(Gerard Wynn is a Reuters market analyst. The views expressed
are his own.)
By Gerard Wynn
LONDON, March 15 Countries struggling to
plot a greener energy mix face the extra headache of water
scarcity from drought, squeezing their options as they look to
cut carbon emissions and source locally.
Energy choices are still wide open, from hydrogen to wind
power and clean coal, in electricity generation and road
Yet accounting for water, to allow for climate change and
concerns that energy demand compounds water scarcity, forces
For example, policymakers seeking more secure supplies of
liquid transport fuels find that both tar sands and biofuels use
more water than conventional gasoline - estimates put corn
ethanol at 100 or 1,000 times more.
And in a tradeoff with cutting carbon emissions, the
unproven technology of carbon capture and storage could cut CO2
emissions from coal-fired power plants by 90 percent, but
increase water consumption by the same amount.
Low-carbon geothermal and hydro power can both use far more
water than fossil fuels. The exceptions are wind and solar
power, which tick all the boxes (local, low carbon and low
Meanwhile shale gas can use more freshwater from underground
supplies than conventional oil and gas, posing a limit on growth
and a risk for groundwater contamination.
Water is a growing concern because most of the rise in
energy demand will be in developing countries, notably in Africa
which already faces stiff challenges including competition with
irrigation for farming and access to safe drinking water.
Meanwhile increasingly erratic rainfall is one of the main
climate change impacts already observed, from the Mediterranean
to the Indian monsoon, alongside higher temperatures and more
frequent heat waves.
Water is used for resource extraction (oil, gas, coal,
biomass), energy conversion (refining and processing) and power
In primary energy extraction and refining academics agree
that biofuels consume by far the most water, roughly followed in
descending order by tar sands, conventional crude oil, coal,
uranium and natural gas.
Biofuels are especially thirsty, depending on the level of
irrigation, because of the water used to grow farm crops such as
corn and then refine these into ethanol.
Water scarcity has been a theme at the major World Water
Forum in Marseille this week, where the U.N.'s World Water
Development Report cited research that biofuels require up to
1,000 times more water than gasoline, per kilometre.
A Harvard University study reported corn ethanol as one to
two orders of magnitude (10 to 100 times) more thirsty than
Meanwhile, shale gas appears to be in the same range as
conventional gas, but poses a threat as exploitation grows.
A report prepared for the U.S. Department of Energy in 2010
("Water Management Technologies Used by Marcellus Shale Gas
Producers") found an average U.S. well used 2.2 million gallons
of freshwater, and concluded that for the vast Marcellus field
in the east of the country: "If the number of new shale gas
wells continues to rise rapidly, water supplies could become a
Electricity generation also compounds water use, for example
in cooling to remove waste heat and to generate steam to drive a
A Global Environment Facility report, also published this
week, estimated that an average, 1 gigawatt thermal power plant
(burning fossil fuels or using nuclear power generation) used
the equivalent of 25 Olympic-sized swimming pools a day.
But there are differences: in particular the experimental
technology carbon capture and storage (CCS), meant to all but
eliminate CO2 emissions from fossil fuel power plants, increases
water consumption by 50-90 percent, according to a study by the
World Energy Council (WEC).
That's because of cooling in the CO2 capture process itself
and because extra energy is needed to run the plant.
After CCS and hydro power (potentially a massive water
consumer through evaporation), in descending order come nuclear
power and then traditional coal power, advanced coal, gas, solar
and wind power, according to the WEC study.
Consumption is an equal concern in developed countries: the
east of England was recently declared in drought, an expected
climate trend which led the ratings agency Standard and Poor's
to warn of higher costs to water and power companies.
Britain's Environment Agency says the electricity generation
sector is the second biggest abstracter after public water.
The key concern is that emerging sources of energy
worldwide, from tar sands to biofuels and CCS technology, are
more water-intensive than traditional fuels, while curbing water
use may conflict with cutting carbon.
The U.N. report this week made recommendations including:
1. Improve water data (water consumption estimates for shale
gas and tar sands, massive emerging resources, are sometimes
2. Integrate water and energy plans and policy, given that
mutual dependence can reinforce demand: water is needed to
produce energy, and energy to extract water
3. Support fuels which are local, low-carbon and low-water
4. Use reclaimed water (from industry or waste) for energy
production wherever possible
5. Invest in water and energy conservation and efficiency
(Reporting by Gerard Wynn; editing by Jason Neely)