their maximum capacity. On a blustery day, the wind-generated power forced through the system could have caused a massive and unrecoverable surge.
In a sense, the eclipse was a stress test for those systems heavily invested in solar power. They appear to have passed, sort of. Power companies in Europe and elsewhere were able to handle the extreme fluctuation in solar energy production because they had lots of warning of the impending eclipse and took precautionary measures. Fossil fuel power plants were brought to immediate standby status. Power grid managers across Europe developed coordinated strategies which included informing some of their foreign customers that they could be cut off if the power drop became particularly severe. Industry was asked to cut back on demand.
While Europe dodged a bullet, this experience also cast into high relief the complex nature of modern electric power grids, growing ever more so as new sources of energy are added, and the dangers of being too dependent on any one source of power. Stated another way, it also underscored the need to retain a significant reserve power production capability that is not dependent on variable energy sources such as solar and wind. Utility companies and regulators around the world are struggling to define the amount of standby generation capability that a utility must retain even as they invest more in renewables, as well as who pays for this infrastructure.
Last week’s solar eclipse raised another question for the energy sector and those who regulate it. What kind of stress tests should be required? It is unlikely that anyone would have proposed a test as stressing as what actually happened. This means that the European grid could have been judged to be adequately safeguarded against power fluctuations only to have it fail in the face of an unexpected event. Also, typically stress tests are built around single events. But as discussed above, the combination of a predictable stress event, the solar eclipse, and one more difficult to predict, high winds across Europe, could have collapsed the grid.
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