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Water in relation to
food and energy
Arjen Hoekstra
University of Twente / Water Footprint Network
www.waterfootprint.org
Overview of presentation
- Dilemmas in freshwater allocation
- Water footprint of Dutch consumers
- The water footprint concept- Water for food
The water-energy nexus
- National water foot rints
- What can we do?
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Limits to freshwater use
Freshwater consumptionAgricultural products- Food
- Fibres cotton
Freshwater availabilityPrecipitation on land- Evapotranspiration (green water)
- Runoff blue water
TRADE
- Biofuels
Forestry products
- Timber
- Paper- Firewood, charcoal
Aquaculture products
Industries
Domestic water supply
Freshwater pollutionPoint sources
Diffuse sources
Waste assimilation capacity- Maximum allowable concentrations
- Decay rates
Dilemmas in freshwater allocation
Water allocation dilemmas- Water for consumption versus water for
TRADE
- Water for food versus nature
- Water for food versus bio-energy
What goal deserves priority?- Food security to all?
- Allocation to highest added value?- Sustainable water use?
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Production
Globalization of water
Water consumption and
pollution related to production
for export; water is not factored into
the price of traded commodities
TRADETrade
Consumption
Water saving, but also
water dependency
The total water footprint of a consumer in NL
about 2% of the water footprint is at home.
,
about 98% of the water footprint is invisible, it is relatedto the products consumers buy in the supermarket.
3448 litre/day for agricultural products
541 litre/da for industrial roducts
about 95% of NLs water
footprint lies abroad.
[Mekonnen & Hoekstra, 2011]
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Global water footprint of Dutch consumption
soybean
95% of the water footprint
is outside its own borders
[Mekonnen & Hoekstra, 2011]
Coto Doana National Park, southern Spain
raw err es or expor
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19892008
Former Aral Sea, Central Asia
Cotton for export
Calculated lake level
without accounting for
water abstraction
Flowers from KenyaDecline of lake level in Lake Naivasha
[Mekonnen & Hoekstra, 2010]
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Soybeans, deforestation,
Mato Grosso, Brazil
Use of green water
The water footprintconcept
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the volume of fresh water used to produce the product,
The water footprint of a product
summed over the various steps of the production chain.
when and where the water was used:
a water footprint includes a temporal and spatial dimension.
Green water footprint
The water footprint of a product
volume of rainwaterevaporated
or incorporated into product
Blue water footprint
volume of surface or groundwater
evapora e or ncorpora e n o pro uc
Grey water footprint
volume ofpolluted water.
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Direct water footprint Indirect water footprint
Components of a water footprint
Green water footprint Green water footprint
Blue water footprint Blue water footprint
Water
consumptionReturn flow
Water withdrawal
Grey water footprint Grey water footprint
Water
pollution
[Hoekstra et al., 2011]
The traditional
statistics
on water use
Grey water footprint
volume of polluted freshwater that associates with the
production of a product in its full supply-chain.
calculated as the volume of water that is required to assimilate
pollutants based on ambient water quality standards.
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Applic. rate = 1 kg/ha L
Grey water footprint related to atrazine in
corn production in the USA
Leaching rate = 5%
A = 30 million ha
cmax = 3 g/l (EPA, 2005)
cnat = 0 g/l
Y= 9 ton/ha Prod = 270 million ton/yr
= . m on
kg/yr
= 500 109 m3/yr
Total WFgrey of activity = (cmax cnat)
Plane spraying pesticide on maize
(Zea mays), California, USA
Total renewable water resources in USA =
3,051 109 m3/yr (AQUASTAT, 2007)
Grey water footprint < runoffAssimilative capacity
The environmental impact of the grey water footprint
Full assimilativecapacity of the river
used
Grey water footprint = runoff
Pollution exceeding
the assimilative
capacity of theenvironment
Grey water footprint > runoff
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Blue water footprint Blue water availability
Blue water scarcity
[Hoekstra & Mekonnen, 2011]
Number of months with blue water scarcity > 100%
[Hoekstra & Mekonnen, 2011]
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14000
16000
m3/sIndus River Basin Natural
runoff
4000
6000
8000
10000
12000
Environmental
flow requirement
Bluewaterfootprint
0
2000
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Bluewateravailability
The water footprintof food
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sugar crops 200 litre/kg
global averages
The water footprint of food products
vegetables 300 litre/kg
starchy roots 400 litre/kg
fruits 1000 litre/kg
cereals 1600 litre/kg
pulses 4000 litre/kg
poultry 4000 litre/kg
pork 6000 litre/kg
beef 15000 litre/kg
[Mekonnen & Hoekstra, 2010]
The water footprint of a cow
Food
1300 kg of grains
[Hoekstra & Chapagain, 2008]
(wheat, oats, barley, corn, dry peas, soybean, etc)
7200 kg of roughages
(pasture, dry hay, silage, etc)
Water
24000 litres for drinking
7000 litres for servicing.
99%
1%
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The water footprint of beef
[Hoekstra & Chapagain, 2008]
The water footprint of a hamburger
[Hoekstra & Chapagain, 2008]
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Meat versus vegetarian diet
Meat diet kcal/day litre/kcal litre/day Vegetarian
dietkcal/day litre/kcal litre/day
Industrial
countries n ma
origin950 2.5 2375
n ma
origin300 2.5 750
Vegetable
origin2450 0.5 1225
Vegetable
origin3100 0.5 1550
Total 3400 3600 Total 3400 2300
Developing
coun r es
origin350 2.5 875
origin200 2.5 500
Vegetable
origin2350 0.5 1175
Vegetable
origin2500 0.5 1250
Total 2700 2050 Total 2700 1750
Meat versus vegetarian diet
Meat diet kcal/day litre/kcal litre/day Vegetarian
dietkcal/day litre/kcal litre/day
Industrial
countries n ma
origin950 2.5 2375
n ma
origin300 2.5 750
Vegetableorigin
2450 0.5 1225 Vegetableorigin
3100 0.5 1550
Total 3400 3600 Total 3400 2300
Developing
coun r es
origin350 2.5 875
origin200 2.5 500
Vegetable
origin2350 0.5 1175
Vegetable
origin2500 0.5 1250
Total 2700 2050 Total 2700 1750
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Meat versus vegetarian diet
Meat diet kcal/day litre/kcal litre/day Vegetarian
dietkcal/day litre/kcal litre/day
Industrial
countries n ma
origin950 2.5 2375
n ma
origin300 2.5 750
Vegetable
origin2450 0.5 1225
Vegetable
origin3100 0.5 1550
Total 3400 3600 Total 3400 2300
Developing
coun r es
origin350 2.5 875
origin200 2.5 500
Vegetable
origin2350 0.5 1175
Vegetable
origin2500 0.5 1250
Total 2700 2050 Total 2700 1750
The water-energy nexus
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The water sector is becoming more energy-intensive.
Water - energy nexus
pumping deeper groundwater
large-scale (inter-basin) water transfers
The energy sector is becoming more water-intensive.
biomass
increasin water use in minin fossil fuels
Primary energy carriers Global average water
footprint (m3/GJ)
Water footprint of energy
Non-renewable Natural gas 0.11
Coal 0.16
Crude oil 1.06
Uranium 0.09
Renewable Wind ener 0.00
Solar thermal energy 0.27
Hydropower 22
Biomass energy 70 (range: 10-250)
[Gerbens-Leenes, Hoekstra & Van der Meer, 2008]
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Source examples
Energy from biomass
Starch crops barley, cassava, maize, paddy rice, potato,
sorghum, rye, wheat
Sugar crops sugar beet, sugarcane
Oil crops soybean, rapeseed, jatropha
Trees poplar
[Gerbens-Leenes, Hoekstra & Van der Meer, 2008]
BIOMASS
RESIDUE
ELECTRICITY
HEAT
Production-chain bio-energy
CROP YIELD
RESIDUE
EXTRACTION
BIODIESEL
ETHANOL
[Gerbens-Leenes, Hoekstra & Van der Meer, 2008]
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Water footprint of
biomass energy
3
] 3 water footprint of biomass [m /ton]water footprint of bio-energy [m /GJ
energy yield [GJ/ton]
33 crop water use [m /ha]water footprint of biomass [m /ton]=
crop yield [ton/ha]
Water footprint of biofuels from different crops [litre/litre]
Car driving on
bio-ethanol from
sugar beet:
40-210 litre/km
[Gerbens-Leenes, Hoekstra & Van der Meer, 2009]
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WF of bio-energy >> WF of other forms of energy
The water-energy nexus
WF bio-heat or electricity < WF biofuels
WF bio-ethanol < WF biodiesel
Sugar beet most water-efficient energy crop
Large country differences
Water footprint of humanity will increase substantially withthe increase of bioenergy
Water footprint of nations andinternational virtual water trade
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total amount of water that is used to produce the goods and services
Water footprint of national consumption
consumed by the inhabitants of the nation.
two components:
internal water footprint (inside the country).
external water footprint (in other countries).
water ootpr nt o nat ona consumpt on =
water footprint within the nation + virtual water import virtual water export
International virtual water flows
Virtual water flow (m3/yr) =
Trade volume (ton/yr) Product water footprint (m3/ton)
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Water footprint of national consumption
[Mekonnen & Hoekstra, 2011]
Water footprint of national consumption
Global average water footprint
[Mekonnen & Hoekstra, 2011]
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National virtual water balances
[Mekonnen & Hoekstra, 2011]
Virtual water transfers in China
52Gm3/yr
[Ma et al., 2006; Hoekstra & Chapagain, 2008]
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46
5
North
India
Virtual water flows India
9
4
2
9
22
10
8 +34
1
13
East
India
West
India
+4
South
India
[Kampman et al., 2008]
What can we do?
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Industry Agriculture
Green WF Not relevant. Decrease green water footprint
increase green water productivity (ton/m3),
The ultimate perspective
increase production from rain-fed lands
Blue WF Zero blue water footprint
recapture and recycle evaporation flow
Decrease blue water footprint
increase blue water productivity (ton/m3),
adopt better irrigation techniques and
practices
Grey WF Zero grey water footprint
zero pollution recapture chemicals and
heat from wasteflow - recycle
Reduce use artificial fertilisers & pesticides
organic farming
Towards supplementary or deficit irrigation
and application of precision irrigation techniques
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Towards full water recycling in industries:
zero blue water footprint
Make better use of green water
Increase water
productivity in
rain-fed
agriculture
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Towards organic farming: zero grey water footprint
Towards full recycling of materials and heat:
zero grey water footprint
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Water neutral urban expansion
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