Although hydropower generation is a major water user, most of the water used is returned to the river downstream even though it is in part consumptive (reservoir evaporation) and has important impacts on other attributes of streamflows (timing and quality). However, the benefits of hydropower generation do not always flow to the people who depend on rivers for their livelihoods.
photo by Andrew Clarke
Hydroelectricity is currently the largest renewable source for power generation in the world. Hydropower’s share in total electricity generation is expected to remain around 16% through 2035. In Latin America and the Caribbean, hydropower provides some 65% of all electricity generated (even more in Brazil, Colombia, Costa Rica, Paraguay and Venezuela); the world average is 16%.
Thermal power plants are responsible for roughly 80% of global electricity production. Power plant cooling is responsible for 43% of total freshwater withdrawals in Europe, nearly 50% in the USA, and more than 10% in China.
Global water withdrawals are projected to increase by 55% through 2050 due to growing demands from manufacturing (400%), thermal electricity generation (140%) and domestic use (130%). The largest proportion of this growth will occur in countries with developing or emerging economies and increasing standards of living, through their greater demand for food, energy and other goods, the production of which can require significant quantities of water. Roughly 75% of all industrial water withdrawals are used for energy production. Groundwater is the primary source of drinking water worldwide: globally, the rate of groundwater abstraction is increasing by 1-2% per year. There is clear evidence that groundwater supplies are diminishing, with an estimated 20% of the world's aquifers being over-exploited, some critically so.
Whereas energy is required mainly for the provision of water services, water resources are required in the production of energy. In 2010, 15% of the world’s total water withdrawals – about 583 billion m3, or roughly 75% of all industrial water withdrawals - were used for energy production. Water demand for energy will certainly increase as energy demand is expected to increase by more than one third in the period 2010–2035. Approximately 90% of global power generation is water intensive: water is used directly for hydropower generation as well as for all forms of thermal power generation schemes.
Over 1.4 billion people currently live in river basins where the use of water exceeds minimum recharge levels
Over 1.4 billion people currently live in river basins where the use of water exceeds minimum recharge levels, leading to the desiccation of rivers and depletion of groundwater. In 60% of European cities with more than 100 000 people, groundwater is being used at a faster rate than it can be replenished.
Part of the current pressure on water resources comes from increasing demands for animal feed. Meat production requires 8-10 times more water than cereal production.
The world’s population is growing by about 80 million people a year, implying increased freshwater demand of about 64 billion cubic metres a year. Competition for water exists at all levels and is forecast to increase with demands for water in almost all countries.
70% of the blue water withdrawals at global level go to irrigation. Irrigated agriculture represents 20% of the total cultivated land but contributes 40% of the total food produced worldwide.70% of the blue water withdrawals at global level go to irrigation. Irrigated agriculture represents 20% of the total cultivated land but contributes 40% of the total food produced worldwide.