| Market forces


Jeremy Wilcox is managing director of the Energy Partnership, an independent Thailand-based energy and environment consulting firm 8/27 Sukhumvit Soi 8, Klongtoey, Bangkok 10110, Thailand | T: +66 2 653 1263 | Mobile: +66 860993375 | S: energypartnership


A not so modern power system


The blackout across the Iberian Peninsula on 28 April presented a timely reminder that most of Europe’s power transmission system is ageing, with approximately 40% of its distribution grids over 40 years old. It is an inconvenient truth that the grid was developed for conventional generation using conventional technology, not for modern renewable generation, and that accelerating investment in renewable capacity has not been matched by investment in the grid.


As aged grids have been progressively loaded with intermittent renewable capacity without accompanying investment in the grid enhancing technologies to keep the power systems secure and reliable, it was perhaps only a matter of time before a blackout on this scale happened. The technology challenges of integrating wind and solar capacity onto the grid are well known, but seemingly not considered a sufficient risk to grid reliability and security. Simply put, wind and solar plant lack the inertia that is essential to maintain grid stability. Power grid inertia refers to the resistance of a power system to changes in frequency and is primarily provided by the rotating masses of large generators in conventional power plants. This inertia helps stabilise the grid by balancing supply and demand fluctuations and allows for a temporary buffer when a large power plant fails. Solar and wind power generation systems, and especially those connected to the grid through inverters, do not have the same inherent inertia as traditional generators. Solar panels and wind turbines are typically designed to convert their output to the grid frequency using power electronics, which decouples them from the mechanical inertia of rotating masses. As more renewables are integrated into the grid, the overall inertia of the system decreases, potentially leading to faster and more significant frequency fluctuations. Without sufficient inertia, the grid may become more susceptible to cascading failures and blackouts during disturbances.


While there is as yet no defined cause of the Iberian blackout, an obvious scapegoat


The blackout does not challenge the


transition to net zero; it challenges the pace of the transition


is renewable energy. Grid data shows that solar supply fell 55% immediately before the blackout, suggesting that a sharp fall in inertia destabilised the grid. But the solar supply fell sharply when there was no change in sunshine, which suggests the cause is more complex than simply a lack of solar, and potentially, also raises questions about grid management. At the time of the blackout only three of Spain’s seven nuclear units were operational, which is usual during periods of high renewable production as the taxation on nuclear makes it uneconomic to run nuclear at the low power prices when supply is predominantly from renewables. If the full suite of nuclear plants had been operating, they would have helped to balance the grid. Unsurprisingly there have been calls for nuclear taxation to be reviewed. While operating a power system mostly on wind and solar may be theoretically possible this has yet to be demonstrated on any large grid. And to reliably operate a predominantly, or fully, renewable supplied system would require several grid-enhancing solutions that are only just beginning to enter operational service at scale.


In particular, the system would require grid-forming inverters that let solar, wind, and batteries regulate grid frequency and voltage, which strengthens the grid compared to currently common grid-following inverters that cannot adjust to grid fluctuations. A large fleet of charged battery systems to automatically release power in response to loss of generation from one or more power plants, maintaining grid frequency and the balance of supply and demand until reserve generators can come online would also be beneficial, as would ancillary supporting equipment


… accelerating investment in renewable capacity has not been matched by investment in the grid


such as synchronous condensers and static synchronous compensators that can similarly provide the necessary frequency support to correct for grid fluctuations.


Europe’s investment in grid security is woeful. Take battery storage. Europe has 10.8 GW of battery storage that will increase to 50 GW by 2030, but significantly less than the 200 GW that the European Association for Storage of Energy says is required.


The European Commission has estimated that Europe needs to invest over two trillion euros in grids by 2050. In 2024 Europe invested €80 billion in grids, up from €50-70 billion in previous years, while analysts at Bruegel claim annual investments will have to increase to €100 billion. Even a 20% annual increase in grid investment may be insufficient to provide the necessary security, and any investment will have to be recovered in customer bills. Following the blackout, Spanish utility Endesa called for returns on investment in the grid to be increased to 7.5% from the current 5.6%, and for the cap on how much companies can invest to be raised. The need to balance renewable capacity investment with grid enhancement technologies will likely see similar conversations elsewhere in Europe, and globally.


The blackout does not challenge the transition to net zero; it challenges the pace of the transition. Much of the necessary grid enhancing technologies are at the early stage of development but wait maybe five to ten years and the technology will be more advanced and fully commercialised at scale. In terms of cost, delaying net zero by a decade (or longer) will be less expensive with grid investment spread over a longer period.


But whichever net zero approach is followed there will likely be a higher cost to ensure stability and mitigate against future blackouts caused by grid instability. Net zero may not prove to be as affordable as its advocates claim, and modern power systems are not as modern as they like to believe.


www.modernpowersystems.com | June 2025 | 9


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