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The Water Footprint of Energy Carriers

Author(s): Winnie Gerbens- Leenes, Arjen Y. Hoekstra, Theo H. Van Der Meer

Keyword(s): Sustainability, climate change, energy, biomass, natural resource use, water footprint

Article:

Poster:

Session: OS4i Water and energy

AbstractAbstract conference 13th IWRA World Water Congress 2008, 1-4 September, Montpellier, France

The

Water Footprint of Energy Carriers

P.W. Gerbens-Leenes*, A.Y. Hoekstra and Th. H. van der

Meer
University of Twente, the Netherlands

Introduction
Today, the scientific as well as the

international political community consider global change often in relation to climate change. It is generally recognized

that emissions of greenhouse gasses, such as CO2 from fossil energy carriers, are responsible for anthropological

impacts on the climate system. A shift towards CO2-neutral energy carriers, such as biomass, is heavily promoted.

Important issues in this respect are trade offs and interplays with other factors that play a role in global changes other

than climate change, such as, for example, the availability and increased pressure on global water resources.

The use of energy in society requires water. Energy carriers are often made available with water, for example, for

coal mining, or produced with water, for example, biomass. The objective of this study is to calculate the water

footprint (WFP) of different types of biomass and compare these results with the WFP of other energy carriers, such

as fossil energy carriers (coal, natural gas, oil), and types of energy, such as wind energy and solar thermal electricity.

Method
Agriculture, providing biomass for different purposes, requires about 86% of the worldwide

fresh water use. In many parts of the world, the use of water for agriculture already competes with other uses such

as urban supply and industrial activities. A tool that addresses international virtual water flows is the concept of the

WFP. This tool has been introduced by Hoekstra and Hung (2002) and has been developed further by Chapagain

and Hoekstra (2004). Those authors define the WFP as the total annual volume of freshwater used to produce the

goods and services related to a certain consumption pattern. So far, the tool has been used to assess the WFP of

food and cotton consumption. This study assesses the WFP of various types of biomass by applying the WFP

concept resulting in the WFP of biomass in m3 per GJ. Next, the study compares this WFP with data on water

requirements of other energy carriers and types of energy from literature.
Results and discussion
Results

show large differences per unit of energy. The WFP of wind energy is zero, of natural gas 0.10 m3 per GJ, of coal

0.04, of nuclear energy 0.09, of thermal solar energy 0.3, of oil 0.8 and of biomass (average) 22.6 m3 per GJ.

Based on an energy use of 100 GJ per capita per year in western societies, a mix from coal, oil, nuclear energy and

gas requires 26 m3 of water, while 100 GJ from biomass requires 2260 m3. This requirement competes with water

for food, which lies in the same order of magnitude.
Conclusions
Biomass requires much more water per unit

of energy than the average fossil energy carrier. A shift in western societies from generally applied energy (fossil and

nuclear energy) towards energy from biomass causes a ninety fold increase of the WFP of energy and puts large

claims on scarce fresh water resources. Strategies towards larger biomass use for energy should take this large WFP

into account.

Keywords: Sustainability, climate change, energy, biomass, natural resource use, water

footprint

Chapagain, A.K., Hoekstra, A.Y., 2004 Water footprints of nations. Value of Water Research

Report Series No. 16. UNESCO-IHE Delft, the Netherlands. www.waterfootprint.org

Hoekstra, A.Y.,

Hung, P.Q., 2002. Virtual water trade: a quantification of virtual water flows between nations in relation to

international crop trade. Value of Water Research Report Series, No. 11. UNESCO-IHE, Delft, the Netherlands.

* Corresponding author. Faculty of Engineering and Technology, Water Engineering and Management,

University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
P: + 31 53 489 2080, E:

P.W.Gerbens-Leenes@ctw.utwente.nl, I: www.utwente.nl

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The Water Footprint of Energy Carriers