In the ET scenario, CO2 emissions from energy use continue to edge up through much of the Outlook, increasing by around 7% by 2040.
The upward pressure on carbon emissions from continuing population growth and, most importantly, increasing prosperity in the developing world is largely offset by quickening gains in energy intensity and to a lesser extent by changes in the fuel mix reducing the level of carbon intensity.
Although the rate of growth in carbon emissions is much slower than in the past 20 years, emissions are still growing more quickly than the sharp decline likely to be necessary to be consistent with achieving the Paris climate goals (see the alternative ‘Rapid transition’ scenario below).
Despite the carbon intensity of the global power sector falling by around a third over the Outlook, the rapid growth in electricity consumption means that the power sector is the largest source of increase in CO2 emissions over the same period, with its share in the global energy system increasing to around 40% by 2040. This is higher than industry or transport which each account for around a quarter of CO2 from energy use, with buildings contributing the remainder (10%).
In the RT scenario, CO2 emissions fall by around 45% by 2040 relative to current levels. The scale of this reduction is broadly in the middle of a range of external projections which claim to be consistent with meeting the Paris climate goals, and is broadly similar to the reduction in carbon emissions in the IEA’s Sustainable Development Scenario.
Around two-thirds of the reductions in CO2 relative to the ET scenario stem from the substantial decarbonization of the power sector. The power sector is the single largest source of CO2 emissions from energy use, and the extensive fuel-on-fuel competition means policy interventions can have significant impacts on the fuel mix.
The reduction in CO2 from industry and buildings accounts for much of the remaining reduction in emissions, reflecting improved efficiency, greater use of CCUS and switching into lower-carbon fuels.
Despite the large number of policy measures and initiatives applied in the transport sector, the reduction in CO2 is relatively small.
The fall in carbon emissions in the RT scenario relative to 2017 levels reflects a combination of: gains in energy efficiency; a switch to lower-carbon fuels; and greater use of CCUS.
The gains in energy efficiency means energy demand increases by around 20% in the RT scenario by 2040, compared with a third in the ET scenario.
The shift to lower carbon fuels reflects a combination of rapid growth in renewable energy – which more than accounts for the entire increase in primary energy – and a sharp contraction in the use of coal. By 2040, renewables account for around 30% of primary energy.
Despite the strong growth in renewables, oil and gas account for close to 50% of primary energy in 2040 in the RT scenario. The level of oil consumption falls to around 80 Mb/d in 2040, with roughly 60% of this remaining use in transport and much of the rest in the non-combusted sector. In contrast, gas continues to grow aided by growing use of CCUS – with close to a third of natural gas in the RT scenario in 2040 being used in conjunction with CCUS.
CCUS is used in both power and industry and captures almost 4.5 Gt of CO2 emissions by 2040 in the RT scenario.