Do the UK’s ambitious zero-carbon power system plans add up?

The UK’s new Labour centre-left government, elected on 4 July, aims to create a zero-carbon electricity system by 2030. To achieve this, it has ambitious plans to expand renewable capacity in the GB electricity market.

This means doubling onshore wind to 30 GW, tripling solar to 51 GW and quadrupling offshore wind to 54 GW. Other policy commitments include investment in carbon capture and storage (CCS), hydrogen, marine energy and long-term energy storage. It also aims to extend the lifetime of existing nuclear plants, develop a fleet of small modular reactors and build Sizewell C alongside Hinkley Point C, which is already under construction. 

So, how credible are these plans and what progress has been made in the first 100 days of government? 

UK renewable capacity targets

Let’s start with the renewable capacity targets. Tripling the UK's solar generation would require an annual build out of 25% of last year’s capacity. While that’s a significant amount of solar to build, current growth rates are 15-20% annually. Sustained growth and expanding capacity and supply chains to 25% annually seem achievable, especially with the ongoing reductions in the cost of solar panels. The government made a good start by granting permission to build three solar farms totalling 1.4 GW soon after taking office. So this target seems credible and likely to be met, or almost met, by 2030.

However, onshore wind is a different story because England and Wales have had a de facto ban on building new sites due to strict planning regulations. This policy was reversed by the Labour government days after the election. Development in the sector promises to be ramped up in a way we haven’t seen for a generation. But will it be enough? Some onshore wind was built during the previous government so doubling capacity by the end of the decade would be tough but still doable. 

Then there is offshore wind. The UK has 14 GW of operational capacity and will have 97 GW in total if all projects in the pipeline are built, although these projects take a long time to build. There is an additional 13 GW expected from recent government auctions, but the long build times suggest that the last chance to get projects funded for delivery by 2030 requires them to procure the remaining 27 GW in 2025. This is not realistic. On top of that, building offshore wind further out to sea is challenging, making the 2030 quadrupling target highly unlikely and even a threefold increase difficult to achieve.

Looking at the other technologies in the government manifesto, there is a commitment to invest in CCS. But this has never been achieved at scale and has proved expensive to implement. So providing any meaningful contribution to zero power electricity system by 2030 years is doubtful.  

Which brings us to hydrogen. There is a joke in the electricity industry that hydrogen is the future and the answer to everything, but so far nothing has been built at GW scale, and the chances of getting anything by 2030 is again doubtful.

I believe we will see some marine energy built but at MW, not GW scale, over the next six years. It is unlikely to be at any significant capacity, as challenges with the harsh marine environment remain unresolved.  

The government’s recent decision to establish a cap-and-floor funding mechanism is accelerating interest in long duration energy storage (LDES). This means that storage has a less risky environment for investment. At scale, two primary types of storage systems are viable: lithium-ion electrochemical storage and pumped storage. The proposed scheme appears particularly focused on supporting large-scale pumped storage. However, this type of infrastructure involves significant engineering challenges, including tunnelling through rock and dam construction, which are high-risk and complex undertakings. Given these hurdles, and the fact that specific regulations for the cap-and-floor framework are still being developed, it seems unlikely that substantial infrastructure will be operational by 2030.

Finally, nuclear. I think Hinkley Point C might be ready by 2030 after multiple delays which would bring just over 3 GW online, although further setbacks are still possible. Sizewell C’s funding still needs to be finalised and small modular reactors are not going to come onstream until the mid 2030s at the earliest. This will mean that nuclear capacity will likely remain static as the last of the aging advanced gas-cooled reactor (AGR) fleet will be broadly retired by the end of 2030 as underlying issues with the graphite blocks in the reactors take their toll.  

The UK power system: 2030

Let’s take a closer look at what this new system would look like. The charts below were created using Montel Analytics data and show the half-hourly fuel mix for December 2023 and June 2024.

Then we can jump forward to 2030 in the following charts by tripling wind and solar, creating massive surplus generation (shown in red) which could be put into long-term energy storage or exported to neighbouring countries via interconnections.

There is a small amount of residual generation need when the wind does not blow and the sun does not shine so we still need either gas, LDES or interconnector imports to fill that gap. The other option is to leverage demand side response to shift demand held in storage and the big fleet of electric vehicles that are coming. 

So, the big question is will we get a zero-carbon energy system by 2030?  

The likelihood of reaching a nearly zero-carbon electricity system by the end of the decade is complex. While increased deployment of lithium-ion battery storage, whether static or in vehicles, could support a renewable-dominant grid, some “must-run” gas-fired power stations would likely remain operational due to their roles in industrial steam processes, which are not easily replaced by other sources.  

Extensive new cabling is needed to transfer power efficiently, prompting the government to call for a strategic spatial energy plan to determine the best locations for new power stations and cable routes. New technologies like synchronous condensers and grid-forming batteries are being deployed. These will help with system stability and bring more flexibility. Promising trials in demand flexibility are underway for both industrial and domestic uses. Interconnection capacity, however, is not expected to increase significantly by 2030, with only the Neuconnect link to Germany likely to add 1.4 GW to the existing 10 GW. Regulatory challenges with the EU’s energy market and the carbon border adjustment mechanism may also hinder optimal interconnector use. 

Ultimately, with sufficient build-out of lithium-ion and other energy storage solutions, a near-zero-carbon electricity grid may still be achievable, if not likely. This would allow renewables to be better integrated, potentially allowing for periods of several days or even weeks where the grid operates with minimal carbon emissions. So it could be very close to zero carbon - which would be a great policy success for the government.

This article originally appeared as a column on montelnews.com