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A diverse future energy mix

An electric car

The UK is potentially facing an energy gap caused by the closure of old power stations and dwindling North Sea gas reserves. To ensure electricity supplies continue uninterrupted it will be important for new generating plants to be built by 2020.

So some urgent decisions have to be made as to how to bridge the energy gap. These decisions have to take into account the limitations of the different energy sources and their generating technologies.


Capacity versus demand

Existing UK power stations have an estimated combined capacity of around 90 million kilowatts (kW). This is sufficient to fulfil the country's current electricity needs, which typically peak at around 60 million kW, plus an acceptable margin. But nine of the UK's fossil fuel power stations are due to close by 2015, under European directives aimed at reducing pollutants such as oxides of sulphur and nitrogen. In addition, nine of the UK’s ten existing nuclear power stations are scheduled to close by 2023. Some of these may continue operating after the scheduled shutdown date, provided the Office for Nuclear Regulation (ONR) is satisfied that this is safe, but eventually they will need to be replaced.

These closures would deprive the UK of about 20 million kW of capacity. Even if peak demand does not increase by this point - and in fact it is expected to rise as electricity is increasingly used to power transport and heating - this would mean that nearly every power station in the UK would need to operate at its full capacity during periods of high electricity demand or risk a potential shortfall between supply and demand - an energy gap.

Closing the gap

To help close this potential gap, effort needs to be made to reduce demand through energy efficiency measures, and new power stations need to be brought online. However, the options for building new power stations are constrained by the limitations of the different fuel sources. For example, by 2050, the UK is legally bound to reduce its carbon emissions to a level 80% lower than they were in 1990, so there is a strong motivation for any new generating capacity to be low-carbon.

Given their long life, many power stations built in 2020 are likely to be still generating electricity in 2050. The right decisions as to what type of generating plants to build has to be made now. At the same time, the UK's fossil fuel reserves are diminishing. So any new fossil fuel power stations could potentially increase the country’s reliance on imports in the long term - the security of supply and affordability of which can be uncertain due to increasing global demand.

Electrification of transport and space heating

Furthermore, over the next two decades the UK is likely to undertake significant electrification of transport, which is heavily reliant on oil, and space heating, currently fulfilled largely by gas.

As low-carbon sources of energy, such as wind and nuclear power, are increasingly used to generate electricity, electrification will benefit the UK in two ways: by helping to further reduce greenhouse gas emissions and reduce reliance on dwindling fossil-fuel reserves. But it will also increase the demand for electricity, which means bridging the energy gap will be even more important.

Best solution: an energy mix plus energy efficiency

No one fuel source provides all the answers. Each has limitations: fossil fuels put too much carbon dioxide (CO2) in the atmosphere  and will eventually run out; nuclear energy creates radioactive waste; renewables like wind and solar are intermittent and expensive; and many generating technologies suffer from a lack of suitable sites, lengthy planning and approval procedures, or insufficient industrial capacity.

But the challenge of the energy gap is by no means insurmountable. Used together, different generating technologies have individual strengths that help to make up for each other’s weaknesses.

Sustained action on energy efficiency, demand management, a smart grid and a diverse energy mix encompassing renewables, fossil fuel generation fitted with carbon capture and storage and nuclear power should help to ensure low-carbon, secure, affordable electricity supplies for the UK for decades to come.

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