Geoscience Reference
In-Depth Information
for irrigation and livestock. For groundwater pumping, EPRI suggests a value of about
700kWh/million gallons (0.185 kWh/m
3
). For surface water EPRI assumed an average
value of 300 kWh/million gallons (0.079 kWh/m
3
).
Fischer et al. (2007) have estimated the impact of global warming on U.S. irrigation,
based on U.N. Food and Agricultural Organization-derived water deicits for various
IPCC SRES scenarios. The cost of providing irrigation to an additional hectare of land
was $290/ha, or $57/1000m
3
, which includes “cost of supplying water from diferent
sources, investment in irrigation equipment, facilities, land improvement, and computer
technology; maintenance and repair, and labor”. Additionally, they estimated pumping
and energy cost and/or water price, operation and maintenance, and labor at $371/m
3
.
Unfortunately, they did not report the amount of energy assumed to be used.
DOE 2011 reported that water use in buildings in 2005 in the United States was es-
timated at 39.6 billion gallons per day, which was about 10% of all water consumption
in the United States. Between 27 billion and 39 billion kWh were consumed nationally
to pump, treat, distribute and clean the water used in the buildings sector, or about
0.7 to 1 percent of national net electrical generation in that year. Water use in the build-
ings sector also reportedly grew by 27% between
1985 and 2005 (DOE, 2011), but the literature review for this study did not ind esti-
mates of the impact of climate change on non-agricultural water demand.
A small number of studies provide data on the costs of withdrawing, pumping, and
treating water, although they do not directly examine the impact of climate change on
these costs (Table 3). For example, Novotny (2010) states that about 7% of all U.S. energy
use is for water and wastewater treatment. One percent or more is used to transport
water and wastewater. Novotny also notes that domestic indoor water use ranges from
242 L/capita/day for a household without water conservation to 136 L/capita/day for a
household practicing water conservation. Landscaping and other outdoor uses, leaks,
and swimming pools increase the total to 650 L/capita/day (Novotny, 2010). GAO (2011)
notes that “the energy demands of the urban water cycle vary by location; therefore,
consideration of location-speciic and other factors is key to assessing the energy needs
of the urban water lifecycle.”
They go on to note that factors include the source and quality of the water, distance
and topography for conveyance, age and condition of the system (especially leakage
rates), and level and type of treatment, all of which can vary signiicantly over even
short distances (GAO, 2011, Stillwell et al., 2011, Stokes and Hovarth, 2009, Cooley et
al., 2007). However, consumption of energy for treating water and wastewater are ap-
proximately linear in the amount of water treated (Stillwell et al., 2011); so if sources of
water and methods of treatment are constant, the additional energy consumption re-
quired for this purpose under a changed climate would be proportional to the amount
of additional water required. In theory, climate change that raised the average tem-
perature of the atmosphere would also raise water temperatures for surface water (See
Section IIIB, 2), and might also increase water consumption in landscaping. In the case
of California, Stokes and Hovarth (2009) calculated energy consumption for a number
of options to meet population growth. However energy costs would be similar on a
per-volume basis to meet climate change-related shortfalls in supply or climate change-
related increases in demand. Stokes and Hovarth's most costly scenario, providing all
