All You Need to Know about National Grid's £35bn Investment Plan RIIO-T3

The UK’s energy network is at a turning point. Over the next five years, decisions made now will shape our ability to meet net zero targets and secure reliable power for decades to come. At the heart of this shift is National Grid Electricity Transmission’s RIIO T3 Business Plan for 2026 to 2031, which sets out how to modernise the UK’s power infrastructure at a scale not seen in 70 years.

With £35billion earmarked for investment, the plan is comparable in size to major infrastructure projects like HS2 and Crossrail. But while those transport schemes have faced delays and cost overruns, the energy transition cannot afford to stall. The challenge ahead is enormous, and this article explores what is planned, what could go wrong, and what it will take to deliver.

We've pored over National Grid's  101-page business plan so you don't have to. Over three hours of reading shortened to just six minutes.

Expanding the Grid: A Transformation That Cannot Wait

Our energy grid is like the strategic road network and as we place greater demands on it we must reinforce the connections and increase capacity where bottlenecks occur.

This latest regulatory business plan focuses on three major objectives. 

1. Strengthening the network by adding new capacity, upgrading existing lines, and integrating more renewable energy sources.
2. Accelerate connections to reduce the long wait times that have left clean energy projects sitting idle for years. 
3. Building resilience in the grid, not just to cope with climate change but also to withstand cyber threats and the growing complexity of energy supply and demand.

There are some big numbers in this plan which represent huge challenges to our construction sector.  The investment includes £26.5 billion to support net zero goals, enabling 50 gigawatts of offshore wind capacity. The plan also aims to connect 35 gigawatts of generation and 19 gigavolt amperes of demand while upgrading 3,500 kilometres of overhead lines and constructing 1,100 kilometres of new circuits.  Alongside this, the energy sector will need to expand its workforce by 50 percent to meet the demands of these projects.

But what happens if we don’t achieve the benefits of this plan?

The Cost of Inaction: Why Delays Mean Higher Bills

This is not just about future proofing. The UK’s grid was built for a different era, and every delay adds costs that are ultimately passed on to consumers.  One of the most striking figures in the business plan is the potential to save £12 billion by reducing constraint costs. These occur when electricity is generated in one part of the country but cannot be transported where it is needed. 

Generators then have to be paid to switch off while activating alternative sources elsewhere, a cost that is ultimately reflected in household energy bills. Constraint costs reached a record £1.94 billionn in 2023. National Grid estimates that its planned upgrades could reduce this burden and save the average household £40 per year. However, this assumes that projects are delivered on schedule. If planning approvals, workforce expansion, or supply chain investments fall behind, these savings will quickly disappear.

Delivery Challenges: The Supply Chain Squeeze

One of the biggest risks to delivery is UK supply chain constraints. Lead times for key transmission equipment have doubled in the past two years, and high voltage direct current cable manufacturing capacity is fully booked until the end of the decade! The UK’s labour shortage is no secret. An extra 290,000 workers will be needed by 2030, an 80 percent increase on the current workforce.

To address these risks, National Grid is bringing suppliers into projects at an earlier stage to prevent late cost increases. It is also securing long term regional partnerships with contractors rather than relying on fluctuating market prices. Additionally, it is purchasing land for future substations and infrastructure before demand peaks.

These measures should bring more stability but with supply chains stretched and costs rising, nothing is guaranteed.

Who Is Going to Build It? The Workforce Shortage Problem

Even with funding in place, the UK energy sector is facing a shortage of skilled workers. This is particularly acute in fields such as electrical engineering, grid planning, and high voltage systems. The workforce is expected to grow by 53 percent by 2031, with over 1,100 new trainees, apprentices, and graduates joining the sector. National Grid has allocated £150m for skills and innovation programmes, but training takes time and demand is rising faster than supply.

If domestic recruitment and training do not keep pace, the UK may need to import more skilled labour at a higher cost, which may reduce the economic benefits of these infrastructure investments.

Planning Bottlenecks: Will Local Opposition Slow Things Down?

One of the biggest risks to delivery is not technical but political. Large scale transmission projects require planning approvals, and history shows that these can take years. More than 23,000 people have taken part in consultations on grid expansion projects, and early opposition is already forming around some offshore wind transmission corridors. If planning approvals become a sticking point, key projects could be pushed back, causing costs to escalate.

National Grid is aiming to get local communities engaged earlier, making sure projects fit into regional economic plans. However, meaningful progress will require planned and well publicised government reforms to streamline approvals. Without these changes, the UK could be left with world class energy projects stuck in planning limbo.

A Plan of Necessity, Not Choice

This is more than a business plan. It is a test of whether the UK can actually deliver on its net zero commitments. If successful, it will mark a fundamental shift in how the country plans and builds energy infrastructure. If it fails, the result will be energy gridlock, higher consumer costs, and growing frustration over the slow pace of change.

The challenge is immense, but so is the opportunity. Reinforcing the grid at this scale will require faster decision making, better coordination and collaboration between government and industry, and a more flexible approach to delivery. 

Will the UK’s infrastructure sector be able to step up?

One thing is certain, standing still won’t keep the lights on!