Spain’s Grid Warns Power Supply at Risk after Voltage Swings – Can Texas and California learn from their mistakes?

Spain’s aggressive push towards renewable energy has brought both environmental benefits and significant challenges to its power grid. Red Electrica, the country’s grid operator, recently warned that sharp voltage swings are putting the power supply at risk, echoing the vulnerabilities exposed during the massive blackout in April 2025.

These fluctuations, largely attributed to the intermittent nature of wind and solar power, highlight the consequences of rapid renewable integration without adequate planning for stability. The warning comes amid ongoing voltage issues observed over the past two weeks, particularly during low-demand periods with high solar output. Without urgent measures, such as keeping more thermal plants in reserve, these swings could trigger automatic disconnections and lead to widespread outages similar to the April event.

The Devastating April 2025 Blackout

On April 28, 2025, an unprecedented overvoltage event caused a cascading failure that shut down the entire national grids of Spain and Portugal, affecting around 60 million people for over 10 hours in many areas.

Parts of France were also briefly impacted. This was described as the first known blackout caused solely by overvoltage, leading to automatic disconnections of generation and consumption.

The outage resulted in at least eight confirmed deaths—seven in Spain and one in Portugal—due to circumstances like candle fires and generator exhaust fumes.

Economic losses were estimated between €2 billion and €5 billion.

In the aftermath, misinformation about renewables’ role proliferated, though investigations pointed to voltage regulation failures amid high renewable penetration.

Since the blackout, Spain has increased natural gas usage and curtailed solar output to stabilize the grid, underscoring the need for better management of variable renewables.

Spain’s Current Energy Mix

Spain leads Europe in renewable deployment, with renewables accounting for about 64% of electricity generation in 2024, rising from previous years.

By early 2025, the share reached record levels, with wind and solar each contributing around 20-25%, hydro at 11-15%, and nuclear at 19%.

Fossil fuels, mainly gas, make up the remaining 20-23%, with coal nearly phased out at 1%.

This mix has driven low-carbon electricity to over 80%, but the variability of wind and solar—without sufficient storage or dispatchable backups—has strained grid stability, as seen in the recent voltage swings.

Energy Plans for Spain and the EUSpain’s Integrated National Energy and Climate Plan (PNIEC) sets ambitious targets: 81% renewable power by 2030 (up from 74% previously) and 48% of final energy from renewables.

This includes 62 GW of wind (3 GW offshore) and 76 GW of solar PV, plus 12 GW of green hydrogen.

The plan aims for 50% energy autonomy, reducing fossil fuel dependence.

At the EU level, the Renewable Energy Directive mandates at least 42.5% renewables in the energy mix by 2030 (aiming for 45%), with climate neutrality by 2050.

These goals emphasize decarbonization but require robust grid upgrades to handle intermittency. While these targets promote sustainability, Spain’s recent issues suggest that rapid deployment without parallel investments in storage, transmission, and reserves could lead to more instability.

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Comparisons to California and Texas

To contextualize Spain’s challenges, let’s examine similar transitions in California and Texas.

California: Progress with Precautions

California’s energy mix is 77% low-carbon, with renewables at about 50-60% in recent years, including high solar and wind shares.

Despite past rolling blackouts in 2020 due to heatwaves and supply shortfalls, the state has strengthened its grid. In 2024, California claimed to have run on 100% renewables for parts of 98 days without blackouts or cost increases, thanks to battery storage and diversified resources. But at what cost? California’s electric rates have grown 3.2 times faster than those of any other state.

1. Renewable Integration Gaps: Daily curtailment reports show persistent solar oversupply, with insufficient storage to capture excess energy. By 2045, California needs 148,000 MW of new clean capacity, but progress lags.
2. Funding Cuts: Slashed reliability budgets limit emergency response capabilities, leaving communities like Kern River Valley vulnerable.
3. Inequitable Infrastructure: Rural and low-income areas, including Kern County, face more outages due to underfunded distribution networks. A 2021 study highlighted these disparities, which persist in 2025.
4. Wildfire Mitigation Overreach: While PSPS events aim to prevent fires, their overuse disrupts lives and erodes trust. SCE’s criteria for shutoffs—based on wind and weather—often seem overly cautious, as seen in Kern River Valley.

A Contrarian Perspective: Is Progress an Illusion?

Robert Bryce has written extensively about the cost. We recommend subscribing on https://robertbryce.substack.com/

Leaders report improved reliability for 2025, integrating more storage to mitigate intermittency.

Unlike Spain, California’s proactive measures, such as temporarily extending the lifespan of gas plants, have prevented major failures recently. If they don’t add more natural gas, they will face rolling blackouts. Simple math.

Texas: Lessons from Extreme Weather

Texas’s grid, managed by ERCOT, relies on gas (about 40-50%), with renewables growing to 25-30% (mostly wind).

The 2021 winter storm caused a massive blackout, leaving over 4.5 million people without power for days, with hundreds of deaths and billions in damages.

Failures affected all sources—gas infrastructure froze, and wind turbines iced over—but the isolated grid prevented imports from other states.

The Permian Basin in Texas is a major natural gas producer, and as pipelines are added, it can sell the gas rather than flare it. We are also seeing a trend in the basin that it is becoming more gassy. That is not as bad as you think, as demand for natural gas is rising. I would look to drop a data center in the Midland area, as gas is really low, and sometimes even negative due to the lack of takeaway pipelines.

Texas needs to take a hard look at its system and not add any more wind or solar, as it is on the edge of oversupply, and too often, natural gas plants are forced offline to give priority to wind or solar. Plants are even considering moving the turbines to other locations due to the intermittent payment schedule.  Then, wind or solar is paid not to produce. A wacky system.

Post-2021 reforms included winterization, but vulnerabilities persist, as seen in later cold snaps.

Texas’s experience shows that over-reliance on any single source, combined with weather extremes and grid isolation, amplifies risks—paralleling Spain’s renewable-heavy approach without sufficient backups.

Comparative Overview

Conclusion: Balancing Ambition with Reliability

Spain’s grid woes serve as a cautionary tale for the EU’s green transition. While ambitious targets are crucial for combating climate change, installing vast amounts of wind and solar without comprehensive plans for grid stability, storage, and backup power can endanger supplies and lives. California demonstrates that, with strategic subsidies that raise consumer costs and substantial investments, renewables can coexist. But at what cost? Whereas Texas highlights the perils of unpreparedness. Texas ERCOT and the Republicans own the decisions they have made, and currently have half the energy costs to consumers that Californians face. But they are at a critical juncture, and they have resources that Californians don’t. An active oil and gas support system. Gavin Newsom’s California has been turned into a National Security Disaster that is currently unfolding.

Texas, don’t be like Spain or California.

As Europe pushes forward, policymakers must prioritize resilient infrastructure to avoid repeating these mistakes.

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