Two weeks ago, Spain achieved the holy grail of Eurocrat techno-climatist dreams: 100% renewable power on the national grid.
Reportedly, on that day: “Wind generated 256 GWh, accounting for 45.8% of total output. Solar supplied 27%.” Hydroelectricy supplied 23.1% of the mix. Solar thermal contributed 2%, and other renewable and renewable waste supplied a combined 2.1%
All is swimmingly good in renewable Europe and zero carbon targets should be just around the corner, right?
However, barely had the congratulatory backslapping stopped when the system shut down with blackouts all over the Iberian Peninsula and southern France, affecting about 55 million people and lasting more than half a day.
Are these two things related? Well, yes, actually.
Monday’s blackouts were preceded by unusual weather conditions which involved extreme temperature gradients causing localised high winds, and this may have precipitated oscilation in high voltage lines which caused a cascade failure across the entire peninsula, and could easily have caused an infection across a wider continental system.
“Maybe the Russian hackers done it” some said, grasping for straws; but according to Spain’s national Grid operator, REE, everybody’s favourite villain was innocent on this occasion.
This was a complex technological problem which has not been explained in detail yet, but REE has said that the immediate cause of the blackout was “very strong oscillation in the electrical network”.
As Loreal used to say, here comes the science bit.
After a period of high sun intensity the grid in Spain was running mainly on solar. Just before the blackout, 60.64% of the electricity supplied to the grid was generated by solar panels.
As can be noted from above, wind contributed 12.02%. Sun and wind renewables, including solar thermal, (or weather dependent unreliables if you prefer) contributed approximately 78% of the grids power just 5 minutes before the Grid failure.
A rare extreme weather anomaly was occurring in Western Spain as extreme temperature gradients caused sudden very strong local winds.
Initial reports, as I have pieced them together, explain that this caused the power lines to go into a low frequency gallop; into what engineers call “an induced atmospheric vibration.” This triggered safety systems to decouple parts of the grid to prevent this oscillation bleeding over into other parts of the grid causing instability and failure.
This in turn caused a sudden boom in power which the grid couldn’t absorb and this led to emergency decoupling as parts of the grid went into protective shutdown. This led to a cascade of the same action throughout the system as the load shocks caused surges, which even went as far as decoupling from the greater continental couplers causing immediate failure of the entire grid.
Although this detailed explanation hasn’t been officially ascribed, the initial official explanation is that extreme temperature gradients were affecting High Voltage transmission lines, causing “very strong oscillation in the electrical network”.
These “oscillations” refer to a crucial control variable in every power grid, that of balancing the grid’s supply and load.
When load exceeds supply it causes a dip in frequency. For visualization purposes, imagine a car on a flat road which suddenly goes uphill, and the driver doesn’t press down on the accelerator. The car slows. That slowing car’s wheels spin slower, that is the frequency of this system. If the driver does not supply more on the accelerator (or shift the load by changing down gears) the car will stall.
That other parameter which has to be closely controlled is frequency. The power grid in Europe runs at 50 Hertz. All power sources feeding to the grid must supply electricity at this frequency. A mismatch in this causes massive instability as differing power sources shift out of phase. This would be massively No Bueno as the Spanish would say.
All things being equal, and the suppliers are designed to deliver 50Hz, the system frequency is in effect a proxy for load/supply balance. There is very little tolerance in the system for variations frequency. If the frequency drops by as much as 0.2 Hz it triggers emergency action. A 0.5 Hz divergence from 50 Hz leads to system–wide cascading failure territory, as Michael Shellenberger explains
Just after 12:30 pm on April 28th the entire European grid was seriously close to total blackout.
How is this happening now and why is it an increasing problem now?
As it happens this was never a serious problem in our old power grid because of a thing called “spinning inertia,” which is an inbuilt automatic safety component of the old style turbine-driven power generation model. Note: this does not apply to wind turbines which are decoupled from the grid for technical reasons.
Electricity, in combustion-driven power plants, is generated by sending high pressure steam through a turbine which in turn generates electricity through back EMF in massive electrical motors. These turbines and motors, weighing many tones, have massive inertia and take a long time to slow down under changing conditions. Whether the change is on the load side or generation side, a sudden shock will have negligible impact on the speed of the turbines. Therefore, in such a grid, the frequency of the output voltage is impervious to large shocks in demand such as power surges etc. This spinning inertia, which is indelibly connected to the physical size of the generation technology, has kept our grids very stable over the past century.
This is all understood by the technologists and electrical engineers who designed and managed our generation and distribution grids.
Hydro electricity also benefits from spinning inertia.
Solar panels and wind turbines do not inherently have this inertia. They generate DC current, which through a system of power electronics controlled invertors generates an AC voltage which is fed to the grid. They match the grid’s frequency by following the voltage in the grid, so the grid needs to have some form of autocorrective frequency generation such as the traditional spinning capacity supplied by fossil fuel power plants. This presents a problem if there is no spinning capacity in the grid to match to.
As simple as this seems, the solar farms cannot reliably generate the tolerable AC signal if there is nothing to match to.
As we noted earlier Spain’s grid, at the time of failure, was very heavily reliant on renewables and so was not protected from load shock by spinning inertia.
As Michael Shellenberger pointed out in his article explaining the Spanish grid problem:
“In a traditional power grid dominated by heavy spinning machines — coal plants, gas turbines, nuclear reactors — small disturbances, even from severe weather, are absorbed and smoothed out by the sheer physical inertia of the system. The heavy rotating mass of the generators acts like a shock absorber, resisting rapid changes in frequency and stabilizing the grid.
“But in an electricity system dominated by solar panels, wind turbines, and inverters, there is almost no physical inertia. Solar panels produce no mechanical rotation. Most modern wind turbines are electronically decoupled from the grid and provide little stabilizing force. Inverter-based systems, which dominate modern renewable energy grids, are precise but delicate. They follow the frequency of the grid rather than resisting sudden changes.”
Getting to the policy failure of the matter, Shellenberger adds: “But none of this should have been a surprise. The underlying physics had been understood for years, and the specific vulnerabilities had been spelled out repeatedly in technical warnings that policymakers ignored.”
These warnings are not new. Quoting Shellenberger again: “In 2017, ENTSO-E, the European Network of Transmission System Operators for Electricity, published a major report warning that rising levels of inverter-based generation would cause frequency deviations to grow larger and faster after disturbances.”
Since that report there have been multiple power grid blackouts under these very conditions. Such as in 2016 in South Australia in 2016, and the UK in 2019, National Grid ESO LFDD 09/08/2019 Incident Report to name just two.
The question is, why do the policy makers repeatedly ignore the warnings about the multitudinous vulnerability of renewables?
Is it that they are addicted to magical thinking? That, driven by a sense of eschatological urgency, they believe that renewable are the magic solution that will deliver the carbon neutral heaven, regardless of costs. Could it be that nthey don’t want to see the problem, and when a blackout occurs it’s just taken as part of the equation and not really a problem?
The engineers keep pointing out the problems. The politicians, driven by ideology and motivated magical thinking, keep ignoring them. So metaphorically speaking, after the blackout we wake up with a hangover and no idea how we got here.