It is important to select bioful crops for each region according to the availability of water Researchers at the University of Twente (Holland) have calculated the ‘water footprint’ (the amount of water required for cultivation) of biomass crops.
The primary objective of the study was to estimate the water footprint per unit of bioenergy (e.g. per unit of electricity, ethanol and heat). Winnie Gerbens-Leenes, Arjen Hoekstra and Theo van der Meerfound found that bioenergy makes heavy demands on scarce water supplies compared to other sources of energy.
Whole plant
The generation of bioelectricity is significantly more water-efficient – by a factor of two – than the production of biofuel. A significant cause is that in the case of the former, the whole plant is used and in the case of the latter, only the sugar, starch or oil from the seeds is used. In the case of second-generation biofuels, ethanol can also be made from the stalk and leaves, which will have a favourable effect on water consumption.
The researchers show the water footprint of 13 crops: the volume of water – rainwater and irrigation – required per gigajoule of energy production. In respect of various applications of biomass, the researchers present the impact that the cultivation of crops has on water consumption.
Of the crops studied, the most suitable for generating bioelectricity are corn, sugar beet and sugar cane, while the least appropriate are rapeseed and jatropha, the latter having a water footprint that is 10 times larger. The most water-efficient crops for bioethanol production are sugar beet and potato, followed by sorghum (one litre of bioethanol made from sugar beet takes 1,400 litres of water, compared to 2,500 litres for sugarcane for example), while the most water-efficient crops for biodiesel production are soya and rapeseed, with jatropha requiring the most water.
1 litre of diesel, 14,000 litres of water
By linking the water consumption to the location and climate data, it is possible to select the optimum production region for each crop. This makes it easier to prevent biomass cultivation from jeopardising food production in regions hit by water scarcity.
An example is biodiesel, made from rapeseed, soya or jatropha. On average, it takes 14,000 litres of water to produce one litre of biodiesel from rapeseed or soya. However, the water footprint for rapeseed in Western Europe is significantly smaller than in Asia. For soya, India has a large water footprint, while the figures for countries such as Italy and Paraguay are more favourable. Jatropha, which is increasingly used for biomass production, has an even less favourable water footprint of 20,000 litres of water on average for one litre of biodiesel.
This research introduces a new concept into the bioenergy debate. Until now, the discussion has mainly focused on the question of whether food crops should be used to produce fuel. However, underlying this concern is the question of how we should deploy our limited supplies of fresh water, since water used for bioenergy – whether it be for a food crop such as corn or a non-food crop such as jatropha – cannot be used for food production, drinking water or for maintaining natural eco-systems.
The primary objective of the study was to estimate the water footprint per unit of bioenergy (e.g. per unit of electricity, ethanol and heat). Winnie Gerbens-Leenes, Arjen Hoekstra and Theo van der Meerfound found that bioenergy makes heavy demands on scarce water supplies compared to other sources of energy.
Whole plant
The generation of bioelectricity is significantly more water-efficient – by a factor of two – than the production of biofuel. A significant cause is that in the case of the former, the whole plant is used and in the case of the latter, only the sugar, starch or oil from the seeds is used. In the case of second-generation biofuels, ethanol can also be made from the stalk and leaves, which will have a favourable effect on water consumption.
The researchers show the water footprint of 13 crops: the volume of water – rainwater and irrigation – required per gigajoule of energy production. In respect of various applications of biomass, the researchers present the impact that the cultivation of crops has on water consumption.
Of the crops studied, the most suitable for generating bioelectricity are corn, sugar beet and sugar cane, while the least appropriate are rapeseed and jatropha, the latter having a water footprint that is 10 times larger. The most water-efficient crops for bioethanol production are sugar beet and potato, followed by sorghum (one litre of bioethanol made from sugar beet takes 1,400 litres of water, compared to 2,500 litres for sugarcane for example), while the most water-efficient crops for biodiesel production are soya and rapeseed, with jatropha requiring the most water.
1 litre of diesel, 14,000 litres of water
By linking the water consumption to the location and climate data, it is possible to select the optimum production region for each crop. This makes it easier to prevent biomass cultivation from jeopardising food production in regions hit by water scarcity.
An example is biodiesel, made from rapeseed, soya or jatropha. On average, it takes 14,000 litres of water to produce one litre of biodiesel from rapeseed or soya. However, the water footprint for rapeseed in Western Europe is significantly smaller than in Asia. For soya, India has a large water footprint, while the figures for countries such as Italy and Paraguay are more favourable. Jatropha, which is increasingly used for biomass production, has an even less favourable water footprint of 20,000 litres of water on average for one litre of biodiesel.
This research introduces a new concept into the bioenergy debate. Until now, the discussion has mainly focused on the question of whether food crops should be used to produce fuel. However, underlying this concern is the question of how we should deploy our limited supplies of fresh water, since water used for bioenergy – whether it be for a food crop such as corn or a non-food crop such as jatropha – cannot be used for food production, drinking water or for maintaining natural eco-systems.
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