What is driving the UK’s emissions reduction – cleaner fuels or reduced energy needs?

10 Mar 2017

 On 6 March 2016, the Carbon Brief1 announced that the UK’s CO2 emissions were now at the lowest level since 1894. The scale of recent reductions was credited to falling demand for coal between 2014 and 2016. 

Dr Anne Owen, a researcher with both the UK Energy Research Centre (UKERC)2 and the Centre for Industrial Energy, Materials and Products (CIEMAP)3 took a closer look at the drivers of emissions reduction. Between 1970 and 2016, the UK’s CO2 emissions reduced from 620 to 380 MtCO2. This is a reduction of 39%. But is this emissions reduction due to the UK’s energy needs being met by increased renewables and less coal or does the UK simply use less energy in its homes and factories than it used to? 


Using a technique called structural decomposition analysis, it is possible to unpick the drivers of this change in emissions. The black line on the graph below shows how the UK’s emissions have reduced by 240 MtCO2. The red line shows the effect of the UK’s changing energy demand on emissions and the purple line reveals the effect of the changing fuel mix. The analysis demonstrates that if the UK’s fuel mix had stayed the same as it was in 1970, by 1997 the effect of increased demand would have increased emissions by 100 MtCO2In reality, changes in the fuel mix between 1970 and 1997 offset the increased demand leading to an overall reduction of around 107 MtCO2. However, if levels of demand had remained at their 1970 levels, by 1997 we would have seen a reduction of 195 MtCO2!



Figure 1: The graph shows the change in the UK's  CO2 emissions compared to 1970, distinguishing the effect of changing demand versus changing mix of fuels 

Prior to 1997 the changing fuel mix was the main driver of emissions reduction. During this period, demand for coal reduced by over 50% and gas use increased six fold during the ‘dash-for-gas’. The CO2 emissions generated from using coal are double those from using gas to produce an equivalent amound of energy, leading to the reduction observed. 

Between 1997 and 2012 the UK’s fuel mix remained fairly constant and did not have an effect on emissions reduction but demand continued to fall (by 17%) leading to a reduction in CO2 of 50 Mt in this time period.  


From 2012 to 2016 demand reduced by a smaller amount (7%) and the changing fuel mix had a larger influence on the overall emissions, leading to a reduction of 85 Mt CO2. In this time period, when the CO2 emissions reduced by 85 Mt, demand reductions contributed to 30Mt of the decrease, and fuel mix changes contributed to 55 Mt.  


Over all, between 1970 and 2016, demand reductions have contributed to one sixth of the emissions reduction with fuel mix changes making up the remainder. Clearly there is great potential for reductions in demand to play an increasing role in emissions reduction. 


Since the 1970s, greater proportions of the supply chains of products purchased by purchased by UK households and industries sit abroad. Future work by colleagues in UKERC and CIEMAP aims to explore to what extent demand reductions have been driven by the outsourcing of UK industries or whether the reduction in industrial energy use is due to improved energy efficiency practices.