The need to rapidly develop a huge amount of transmission infrastructure to bring green energy onshore and distribute it around the country means novel approaches to capital delivery. The Accelerated Strategic Transmission Investment framework is proving crucial as the UK races to develop new offshore wind resources.

2030 is a milestone on the road to a decarbonised economy. It’s a date that, right now, brims with potential – the potential for a better, cleaner energy system and with that the hope of avoiding the worst effects of climate change.

But it is only potential. Some are concerned the UK is falling short of its goal when it comes to cutting carbon dioxide emissions by 68% compared to 1990 levels by 2030. Others say the current government is not as committed to the environment as its immediate predecessors. That’s set against a landscape in which many believe temperatures will breach 1.5°C above pre-industrial levels before the end of the decade; a year in which record-breaking wildfires have raged in Canada, cloaking major Canadian and US cities in smog, devastating heatwaves and floods have battered India, and Cyclone Freddy became one of the longest lived tropical cyclones in history.

Climate change is here, its effects are more and more apparent, and the UK has a major role to play in combating it. Decarbonising our electricity supply will be crucial, and with bountiful resources of wind, we have the means to move to a zero-carbon system. That means rapidly delivering on a target of 50GW of offshore wind capacity by 2030 – but that new capacity is no good if it can’t be delivered wherever it is needed.

Enter ASTI.

The Accelerated Strategic Transmission Investment framework is Ofgem’s scheme for delivering the transmission infrastructure to get new offshore wind energy to market, and delivering it quickly. ASTI features 26 strategic projects [see table below], all of which are due for completion in the next seven years. They include HVDC subsea and onshore links, network reinforcements, and double circuits (which deliver more power to a given area).

The electricity transmission networks Scottish and Southern Electricity Networks (SSEN) and National Grid are using ASTI to fast-track a tranche of transmission projects to meet the requirements of the next generation of offshore wind farms. The networks say the previous delivery mechanism for projects of this type, the Large Onshore Transmission Investments (LOTI) scheme, which involves a transactional multi-stage approval process, would be too slow.

“We would get approval to submit a needs case, submit a needs case, and then get approval for the needs case [with LOTI],” explains SSEN Transmission’s director of customers and stakeholders Christianna Logan. “That meant multiple consultations with Ofgem, which can take many years.

“At SSEN, we said that with the timeline to develop and construct offshore wind projects, if we added all that time for approval, it would be hard to hit 2030.”

Joe Northwood, director of operational support in strategic infrastructure for National Grid Electricity Transmission, says the scale and pace of high voltage transmission projects required in the next few years is unprecedented. “For bringing green electrons onshore, in some cases there is no adjacent network – or no network whatsoever.”

How does ASTI work?

These concerns led to the development of ASTI. ASTI exempts overall responsibility for projects – the delivery mechanism – from competition, with incumbent transmission owners taking on each scheme in the framework.

SSEN says it worked with the regulator and system operator to identify projects that should be sped up under the new regime instead of what Logan describes as LOTI’s “piecemeal” approach. “Rather than go through approvals individually, project by project, and justify the need, we identified a tranche of projects needed for 2030 and that really helped us accelerate the process with Ofgem.”

It also helped that the goal is crystal clear. The offshore wind leasing rounds mean greater certainty about where wind farms will be located and their capacity. National Grid has worked backwards from this to determine the infrastructure required to bring energy onshore. This led to the government-led Offshore Transmission Network Review and the ESO’s Holistic Network Design, effectively a ”blueprint” for getting to 50GW of offshore wind by 2030, says Northwood.

A project-by-project approach, he agrees, would not have worked. “In the past we would work like that. But it is a staccato, stop-start approach in a linear fashion from pre-construction to construction, working hand in hand with the regulator.”

Now the certainty over capacity and transmission infrastructure that needs to be built is enabling National Grid to involve the supply chain early on, at the pre-construction phase. A series of projects is progressing simultaneously, which Northwood says unlocks a number of societal, technological and supply chain benefits – including a project delivery system that can underpin the UK’s longer term 2050 net zero target.

He says: “The way in which we deliver infrastructure and set ourselves up as a sector to be faster, more agile, and more societally focused in delivering infrastructure, will enable the period between 2030 and 2050 to be more efficient.” To achieve this vision, National Grid is partnering with the supply chain on the Great Grid Upgrade and, looking longer term, the ESO’s Central Strategic Network Plan, the successor to the Holistic Network Design. There is now an “ongoing conversation” with Ofgem, the government and the system operator about continuing with an ASTI-style rolling investment framework, Logan adds.

“Historically with infrastructure, the pattern has been to wait for demand to occur and then build. If we do that here, the infrastructure simply won’t be there when it’s needed,” says Northwood.

Community engagement and skills in Scotland

SSEN’s patch covers a quarter of the UK’s land mass and many areas of outstanding natural beauty such as national parks and protected woodlands. Logan says local communities “want to know everything” about what SSEN is building. Again, ASTI’s holistic approach to infrastructure is helping. “If we consult on a project and six months down the line come back with another, it can feel as if we are not being transparent. ASTI enables high-quality engagement about the overall plan, so we get communities’ views on the infrastructure as a whole.”

It’s not always possible to accommodate their wishes. For example, the preference may be not to build overhead transmission lines in favour of underground schemes, but this can be more expensive – cost which would eventually be borne by consumers – and have a detrimental impact on the environment. That means compromises.

“We involve all the stakeholders and hope for mutually acceptable outcomes; they might not be everyone’s choice, but something we can all accept is the right way forward,” Logan explains.

One of the potential constraints on growth of renewable energy in the UK is skills. But the certainty ASTI provides will encourage the supply chain to develop the workers it needs to deliver infrastructure for future offshore and onshore green energy projects. “On the back of this coordinated programme there is the opportunity to develop skills academies and centres of excellence,” says Northwood. This will provide jobs and training for people keen to transition from offshore oil and gas, he adds.

Logan acknowledges there are skills issues. “There is insufficient resource within the supply chain, but we have time to get that resource lined up. That’s a Europe-wide problem for utilities,” she points out.

“But we have already had great success bringing people in from carbon-intensive sectors. People are attracted from offshore because we are delivering net zero, and they know the work is secure for the next few decades.”

The development of the infrastructure, supply chain, and skills base may present a benefit to UK plc comparable with our financial services sector, Northwood concludes.

“There is the opportunity to put the UK on the map. Where financial services were our international offering, the energy transition and clean energy could be next.”

The need for speed: Digitalisation and community engagement

Stakeholder and community engagement is vital for SSEN’s plans in Scotland. There is a “small group” of people who are dissatisfied with building infrastructure in any scenario and are not concerned about net zero, Christianna Logan says.

It’s important that consultation takes place early. Route corridors for overhead lines must be mapped and analysed. Issues that SSEN has not picked up in its documentation or surveys are often relayed via feedback from the community. The terrain is challenging, and requests are sometimes made that infrastructure is built underground, although this may not be possible and can have a negative impact on wildlife.

Being able to devise numerous alternative routes is key to doing things quickly. SSEN is using specially developed software that has been programmed to understand restrictions and work around them to devise infrastructure routes.

“Historically, we would have had people sitting at a desk and looking at maps,” explains Logan. “What’s brilliant about the software is we can teach it restrictions – impact on woodland, for example – and it can analyse hundreds of scenarios. You can see the impact along with the environmental, technical and socioeconomic factors.

“It tells us what the best – or ‘least constraint’ – routes are. Our consultations are then informed by what the software has told us. It’s a great example of digitalisation speeding things up.”

ASTI projects (source: Ofgem)

Project Description TO Optimal date
AENC New 400kv double circuit north East Anglia NGET 2030
ATNC New 400kv double circuit south East Anglia NGET 2030
OPN2 New 400kv double circuit Norton-Osbaldwick NGET 2027
GWNC New 400kv double circuit Humber-Lincolnshire NGET 2030
CGNC New 400kv double circuit Creyke Beck-Humber NGET 2030
EDEU 400kv upgrade Brinsworth-Chesterfield-High Marnham NGET 2028
EDN2 New 440kv double circuit Chesterfield-Ratcliffe-on-Soar NGET 2030
BTNO New 400kv double circuit Branford-Twinstead NGET 2028
PTC1 Cable replacement Pentir-Trawsfynydd NGET 2028
PTNO North Wales reinforcement NGET 2029
TKRE Grain-Tilbury-Kingsnorth upgrade NGET 2028
HWUP Uprate Hackney, Tottenham and Waltham Cross NGET 2027
SCD1 Suffolk-Kent offshore HVDC link NGET 2030
BLN4 Beauly-Loch Buidhe 400kv reinforcement SSE 2030
SLU4 Loch Buidhe-Spittal 400kv reinforcement SSE 2030
BBNC New 400kv double circuit Beauly-Blackhillock SSE 2030
BPNC New 400kv double circuit Blackhillock to Peterhead SSE 2030
BDUP Beauly-Denny 400kv uprating SSE 2030
TKUP East coast onshore 400kv Phase 2 reinforcement SSE / SPT 2030
PSDC Spittal-Peterhead HVDC reinforcement SSE 2030
E4D3 Peterhead-Drax HVDC SSE / NGET 2029
E4L5 Peterhead-south Humber HVDC SSE / NGET 2030
W. Isles Arnish-Beauly HVDC SSE 2030
DWNO Denny-Wishaw 400kv reinforcement SPT 2028
E2DC Torness-Hawthorn Pit HVDC SPT / NGET 2027
TGDC East Scotland-south Humber HVDC SPT / NGET 2030