IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Working Group III: Mitigation of Climate Change

4.4.4.1 Mitigation potentials of the electricity supply sector

Based on the method described above and the results from the analysis (Table 4.20), the following conclusions can be drawn.

With reference to the baseline:

a) power plants existing in 2010 that remain in operation by 2030 (Table 4.20), including coal, oil and gas-fired, continue to generate 12,111 TWh/yr in 2030 (38% of the total power demand) and produce 5.77 GtCO2-eq/yr of emissions;

b) new additional plants to be built over the 20-year period from 2010 generate 11,471 TWh/yr by 2030 and new plants built to replace old plants generate 8074 TWh/yr;

c) the share of all new build plants burning coal, oil and gas produce around 10 GtCO2-eq/yr by 2030, thereby giving total baseline emissions of 15.77 GtCO2-eq/yr (Table 4.8).

For costs < 20 US$/tCO2-eq avoided:

a) The baseline generation from fossil fuel-fired plants in 2030 of 22,602 TWh (including 14,618 TWh from new generation) reduces by 22.5% to 17,525 TWh (including 9541 TWh of new build generation) due to the increased uptake of low- and zero-carbon technologies. This is a reduction from the 71% of total generation in the baseline to 55%.

b) Of this total, fuel switching from coal to gas results in additional gas-fired plants generating 1,495 TWh/yr by 2030, mainly in non-OECD/EIT countries, and thereby avoiding 0.67 GtCO2-eq/yr of emissions.

c) Renewable energy generation increases from the 2030 baseline of 6126 TWh/yr to 7904 TWh/yr (6122 TWh/yr from new generation plus 2336 TWh/yr remaining in operation from 2010). The share of generation increases from 19.4% in 2010 to 26.7% by 2030.

d) The nuclear power baseline of 2929 TWh/yr by 2030 (9.3% of total generation) increases to 5673 TWh/yr (17.9% of generation), of which 3882 TWh/yr is from newly built plants.

e) Overall, GHG emissions are reduced by 3.95 GtCO2-eq giving 25.0% lower emissions than in the baseline. Around half of this potential occurs in non-OECD/EIT countries with OECD countries providing most of the remainder.

f) Should just 70% of the individual power-generation shares assumed above for all the mitigation technologies be achieved by 2030, the mitigation potential would reduce to 1.69 GtCO2-eq.

g) This range is in reasonable agreement with the TAR analysis potential of 1.3 to 2.5 GtCO2-eq/yr for less than 27 US$/tCO2-eq avoided (IPCC, 2001), because this potential was only out to 2020, the baseline has since been adjusted, and since the TAR was published there has been increased acceptance for improved designs of nuclear power plants, an increase in development and deployment of renewable energy technologies and a better understanding of CCS technologies.

For costs <50 US$/tCO2-eq avoided:

a) Fossil-fuel generation reduces further to 13,308 TWh/yr (of which 5324 TWh/yr is from new build plants) and accounts for 42% of total generation.

b) Renewable-energy generation increases to 10,673 TWh/yr by 2030 giving a 33.7% share of total generation. Solar PV and CSP are more costly (Table 4.19) so they can only offer substitution for fossil fuels above 50 US$/tCO2-eq avoided.

c) Nuclear power share of total generation remains similar since other technologies now compete.

d) CCS now becomes competitive and 2003 TWh/yr is generated by coal and gas-fired plants with CCS systems installed.

e) Overall GHG emissions in 2030 are now reduced by 6.44 GtCO2-eq/yr below the baseline, although if only 70% of the assumed shares of total power generation for all the mitigation technologies are reached by 2030, the potential declines to 3.05 GtCO2-eq. Non-OECD/EIT countries continue to provide half of the mitigation potential.

For costs <100 US$/tCO2-eq avoided:

a) As more low- and zero-carbon technologies become competitive, fossil-fuel generation without CCS further reduces to 11,824 TWh in 2030 and is now only 37% of total generation.

b) New renewable energy generation increases to 8481 TWh/yr by 2030, which together with the plants remaining in operation from 2010, gives a 34% share of total generation.

c) Nuclear power provides 3574 TWh or 17% of total generation.

d) Coal- and gas-fired plants with CCS account for 3650 TWh/yr by 2030 or 12% of total generation.

e) The overall mitigation potential of the electricity sector is 7.22 GtCO2-eq/yr which is a reduction of around 45% of GHGs below the baseline. If only 70% of the assumed shares of power generation by all low- and zero-emission technologies are achieved, then the potential would be around 45% lower at 3.97 GtCO2-eq. Non-OECD/EIT countries contribute over half the total potential.

No single technological option has sufficient mitigation potential to meet the economic potential of the electricity-generation sector. To achieve these potentials by 2030, the relatively high investment costs, the difficulties in rapidly building sufficient capacity and expertise, and the threats resulting from introducing new low-carbon technologies as perceived by the incumbents in the existing markets, will all need to be addressed.

This analysis concentrates on the individual mitigation potentials for each technology at the high end of the wide range found in the literature (Figure 4.29b; IEA, 2006a; IEA, 2006b). This serves to illustrate that significant reductions in emissions from the energy-supply sector are technically and economically feasible using both the range of technology solutions currently available and those close to market. Reducing the individual assumed shares of the technologies in the 2030 power generation mix by 30% gives less ambitious potentials that are closer to the lower end of the ranges found in the literature (Figure 4.29a). Energy-efficiency savings of electricity use in the buildings (Chapter 6) and industry (Chapter 7) sectors will reduce these total emissions potentials (Section 11.3.1).

Table 4.20: Projected power demand increase from 2010 to 2030 as met by new, more efficient additional and replacement plants that will displace 60% of existing plants at the end of their life. The potential mitigation above the baseline of GHG avoided for <20 US$/t, <50 US$/t and <100 US$/tCO2-eq results from fuel switching from coal to gas, a portion of fossil-fuel generation being displaced by nuclear, renewable energy and bioenergy in each region and CCS.

 Power plant efficiencies by 2030 (based on IEA 2004a)a (%) Existing mix of power generation in 2010 (TWh) Generation from additional new plant by 2030 (TWh) Generation from new plant replacing old, existing 2010 plant by 2030 (TWh) Share of mix of generation of total new and replacement plant built by 2030 including CCS at various costs of US$/tCO2-eq avoidedb Total GtCO2-eq avoided by fuel switching, CCS and displacing some fossil fuel generation with low carbon option of wind, solar, geothermal, hydro, nuclear and biomass 
<20 US$/t TWh <50 US$/t TWh <100 US$/t TWh <20 US$/t <50 US$/t <100 US$/t 
OECD   11302 2942 4521   7463   1.58 2.58 2.66 
Coal 41 4079 657 1632 899 121       
Oil 40 472 -163c 189 13       
Gas 48 2374 1771 950 1793 637 458       
Nuclear 33 2462 -325 985 2084 2084 1777       
Hydro 100 1402 127 561 1295 1295 1111       
Biomass 28 237 168 95 263 499 509       
Other renewables 63 276 707 110 1116 1544 1526       
CCS         1282 2082       
EIT   1746 722 698   1420   0.32 0.42 0.49 
Coal 32 381 13 152 72 46 29       
Oil 29 69 -8 28 11       
Gas 39 652 672 261 537 357 240       
Nuclear 33 292 -20 117 442 442 442       
Hydro 100 338 35 135 170 170 170       
Biomass 48 47 109 121       
Other renewables 36 10 23 142 167 191       
CCS         123 222       
Non-OECD/EIT   7137 7807 2855   10662   2.06 3.44 4.08 
Coal 38 3232 3729 1293 2807 1697 1133       
Oil 38 646 166 258 297 179 120       
Gas 46 1401 2459 560 3114 2279 1856       
Nuclear 33 231 289 92 1356 1356 1356       
Hydro 100 1472 874 589 1463 2106 2106       
Biomass 19 85 126 34 621 1294 1443       
Other renewables 28 70 164 28 1004 1154 1303       
CCS         598 1345       
TOTAL   20185 11471 8074 19545 3.95 6.44 7.22 

a Implied efficiencies calculated from WEO 2004 (IEA, 2004b) = Power output (EJ) / Estimated power input (EJ). See Appendix 1, Chapter 11.

b At higher costs of US$/tCO2 avoided, more coal, oil and gas power generation is displaced by low- and zero-carbon options. Since nuclear and hydro are cost competitive at <20 US$/tCO2-eq avoided in most regions (Table 4.9),and the rate of building new plants is constrained, their share remains constant.

c Negative data depicts a decline in generation, which was included in the analysis.

Source: Based on IEA, 2004a.

4.29

´╗┐´╗┐Figure 4.29: Indicative low(a) and high(b) range estimates of the mitigation potential in the electricity sector based on substitution of existing fossil-fuel thermal power stations with nuclear and renewable energy power generation, coupled with energy-efficiency improvements in power-generation plants and transmission, including switching from coal to gas and the uptake of CCS. CHP and heat are not included, nor electricity savings from energy-efficiency measures in the building and industry sectors.

Source: Based on IEA, 2006a; IEA, 2006b.