Water - Energy

Arjen Hoekstra

Professor in Water Management – University of Twente – the Netherlands

Scientific Director – Water Footprint Network

www.waterfootprint.org

Water-energy

The water sector is becoming more energy-intensive. desalination pumping deeper groundwater large-scale (inter-basin) water transfers

The energy sector is becoming more water-intensive. biomass

Water footprint of energy

Primary energy carriers Global average water

footprint (m3/GJ)

Non-renewable Natural gas 0.11

Coal 0.16

Crude oil 1.06

Uranium 0.09

Renewable Wind energy 0.00

Solar thermal energy 0.27

Hydropower 22

Biomass energy 70 (range: 10-250)

[Gerbens-Leenes, Hoekstra & Van der Meer, 2008]

Energy from biomass

Source Energy products after combustion

Liquid or solidenergy products

Starch crops Heat, electricity Bio-ethanol

Sugar crops Heat, electricity Bio-ethanol

Oil crops Heat, electricity Bio-diesel

Trees Heat, electricity Charcoal

Organic waste Heat, electricity

[Gerbens-Leenes, Hoekstra & Van der Meer, 2008]

Energy from biomass

Source examples

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

CROP YIELD

RESIDUE

EXTRACTION YIELD

ELECTRICITY

HEAT

BIODIESEL

ETHANOL

Production-chain bio-energy

[Gerbens-Leenes, Hoekstra & Van der Meer, 2008]

Water footprint ofbiomass energy

[GJ/ton] yield energy [ton/ha] yield crop

/ha][m use watercrop]/GJ[m energy-bio of footprint water

33

Global average water footprint of biofuels from different crops

m3/GJ

0

50

100

150

200

250

300

350

400

450S

ugar

bee

t

Pot

ato

Sug

ar c

ane

Mai

ze

Cas

save

Bar

ley

Rye

Pad

dy r

ice

Whe

at

Soy

bean

Rap

esee

d

Sor

ghum

m3

per

GJ

bio

-eth

ano

l o

r b

iod

iese

l Green water footprint

Blue water footprint

[Gerbens-Leenes, Hoekstra & Van der Meer, 2008]

Water footprint of biofuels from different crops [litre/litre]

[Gerbens-Leenes, Hoekstra & Van der Meer, 2008]

Conclusions

WF of bio-energy >> WF of other forms of energy

WF bio-heat or electricity < WF biofuels WF bio-ethanol < WF biodiesel Sugarbeet most water-efficient energy crop

Large country differences

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Slide layout