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Meeting the challenge of decarbonising the energy system

 With an emissions trajectory of 2°C needed to limit global warming, University College London’s Professor Paul Ekins discusses the decarbonisation dilemma.


The world is heading for a 5°C jump in temperatures by the end of the century if a business as usual scenario is implied, which according to Professor Paul Ekins would be “catastrophic.”


The 2°C scenario is the internationally agreed target set to limit global warming. This is achievable by decarbonising the energy system, but the Deputy Director of the UK Energy Research Centre admits that it is “an extraordinary challenge”.


He concedes that the energy trilemma – affordable energy, secure energy, and decarbonisation – is not always mutually supportive: “Therefore, the policy challenge is trying to achieve enough on each one of the three in order to make progress on all of them.”


And at present, there is a substantial gap between what countries are pledging through intended nationally determined contributions and the levels required to start an emissions decline.



Over a 10-year period, University College London built an energy system model at global, European and national levels. Using the TIMES Integrated Assessment Model (TIAM), a cost-optimal global energy system was established that would meet energy demands within 16 world regions.


Ekins explains: “It’s basically the energy system from primary fuel sources through to end uses.”


It starts by taking the end use service demands in terms of heat, power and mobility.


“Then the model works out the least cost way of supplying those energy services demands given the whole range of primary fuels and various conversion technologies, logistics and transport,” he adds. “There are tens of thousands of technologies in a model like this and all of them have to be costed.”


“So it models the energy system; it optimises the energy service demands of these 16 regions. Then it calculates the impact of selected primary energy sources on emissions and it’s linked to a climate model which gets you a temperature rise from that.”


Burning all current fossil fuel reserves would exceed the 2°C ‘carbon budget’ by around three times. However, it was unknown which reserves were and were not developed or who owned them. UCL’s TIAM model established the ownership of fossil fuel reserves which are unburnable.



Facing uncertainty

Making projections for the future carries a lot of uncertainty and “we have to make assumptions on all of them,” admits Ekins, who is also Director of UCL’s Institute for Sustainable Resources.


Two of the principal uncertainties are obviously to do with cost – the cost of fossil fuels and the cost of the “very wide range” of low carbon technologies which policy-makers are seeking to replace fossil fuels with.

“They range from the actual technologies that produce the energy – like wind turbines, like photo-voltaic panels – but also to the energy system’s cost. The fact that you need a different type of grid,” he comments.

“If we are moving to electric vehicles, we need different charging stations. They need to be available all over the country.”


Another issue is energy demand: “Will we become much more energy efficient, and will that reduce the demand for energy because we don’t want to spend a lot of money on energy supply if there isn’t the demand for it?”


He also highlights climate policy: “How serious are we going to get about reducing carbon emissions?” and the effect of climate change on the energy system.


The challenge for policy-makers is “to do enough on each of those uncertainties at reasonable cost because you can reduce uncertainty but it costs money to reduce uncertainty.”


Bridging fuel

From the model, it emerges that gas is a “significant bridge” to a low carbon future.


The rationale behind the use of gas is that it is the lowest carbon intensive of the fossil fuels: “We are going to need to use fossil fuels for the next few decades in order to satisfy our energy service demands if we don’t want our economies to collapse. Much better to use gas than coal.”

Ekins says that the model shows clearly that if you put a carbon restraint on, coal production falls off very quickly. He explains: “Gas steps in to take some of that energy demand and carbon emissions are reduced by that 50 per cent by doing that while at the same time, obviously, we keep the energy flowing.


“Eventually, the carbon restraint becomes so tough that you have to reduce your use of gas as well. By that time, one hopes that the really low carbon forms of energy will be able to step up to the plate.”


Countries move at their own pace, driven by their own political systems, by their own energy systems, and by their own indigenous resources, he notes.


For example, as wind becomes cheaper, it could be imagined that Ireland, with a very large wind resource, will deploy an increasing amount of wind resource as will the UK. Countries with a lot of sun could deploy considerable quantities of photovoltaics which in turn, would produce a different dynamic in global energy markets.


In conclusion, Ekins believes that multiple pathways must be taken to achieve decarbonisation: “There’s no single solution.”


Heat, power and road fuels all have multiple uses and all need to be considered together. “That is the strength of the kind of modelling approach that we are trying to adopt,” he remarks. Adapting grids requires “strong, sustained and adaptive policy.”


Decarbonisation is an extraordinary challenge,” Ekins reflects. “No human society has ever tried to do something like this – tried to change an absolutely fundamental part of the economic system before markets were fully ready to do the job.”