Editing IPCC:AR6/WGIII/Chapter-6 (section)

== Executive Summary ==

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'''Warming cannot be limited to well below 2°C without rapid and deep reductions in energy system carbon dioxide (CO''' 2 ''') and greenhouse gas (GHG) emissions.''' In scenarios limiting warming to 1.5°C (&gt;50%) with no or limited overshoot (2°C (&gt;67%) with action starting in 2020), net energy system CO 2 emissions (interquartile range) fall by 87–97% (60–79%) in 2050. In 2030, in scenarios limiting warming to 1.5°C (&gt;50%) with no or limited overshoot, net CO 2 and GHG emissions fall by 35–51% and 38–52% respectively. In scenarios limiting warming to 1.5°C (&gt;50%) with no or limited overshoot (2°C (&gt;67%)), net electricity sector CO 2 emissions reach zero globally between 2045 and 2055 (2050 and 2080). ( ''high confidence'' ) {6.7}

'''Limiting warming to well below 2°C will require substantial energy system changes over the next 30 years. This includes reduced fossil fuel consumption, increased production from low- and zero-carbon energy sources, and increased use of electricity and alternative energy carriers.''' Coal consumption without carbon capture and storage (CCS) falls by 67–82% (interquartile range) in 2030 in scenarios limiting warming to 1.5°C (&gt;50%) with no or limited overshoot. Oil and gas consumption fall more slowly. Low-carbon sources produce 93–97% of global electricity by 2050 in scenarios that limit warming to 2°C (&gt;67%) with action starting in 2020. In scenarios limiting warming to 1.5°C (&gt;50%) with no or limited overshoot (2°C (&gt;67%) with action starting in 2020), electricity supplies 48–58% (36–47%) of final energy in 2050, up from 20% in 2019. ( ''high confidence'' ) {6.7}

'''Net-zero energy systems will share common characteristics, but the approach in every country will depend on national circumstances.''' Common characteristics of net-zero energy systems will include: (i) electricity systems that produce no net CO 2 or remove CO 2 from the atmosphere; (ii) widespread electrification of end uses, including light-duty transport, space heating, and cooking; (iii) substantially lower use of fossil fuels than today; (iv) use of alternative energy carriers such as hydrogen, bioenergy, and ammonia to substitute for fossil fuels in sectors less amenable to electrification; (v) more efficient use of energy than today; (vi) greater energy system integration across regions and across components of the energy system; and (vii) use of CO 2 removal (e.g., direct air carbon capture and storage (DACCS) and bioenergy with carbon capture and storage (DACCS, BECCS)) to offset any residual emissions. ( ''high confidence'' ) {6.6}

'''Energy demands and energy sector emissions have continued to rise.''' From 2015 to 2019, global final energy consumption grew by 6.6%, CO 2 emissions from the global energy system grew by 4.6%, and total GHG emissions from energy supply rose by 2.7%. Methane emissions, mainly fugitive emissions from oil, gas, and coal, accounted for 18% of GHG emissions in 2019. Coal electricity capacity grew by 7.6% between 2015 and 2019, as new builds in some countries offset declines in others. Total consumption of oil and oil products increased by 5%, and natural gas consumption grew by 15%. Declining energy intensity in almost all regions has been balanced by increased energy consumption. ( ''high confidence'' ) {6.3}

'''Prices have dropped rapidly over the last five years for several key energy system mitigation options, notably solar photovoltaics (PV), wind power, and batteries.''' From 2015 to 2020, the prices of electricity from PV and wind dropped 56% and 45%, respectively, and battery prices dropped by 64%. Electricity from PV and wind is now cheaper than electricity from fossil sources in many regions, electric vehicles are increasingly competitive with internal combustion engines, and large-scale battery storage on electricity grids is increasingly viable. ( ''high confidence'' ) {6.3, 6.4}

'''Global wind and solar PV capacity and generation have increased rapidly.''' Solar PV grew by 170% (to 680 TWh); wind grew by 70% (to 1420 TWh) from 2015 to 2019. Policy, societal pressure to limit fossil generation, low interest rates, and cost reductions have all driven wind and solar PV deployment. Solar PV and wind together accounted for 21% of total low-carbon electricity generation and 8% of total electricity generation in 2019. Nuclear generation grew 9% between 2015 and 2019 and accounted for 10% of total generation in 2019 (2790 TWh); hydroelectric power grew by 10% and accounted for 16% (4290 TWh) of total generation. In total,low- and zero-carbon electricity generation technologies produced 37% of global electricity in 2019. ( ''high confidence'' ) {6.3, 6.4}

'''If investments in coal and other fossil infrastructure continue, energy systems will be locked in to higher emissions, making it harder to limit warming to well below 2°C.''' Many aspects of the energy system – physical infrastructure; institutions, laws, and regulations; and behaviour – are resistant to change or take many years to change. New investments in coal-fired electricity without CCS are inconsistent with limiting warming to well below 2°C. ( ''high confidence'' ) {6.3, 6.7}

'''Limiting warming to well below 2°C will strand fossil-related assets, including fossil infrastructure and unburned fossil fuel resources.''' The economic impact of stranded assets could amount to trillions of dollars. Coal assets are most vulnerable over the coming decade; oil and gas assets are more vulnerable toward mid-century. CCS can allow fossil fuels to be used longer, reducing potential stranded assets. ( ''high confidence'' ) {6.7}

'''A low-carbon energy transition will shift investment patterns and create new economic opportunities.''' Total energy investment needs will rise, relative to today, over the next decades, if warming is limited to 2°C (&gt;67%) or lower. These increases will be far less pronounced, however, than the reallocations of investment flows that are likely to be seen across sub-sectors, namely from fossil fuels (extraction, conversion, and electricity generation) without CCS and toward renewables, nuclear power, CCS, electricity networks and storage, and end-use energy efficiency. A significant and growing share of investments between now and 2050 will be made in emerging economies, particularly in Asia. ( ''high confidence'' ) {6.7}

'''Climate change will affect many future local and national low-carbon energy systems. The impacts, however, are uncertain, particularly at the regional scale.''' Climate change will alter hydropower production, bioenergy and agricultural yields, thermal power plant efficiencies, and demands for heating and cooling, and it will directly impact power system infrastructure. Climate change will not affect wind and solar resources to the extent that it would compromise their ability to reduce emissions. ( ''high confidence'' ) {6.5}

'''Electricity systems powered predominantly by renewables will be increasingly viable over the coming decades, but it will be challenging to supply the entire energy system with renewable energy.''' Large shares of variable solar PV and wind power can be incorporated in electricity grids through batteries, hydrogen, and other forms of storage; transmission; flexible non-renewable generation; advanced controls; and greater demand-side responses. Because some applications (e.g., air travel) are not currently amenable to electrification, 100% renewable energy systems would likely need to include alternative fuels such as hydrogen or biofuels. Economic, regulatory, social, and operational challenges increase with higher shares of renewable electricity and energy. The ability to overcome these challenges in practice is not fully understood. ( ''high confidence'' ) {6.6}

'''Multiple energy supply options are available to reduce emissions over the next decade.''' Nuclear power and hydropower are already established technologies. Solar PV and wind are now cheaper than fossil-generated electricity in many locations. Bioenergy accounts for about a tenth of global primary energy. Carbon capture is widely used in the oil and gas industry, with early applications in electricity production and biofuels. It will not be possible to widely deploy all of these and other options without efforts to address the geophysical, environmental-ecological, economic, technological, socio-cultural, and institutional factors that can facilitate or hinder their implementation. ( ''high confidence'' ) {6.4}

'''Some mitigation options can provide more immediate and cost-effective emissions reductions than others, but a comprehensive approach will be required over the next 10 years to limit warming to well below 2°C.''' There are substantial, cost-effective opportunities to reduce emissions rapidly in several sectors, including electricity generation and light-duty transportation. But near-term reductions in these sectors will not be sufficient to limit warming to well below 2°C. A broad-based approach across the energy sector will be necessary to reduce emissions over the next 10 years and to set the stage for still deeper reductions beyond 2030. ( ''high confidence'' ) {6.4, 6.6, 6.7}

'''Enhanced integration across energy system sectors and across scales will lower costs and facilitate low-carbon energy system transitions.''' Greater integration between the electricity sector and end use sectors can facilitate integration of variable renewable energy (VRE) options. Energy systems can be integrated across district, regional, national, and international scales. ( ''high confidence'' ) {6.4, 6.6}

'''The viable speed and scope of a low-carbon energy system transition will depend on how well it can support sustainable development goals (SDGs) and other societal objectives.''' Energy systems are linked to a range of societal objectives, including energy access, air and water pollution, health, energy security, water security, food security, economic prosperity, international competitiveness, employment. These linkages and their importance vary among regions. Energy sector mitigation and efforts to achieve SDGs generally support one another, though there are important region-specific exceptions. ( ''high confidence'' ) {6.1, 6.7}

'''The economic outcomes of low-carbon transitions in some sectors and regions may be on a par with, or superior to those of an emissions-intensive future.''' Cost reductions in key technologies, particularly in electricity and light-duty transport, have increased the economic attractiveness of near-term low-carbon transitions. Long-term mitigation costs are not well understood and depend on policy design and implementation, and the future costs and availability of technologies. Advances in low-carbon energy resources and carriers such as next-generation biofuels, hydrogen produced from electrolysis, synthetic fuels, and carbon-neutral ammonia would substantially improve the economics of net-zero energy systems. ( ''medium confidence'' ) {6.4, 6.7}

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