The electricity scenario

As power plants last 30 years or more, he extent to which the world electricity supply in 2050 will be renewables-intensive depends in part on utility investment decisions made over the next decade. Table 2 shows the electricity supply scenario [29].

The potential contribution of intermittents depends on regional weather and land use restrictions. Their share in the energy generation would increase from 20% in 1990 (mostly hydroelectric power) to about 60% in 2025, with roughly comparable contributions from hydropower, intermittent renewables (wind and direct solar power), and biomass. The contribution of intermittent renewables could be as high as 30% by the middle of the next century.

Many utilities around the world are adopting natural gas, gas turbine-based power systems as the
thermal-electric technology of choice. The low cost and operational advantages of these turbine systems make them attractive in serving the needs of many utility planners today, as well as in the future when intermittent renewables could play large roles. Emphasis on gas turbines in the near term makes it possible to avoid commitments to large conventional power plants while alternatives, including renewables, are explored. Also, the dispatch of many small-scale gas turbines distributed around a utility’s service territory will provide utilities with valuable experience that can eventually be transferred to dispersed renewable systems.

A high rate of penetration by intermittent renewables without electric storage would be facilitated

  1990     2025     2050    
  IC* DC** Global IC* DC** Global IC* DC** Global
Coal 3,197 585 3,782 754 1,517 2,271 - 2,032 2,032
Oil 737 305 1,042 - - - - - -
Natural gas 864 235 1,099 2,096 2,652 4,748 2,289 5,881 8,170
Nuclear 1,337 62 1,399 1,588 246 1,834 1,588 246 1,834
Hydro 1,296 584 1,880 1,930 1,839 3,769 2,140 2,645 4,785
Intermittents - - - 2,309 2,342 4,651 4,038 5,538 9,576
Bagasse - - - 20 1,108 1,128 20 1,315 1,335
Biomass - - - 1,377 1,009 2,386 2,388 1,696 4,048
Methanol - - - 57 163 220 82 266 348
Geothermal 15 - 15 197 - 197 212 - 212
Other 21 - 21 - - - - - -
TOTAL 7,463 1,771 9,239 10,328 10,876 21,204 12,757 19,619 32,376

Table 2: Electricity supply scenarios, in TWh/year (*Industrialised Countries, ** Developing Countries) [29]

by emphasis on advanced natural gas-fired gas turbine power generating systems. Such power generating systems (characterised by low capital cost, high thermodynamic efficiency, and the flexibility to vary the electrical output quickly in response to changes in the output of intermittent power generating systems) would make it possible to back up the intermittent renewables at low cost, with little need of electrical storage.

Because of these advantages, the role of natural gas is assumed to increase rapidly in the global scenario, with its share in power generation increasing from 12% in 1990 to 25% in 2025 to 2050.

It is assumed that biomass is preferred over coal whenever coal shows no obvious economic advantage. Under this assumption, the biomass share in power generation would be about 18% in the period 2025 to 2050, and coal would be used for power generation primarily in regions where availability of inexpensive renewable resources is limited. As a result, the amount of electricity produced from coal at the global level would be reduced by 46% between 1990 and 2050; because of growing efficiency of coal use (with all coal power provided by fuel cells in 2050) the amount of coal needed for power generation would be reduced more, by 70%.

In most regions it was assumed that nuclear power generation between 2025 and 2050 would be at the level of the output of plants that are now either operating or under construction. Accordingly, the amount of nuclear power generated world-wide in 2025 and beyond would be 31% more than in 1990. Only modest further reductions in CO2 emissions could be achieved by complementing the renewables deployed in the renewables-intensive scenario with more nuclear power substituted for fossil fuels in power generation, because the power sector accounts for such a small fraction of the CO2 generated in this scenario.

Although hydroelectric power is economically attractive, environmental concerns and other restrictions will limit its growth. As a result of considering such restrictions on a region-to-region basis, the global share of power generation accounted by hydroelectricity would decline from 20% to 15% by 2050. However, its relative contribution to peak power might not decline in generation, if more generating turbines are added at each installation to improve the capability to follow load and the variable output of intermittent renewables.