Worldwide energy supply

From 2015 to 2017 worldwide production increased 2%, mainly in Russia (7%), the Mid-East (8%) and India (5%), while China produced 3% less and the EU 2% less. From 2017 to 2019 world energy increased 5%, mainly in the USA (15%) and China (9%).[5] From 2015 to 2018 wind energy increased 52% and solar energy 123%.[6]

In the period 2005-2017 worldwide final consumption[1] of

• coal increased 23%,
• oil and gas increased 18%,
• electricity increased 41%.

Some fuel and electricity is used to construct, maintain and demolish/recycle installations that produce fuel and electricity, such as oil platforms, uranium isotope separators and wind turbines. For these producers to be economic the ratio of energy returned on energy invested (EROEI) or energy return on investment (EROI) should be large enough. There is little consensus in the technical literature about methods and results in calculating these ratios.

Paul Brockway et al. find that such ratios, measured at the primary energy stage at the well, should instead be estimated at the final stage where energy is delivered at end users, including energy needed for conversion and transport. They calculate global EROI time series in the years 1995–2011 for fossil fuels at both primary and final energy stages and concur with common primary-stage estimates ~30, but find very low ratios at the final stage: around 6 and declining. They conclude that low and declining EROI values may lead to constraints on the energy available to society. And that renewables-based EROI may be higher than fossil fuels EROI when measured at the same final energy stage.[9]

If at the final stage the energy delivered is E and the EROI equals R, then the net energy available to society is E-E/R. The percentage available energy is 100-100/R. For R>10 more than 90% is available but for R=2 only 50% and for R=1 none. This steep decline is known as the net energy cliff.

Marco Raugei with 20 coauthors find EROI 9-10 for PV systems in Switzerland as the ratio of the total electrical output to the ‘equivalent electrical energy’ investment. They criticize inclusion of energy storage in the calculation of EROI for PV panels or windturbines, as it would make the result incompatible with conventional EROI calculations for other electricity generating installations. Measuring the performance of energy technologies ought to be done in a comprehensive analysis of a country's energy system.[10]

The IEA presents four scenarios in its World Energy Outlook 2020 report.[11]

In the Stated Policies Scenario (STEPS) and the Delayed Recovery Scenario (DRS) the IEA assesses the likely effects of 2020 policy settings. Global energy demand rebounds to pre-COVID pandemic level around 2024 (p.27,28). Energy-related CO₂ emissions will, after a 7% fall in 2020, rebound around 2022 and rise to about 35 gigatonnes (Gt) in 2030 (Figure 1.3), far from the immediate peak and decline in emissions that is needed to meet the Paris Agreement (p.87). Air pollution causes nearly 6 million premature deaths in 2030, about 10% more than today (p.32).

The Sustainable Development Scenario (SDS) assesses what is needed to meet the Paris Agreement. Investment in clean energy and electricity networks rises from $0.9 trillion in 2019 to $2.7 trillion in 2030 (p.88). Then the share of solar PV and wind in global generation rises to 30% (p.34). Together with other low-carbon sources (mainly hydro and nuclear) they generate almost two-thirds of all electricity (p.54). The share of coal drops to 15% (p.19). Methane emissions are reduced by 75% from 2019 levels (p.106). Fossil share in the primary energy mix falls but remains large, around 70% in 2030 (p.104).

Still the SDS holds that net-zero CO₂ emissions globally can be reached by 2070. SDS would provide a 50% probability of limiting the temperature rise to less than 1.65 °C (p.54) but no details are given how.

In the Net Zero Emissions by 2050 (NZE2050) Scenario (Chapter 4) CO₂ emissions from the power sector decline by around 60% between 2019 and 2030. Worldwide annual solar PV additions expand from 110 GW in 2019 to nearly 500 GW in 2030. NZE2050 would require an unprecedented mobilisation of resources worldwide. That is clearly not happening.[12]

Many scenario's are possible. The actions taken by governments will be decisive in determining which path to follow. As of 2019, there is still a chance of keeping global warming below 1.5°C if no more fossil fuel power plants are built and some existing fossil fuel power plants are shut down early, together with other measures such as reforestation.[13]

Alternative Achieving the Paris Climate Agreement Goals scenarios are developed by a team of 20 scientists at the University of Technology of Sydney, the German Aerospace Center, and the University of Melbourne, using IEA data but proposing transition to nearly 100% renewables by mid-century, along with steps such as reforestation. Nuclear power and carbon capture are excluded in these scenarios.[14] The researchers say the costs will be far less than the $5 trillion per year governments currently spend subsidizing the fossil fuel industries responsible for climate change (page ix).

In the +2.0 C (global warming) Scenario total primary energy demand in 2040 can be 450 EJ = 10755 Mtoe, or 400 EJ = 9560 Mtoe in the +1.5 Scenario, well below the current production. Renewable sources can increase their share to 300 EJ in the +2.0 C Scenario or 330 PJ in the +1.5 Scenario in 2040. In 2050 renewables can cover nearly all energy demand. Non-energy consumption will still include fossil fuels. See Fig.5 on p.xxvii.

Global electricity generation from renewable energy sources will reach 88% by 2040 and 100% by 2050 in the alternative scenarios. “New” renewables — mainly wind, solar and geothermal energy — will contribute 83% of the total electricity generated (p.xxiv). The average annual investment required between 2015 and 2050, including costs for additional power plants to produce hydrogen and synthetic fuels and for plant replacement, will be around $1.4 trillion (p.182).

Shifts from domestic aviation to rail and from road to rail are needed. Passenger car use must decrease in the OECD countries (but increase in developing world regions) after 2020. The passenger car use decline will be partly compensated by strong increase in public transport rail and bus systems. See Fig.4 on p.xxii.

CO₂ emission can reduce from 32 Gt in 2015 to 7 Gt (+2.0 Scenario) or 2.7 Gt (+1.5 Scenario) in 2040, and to zero in 2050 (p.xxviii).