Water for people.pdf - WHO Thailand Digital Repository

2 5 4 / C H A L L E N G E S T O L I F E A N D W E L L - B E I N GDeveloping Energy to Meet Development Needsplay an important role. In addition, at these higher income levels,the need for space heating may decline because houses may bebetter constructed.Table 10.2 shows the use of energy for cooking and heating inrural Mexico. In each of the three regions, as incomes rise thepercentage shares for cooking decline, while those for waterheating increase sharply, and those for space heating first increaseand then decline.End-use of energy varies between regions. For eastern Africa, ithas been estimated that 55 percent of the biomass fuel is used forcooking, 20 percent for water heating, 15 percent for space heatingand 10 percent for ironing and other minor uses. In a survey of sixlow-income villages of southern India, where space heating needsare negligible, little variation in end-use shares was found, withcooking between 76 percent and 81 percent, water heatingbetween 14 and 19 percent, and lighting by kerosene and someelectricity between 2 and 3 percent. In contrast, in Chile’s muchcooler climate, a survey of eight rural villages found that cookingaccounted for 42 to 55 percent and space heating for 23 to 52percent, while water heating absorbed 14 to 22 percent, except onevillage with 6 percent. Clearly, understanding rural energy demandsrequires closer examination of the major household end-uses,cooking, lighting and space heating.The provision of an adequate modern energy supply for waterrelatedactivities in rural areas of developing countries offers manyadvantages, including time saved not having to travel to collectwater, thus increasing productivity; easier access to water throughpumping of drinking water, irrigation water and water for animalhusbandry; health benefits (ranging from water purification throughfiltration to reduced medical costs when boiling water for sterilizationis unnecessary); and health and environmental benefits through thedischarge of wastewater from canals, septic tanks and latrines.Energy also allows wastewater to be treated through aeration.Hydropower Water and EnergyGenerationHydropower is available in a range of sizes from a few hundredwatts to over 10 gigawatts (GW). At the low end of the spectrum,small hydropower can be divided into three categories. Thedefinitions of the categories vary, but are broadly: micro (less than100 kilowatts [kW]), mini (100 kW to 1 megawatt [MW]) and small(1 MW to 10 MW) hydro. Micro- and mini-hydro systems aregenerally stand-alone systems, that is, they are not connected tothe electricity grid.Worldwide electricity production by hydropowerHydropower is already a major contributor to the world’s energybalance, providing, as shown in figure 10.1, 19 percent of totalelectricity production (2,740 terawatts per hour [TWh] in 2001),(IHA, 2002). It is by far the most important and widely usedrenewable source of electricity. According to the IHA, there are377 TWh either under construction or in the planning stage, andthe equivalent of some 4,000 to 7,500 TWh of remaining potential. 1Over the last ten years, the development of new hydropowercapacity has kept pace with the overall generation increase in theelectricity sector (in 1992 the total was 2,105 TWh). In fact,hydropower’s relative contribution of about one fifth has remainedconstant.A major benefit is that the continuing development ofhydroelectric potential will reduce emissions of greenhouse gasesand other air contaminants from thermal power plants. Eachadditional terawatt of hydropower per hour that replaces coalgeneratedelectricity offsets 1 million tons a year of carbon dioxideequivalent. One third of the total carbon dioxide global emissions of22,7 billion in 1995 (WRI et al., 1998) was produced by the energyTable 10.2: End-use of energy for cooking and heating in rural Mexico (in percentages)Region 1 incomes Region 2 incomes Region 3 incomesLow Medium High Low Medium High Low Medium HighCooking 82.6 58.5 50.3 85.4 79.7 57.6 83.3 82.6 48.9Water heating 2.0 9.1 34.0 10.5 36.7 – 4.3 4.3 –Space heating 6.5 32.4 15.7 9.1 9.8 5.7 7.0 13.1 –Total energy 11.5 10.2 8.3 9.1 7.9 5.9 9.1 7.9 5.9In each of the three regions, there is a direct correlation between income and the end-uses: the higher the income, the lower the share of energy used for cooking, but the higher the share forwater heating. Space heating energy use shows a tendency to rise with incomes, then to decrease.Source: Guzman, 1982.1. The World Energy Council estimates the remaining economically exploitable capability at 7,500 TWh/year: http://www.worldenergy.org/wec-geis/publications/reports/ser/hydro/hydro.asp/