High Voltage Grid – the bottleneck to net zero carbon?

This blog looks at where the national grid is currently and the key challenges that lie ahead in providing a more resilient UK-wide infrastructure to support the transition to net zero carbon by 2050 and some potential solutions for consideration to help achieve this.

As the UK starts to implement more technologies such as electric heat pumps and electric vehicle charging, we must stop and assess the age, condition, capacity, and the current fragility we have in the national high voltage distribution system.

It appears a simple strategy, replace what we have with bigger, right? In theory, yes, but we must ask ourselves some important questions.

Do we have enough capacity and is the network ready?
A lot of the nation’s high voltage network is nearing or past its recommended serviceable life which is a cause for concern. This is already causing risk around capacity availability as well as failure of key cabling and equipment especially when we put more strain on the network.

It is predicted that the demand by 2040 will more than double what we currently have with a need to replace the ageing infrastructure as well as upgrade it. It is estimated that we will need more than 600,000km of new electric lines within the next 17 years, that is more than 100 km of cabling being lay each day until 2040 if we are to meet the governments climate goals. To put this into perspective, the UK would need to connect about four times as much new transmission capacity to the network in the next seven years than has been built since 1990.

The Climate Commission Committee (CCC) predicts that that by 2050 we will need to double our capacity based on increase demand from the built estate, surface transport and industry.

Will renewable energy provide enough on its own?
With the need and drive for greener energy increasing, we must think about the source of green energy and how reliant we are on certain renewable technologies such as wind and solar. As these are linked with the climate, do we need other sources of non-fossil fuel generation to ensure the capacity is available in all climate scenarios?

The projected seasonal demand and renewable energy generation from the CCC shown below highlights that 100% renewable energy will not be sufficient on its own when compared to the projected demand.

This highlights the need for alternative energy sources such as nuclear, hydro, or green hydrogen turbine generation to meet the projected maximum demand as well as supporting the grid in the event renewables are not producing the required output.

Energy storage and are batteries the right solution?
It is likely that the grid will require a large element of energy storage to support peak demand and support when renewable generation is not producing sufficient levels. Currently the level of investment and projects are amounting to an average of 0.5 GW per year. To maintain the future demand, more large-scale storage projects such as the new build 2.3GW contract for 2023/2024 and the 5GW for 2026/2027 are required.

Majority of large-scale energy storage in the UK is based around mass battery storage with the leading technology being lithium-ion type batteries. Consideration must be given to the life expectancy and costs of replacement of these types of batteries and technology with an operation window of approx. 12 years. This is an on-going replacement cost that needs to be factored into budgets.

We also should stop and assess the Whole Life Carbon (WLC) of these batteries. With materials such as cobalt and lithium having an estimated 1.5+ Million and 1.3+ Million tonnes of carbon dioxide (CO₂e) annually in the mining process alone, which equates to an average of 15 tonnes of CO₂ per tonne of lithium, are these good for the environment? We also need to consider the journey these materials take after the mining process with the transport of these materials to manufacturing plants throughout the world, the complete carbon footprint of lithium-ion batteries needs to be considered.

Lithium-ion batteries were commercialised back in 1991, the world is eagerly waiting for the next technology jump in battery technology. Alternatives are out there being developed and researched, such as calcium-ion, solid state batteries as well as diamond batteries (or nuclear batteries), but when will they be commercially viable? Calcium-ion batteries are removing the need for materials such as cobalt and lithium and are currently in use for residential houses with the next step being onto electric vehicles and mass storage. These provide a much smaller carbon footprint with the same output and life expectancy, a good steppingstone towards the next technological jump in battery technology.

Should we be looking at alternative energy storage? There are plenty more technologies we need to consider such as hydro-electric, gravity generation and thermal storage.

How much will it cost?
With the levels of interventions and investment needed, it is projected that we will need an estimated £54 billion to reinforce the network for 2050.

No doubt there will be a need for cost saving and the dreaded ‘value engineering’. Will one of the options be the increase in use of overhead lines and pylons? These can be up to 10 times cheaper than to bury the cables, are we now going to see more visible networks throughout the UK? It feels like this is unavoidable to renew the network, but at what cost to the environment and in some places to the scenery.

Is the grid getting harder to balance?
The residential installation in the UK is mostly 230V single phase, not 400V three phase like other countries in Europe. This will come with the risk of imbalance in the network with households having a mixture of fossil fuel heating versus electric heat pumps as well as electric vehicle chargers.

Add to this the potential of imbalance of retrofitted solar panels feeding back to the grid through the single-phase installations making it challenging for the network operators to balance and predict the overall network.

Currently, this is being professionally managed by the staff in the control rooms throughout the UK who are equally as good at predicting demands based on weather forecasting. They use some extremely useful tools and are constantly developing new tools to manage this. As more of the nation transition to these technologies the grid will naturally start to see a better balance across the phases.

Conclusion and further thoughts
In summary, the current national grid needs major replacement and upgrading before we get anywhere near the future requirement. There is a base renewal as well as capacity upgrading needed across the whole of the nation.

We are on the right track for majority renewable energy, but it is not the complete solution. With demand projections being more than generated, we must look at alternative non-fossil fuel generation to meet demand and provide resilience.

Energy storage will become more common, the question will be what will it be? Batteries are leading the way for electricity storage but come with their complications and there are more technologies out there to consider. The reality will be that this will be a mixture of technologies to help us achieve our goals.

The costs associated are eye watering, which may help with the reasoning behind our current energy bills. But let us not lose sight that this is a major infrastructure replacement and upgrade which will take time and a lot of money!

As more of the nation adopt these technologies, the grid will naturally balance itself out. But we can sleep at night knowing the control room staff have the tools available to control and predict to keep the grid operating safely.

There are still a lot more unanswered questions and risks associated with this topic such as:

1. Do we have sufficient skilled workforce to carry it out?
2. Can the supply chain support the amount of new cabling/copper?
3. Is it realistic to achieve this by 2050?

Only time will tell, as engineers, I am sure we will do everything in our power to deliver a sustainable and reliable network.