The Paris Agreement’s goals require significant change in how we use and produce energy on a global level. This energy transition must be started immediately and without further delay, and concerns energy-producing industry and utilities as well as every energy consumer—from the industry level down to the residential sector. A combination of energy efficiency and the use of renewable energies will involve new business concepts for the energy sector, which will require entirely new policies that provide a new market framework. The implementation of new technologies and business concepts will include policy changes on the community level as well as by national governments and international organizations. While the 2.0 °C Scenario allows for a 3–5 years transition period in which to implement policy measures, the 1.5 °C Scenario allows no further delay but requires an immediate start, at the latest in 2020. Therefore, the 1.5 °C Scenario presented in this book provides a technical pathway that assumes and allows no political delay, and may therefore be seen as a technical benchmark scenario.
During the development of the energy scenario pathways, it became clear that even the most ambitious ‘man-on-the-moon’ program—if focussed only on the energy sector—would not be enough. Therefore, the political framework required to implement the Paris Agreement on national levels must also take the land-use sector, as well as the main GHGs, methane, N2O, and fluorinated gases, into account.
The following sections present the main findings and lessons of this research project, and highlight its limitations and further research requirements. Finally, we provide policy recommendations for the energy sector in order to implement the -energy scenarios.
13.1 Findings and Limitations—Modelling
The following section focuses on the main findings in all parts of the research, with priority given to high-level lessons, to avoid the repetition of previous chapters.
13.1.1 Key Findings—Renewable Energy Potential Mapping
Various research projects have analysed renewable energy potentials and all have in common that the renewable energy potential exceeded the current and projected energy demands over the next decades by an order of magnitude. However, regional distributions are uneven, and especially in densely populated regions, such as urban areas, the local renewable energy resource might be unable to supply the demand. Therefore, renewable energies might have to be transported by power lines or in the form of gasified or liquid renewable fuels to the demand centre. However, all 10 regions and 75 sub-regions examined had sufficient renewable energy resources to meet the regional needs.
13.1.2 Limitations and Further Research—Renewable Energy Potential
The quality of data varies significantly across the regions and especially detailed high-resolution surveys have their limits. Due to the limited available data, detailed mapping of the Eurasia region—especially for Russia and parts of central Asian countries—was not possible. Therefore, in this case, we relied on research published in the scientific literature. Onshore wind data were generally only available for 80 m above the ground, whereas no data for 100–120 m were available in most cases. However, modern wind turbines operate at those higher levels and wind resources are generally better at these elevations. Therefore, further research is required using open source data for onshore and offshore wind data at the 100 m level.
13.1.3 Key Findings—Transport Scenario
Transport modelling has shown that the 2.0 °C and 1.5 °C pathways can be met when strong and determined measures are taken, starting immediately. They include rapid electrification across passenger and freight transport modes, a shift towards more energy-efficient transport modes, and a build-up of biomass and synfuel capacities for the transport modes that are less inclined towards electrification due to range or constructional constraints, as is the case in aviation. In the road sub-sector, which is the most relevant emission source in the transport area, battery electric and fuel-cell electric vehicles must be widely introduced, which will also require a stringent parallel build-up of recharging and refuelling infrastructures.
In general, we found that beyond pure technical measures with regard to powertrain shifts and overall efficiency enhancements, fundamental changes in today’s mobility patterns will also be required to meet the 2.0 °C Scenario, and even more so for the 1.5 °C pathway. This will apply particularly to the car use habits in the OECD countries. In essence, definite limitations on transport activities and modal shifts towards mainly buses and railways in some world regions and sub-sectors will be required to meet the Paris goals. However, the Non-OECD world regions will mainly increase their overall transport activity until 2050. The 2.0 °C and 1.5 °C transport scenario pathways will not be achieved automatically, but will require long-sighted infrastructural and transport policy framework settings on both inter- and intra-governmental levels.
13.1.4 Limitations and Further Research Requirement—Transport
The statistical databases for several world regions on transport activities and fleet and powertrain shares are limited, and in those cases, projections, conclusions by analogy, and estimations were required in our modelling. Therefore, further studies should focus on enhancing these databases and specify the modelling in more detail, which could also include case studies of countries instead of regions, to better address spatial particularities in the transport models. Detailed investigations of mode shift potentials, based on infrastructure capacity constraints, were considered to some extent, but deserve more in-depth modelling in future works. Further research is required to refine the coupling of renewable energy potentials, transport infrastructure upgrades, and the expansion of on-board energy storage usage.
13.1.5 Key Findings—Long-Term Energy Scenario
The 2.0 °C and the 1.5 °C scenarios both represent ambitious pathways that require fundamental changes in current energy consumption and supply. The key strategies of these pathways are the implementation of renewable energy technologies and efficiency improvements in all sectors. The electrification of the transport and heating sectors and the diversification of supply technologies are core elements of both alternative scenarios. Besides numerous technical and structural improvements, behavioural changes among end-users and major changes in investment activities and strategies must be achieved. This applies, for example, to the per capita electricity consumption (electric appliances without heating) of ‘residential and other sectors’, which will decrease in OECD countries by one third between 2015 and 2050 in the 1.5 °C Scenario, but will grows in the non-OECD regions by only 70% in the same period. This could imply limitations on personal consumption compared with today’s standards, particularly in OECD countries—at least for as long as fossil fuels still play a significant role. Another example is the final energy demand per $GDP in the ‘Industry’ sector, which will decrease by 65% in OECD regions and by 80% in non-OECD regions, an ambitious pathway that will require stringent technology change and replacement strategies and supporting regulatory and governance measures to trigger huge investments for its realization.
On the energy supply side, considerable contributions in the future are assumed from wind and solar power, electrification and synthetic fuel use in transport and heating, sustainable biomass use, especially for co-generation and biofuels, and district heating systems that integrate solar, geothermal, and ambient heat potentials. The exploitation of renewable energy potentials depends strongly on regional conditions. In regions such as India and China, a 100% renewable electricity supply will require the extensive use of existing potentials. The global installed capacities of renewable power generation technologies will increase by a factor of more than 12, from 2000 GW in 2015 to more than 25,000 GW in 2050. Cumulative investments for power generation are estimated to increase between 2015 and 2050 by up to around US$ 50,000 billion compared with around US$20000 billion in the reference case. Fuel cost savings could offset around 90% of the additional investment costs as consequence of the fossil fuel phase-out and reductions in demand, but without considering the additional infrastructure demands of the transition arising from grid expansion, storage, and other flexibility demands. In the scenarios, large-scale and long-range electricity transport between Europe and the MENA countries is assumed to be a possible and promising example of supra-regional exchange between regions of production and regions of demand. Many of these import/export relationships must also be realized among countries within individual world regions (which are thus not resolved in our model) to increase the security and cost-efficiency of the energy supply. Decentralization and digitalization, but also the efficient implementation of new respectively the expansion of existing central infrastructures, are other implicit core elements of the scenario narratives. The large-scale generation and use of synthetic fuels are expected to play key roles in the deep-decarbonisation scenario, at least if the intensity of today’s freight transport and air traffic is to be maintained, despite the huge energy losses this option will have. Both alternative scenarios, especially the 1.5 °C Scenario, require a rapid reduction in the final energy demand and, as far as possible, stagnation in the strong global growth in the demand for energy services, at least for as long as fossil energies dominate the energy supply structures.
Besides the structural similarities between both the 2.0 °C and 1.5 °C Scenarios, one main difference between them is the rate of transformation: To maintain the average global temperature increase due to climate change below 1.5 °C, the transformation must be accomplished as fast as technically possible. The trend in increasing global energy-related CO2 emissions must be reversed as soon as possible (in the early 2020s, at the latest) and emissions must be reduced by 70% in 2035 and by 85% in 2040 (compared with emission levels in 1990). Every single year without significant emission reductions on the global level will dramatically reduce our chance to confine global warming to 1.5 °C. In contrast, in the 2.0 °C Scenario, emission reductions in 2035 may be in the order of 40% and 65% in 2040, leaving a little more time for the transition process.
13.1.6 Limitations and Further Research Requirement—Long-Term Energy Scenario
The 1.5 °C Scenario may seem more difficult than similarly ambitious scenarios that were made 10 to even 20 years ago. However, the opportunities to respond to climate change have been largely wasted in the last two decades, and all transition processes have faced huge obstacles in the past due to the inertia and conflicting aims of societies, governments, and most relevant stakeholders. Too often, more attention has been paid to doubters than to facts. Therefore, the scenarios also show that the longer the governments wait, the more difficult it will be to prevent severe climate damage and the greater will be the technical and economic challenges that will be encountered in the energy system transformation.
The coarse regional resolution of such global scenarios does not allow sufficient account to be taken of sub-regional differences in energy demand and the characteristic and favourable possibilities of sustainable supply. However, it can provide rather fundamental insight into basic technical and structural possibilities and requirements of a target-oriented pathway. Our results clearly reveal and quantitatively describe that the coming years will be most critical regarding a successful energy transition because for both parts of the energy transition—efficiency improvement/demand reduction and the implementation of new technologies—huge investments and fundamental changes in producing, distributing, and consuming energy will be needed. Such transformation processes must be analysed and planned carefully under the complex economic and societal framework conditions of each region, down to the country, sub-country, and community levels. Such analyses can then form the basis for the further investigation of the economic implications of these pathways.
Another limitation of this approach is that the economic, technical, and market assumptions made probably have limited consistency. Carbon, fuel, and technology costs are assumed independently of the assumptions regarding overall economic development and the final energy demand. It also remains unclear to what extent the energy transition will change the overall material demand and activity of the manufacturing industry. Furthermore, which economic framework conditions and market mechanisms will be necessary for rapid decarbonisation remain largely unclear, as is whether the current market mechanisms are capable of supporting the fundamental paradigm shift of this target-oriented energy transition.
13.1.7 Key Findings—Power Sector Analysis
Although there are significant differences across all the regions and sub-regions analysed, there are some similarities:
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Increasing loads: The loads in all regions will increase significantly between 2020 and 2050, due to increased electrification of the transport and, to some extent, the heating sectors. Higher loads will require the adaptation of power-lines and transformer stations, especially on distribution grids where electric vehicles are most likely to be charged.
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Increasing reverse power flows: Almost all regions will have periods of negative residual load, when generation is higher than the required load within a specific period of time. This leads to reversed power flow, and the generated electricity must be transported to other regions. The dominant power-generation technologies are wind and solar photovoltaic (PV). Solar PV is mainly connected to the distribution grid and export requires that the electricity must be able to flow from low- to medium-voltage levels, which requires adaptation at transformer stations.
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Ratio between maximum variable generation capacity and maximum load: The results presented in Chap.
8 suggest that a ratio of 180% variable renewable capacity to the maximum load represents the optimum relationship. If the capacity were higher, short-term peaks would appear more frequently, which would lead to higher curtailment, or high storage and transmission demands. Example: The maximum load of a region is 100 GW and the installed capacity of wind and solar PV combined is 180 GW. Short-term peaks are relatively rare, and curtailment is below 10% of the total annual generation potential. If the variable power generation were above 200 GW, while the load remained at 100 GW, the curtailment rates would increase significantly, to 15% and higher.
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Technology variety reduces storage demand: The combination of solar PV and wind leads to a lower storage demand than does a solar- or wind-dominated supply scenario. The relative interaction between the available wind and solar resources, not just in regard to day and night, but also seasonally, will reduce the storage demand in all regions. Therefore, the levelized cost of electricity generation cannot be seen in isolation. Even if, for example, wind is more expensive than solar PV in one region, a combination of wind and solar will lead to a reduction in storage demand and lower systems costs.
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Variety in storage technology and sector coupling: The combination of battery and hydro pump storage technology and the conversion of the gas sector to hydrogen and synthetic fuels will be beneficial. The hydrogen produced can be used for the management of demand, and hydrogen-fuelled power plants can provide valuable dispatch services.
13.1.8 Limitations and Further Research Requirement—Power Sector Analysis
Measured load curves for regions, countries, or states/provinces are often unavailable and, in some countries, are even classified information. Therefore, it was not always possible to compare the calculated loads with actual current actual. However, the comparison of 2020 calculations with current maximum loads for regions and countries with published data showed that the calculations were within a ± 10% range. However, verification was not possible for several regions. Therefore, our analysis may over- or underestimate the current loads and therefore the future projections of loads as well. Therefore, the optimal ratio of maximum load to installed variable capacity requires further research.
More research is also required to verify the thesis of an optimal ratio between the variable generation and maximum load, because the sample size of this study was not sufficient to ensure validity. Furthermore, the optimal mix of solar and wind requires better meteorological data and actual measured load profiles. Access to more detailed data to calculate more case studies is vital to determining the possible optimal combination of wind and solar.
13.1.9 Key Findings—Non-energy Scenarios
The key finding of the land-use-related emission scenarios is that a dedicated concerted effort to sequester carbon by reforestation and forest restoration could re-establish the terrestrial carbon stock of pre-industrial times. That would undoubtedly come with multiple co-benefits, but would not be without challenges. After all, there is a reason why humans in the various corners of the planet pursued deforestation, whether for short-term and short-sighted gains or to establish agricultural areas that fed an increasing population. Therefore, land-use conflicts and trade offs are an inherent part of future mitigation actions, whether CO2 sequestration is pursued by reforestation sequestration or by some biomass and CCS use. Nevertheless, the important result of this study is that the addition of land-use CO2 and other GHG emission pathways to energy-related scenarios yields scenarios that stay below or get below 1.5 °C warming without a reliance on massive net negative CO2 emission potentials towards the second half of this century.
Going beyond the land-use CO2 emission pathways that we sketched for a series of sequestration options, we also designed trajectories for all the other GHGs and aerosols. An unprecedented wealth of scenario information is now available thanks to the recent concerted efforts of the larger integrated assessment community. Designing a novel method here, the Generalized Quantile Walk method, we were able to distil non-CO2 pathways from this rich scenario database—in a way that respects the correlations and dependencies between energy-related CO2 and other gas emissions. This is not only a new methodological advance in scenario research, but also key to the proper estimation of the climate effects of the energy-related CO2 scenarios designed in the main part of this study.
13.1.10 Limitations and Further Research Requirement—Non-energy Scenarios
There are a number of limitations associated with the derived non-energy-related emission trajectories. Possibly the most important opportunity for future research will involve a more fine-grained look at land-use-based sequestration options in various countries and biomes. This study assumed only a rather coarse approximation of the available land areas, sequestration rates, and cumulative changes in land carbon stocks to estimate the potential and time trajectories of those reforestation, forest restoration, agroforestry, and other land-based sequestration options.
In terms of the non-CO2 emission trajectories, this study relied heavily on the collective wisdom embodied within a large set of literature-reported scenarios. Although we have designed probably the most advanced method to distil that knowledge into emission trajectories that are consistent with our energy-related pathways, this meta-analytical approach is not without its limitations. In particular, a bottom-up energy-system and land-use/agricultural model must be able to estimate methane and N2O emissions from various agricultural activities in a more coherent way, which could provide results on a regional level. Such regionally and sectorally specific information would, in turn, allow the examination of various mitigation options for non-CO2 emissions. This bottom-up modelling capacity is missing from our meta-analytical approach.
13.1.11 Key Findings—Employment Analysis
The occupational employment analysis was developed in 2018 to improve the database for the ‘just transition’ concept. Not only is the number of jobs that will be created or lost as a result of a global or regional energy transition important, but also the specific occupations that will be to develop a socially sound transition. This analysis breaks new grounds because very little information has been available. However, the results indicate that even within the seven occupation types, job losses are the exception and almost all trades will gain more jobs.
Very specialized jobs, such as machine operators in coal mines, will be lost and there will be no replacement. Therefore, a detailed analysis of all sectors is required to identify those highly specialized tasks and to develop re-training possibilities.
13.1.12 Limitations and Further Research Requirement—Employment Analysis
The data available on the detailed employment requirements for renewable energies are very limited. Although there are some data for solar PV and onshore and offshore wind, there are almost none for concentrated solar power plants or geothermal energy. Furthermore, occupational surveys of the heating and energy efficiency sectors are required.
13.1.13 Key Findings—Mineral Resource Analysis
Lithium sees the highest projected increase from mined ore of around 40 times current production to above 80 times current production should future technologies be introduced without recycling.
Cumulative primary lithium demand by 2050 for the majority of scenarios is above current reserves of lithium except for the “potential recycling” scenario but less than known resources. The scenarios anticipate a scale up in resource exploration, discovery and production for primary resources to meet demand—assuming lithium-ion batteries continue to dominate as the chemistry of choice. It is important that future mines be responsibly developed and that battery designs be compatible with circular-economy thinking. Significant infrastructure for reuse and recycling will need to be developed to achieve high rates of lithium recycling.
For cobalt, future scenarios exceed currently known reserves and approach currently known resources in 2050. Given the concentrated supply source from the Democratic Republic of Congo, this will continue to keep pressure on exploring alternative battery chemistries and on increasing cobalt recycling. Attention must continue to be paid to reducing the social and environmental impacts of supply whilst supporting development noting the significant adverse impacts on human and environmental health associated with cobalt mining. While the value of cobalt in EV battery recycling is already an important component of the recycling economics because of supply limitations, the social and environmental challenges provide a further driver for increasing recycling.
For silver, the potential of materials efficiency (using less silver per GW solar PV panel) has potential to reduce demand owing to the long lifetimes of PV panels. Under some scenarios using future technology with recycling, the levels of silver demand are similar to current production.
13.1.14 Limitations and Further Research Requirement—Mineral Resource Analysis
This study focuses only on the metal demand for renewable energy (generation and storage) and transport and does not consider other demands for these metals. However, it is expected that with the increase in renewable energy, renewable energy technologies will consume a greater share of these metals and it is anticipated that this growth will have significant influence on overall market dynamics, including influencing prices, which may feedback to efforts to reduce material intensity and invest in reuse and recycling infrastructure.
Promoting the transition to circular economy for both renewable energy and resource cycles; and adopting a systems view that considers available supply as well as social and environmental factors is critically important. To support sustainable development goals, both the primary and secondary sources of the resources required to underpin this renewable energy transformation needs to be stewarded as the supply chains develop. The high total demand requirements for energy metals, demonstrates the importance of redesigning technologies and systems to eliminate the adverse social and environmental supply chain impacts, to promote long-life products, and to actively encourage efficient material use in both energy and transport sectors.