Latest research

Sustainability, efficiency and equitability of water consumption and pollution in Latin America and the Caribbean

Authors: Mesfin M. Mekonnen, Markus Pahlow, Maite M. Aldaya, Erika Zarate and Arjen Y. Hoekstra.

Abstract: This paper assesses the sustainability, efficiency and equity of water use in Latin America and the Caribbean (LAC) by means of a geographic Water Footprint Assessment (WFA). It aims to provide understanding of water use from both a production and consumption point of view.

The study identifies priority basins and areas from the perspectives of blue water scarcity, water pollution and deforestation. Wheat, fodder crops and sugarcane are identified as priority products related to blue water scarcity. The domestic sector is the priority sector regarding water pollution from nitrogen. Soybean and pasture are priority products related to deforestation. We estimate that consumptive water use in crop production could be reduced by 37% and nitrogen-related water pollution by 44% if water footprints were reduced to certain specified benchmark levels.

The average WF per consumer in the region is 28% larger than the global average and varies greatly, from 912 m3/year per capita in Nicaragua to 3468 m3/year in Bolivia. Ironically, the LAC region shows significant levels of undernourishment, although there is abundant water and food production in the region and substantial use of land and water for producing export crops like soybean.

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The consumptive water footprint of electricity and heat: a global assessment

Authors: Mesfin M. Mekonnen, P. W. Gerbens-Leenes and Arjen Y. Hoekstra

Abstract: Water is essential for electricity and heat production. This study assesses the consumptive water footprint (WF) of electricity and heat generation per world region in the three main stages of the production chain, i.e. fuel supply, construction and operation. We consider electricity from power plants using coal, lignite, natural gas, oil, uranium or biomass as well as electricity from wind, solar and geothermal energy and hydropower.

The global consumptive WF of electricity and heat is estimated to be 378 billion m3 per year. Wind energy (0.2–12 m3 TJe−1), solar energy through PV (6–303 m3 TJe−1) and geothermal energy (7–759 m3 TJe−1) have the smallest WFs, while biomass (50 000–500 000 m3 TJe−1) and hydropower (300–850 000 m3 TJe−1) have the largest. The WFs of electricity from fossil fuels and nuclear energy range between the extremes. The global weighted-average WF of electricity and heat is 4241 m3 TJe−1. Europe has the largest WF (22% of the total), followed by China (15%), Latin America (14%), the USA and Canada (12%), and India (9%). Hydropower (49%) and firewood (43%) dominate the global WF. Operations (global average 57%) and fuel supply (43%) contribute the most, while the WF of construction is negligible (0.02%).

Electricity production contributes 90% to the total WF, and heat contributes 10%. In 2012, the global WF of electricity and heat was 1.8 times larger than that in 2000. The WF of electricity and heat from firewood increased four times, and the WF of hydropower grew by 23%. The sector’s WF can be most effectively reduced by shifting to greater contributions of wind, PV and geothermal energy.

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Water footprint accounting and scarcity indicators of conventional and organic dairy production systems

Authors: Julio Cesar Pascale Palhares, Jose Ricardo Macedo Pezzopane

Abstract: The amount of water that is used in animal agriculture influences society’s view of its environmental sustainability. Estimates of how much water is consumed to produce one kg of milk remain scarce. Such information needs to be given to society and water resource managers. The aim of this study were to assess the water footprint of both a conventional and an organic dairy production system and identified the components and processes that have the greatest water use in terms of green, blue, gray water, and virtual water. Additionally, it analyzed the impact of element on gray water footprint, and utilized indicators to evaluate the water scarcity.

These were done following a water footprint method compliant with Water Footprint Network. Green water footprint was the most significant contributor to the total footprint values for both systems. This situation can be understood as an opportunity to improve the agriculture water use efficiency and promote the integration between agriculture and livestock. Virtual water represents from 39% to 57% of footprint value for the conventional and from 32% to 59% for the organic. The consumption of water for irrigation accounted for the greatest percentage of blue water, 95% for conventional and 96% for organic. The element used to calculate gray water footprint has a significant impact on its values.

Footprints calculated having phosphorus as element were 1.5 and 1.9 times higher for conventional and organic, respectively. Both conventional and organic farms showed an equal green water scarcity index (1.1) and despite the two farms are located in places with high rainfall, they suffered green water scarcity The blue water scarcity index was 0.11 for conventional and 0.13 for organic.

Study concluded that a product with a lower water footprint could be more damaging to the environment than one with a higher water footprint depending on water availability. The water footprint approach evidenced that nutritional management is crucial to improve water use. Results cannot support the con- sequences in changing the conventional or the organic production system regarding the use of water. The more efficient water use depends on productions factors and water availabilities that are specific to each system.

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