Key Takeaways
A massive power outage affected Spain, Portugal, and parts of France on April 28, leaving tens of millions without electricity.
Because a steep drop in generation was accompanied by frequency instability, safeguards shut down other generators to protect electrical equipment on the grid.
Spain and Portugal are both highly reliant upon generation from wind and solar power, and many are pointing towards their deficiencies as the possible reason for the outage, although governments are denying any linkage.
Spain recently experienced a day when alternative energy provided 100% of its electricity.
Wind and solar power, in addition to their intermittency and hidden costs, are unable to provide inertia to the grid, which thermal plants, which have been forced to retire, provide.
Investigators will likely take several months to perform a root-cause analysis and determine the sequence of failures that contributed to the blackout.
At about midday on Monday, April 28, large power outages left millions of homes and businesses in Spain and Portugal without power. The countries were in chaos, with traffic snarled, flights grounded, and subway stations across the country without power. Mobile phone and internet networks went down. Hospitals stopped procedures and used generators to administer to patients. Around 12:15 p.m., demand for electricity in Spain dropped from 27,500 megawatts to nearly 15,000 megawatts in about 5 seconds. Portugal’s outage hit its capital, Lisbon, and surrounding areas, as well as northern and southern parts of the country. Even homes in the French Basque Country were without power for a few minutes.
The cause of the massive outage remains unclear, as authorities in neither Spain nor Portugal are able to conclusively determine the problem. However, Portuguese authorities declared that the failure appeared to have occurred across the border in Spain. According to Portuguese distributor E-Redes, the outage was caused by “a problem with the European electricity system.” Red Electrica, Spain’s state grid operator, blamed the outage on a “very strong oscillation” on the electric grid.
Despite that explanation, others feel that there is a good chance that Spain’s reliance on solar energy contributed to the power failure. Less than two years ago, a utility announced it would close Spain’s largest coal plant, the 1,468-megawatt As Pontes facility. To many Europeans, particularly climate activists, the closure of the coal plant was demonstrating “how much renewables are outperforming fossil fuels on price, energy security, and desirability.”
On April 16, Spain’s electric grid ran on 100% alternative energy. At the time of the outage, more than 75% of the electricity came from renewable sources, according to Red Electrica data. On April 21, Spain’s solar production met as much as 79% of demand, reaching a record level of 20,120 megawatts. A few minutes before the blackout, about 60% of the electricity on Spain’s grid was coming from solar power. Some believe that Spain’s electric grid, which produces the second-most solar energy in Europe after Germany, was weakened by its reliance on solar power.
REE, the Spanish grid operator, identified two incidents of power generation loss, probably from solar plants, in Spain’s southwest that caused instability in the electric system and led to a breakdown of its interconnection with France. Spain’s Prime Minister Pedro Sanchez, however, ruled out an excess of renewable energy as a cause of the network’s collapse. According to Sanchez, since Spain’s nuclear power stations had not resumed operating on Tuesday, the day after the outage, they were no more resilient than renewables. But this analysis does not account for the whole picture. As energy expert John Kemp explains, “Spain’s nuclear stations have all been shut down automatically by passive safety systems which respond to any sign of a loss of power from the grid by dropping control rods into reactor cores to stop the reaction.” The fact that nuclear power can operate 90% of the time, providing baseload power, and that France’s grid, which generates most of its electricity from nuclear power, remained operational, did not deter Sanchez from defending renewable energy.
Many Spanish regions declared a state of emergency and deployed 30,000 police. According to Investment bank RBC, the economic cost of the blackout could range between 2.25 billion and 4.5 billion euros. The bank blamed the Spanish government for being too complacent about infrastructure in a system dependent on solar power with little battery storage available to back up the intermittent solar and wind plants. Spain had recovered more than 92% of its power by 5 a.m. on Tuesday, according to Red Eléctrica. The prime minister also pledged that the entire country would have power restored by the end of the day. On Tuesday, Madrid authorities provided free buses to get people to work and the metro and some trains resumed operating, but with delays.
Reliability, Resilience, and Black Start
Electricity transmission system operators must balance generation and load continuously to maintain frequency, requiring adjustments to generation and availability of reserve capacity. In a traditional grid of coal, gas, and nuclear power plants and hydroelectric generators, the grid can self-stabilize because those generators have enormous amounts of inertia and store huge amounts of kinetic energy. If the load exceeds generation, these generators can supply some of the stored energy back to the grid. Thus, they contribute to reliability and resilience by helping the grid recover quickly after a disturbance due to unexpected changes in generation or load. In contrast, solar and wind generators do not provide inertia and frequency control services, unless fitted with special equipment, which is rare and expensive.
With government policies supporting wind and solar power by obscuring their true costs to the grid, more coal, natural gas, and nuclear plants have retired, resulting in reduced system inertia and increased issues with reliability and resilience, particularly on the European grid. In a renewable-dominated system, the stability support traditionally granted by these traditional generators will no longer be available. To deal with this issue, solar and wind generators would need to be required to contribute to frequency control and other grid-forming services by adding more very expensive electricity storage batteries, as well as synchronous condensers and compensators. That will drive up European electricity costs much more than they have already, making more Europeans energy poor.
Grid operators had to perform a complicated “black start” operation to restore electricity supplies to the Iberian Peninsula. Usually, a black start begins with small diesel generators starting up without drawing power from the grid. This process helps gradually re-energize the grid as more generators and transmission lines are brought back into service; then loads can be gradually reconnected as sufficient generation becomes available. Solar power has not traditionally contributed to black start operations.
Conclusion
A massive electricity outage hit Spain and Portugal on Monday, April 28. Investigators will probably take several months to perform a root-cause analysis and determine the sequence of failures that contributed to the blackout. Spain was one of the first European countries to jump on the renewable energy bandwagon, building solar and wind facilities in abundance, but not investing enough in expensive backup power to cover downtime from these intermittent sources. The country is now one of Europe’s largest producers of renewable energy, and many believe that the volatility of supply from solar or wind sources has made its power systems more vulnerable. This blackout is likely to be the first caused by intermittent renewable energy, but there are probably more to come.
