Water footprintBy Elisabeth Küttim, Falko Behr, Thomas Wiedemann

and Lewis Morrison.

Direct & indirect water use

People use lots of water for drinking, cooking and washing, but even more for producing things such as food, paper, cotton clothes, etc.

The water footprint is an indicator of water use that looks at both direct and indirect water use of a consumer or producer.

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Water footprint of products

Potato The global average water footprint of potato is 290 litre/kg. Potato chips cost 1040 litres of water per kilogram of potato chips. 66% green, 11% blue, 22% grey Leather (bovine)A bovine animal at the end of its life time has an average water footprint of 1,890,000 litre. The major fraction (83%) of the water footprint of the animal is attributed to the derived beef, while, on average, 5.5% is attributed to the bovine leather (and the remaining fractions to other products). A fully grown beef cow weighing 250 kg will produce 6 kg of leather so that the water footprint of bovine leather is 17,000 litre/kg. 93% green, 4% blue, 3% grey CottonThe global average water footprint of cotton fabric is 10,000 litre per kilogram. That means that one cotton shirt of 250 gram costs about 2500 litre. A jeans of 800 gram will cost 8000 litre. These figures are global averages. The water footprint of cotton fabric varies from place to place. The water footprint of cotton fabric made with cotton from China is 6000 litre/kg. For cotton from the USA this is 8100 litre/kg, for cotton from India 22500 litre/kg, for cotton from Pakistan 9600 litre/kg and for cotton from Uzbekistan 9200 litre/kg. 54% green, 33% blue, 13% grey CoffeeGlobal average water footprint: 130 litres for 1 cup of coffee. About 18900 litres of water are needed to produce 1 kg of roasted coffee. For a standard cup of coffee (125 ml) we require 7 gram of roasted coffee, so that a cup of coffee costs 130 litres of water. 96% green, 1% blue, 3% grey

Coffee

CoffeeGlobal average water footprint: 130 litres for one cup of coffee.About 18900 litres of water are needed to produce 1 kg of roasted coffee. For a standart cup of coffee (152 ml) we requier 7 gram of roasted coffee, so that a cup coffee costs 130 litres of water. 96% green, 1% blue, 3% grey water

Chocolate

Chocolate

When we assume that chocolate consist of 40% cocoa paste (with a water footprint of 24,000 litre/kg), 20% cocoa butter (34,000 litre/kg) and 40% cane suger (1800 litre/kg), we can calculate that chocolate has a water footprint of about 17,000 litre/kg.

98% green, 1% blue, 1% grey water

Cotton

Tomato

Beef• Beef

• The water footprint of meat from beef cattle (15400 litre/kg as a global average) is much lager than teh footprint of meat from sheep ( 10400 litre/kg), pig (6000 litre/kg), goat (5500 litre/kg) or chicken (4300 litre/kg).

• 93% green, 4% blue, 3% grey water

Beer & Bio-dieselBeer (from barley)The global average water footprint of barley is 1420 litre/kg. When we consider the amount of malted barley to produce beer, the water footprint of beer is 298 litre of water per litre of beer. This means that one glass of beer (250 ml) costs 74 litre. This excludes the water footprint of other (smaller) ingredients used in the beer production process.

Bio-diesel (from soybean)The global average water footprint of soybean is 2145 litre/kg. Assuming a dry mass fraction of 92%, a fat content in the dry mass of 18%, a biodiesel yield of 1 gram per gram fat and a biodiesel density of 0.88 kg/litre, we can calculate that the water footprint of biodiesel from soybean is 11400 litre of water per litre of biodiesel.

Environmental impact of biodiesel

• The environmental impact of biodiesel is diverse.

• Greenhouse gas emissions

LCA

A life-cycle assessment is a technique to assess environmental impacts associated with all the stages of a product's life from-cradle-to-grave .

LCA example

Apples shipped from New Zealand are more eco-friendly than storing apples in a local place eg. Germany.

Sources

http://www.waterfootprint.org/?page=files/WaterFootprintLogo

http://en.wikipedia.org/wiki/Life-cycle_assessment

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