Literature overview of published global and regional renewable energy potential estimates. This section provides definitions for different types of RE potentials and introduces a new category, the economic renewable energy potential in space constrained environments. The potential for utility scale solar and onshore wind in square kilometre and maximum possible installed capacity (in GW) are provided for 75 different regions. The results set the upper limits for the deployment of solar- and wind technologies for the development of the 2.0 °C and 1.5 °C energy pathways.
There is a wide range of estimates of global and regional renewable energy potentials in the literature, and all conclude that the total global technical renewable energy potential is substantially higher than the current global energy demand (IPCC/SRREN 2011). Furthermore, the IPCC has concluded that the global technical renewable energy potential will not limit continued renewable energy growth (IPCC/SRREN 2011). However, the technical potential is also much higher than the sustainable potential, which is limited by factors such as land availability and other resource constraints.
This chapter provides an overview of various estimates of global renewable energy (RE) potential. It also provides definitions of different types of RE potential and presents mapping results for the spatial RE resource analysis (see Sect. 1.3 in Chap. 3)—[R]E-SPACE. The [R]E-SPACE results provide the upper limit for the deployment of all solar and wind technologies used in the 2.0 °C and 1.5 °C Scenarios.
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7.1 Global Renewable Energy Potentials
The International Panel on Climate Change—Special Report on Renewable Energy Sources and Climate Change Mitigation (IPCC-SRRN 2011) defines renewable energy (RE) as:
“ (…) any form of energy from solar, geophysical or biological sources that is replenished by natural processes at a rate that equals or exceeds its rate of use. Renewable energy is obtained from the continuing or repetitive flows of energy occurring in the natural environment and includes low-carbon technologies such as solar energy, hydropower, wind, tide and waves and ocean thermal energy, as well as renewable fuels such as biomass.”
Different types of renewable energy potentials have been identified by the German Advisory Council on Climate Change (WBGU)—World in Transition: Towards Sustainable Energy Systems, Chap. 3, page 44, published in 2003: (WBGU 2003) (Quote):
“Theoretical potential: The theoretical potential identifies the physical upper limit of the energy available from a certain source. For solar energy, for example, this would be the total solar radiation falling on a particular surface. This potential does therefore not take account of any restrictions on utilization, nor is the efficiency of the conversion technologies considered.
Conversion potential: The conversion potential is defined specifically for each technology and is derived from the theoretical potential and the annual efficiency of the respective conversion technology. The conversion potential is therefore not a strictly defined value, since the efficiency of a particular technology depends on technological progress.
Technological potential: The technological potential is derived from the conversion potential, taking account of additional restrictions regarding the area that is realistically available for energy generation. […] like the conversion potential, the technological potential of the different energy sources is therefore not a strictly defined value but depends on numerous boundary conditions and assumptions.
Economic potential: This potential identifies the proportion of the technological potential that can be utilized economically, based on economic boundary conditions at a certain time […].
Sustainable potential: This potential of an energy source covers all aspects of sustainability, which usually requires careful consideration and evaluation of different ecological and socio-economic aspects […].” (END Quote)
For the development of the 2.0 °C and 1.5 °C Scenarios, an additional renewable energy potential—the economic renewable energy potential in a space-constrained environment (Sect. 3.2 in Chap. 3)—has been analysed and utilized in this study.
The theoretical and technical potentials of renewable energy are significantly larger than the current global primary energy demand. The minimum technical potential of solar energy, shown in Table 7.1 (Turkenburg et al. 2012), could supply the global primary energy of 2015 112 times over.
Table 7.1
Theoretical and technical renewable energy potentials versus utilization in 2015
Renewable energy resource
Theoretical potential (Annual energy flux) [EJ/year] IPCC 2011
Technical potential [EJ/year] Global energy assessment 2012, Chap. 11, p. 774
Utilization in 2015 [EJ/year] IEA-WEO 2017
Solar energy
3,900,000
62,000–280,000
1.3
Wind energy
6000
1250–2250
1.9
Bioenergy
1548
160–270
51.5
Geothermal energy
1400
810–1545
2.4
Hydropower
147
50–60
13.2
Ocean energy
7400
3240–10,500
0.0018
Total
76,000–294,500
(Total primary energy demand 2015) 555 EJ/year
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However, the technical potential is only a first indication of the extent to which the resource is available. There are many other limitations, which must be considered. One of the main constraints on deploying renewable energy technologies is the available space, especially in densely populated areas where there are competing claims on land use, such as agriculture and nature conservation, to name just two.
It is neither necessary nor desirable to exploit the entire technical potential. The implementation of renewable energy must respect sustainability criteria to achieve a sound future energy supply. Public acceptance is crucial, especially because the decentralised character of many renewable energy technologies will move systems closer to consumers. Without public acceptance, market expansion will be difficult or even impossible (Teske and Pregger 2015). The energy policy framework in a particular country or region will have a profound impact on the expansion of renewables, in terms of both the economic situation and the social acceptance of renewable energy projects.
7.1.1 Bioenergy
The discrepancy between the technical potential for bioenergy and the likely sustainable potential raises some issues that warrant further discussion. Recent analyses put the technical potential for primary bioenergy supply at 100–300 EJ/year. (GEA 2012; Smith et al. 2014). However, the dedicated use of land for bioenergy—whether through energy crops or the harvest of forest biomass—raises concerns over competition for land and the carbon neutrality of bioenergy (Field and Mach 2017; Searchinger et al. 2017). Research that focused on the trade-offs between bioenergy production, food security, and biodiversity found that less than 100 EJ /year. could be produced sustainably (Boysen et al. 2017; Heck et al. 2018), although such production levels would be dependent on strong global land governance systems (Creutzig 2017).
The carbon neutrality of bioenergy is based on the assumption that the CO2 released when bioenergy is combusted is then recaptured when the biomass stock regrows (EASAC 2017). Most land is part of the terrestrial carbon sink or is used for food production, so that harvesting for bioenergy will either deplete the existing carbon stock or displace food production (Searchinger et al. 2015, 2017). The use of harvested forest products (e.g., wood pellets) for bioenergy is not carbon neutral in the majority of circumstances because an increased harvesting in forests leads to a permanent increase in the atmospheric CO2 concentration (Sterman et al. 2018; Smyth et al. 2014; Ter Mikaelian et al. 2015). Leaving carbon stored in intact forests can represent a better climate mitigation strategy (DeCicco and Schlesinger 2018), because increased atmospheric concentrations of CO2 from the burning of bioenergy may worsen the irreversible impacts of climate change before the forests can grow back to compensate the increase (EASAC 2017; Booth 2018; Schlesinger 2018).
Bioenergy sourced from wastes and residues rather than harvested from dedicated land can be considered carbon neutral, because of the ‘carbon opportunity cost’ per hectare of land (i.e., bioenergy production reduces the carbon-carrying capacity of land) (Searchinger et al. 2017). The supply of waste and residues as a bioenergy source is always inherently limited (Miyake et al. 2012). Although in some cases, burning residues can still release more emissions into the atmosphere in the mid-term (20–40 years) than allowing them to decay (Booth 2018), there is general agreement that specific and limited waste materials from the forest industry (for example, black liquor or sawdust) can be used with beneficial climate effects (EASAC 2017). The use of secondary residues (cascade utilization) may reduce the logistical costs and trade-offs associated with waste use (Smith et al. 2014).
7.2 Economic Renewable Energy Potential in Space-Constrained Environments
Land is a scarce resource. The use of land for nature conservation, agricultural production, residential areas, and industry, as well as for infrastructure, such as roads and all aspects of human settlements, limits the amount of land available land for utility-scale solar and wind projects. Furthermore, solar and wind generation require favourable climatic conditions, so not all available areas are suitable for renewable power generation. To assess the renewable energy potential of the available area, all ten world regions defined in Table 8 in Sect. 1 of Chap. 5 were analysed with the [R]E-SPACE methodology described in Sect. 3 of Chap. 3.
Given the issues involved in dedicated land-use for bioenergy outlined above, we assume that bioenergy is sourced primarily from cascading residue use and wastes, and do not analyse the availability of land for dedicated bioenergy crops.
This analysis quantifies the available land area (in square kilometres) in all regions and sub-regions with a defined set of constraints.
7.2.1 Constrains for Utility-Scale Solar and Wind Power Plants
The following land-use areas were excluded from the deployment of utility-scale solar photovoltaic (PV) and concentrated solar power plants:
After the spatial analysis, the remaining available land areas were analysed for their solar and wind resources. For concentrated solar power, a minimum solar radiation of 2000 kilowatt hours per square meter and year (kWh/m2 year) is assumed as the minimum deployment criterion, and onshore wind potentials under an average annual wind speed of 5 m/s have been omitted.
In the next step, the existing electricity infrastructure of power lines and power plants was mapped for all regions with WRI (2018) data. Figure 7.1 provides an example of the electricity infrastructure in Africa. These maps provide important insights into the current situation in the power sector, especially the availability of transmission grids. This is of particular interest for developing countries because it allows a comparison of the available land areas that have favourable solar and wind conditions with the infrastructure available to transport electricity to the demand centres. This assessment is less important for OECD regions because the energy infrastructure is usually already fairly evenly distributed across the country—except in some parts of Canada, the United States, and Australia. For some countries, coverage is not 100% complete due to a lack of public data sources. This is particularly true for renewable energy generation assets such as solar, wind, biomass, geothermal energy, and hydropower resources.
Fig. 7.1
Electricity infrastructure in Africa—power plants (over 1 MW) and high-voltage transmission lines
×
Figure 7.2 shows the solar potential for utility-scale solar power plants—both solar PV and concentrated solar power—in Africa. The scale from light yellow to dark red shows the solar radiation intensity: the darker the area, the better the solar resource. The green lines show existing transmission lines. All areas that are not yellow or red are unsuitable for utility-scale solar because there is conflicting land use and/or there are no suitable solar resources. Africa provides a very extreme example of very good solar resources far from existing infrastructure. While roof-top solar PV can be deployed virtually anywhere and only needs roof space on any sort of building, bulk power supply via solar—to produce synthetic and hydrogen fuels—requires a certain minimum of utility-scale solar applications. The vast solar potential in the north of Africa—as well as in the Middle East—has been earmarked for the production of synthetic and hydrogen fuels and for the export of renewable electricity (via sub-sea cable) to Europe in the long-term energy scenarios in the 2.0 °C and 1.5 °C Scenarios.
Fig. 7.2
Solar potential in Africa
×
Europe, in contrast, is densely populated and has fewer favourable utility-scale solar sites because of both its lower solar radiation and conflicting land-use patterns. Figure 7.3 shows Europe’s potential for utility-scale solar power plants. Only the yellow and red dots across Europe, most visible in the south of Spain, south of the Alps, south-west Italy, and the Asian part of Turkey, mark regions suitable for utility-scale solar, whereas roof-top solar can be deployed economically across Europe, including Scandinavia.
Fig. 7.3
Europe’s potential for utility-scale solar power plants
×
However, Africa and Europe are in a good position, from a technical point of view, to form an economic partnership for solar energy exchange.
The situation for onshore wind power differs from that for solar energy. The best potential is in areas that are more than 30° north and south of the equator, whereas the actual equatorial zone is less suitable for wind installation. North America has significant wind resources and the resource is still largely untapped, even though there is already a mature wind industry in Canada and the USA. Figure 7.4 shows the existing and potential wind power sites. While significant wind power installations are already in operation, mainly in the USA, there are still very large untapped resources across the entire north American continent, in Canada and the mid-west of the USA.
Fig. 7.4
OECD North America: existing and potential wind power sites
×
Unlike the situation in the USA, wind power in Latin America is still in its initial stages and the industry, which has great potential, is still in its infancy. Figure 7.5 shows the existing wind farm locations—marked with blue dots—and the potential wind farm sites, especially in coastal regions and the entire southern parts of Argentina and Chile.
Fig. 7.5
Latin America: potential and existing wind power sites
×
The available solar and wind potentials are distributed differently across all world regions. Whereas some regions have significantly more resources than others, all regions have enough potential to supply their demand with local solar and wind resources—together with other renewable energy resources, such as hydro-, bio-, and geothermal energies.
Table 7.2 provides an overview of the key results of the [R]E-SPACE analysis. The available areas (in square kilometres) are based on the space-constrained assumptions (see Sect. 2.1 in Chap. 7). The installed capacities are calculated based on the following space requirements (Table 7.2):
Solar photovoltaic: 1 MW = 0.04 km2
Concentrated solar power: 1 MW = 0.04 km2
Onshore wind: 1 MW = 0.2 km2
Table 7.2
[R]E-SPACE: key results part 1
Region
Subregion
Solar
Onshore wind
Potential availability for utility-scale installations
Space potential
Potential availability for utility-scale installations
Space potential
[km2]
[GW]
[km2]
[GW]
OECD North America
Canada East
2,742,668
68,567
2,530,232
12,651
Canada West
2,242,715
56,068
2,180,271
10,901
Mexico
3,365,974
84,149
3,341,940
16,710
USA – South East
269,650
6741
254,976
1275
USA – North East
1,043,033
26,076
1,043,026
5215
USA – South West
1,847,162
46,179
1,840,980
9205
USA – North West
431,277
10,782
427,709
2139
USA – Alaska
1,152,288
28,807
1,091,698
5458
Latin America
Caribbean
34,238
856
34,238
171
Central America
17,529
438
17,603
88
North Latin America
869,811
21,745
869,811
4349
Brazil
1,623,625
40,591
1,623,625
8118
Central South America
1,023,848
25,596
1,024,340
5122
Chile
693,990
17,350
693,990
3470
Argentina
1,651,168
41,279
1,651,168
8256
CSA – Uruguay
32,360
809
32,360
162
Europe
EU – Central
146,797
3670
146,797
734
EU – UK and Islands
22,406
560
22,406
112
EU – Iberian Peninsula
15,608
390
15,608
78
EU – Balkans + Greece
4825
121
4825
24
EU – Baltic
32,090
802
32,090
160
EU – Nordic
218,496
5462
218,496
1092
Turkey
134,354
3359
134,354
672
Middle East
East – Middle East
165,302
4133
5738
29
North – Middle East
91,970
2299
7123
36
Iraq
119,967
2999
9104
46
Iran
586,595
14,665
57,965
290
United Arab Emirates
530
13
530
3
Israel
386
10
217
1
Saudi Arabia
13,284
332
13,284
66
Africa
North – Africa
9,726,388
243,160
9,784,694
48,923
East – Africa
6,378,561
159,464
6,980,497
34,902
West – Africa
8,336,960
208,424
8,669,628
43,348
Central – Africa
7,229,129
180,728
7,509,351
37,547
Southern – Africa
3,269,644
81,741
3,547,591
17,738
Rep. South Africa
1,626,528
40,663
1,650,471
8252
Table 7.3
[R]E-SPACE: key results part 2
Region
Subregion
Solar
Onshore wind
Potential availability for utility-scale installations
Space potential
Potential availability for utility-scale installations
Space potential
[km2]
[GW]
[km2]
[GW]
Non-OECD Asia
Asia-West (Himalaya)
1,315,395
32,885
801,044
4005
South and South East Asia
9062
227
8184
41
Asia North West
184,503
4613
43,710
219
Asia Central North
138,861
3472
81,228
406
Philippines
2634
66
941
5
Indonesia
106,581
2665
12,162
61
Pacific Island States
5510
138
673
3
India
North – India
229,314
5733
163,118
816
East – India
32,511
813
5195
26
West – West
224,355
5609
121,441
607
South – Incl. Islands
129,346
3234
103,177
516
Northeast – India
77,379
1934
1821
9
China
East – China
47,621
1191
39,648
198
North – China
425,350
10,634
825,272
4126
Northeast – China
193,006
4825
192,110
961
Northwest – China
5,642,854
141,071
1,603,909
8020
Central – China
256,272
6407
211,229
1056
South – China
500,211
12,505
317,046
1585
Taiwan
5862
147
2791
14
Tibet
5460
137
377,610
1888
OECD Pacific
North Japan
8697
217
8213
41
South Japan
3567
89
3036
15
North Korea
10,724
268
9854
49
South Korea
2411
60
1892
9
North New Zealand
22,699
567
22,163
111
South New Zealand
25,106
628
46,266
231
Australia – South and East (NEM)
2,080,117
52,003
2,035,523
10,178
Australia – West and North (NT)
2,813,791
70,345
2,762,499
13,812
Note: Mapping Eurasia was not possible because the data files were incomplete.
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