Ageing power lines need makeover

The UK’s power grid needs a radical overhaul to make it fit for purpose in a low-carbon world, as Flemmich Webb reports

The advent of large-scale renewable energy capacity in the UK has come just as the country’s transmission and distribution network needs a complete overhaul. It is also providing the opportunity to revitalise other parts of the country’s infrastructure.

This is just part of the infrastructure upgrade that wind and marine energy is helping to kickstart around the country. As well as the grid, the UK’s port facilities are making themselves ready to deal with the massive turbines that are set to be sited in the waters off the coast.

Much of this work is focused on the east coast – Hull is hoping for a £60-million investment at its Alexandra Dock from Siemens, which has plans to build offshore turbines there, although the company has yet to confirm its final decision.

In Belfast, Denmark’s Dong Energy has plans to build an offshore wind construction facility in Belfast Harbour to help it develop projects in the Irish Sea.

On and offshore, there are also a number of major cabling projects under way. The Western HVDC Link will run between central Scotland and North Wales via an undersea cable running along the north-west coast. It will provide an additional 2,000 megawatts (MW) of capacity on the transmission system and will operational by late-2015.

This is part of works, totalling more than £7 billion of investment earmarked for Scotland’s high voltage network, will be spent on replacing ageing infrastructure and connecting to renewable generators, including new sub-sea links from Scotland’s islands to the mainland.

Connections between the UK and Belgium, France, Denmark and Iceland are under consideration

Further south, the East Anglia Offshore Windfarm project is a joint venture between Scottish Power Renewables and Vattenfall. It has a contract with National Grid to connect 7,200MW of wind generation off the coast of East Anglia to the existing national transmission network. This would include three potential connection points at Norwich, Lowestoft and Bramford.

In Cumbria and Lancashire, National Grid will connect a number of new energy projects to the national electricity network. As well as a number of offshore wind farm projects in the Irish Sea, these include Moorside, the proposed new 3.2-gigawatt (GW) nuclear power station near Sellafield. There is no transmission system serving west Cumbria, so National Grid is currently identifying the best way to connect new energy generation sources with customers.

Moves are also under way to connect to other countries’ grids. The Energy Bridge project will capture wind power generated onshore and offshore in Ireland, and connect to the UK mainland via cables laid under the Irish Sea. In June, Statnett and National Grid signed an agreement to develop an electricity interconnector between Norway and the UK, the world’s longest, with a plan to complete it by 2020.

Connections between the UK and Belgium, France, Denmark and Iceland are also under consideration.

The main reasons for such a dramatic upheaval are the country’s switch to a low carbon economy, renewable energy generation and carbon emission reduction targets, and the need to improve security of supply.

Why does it need doing? The grid is in need of an overhaul as much of it was installed in the 1950s and 1960s, and now needs replacing and upgrading. New generation capacity is needed and much of that capacity will be renewable energy generation; about 60 per cent of all new grid connections are to renewable projects. This requires connecting to generators that are often located in remote places, such as off the far coast of Scotland.  And energy supply will become decentralised, meaning small-scale generators will need to be able to sell energy back to the grid.

In 2010, the gas and electricity regulator Ofgem estimated this would cost about £200 billion over the next decade, £32 billion of which needs to be invested in pipes and wires. That’s a doubling of the rate of investment compared to the previous 20 years.

To fund these infrastructure changes, Ofgem has developed RIIO (Revenue = Incentives + Innovation + Outputs), a new performance-based model for setting the network companies’ price controls, which will run over an eight-year period. “Britain faces an unprecedented need to invest to replace ageing infrastructure, meet environmental targets and deliver secure supplies, “ says Ian Marlee, senior partner, transmission, at Ofgem. “Ofgem’s RIIO price controls ensure this work is carried out in a way that secures network investment at the lowest cost for consumers by incentivising efficiency and penalising poor performance.”

All these infrastructure changes should negate one of the criticisms levelled unfairly against wind and marine energy — that its intermittent nature means it cannot reliably fill the energy generation gap left by old fossil-fuel-hungry power stations.

“The new energy infrastructure will mean it’s not a problem if the wind subsides. With an expanded network, we can transfer energy from one part of the country to the other and import it from Europe,” says Zoltan Zavody, RenewableUK’s grid policy manager. “Also, wind tends to subside gradually, which means there is time to bring reserve power stations up to full speed to keep pace with demand. It’s not a sudden shut off.”

However, the necessary investment will only happen if the government makes an ongoing commitment to renewables. “The grid companies and Ofgem are investing in the network, but if there were to be any suggestion that renewable energy might not be part of future generation plans, the grid companies would hold back investment in necessary grid capacity,” Mr Zavody warns. “Ongoing commitment will give the industry and Ofgem the confidence to invest in the grid capacity required by renewables.”