The energy model helping the UK achieve net zero

A UCL energy system model has become a key tool used by the UK Government in the transition to net zero

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The UK TIMES model was the first national energy model to simulate all UK greenhouse gas emissions.

Since 2015 it has become the UK Government’s primary tool for creating long-term decarbonisation scenarios, and the model provided key insights for the Clean Growth Strategy in 2017 and the Net Zero Strategy in 2021. 

Built on the foundations of its predecessor, UK MARKAL, the UK TIMES model includes greenhouse gases other than CO₂ emitted from agriculture, land use, refrigerants and landfill. This means that it generates scenarios giving a far more accurate picture of the actions necessary to effectively decarbonise the UK economy. 

UK TIMES was created by researchers from the UCL Energy Institute and the UCL Institute for Sustainable Resources at The Bartlett, UCL’s Faculty of the Built Environment. The model can be used to find the most cost-effective ways to meet all of our energy demands while reducing greenhouse gas emissions, both now and in the future, to achieve net-zero targets. 

“Having a single overall model helps each government department to understand the wider challenges, and how their sector fits into that bigger picture.” 
Professor Paul Dodds, UCL Energy Institute
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Photo by Mike Erskine on Unsplash

Photo by Mike Erskine on Unsplash

Planning the bigger picture 

There are many government teams specialising in decarbonisation options and policies – both within the UK Government's Department for Energy Security and Net Zero, and across other departments such as DEFRA, the Department of Transport and the Department for Levelling Up, Housing and Communities. 

As Professor Paul Dodds explains, UK TIMES serves as a valuable conduit to connect disparate teams across government, helping them work together to create a coherent decarbonisation strategy. 

“UK TIMES represents all parts of the energy system, so is able to explore interactions between economic sectors and to identify the required emission reductions in each sector. 

“Having a single overall model helps each team to understand the wider challenges, and how their sector fits into that bigger picture.” 

Paul also outlined a forthcoming development of the model that would make it an even more effective guide to decarbonisation strategy. 

“Energy system models are really good at looking across the whole system, looking at interactions between different economy sectors, and between different fuels. 

“But they often have low spatial and temporal resolution – for example, UK TIMES treats the whole of the UK as a single region.  

“The multi-region version, which we’re working on now, will enable an understanding of the consequences of regional emissions and urban air quality limits. It will enable us to consider the impacts of different regions (such as Scotland or London) adopting different climate policies to the UK Government. In the longer term, we even hope to produce tailored decarbonisation pathways for local councils.” 

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Photo by Sungrow EMEA on Unsplash

Photo by Sungrow EMEA on Unsplash

Practical challenges 

Despite their central role in the efforts to mitigate the climate crisis and reach net zero as soon as possible, researchers face several challenges when creating and maintaining models like UK TIMES. For example, some of the data used to inform the models is commercially sensitive.

“We have six oil refineries in the UK. If we aggregate them into a single pseudo refinery, then that might be fine for the model. But if you’re only modelling Scotland, there is only one refinery – so you know the data there is for Grangemouth, which makes it commercially confidential data.” 

These sensitivities place limits on how the model can be used and distributed, which hampers efforts to share these important tools more widely. Also, such models are often built using expensive commercial software, which places additional constraints on open-source usage. 

Modellers also struggle to maintain consistent levels of funding necessary to maintain and update their models over time. 

“Energy is a funny area, that cuts across economic, social and natural environments, and engineering and physics.  

It is much harder to gain funding for complex models that require ongoing maintenance over a period of years, or for longitudinal studies. 

“Yet these are vital to provide evidence for energy policy and to ensure the billions of pounds that we invest in the UK’s energy system are spent wisely.” 

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Oil rig in Dundee, Scotland. Image credit: Tobias Patrick Wolf on Unsplash

Oil rig in Dundee, Scotland. Image credit: Tobias Patrick Wolf on Unsplash

Combining models for greater impact 

The current version of UK TIMES has other limitations – but not all of these require an upgrade to the model. 

“It has a very low temporal resolution, so you can’t really look at renewable integration or the need for storage in the model. It’s not designed for that. 

“Every sector of the economy is represented in a very aggregated way. For example, we have four typical houses that represent the entire existing housing stock – whereas in reality, there’s a lot more variety.  

“Similarly, we have two typical buildings to represent non-residential stock. It’s the same with different industries, we have to make lots of assumptions.” 

Modellers work round some of these limitations by using UK TIMES in combination with other models to explore more specific scenarios. 

“So if you’re specifically interested in buildings, you’d probably run a building stock model, representing lots of different types of buildings. UK TIMES would provide the overall level of emissions appropriate for the building sector as a whole.

“Then you’d use that in the building stock model to find out which buildings in which places would be most appropriate to decarbonise. 

“Or you might use a transport stock model to look at different types of cars and other transportation to find the best ways to decarbonise the transport systems.” 

Used in this way, UK TIMES provides even greater opportunities for research impact. A notable example of this impact was the modelling framework that was designed by UCL researchers in 2022 to estimate the potential benefits for the UK of reducing future energy demands. 

The researchers used sector-specific models to create simulations of what energy demand reductions might be possible in five areas – agriculture, housing, transport, construction and non-residential buildings. These reductions were limited to what could be achieved without compromising the quality of life enjoyed by UK citizens. 

These simulations were then balanced within UK TIMES to provide four different pathways that could see UK energy demand significantly reduced by up to 52%. 

Paul hopes that researchers in the future can eventually work towards a ‘coherent ecosystem’ of models. 

“The trouble is, it’s only done on an ad-hoc basis. 

But what you want ideally is several models, all with different purposes, strengths and weaknesses, running side by side. And instead of the models giving us different outputs, because they’re looking at a different level of detail, they’d all be using the same assumptions, scenarios and boundary conditions. 

“We've never really built a system where you could more efficiently look at a range of scenarios by formally linking models together – which we could do if we had time and funding.” 

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About the author

photo of Professor Paul Dodds

Professor Paul Dodds

Professor of Energy Systems, UCL Energy Institute

Paul specialises in energy systems modelling and leads the development of the UK TIMES energy systems model, which the Government used to inform the UK’s Net Zero Strategy and several other UK energy strategies. He is leading a major project to understand the implications for the natural world and for human civilisation of overshooting 1.5 C globally. His research spans hydrogen and fuel cells, energy storage, bioenergy and carbon capture and storage.  He has represented the UK Government at International Energy Agency programmes on energy systems and hydrogen. He chairs the low-carbon hydrogen standard and certification working group for the UK Government.  He has given evidence to UK and European select committees. 

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