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Three myths about renewable energy and the grid, debunked via Beyond Nuclear International

By Amory B. Lovins and M.V. Ramana

This story was originally published in Yale Environment 360.


Myth No. 1: A grid that increasingly relies on renewable energy is an unreliable grid.

Going by the cliché, “In God we trust; all others bring data,” it’s worth looking at the statistics on grid reliability in countries with high levels of renewables. The indicator most often used to describe grid reliability is the average power outage duration experienced by each customer in a year, a metric known by the tongue-tying name of “System Average Interruption Duration Index” (SAIDI). Based on this metric, Germany — where renewables supply nearly half of the country’s electricity — boasts a grid that is one of the most reliable in Europe and the world. In 2020, SAIDI was just 0.25 hours in Germany. Only Liechtenstein (0.08 hours), and Finland and Switzerland (0.2 hours), did better in Europe, where 2020 electricity generation was 38 percent renewable (ahead of the world’s 29 percent). Countries like France (0.35 hours) and Sweden (0.61 hours) — both far more reliant on nuclear power — did worse, for various reasons.

The United States, where renewable energy and nuclear power each provide roughly 20 percent of electricity, had five times Germany’s outage rate — 1.28 hours in 2020. Since 2006, Germany’s renewable share of electricity generation has nearly quadrupled, while its power outage rate was nearly halved. Similarly, the Texas grid became more stable as its wind capacity sextupled from 2007 to 2020. Today, Texas generates more wind power — about a fifth of its total electricity — than any other state in the U.S.

Myth No. 2: Countries like Germany must continue to rely on fossil fuels to stabilize the grid and back up variable wind and solar power.

Again, the official data say otherwise. Between 2010 — the year before the Fukushima nuclear accident in Japan — and 2020, Germany’s generation from fossil fuels declined by 130.9 terawatt-hours and nuclear generation by 76.3 terawatt hours. These were more than offset by increased generation from renewables (149.5 terawatt hours) and energy savings that decreased consumption by 38 terawatt hours in 2019, before the pandemic cut economic activity, too. By 2020, Germany’s greenhouse gas emissions had declined by 42.3 percent below its 1990 levels, beating the target of 40 percent set in 2007. Emissions of carbon dioxide from just the power sector declined from 315 million tons in 2010 to 185 million tons in 2020.

So as the percentage of electricity generated by renewables in Germany steadily grew, its grid reliability improved, and its coal burning and greenhouse gas emissions substantially decreased.

In Japan, following the multiple reactor meltdowns at Fukushima, more than 40 nuclear reactors closed permanently or indefinitely without materially raising fossil-fueled generation or greenhouse gas emissions; electricity savings and renewable energy offset virtually the whole loss, despite policies that suppressed renewables. 

Myth No. 3: Because solar and wind energy can be generated only when the sun is shining or the wind is blowing, they cannot be the basis of a grid that has to provide electricity 24/7, year-round.

While variable output is a challenge, it is neither new nor especially hard to manage. No kind of power plant runs 24/7, 365 days a year, and operating a grid always involves managing variability of demand at all times. Even with no solar and wind power (which tend to work dependably at different times and seasons, making shortfalls less likely), all electricity supply varies.

Seasonal variations in water availability and, increasingly, drought reduce electricity output from hydroelectric dams. Nuclear plants must be shut down for refueling or maintenance, and big fossil and nuclear plants are typically out of action roughly 7 percent to 12 percent of the time, some much more. A coal plant’s fuel supply might be interrupted by the derailment of a train or failure of a bridge. A nuclear plant or fleet might unexpectedly have to be shut down for safety reasons, as was Japan’s biggest plant from 2007 to 2009. Every French nuclear plant was, on average, shut down for 96.2 days in 2019 due to “planned” or “forced unavailability.” That rose to 115.5 days in 2020, when French nuclear plants generated less than 65 percent of the electricity they theoretically could have produced. Comparing expected with actual performance, one might even say that nuclear power was France’s most intermittent 2020 source of electricity.


The bottom line is simple. Electrical grids can deal with much larger fractions of renewable energy at zero or modest cost, and this has been known for quite a while. Some European countries with little or no hydropower already get about half to three-fourths of their electricity from renewables with grid reliability better than in the U.S. It is time to get past the myths.

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