At the global scale, greenhouse gas emissions amounted to 33 gigatons of CO2
equivalent in 2014 and may reach 38 gigatons
in 2040, due mostly to the burning of fossil fuels (IEA 2015). Historical data demonstrate trends in decoupling through decarbonization and improved efficiency, but the current trend still indicates a global temperature increase beyond the 2°C threshold target of the Paris Agreement (Figure 4.11) (IEA 2015; United Nations 2015b; IEA 2016). This likely overshoot warrants bolder action.
The economics of transition to low-carbon energy sources have been greatly assisted by a dramatic reduction in the cost of renewables, especially wind and solar photovoltaic systems. Solar photovoltaic systems experienced a price decline of 23 per cent for each cumulative doubling of production over the last 35 years. In many cases these costs are now lower than those of conventional fossil fuel electricity generation technologies (International Renewable Energy Agency [IRENA] 2015). Further reductions are expected making them possibly the best economic-environmental option in practically every country in the world before 2025 (Figure 4.12).
Figure 4.11: Technology wedges to achieve the 2°C pathway
34 30 26 22 18
2010 2020 Year Energy efficiency
Source: IEA (2015).
Fuel & technology switching in end-uses
Baseline 17.9 Gt 450 Scenario 2030 2040
2014 USD/kWh Figure 4.12: Ranges of levelized cost of electricity for different renewable power generation technologies, 2014 and 2025
0.1 Range of 2014 fossil fuel electricity costs 4 0.0
Source: IRENA (2015).
Setting the Stage
Wind onshore Wind offshore Solar PV-Grid CSP PTC (no storage) CSP PTC (6 h storage) CSP ST (6-15 h storage) Biomass-Stoker/BFB/CFB Gt CO2 Biomass-Gasification Biomass-AD Biomass Co-firing Biomass non-OECD Hydropower Geothermal