A global dataset of 5,360 large infrastructure projects reveals that virtually no energy sector escapes budgetary slippage—but nuclear infrastructure stands out as the most financially volatile.
New nuclear power plants exceeded budgets in 97% of cases, while nuclear storage projects overshot costs 92% of the time, with a staggering 5.27× cost multiplier among the worst offenders.
This pattern of chronic overrun is not just a budgeting issue—it’s a strategic liability. In sectors where deployment speed and capital efficiency are critical, multi-year delays and ballooning costs threaten the viability of decarbonization roadmaps. In nuclear’s case, the challenge lies in its bespoke engineering, opaque regulatory pathways, and the absence of standardized designs. Each new plant or storage facility essentially becomes a prototype, leading to unpredictable timelines and cost escalations that deter private capital and erode public trust.
Small modular reactors (SMRs) are often cited as a corrective—offering repeatable designs and factory-based fabrication. But their economic case is theoretical until multiple units demonstrate cost compression through scaled deployment. Until then, they remain a high-risk, high-capital proposition in a market where even conventional nuclear plants struggle to secure financing.
Hydroelectric projects, once considered bankable infrastructure, fare little better. Three-quarters of large dams in the dataset exceeded budgets by an average of 2.86×. These overruns extend beyond the projects themselves. They disrupt wider grid integration plans, delaying the capacity needed to balance intermittent solar and wind resources. Energy transmission—another linchpin of grid stability—overran in 40% of cases, with a 2.66× multiplier, highlighting the consequences of underinvesting in the connective tissue of the energy system.
Meanwhile, mining and heavy industry—the upstream supply chain for energy technologies—present their own volatility. Nearly half of mining projects exceeded budgets, with an average 2.29× cost multiplier for major overruns. This matters not just for mining companies but for the entire energy ecosystem: supply instability in critical minerals like lithium, cobalt, and uranium can delay or derail entire gigawatt-scale clean energy deployments.
Fossil infrastructure is often painted as a model of maturity and efficiency, yet the data paints a different picture. Oil and gas projects had an 81% overrun rate, with fossil-thermal power plants close behind at 59%. Even pipelines—crucial for future hydrogen networks—exceeded budgets in over half of all cases, with a 2.05× average overrun on large projects. These figures suggest that legacy sectors are just as prone to cost inflation, often due to the same root causes: complex permitting, local opposition, and commodity market swings.
In contrast, solar projects show the tightest fiscal discipline. Just 39% experienced cost overruns, and the average overrun multiplier for severe cases was 1.5×—the lowest across all energy sectors. This reflects the advantages of standardized components, modular installation, and relatively short project cycles. Still, even solar is not immune: connection delays and site-specific permitting continue to inject risk into what is otherwise the most scalable generation technology available.
Wind sits somewhere between solar and nuclear. Overruns occurred in just over half of wind projects, with an average 1.97× cost multiplier. Here, supply chain bottlenecks for blades, towers, and transformers—not to mention interconnection queues—contribute to rising costs and stalled timelines, especially in offshore developments.
The cross-sector takeaway is clear: technical potential does not translate to delivered capacity without controlling for execution risk. Solutions lie not just in innovation, but in process: standardizing designs (particularly in nuclear and hydro), improving interagency coordination for permitting, and leveraging digital tools like geological simulations and digital twins in mining and pipelines can tame some of the variance.
Financial structure also matters. Mechanisms like the regulated asset base (RAB) model—already used in some nuclear and transmission projects—can shift risk away from developers and toward institutional investors with longer time horizons. Similarly, off-take guarantees for emerging sectors like SMRs or hydrogen pipelines could mirror the strategies that helped solar and wind scale rapidly over the last decade.
Perhaps most crucially, integrated infrastructure planning needs to replace piecemeal development. The current disjointed approach—where generation, grid, and storage projects are often planned in isolation—creates compounding delays and cost overlaps. Aligning these assets from the outset reduces both direct costs and systemic friction.
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