The water footprint of an individual, community or business is defined as the total volume of freshwater used to produce and consume goods and services. It is an indicator of water use that looks at both direct and indirect water-use of a consumer or producer. Water use is measured in water volume consumed (evaporated) and/or polluted per unit of time.
The total water footprint comprises three different types of water – green water, blue water and grey water. Green water refers to water which has evaporated during crop
The water footprint is one of several concepts and tools developed to measure the impact of water flow and consumption in terms of quality or quantity. Applying various tools helps to gain a more comprehensive view of effects, both isolated aspects as well as interrelated effects of biofuel
growth; Blue water is the amount of (evaporated) surface and ground water used for irrigation; and Grey water refers to water contaminated during the production process.
The international Standard for Water Footprinting specifies requirements and guidelines to assess and report the water footprint based on LCA. The standard aims for consistency with carbon footprinting and other LCA impact categories.
production and agriculture. Water availability varies in space and time, so water appropriation should always be considered in its local context. This can be measured by studying the changes in isotopic composition of local water, or standard mean ocean water (SMOW).
Average water requirement for biofuels Weighted global average values
Source: Gerbens-Leenes et al., The water footprint of bioenergy, 2009. Figure 3.3.2 Average water requirement for biofuels
37 Ethanol crops
Moreover, underlying data sources need to be interpreted in context. For example, rainfed jatropha is produced in Mali as a biofuel, which means that it receives less water than in many comparable contexts, but also with somewhat lower output of biofuel. India in contrast, has been irrigating jatropha to achieve commercially acceptable yields. The two contexts will produce different water footprint measurements. Sugarcane is a good example of how these figures might be confusing, because sugarcane is a water-intensive crop but, depending on local conditions, it can have a lower water footprint relative to fuel output.
Litres of water per litre of biofuel 20 000
Note: 10 000 2 000
1. The blue water footprint is the volume of surface and groundwater consumed as a result of the production of goods or services. 2. The jatropha figure is the average for India, Indonesia, Nicaragua, Brazil, and Guatemala.