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Source: Data from IEA, World Energy Outlook, IEA, Paris, 2004. With permission.

Source: Data from IEA, World Energy Outlook, IEA, Paris, 2004. With permission.

energy in Africa, 29.2% in Latin America, and 32.7% in Asia (Table 1.4; IEA 2005). However, biomass is used very inefficiently for cooking in these countries. Such use has also resulted in significant health problems, especially for women.

The total share of all renewables for electricity production in 2002 was about 17%, a vast majority (89%) of it being from hydroelectric power (Table 1.5).

1.4.7 Wind Power

Wind-energy technology has progressed significantly over the last two decades. The technology has been vastly improved and capital costs have come down to as low as $1000 per kW. At this level of capital costs, wind power is already economical at locations with fairly good wind resources. Therefore, the average annual growth in worldwide wind energy capacity from 2000 to 2003 was over 30% (Figure 1.9) and it continued to grow at that rate in 2004 and 2005. The average growth in the United States over the same period was 37.7%. The total worldwide installed wind power capacity that was 39 GW in 2003 (Figure 1.9), reached a level of 59 GW in 2005 (WWEA 2006). The total theoretical potential for onshore wind power for the world is around 55 TW with a practical potential of at least 2 TW (UNDP 2004), which is about two-thirds of the entire present worldwide generating capacity. The offshore wind energy potential is even larger.

1.4.8 Solar Energy

The amount of sunlight striking the Earth's atmosphere continuously is 1.75 X 105 TW. Considering a 60% transmittance through the atmospheric cloud cover, 1.05X105TW reaches the Earth's surface continuously. If the irradiance on only 1% of the Earth's surface could be converted into electric energy with a 10% efficiency, it would provide a resource base of 105 TW, whereas the total global energy needs for 2050 are projected to be about 25-30 TW. The present state of solar energy technologies is such that solar-cell efficiencies have reached over 20% and solar thermal systems provide efficiencies of 40%-60%. With the present rate of technological development, these solar technologies will continue improving, thus bringing the costs down, especially with the economies of scale.

Solar PV panels have come down in cost from about $30/W to about $3/W in the last three decades. At $3/W panel cost, the overall system cost is around $6/W, which is still too high to compete with other resources for grid electricity. However, there are many off-grid applications where solar PV is already cost-effective. With net metering and governmental incentives, such as feed-in laws and other policies,

FIGURE 1.9 World wind-energy installed capacity and growth rates. (Data from IEA, World Energy Outlook, IEA, Paris, 2004. With permission.)
TABLE 1.6 Growth in Photovoltaics (PV) Demand (2000-2003)


Percent Increase 2000-2003 (%)

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Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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