The NAO has releases a report in to the 拢70bn of investment that Ofgem says will be required to keep pace with new green generation over the next five years.
Much of the grid was built between the 1950s and '70s, around the use of large fossil fuel power stations. To meet DESNZ's aim of generating 95% of electricity from clean sources by 2030, a major programme of investment has been needed.
When the grid cannot transport power effectively, NESO, the National Energy System Operator will often pay wind generators to reduce output, and others, usually gas plants, to increase output. This increases carbon emissions.
The NAO reported that DESNZ has allowed renewable generation to expand faster than the grid. It identifies a lack of spatial planning in 2015, as DESNZ moved to a market led approach to grid planning.
This means that grid constraints could now cost up to 拢7.8bn in 2030, if new upgrages are not accelerated. To meet demand Ofgem estimates transmission owners will need to spend up to 拢70bn, quadrupling current investment. NESO recommends a further 拢89bn invesment beyond 2030.
However, the NAO says many of the 64 projects currently underway are only at an early stage of development. Securing approvals for land use is delaying projects by up to three years. When planned outages are needed for upgrades, as many as two thirds are cancelled or rearranged. And supply chain and skill constraints are also causing delays.
The NAO noted improvements in planning and management, but said many would come too late for the 2030 target. It said that delivering upgrades at lowest cost to consumers will require stronger oversight of delivery, transparent monitoring of progress, and sufficient regulatory capability to scrutinise costs and the operation of incentives.