Less than two years ago, climate activists in Spain celebrated after a utility announced it would close the country’s largest coal plant, the 1,468-megawatt As Pontes facility. According to an activist at Beyond Fossil Fuels, the closure of the coal plant was demonstrating “how much renewables are outperforming fossil fuels on price, energy security, and desirability.”
Earlier this month, renewables looked good. On April 16, Spain’s electric grid ran on 100% alternative energy. And on April 21, as David Blackmon noted on his Substack earlier today, solar production in the country set a new record of 20,120 megawatts, which, for a few hours, met nearly 79% of demand.
That was last week.
Today, Spain, Portugal, and other parts of Europe were hit by a massive blackout that Red Electrica, Spain’s state grid operator, is blaming on a "very strong oscillation" on the electric grid. The outage has resulted in “transport chaos” as traffic lights went dark and subway and train service was halted. Mobile phone networks went down. Spain has declared a state of emergency and some regions are now begining to restore power. While it’s too early to blame any particular cause, there is reason to believe that Spain’s electric grid, which now produces the second-most solar energy in Europe (after Germany), has been weakened by its heavy reliance on solar. A few minutes before the blackout, some 60% of the electricity on Spain’s grid was coming from solar.
Understanding how solar and wind energy weakens the grid requires understanding the physics of electricity, grid inertia, and what a University of Queensland professor has dubbed the “pressure cooker” effect of renewables.
The easiest way to comprehend grid inertia is to think of electricity like water. Unlike the water system, which can tolerate significant changes in pressure and flow rates, the electric grid operates under very tight tolerances that require voltage and frequency to stay within narrow ranges regardless of load or power production changes.
Since the days of Edison, the grid has relied on large generators with a lot of mass. The weight of the spinning parts inside the generators has a lot of inertia that keeps the flow of electricity — think of it as pressure — on the grid at steady levels. The mass of those large generators acts as shock absorbers that allow the grid to absorb sudden changes in load or generation. Using a garden hose as A Question of Power:
The amount of electric power (which is measured in watts, but in this case, think liters) that can be pushed through that hose is the product of the amperes (flow rate) multiplied by the voltage (water pressure). The more pressure (volts) applied to the water in the garden hose, the greater the flow rate (amperes) that can be pushed through it. The higher the pressure and flow rate, the more liters of water (watts) that can be delivered to your house.
I continued:
Just as the local water utility uses its pumps to deliver tons of water at high pressure and volume to its customers, the electric utility uses spinning generators — think of them as electron pumps — to push huge volumes of electrons (water molecules), at high pressure, into the local grid. The key difference between the water grid and the electric grid is that the water grid is far simpler. For instance, if the pressure in the water grid drops, it only means that customers must spend a little more time filling up their coffee pots or swimming pools. On the electric grid, voltage (again, think water pressure) must be kept stable regardless of how many customers are using electricity...The grid must be continually tuned so that electricity production and electricity usage match. Matching generation and consumption helps assure that voltage on the grid stays at near-constant levels. If voltage fluctuates too much, blackouts can occur.
The challenge that wind and solar bring to the grid is that they do not provide the same type of spinning mass (read: inertia) that the electric grid has relied upon for decades.
To understand what happened in Spain, I called a friend of mine. He is an electrical engineer who has worked all over the world selling hardware that detects problems on the electric grid and helps improve grid reliability. He has worked in the field for decades. Given the early stage of the investigation, he was reluctant to be too definitive. Still, he said it is “highly likely” that Spain’s heavy reliance on solar and wind contributed to the blackout. “What we are seeing across all power systems is that they are more brittle. They don’t have enough inertia. They have far less spinning reserve and margin for error. Earlier in my career, it was common to have a 15% minimum spinning reserve.” (Emphasis added.)
By spinning reserve, he referred to the backup power plants operating in case they are needed. Today, he said, electric grids are “running on thin margins with very little spinning reserve.”
The best explanation of grid inertia and its importance was published in 2016 by University of Queensland professor Simon Bartlett. In a paper written for the Energy Policy Institute of Australia, “The ‘Pressure Cooker’ Effect of Intermittent Renewable Generation on Power Systems,” Bartlett declared that the “practical upper limit for renewables is around 40% of total electricity generated.” He continued, “The scale-up of intermittent renewables not only diminishes the robustness of a particular power system but can also magnify the short and long-term risk of investing in non-renewable generation assets and the power grid itself.”
Here's the critical section, in which he explains that in a conventional electricity system:
Rotating kinetic energy in heavy turbines and generators is immediately available and is automatically converted into electricity the instant the power system starts to slow down following an unexpected generator breakdown anywhere in the power system. Electrical and magnetic energy from electrical generators is instantaneously released following a fault on the network, playing a critical role, along with rotating inertia, in power system stability and high speed power system protection. Both wind-power and solar PV are technically incapable of storing, controlling, and releasing energy in any of these ways, and simply convert the available wind or sunshine into electricity depending on the prevailing weather conditions.” (Emphasis added.)
Bartlett went on to say that batteries could, in theory, meet some of the demands of the electric grid, but they “have limited utility compared to conventional methods.”
Again, it’s too early to say why Spain and Portugal got hit by a blackout. However, the outage provides a few key reminders. First and foremost, it shows how disruptive widespread blackouts can be. Second, it demonstrates how fragile our electric grid is. Third, it’s another reminder that we assume the reliability and integrity of the electric grid at our extreme peril. The electric grid is the Mother Network. It is the life-support system upon which our entire civilization depends.
It may be too early to blame alt-energy for the blackout, but it’s clear that Spain’s heavy reliance on solar energy is one of the prime suspects.
This piece first appeared at Robert Bryce Substack.
Robert Bryce is a Texas-based author, journalist, film producer, and podcaster. His articles have appeared in a myriad of publications including the Wall Street Journal, New York Times, Forbes, Time, Austin Chronicle, and Sydney Morning Herald.
Photo: courtesy Robert Bryce Substack.
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