Four of Britain’s nuclear reactors were taken offline due to unexpected faults earlier this month. Owners EDF said it took the “conservative action” after finding a defect in one of the boilers, built in the 1980s.

As nuclear plants are prone to breaking with age, a new report warns network operators across the world should be braced for more of the same.

Britain is by no means a special case. Most of the EU’s 211 operational nuclear plants were built in the 1970s and 1980s and were designed to last around 40 years, so many are due to close.

But with the EU committed to decarbonising its energy sector, and nuclear power able to act as a low carbon source providing electricity around the clock, policymakers face a choice: either spend billions eking out a few extra years of generation, or close the plants and build potentially expensive replacements.

The World Nuclear Industry Status Report 2014 suggests that without swift measures, nuclear power in Europe could be entering its twilight years. It warns that unless policymakers make immediate plans to replace ageing plants, by the mid-2050s, nuclear power across the globe could become a thing of the past.

Ageing plants

Forty years is a typical lifespan for a nuclear power plant built in the 70s or 80s. While it’s quite common for plants to have their operational lifetime extended, particularly in the US, many close earlier.

The map below shows where Europe’s currently operational plants are. The darker the blue marker, the older the power station:

Created using CartoDB from Guardian data. See the interactive version of this map, here.

Were all the plants to close at 40 years, the EU would lose a lot of generating capacity in the next decade or so. The size of the bubble on the chart below shows capacity lost that year if all 40-year old plants are shut. As you can see, most of Europe’s nuclear capacity is due to come offline sometime in the 2020s:

Even if the plants’ lives were extended by ten years, Europe could still face a nuclear power crunch sometime in the 2030s.

At the moment, only four new plants are under construction, adding 4.8 gigawatts of capacity to the grid. If that’s the only new nuclear that’s built – unlikely, as there are plans for more – Europe would lose 120 gigawatts of nuclear generation capacity by the mid-2050s, data from the Word Nuclear Association shows:

Filling the gap

So how are policymakers expecting to fill the gap? One option is to keep nuclear power on the grid. And that’s what the EU expects to happen, to an extent.

This chart from the European Commission’s energy roadmap shows where the region could get its energy from in 2030 and 2050. The yellow diamonds are how much power each technology provided in 2005. The bars on the left show a range of estimates for how much power each technology may provide in the coming decades – 2030 on the left, 2050 on the right.

As you can see, it projects nuclear power meeting about the same amount, or possibly more, of the EU’s demand in 2050 as it did in 2005. That means either building more plants or extending the lifecycles of existing power stations.

The main problem with both options is the cost. Extending the life of an existing nuclear plant could cost between â?¬1 and â?¬4 billion per reactor, according to the status report. New nuclear plants cost anywhere between â?¬3.2 and â?¬20 billion, and recent projects in France, Slovakia and Finland have been beset by delays and budget overruns.

The UK is set to do its bit to replenish the EU’s nuclear electricity stock, with the industry hoping to construct around 16 gigawatts of capacity in the coming years.

Whether that will happen remains uncertain. The government’s most recent effort to stimulate new nuclear investment was criticised for providing poor value for consumers. The European Commission is also investigating the deal for potential breaches of the EU’s state aid regulations.

The UK seems to be swimming against the tide. Germany has decided to close all its nuclear plants by 2022. France is also aiming to significantly reduce its nuclear dependency, recently passing a law which aims to cut nuclear consumption from around 75 per cent today, to 50 per cent in 2025.

So if the EU is going to keep nuclear capacity anywhere near its current level, other countries are going to have to build lots of new plants – and fast.

New nuclear plants currently take an average of 10 years to construct, according to the status report. Two plants in Ukraine that were started in the 1980s are yet to be completed, the report points out.

Replacing 120 gigawatts of nuclear capacity by 2050 means building 150 average sized plants in the next 30 years. That’s five a year. Since 2000, only eight new plants have come online.

A long-term alternative that would fit with the EU’s aim to cut its greenhouse gas emissions is replace nuclear capacity with renewables. Returning to the graph above, you can see the EU wants renewables to grow faster than any other energy source – as they already are.

So renewables are likely to fill some of the capacity gap, but significant upgrades to the EU’s electrical grids and power storage systems are needed before they can perform a similar role to nuclear.

So in the short term the EU is likely to lean on fossil fuels, to an extent.

Coal and gas can perform a similar role to nuclear – providing baseload power around the clock – but emit a lot of carbon dioxide. That means they can’t be a long term replacement for nuclear if the EU is going to hits its climate goals, unless expensive carbon capture and storage technology is added to the plants.

Cutting energy use should also help – the EU is  aiming to reduce energy consumption by 30 per cent by 2030 – which should mean less power stations are needed.

Tomorrow’s problem, today’s headache

Predicting what the EU’s energy mix will look like in the future is difficult. But the status report makes it clear that formulating plans to replace the region’s ageing nuclear fleet is an urgent task.

While Europe’s nuclear plants may have some life left in them yet, the task of replacing them is a problem policymakers must consider now.