Energy companies have promised to spend almost £70bn over five years to help rewire Great Britain’s electricity infrastructure in the global race to shift from fossil fuels to clean electricity.

The companies that own the high-voltage power system – National Grid, SSE and ScottishPower – have submitted spending plans totalling about £68bn to the industry regulator Ofgem for the period from 2026 to 2031, which could support about 100,000 jobs.

The proposals must still be approved by the watchdog, which is expected to balance the need for costly investments in upgrading the power infrastructure to meet climate targets, which is paid for through energy bills, against the need to protect customers from rising costs.

National Grid set out plans to spend up to £35bn over the five years to March 2031, which could include investment of more than £11bn to maintain and upgrade the country’s existing networks, alongside building three major grid projects that have already been approved by the regulator through its fast-track process.

The FTSE 100 energy company has also proposed an investment pipeline of about £24bn; which includes about £15bn to increase network capacity, and a £9bn provision for any additional potential projects that the UK government may need to meet its 2030 clean power targets.

SSE made its plans public last week, outlining investments of £22.3bn in grid infrastructure that includes about £16bn of strategic investments that have already earned the backing of Ofgem through a fast-track framework designed to speed up the process of connecting offshore windfarms to the power grid.

Those proposals also include the potential for an additional £9.4bn of spending that could bring its total investment in the five years to 2031 to about £31.7bn and support up to 37,000 jobs across the UK.

ScottishPower’s plans include £10.6bn of investments such as building 12 new major transmission substations, upgrading 450km of existing power circuits and 87km of overhead lines and 35km of underground cables.

The company, which is responsible for the transmission of electricity in central and southern Scotland, plans to make the grid more resilient and help connect up to 19GW of green power projects to the grid, or enough to power the equivalent of almost 20 million UK households.

This work should help to reduce the amount of money paid to renewable energy developers to turn off their projects when green electricity risks overwhelming the power grid, which ScottishPower estimates could save households up to £167 on their energy bills by 2030.

It will also require ScottishPower to double its transmission workforce by creating about 1,400 new jobs, which could support 11,000 more jobs across the UK economy, the company said.