PNM Water You Thinking:

PNM Water You Thinking:
PNM San Juan Generating Station Replacement Power Plan:
The Impact Fossil Fuels’ Heavy Water Use
in a Drought-Stricken State
by
David Robertson, PE (ret)
June 25, 2014
WATER AND ELECTRICITY GENERATION
As New Mexico experiences its most extensive drought in 130 years (1), water is
becoming increasingly precious. According to the New York Times, Colorado River
reservoirs are being depleted at a rapid rate by the worst drought on the Colorado
in over 1,250 years (2). US Bureau of Reclamation officials report that there is a 5050 chance that Lake Mead’s water will need to be rationed by 2015, something that
has never happened before (2).
Water is inextricably linked to electricity generation from fossil and nuclear fuels.
Currently, over 80% of Public Service Company of New Mexico’s (PNM) electricity is
generated from coal and nuclear (see Table 1 below); all of that 80% consumes
water during electricity generation from the Colorado River system. A significant
portion of the water for Albuquerque and Santa Fe also comes from the Colorado
River system. Twelve percent (12%) of PNM’s electricity is generated from natural
gas and consumes water from the Rio Grande River watershed. PNM’s San Juan
Generating Station in the northwest corner of the state alone consumed 6.3 billion
gallons of water in 2013 (3), which is twice the consumption of the City of Santa Fe
(4). The Four Corners Power Plant, another coal-fired power plant located in
northwestern New Mexico, consumes an additional 5 billion gallons of water per
year.
PERCENT OF ELECTRICITY GENERATED
TYPE OF FUEL
COAL
NUCLEAR
NATURAL GAS
RENEWABLES
TOTALS
PNM CURRENT
ENERGY MIX
PNM REPLACEMENT
PLAN ENERGY MIX
30% RENEWABLE
ENERGY
60%
21%
12%
7%
100%
42%
31%
15%
12%
100%
31%
21%
18%
30%
100%
Table 1. Percent of energy generated by PNM from various resources. The two
replacement scenarios are PNM’s total energy mix after replacement of San Juan
Generating Station Units 2 & 3.
For each kilowatt-hour of electricity generated from coal and nuclear, more than
one-half gallon of water is consumed (see Table 2 below). This does not include the
large inefficiencies of long distance electricity transmission, or the water consumed
in the production and transportation of fuels and the processing of waste products.
For example, the hydraulic fracturing process (“fracking”) to extract natural gas
requires “prodigious” amounts of water (5) – approximately 2 to 4 million gallons
per well (6). Nationally, the water footprint of the average household’s energy use is
five times more than that household’s direct water use (7).
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WATER CONSUMED
(GALLONS PER KILOWATT-HOUR)
0.585
0.768
0.223
0.000
TYPE OF FUEL
COAL
NUCLEAR
NATURAL GAS
RENEWABLES
Table 2. Water consumed for electricity generation, per kilowatt-hour, by type of
energy source (8).
As part of compliance with Clean Air Act Regional Haze Requirements, PNM will be
retiring San Juan Units 2 and 3 at the end of 2017, per agreement with the State of
New Mexico and the federal Environmental Protection Agency. Thus, a replacement
energy plan is needed. PNM is proposing a replacement plan for the energy from San
Juan Units 2 and 3. See Table 1 above. The PNM replacement plan includes more of
each type of energy: coal, nuclear, natural gas, and solar. More nuclear and coal than
any other fuel will be added, and less renewable energy than any other energy
source will be added, according to the PNM plan.
Based on the percentages of different energy sources from Table 1 and the wateruse intensities from Table 2, and assuming 10,000 gigawatt-hours of electricity
generated by PNM in 2018 (this is approximately the amount of energy that PNM
supplies to retail and wholesale customers each year), the amount of water required
for electricity generation for the two replacement plans is readily calculated and is
presented in Table 3 below.
WATER CONSUMED FOR ELECTRICITY GENERATION
(BILLIONS OF GALLONS PER YEAR)
TYPE OF FUEL
COAL
NUCLEAR
NATURAL GAS
RENEWABLES
TOTALS
PNM CURRENT
ENERGY MIX
PNM REPLACEMENT
PLAN ENERGY MIX
30% RENEWABLE
ENERGY
3.51
1.62
0.27
0.O0
5.40
2.46
2.38
0.33
0.00
5.17
1.81
1.62
0.40
0.00
3.83
Table 3. Water consumed for electricity energy generation from various sources for
current energy mix and for energy mix for two replacement scenarios. The two
replacement plans are PNM’s total energy mix after replacement of San Juan
Generating Station Units 2 & 3.
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The PNM replacement plan would use 5.17 billion gallons of water per year to
generate electricity. A 30% renewable energy would use 3.83 billion gallons.
PNM’s plan would use 1.34 billion more gallons, or 35 percent, more water per year
than the 30% renewable energy replacement plan that includes more renewables.
Clearly, in the arid Southwest, and under current climate conditions — which are
likely to get far worse — the renewable energy alternative is the more sensible
approach in terms of water conservation.
REFERENCES
1. “New Mexico In Its Worst Drought Since 1880s”, Albuquerque Journal,
February 18, 2014, by John Fleck, Journal Staff Writer. Retrieved May 14,
2014.
2. “Colorado River Drought Forces A Painful Reckoning For States”, New York
Times, January 5, 2014, by Michael Wines. Retrieved May 14, 2014.
3. 13-000390-UT, PNM response to discovery question CCAE 3-2
4. “A Better Plan To Replace PNM’s San Juan Coal-Fired Power Plant Units 2 &
3”, New Energy Economy, undated. Handout distributed at the Albuquerque
Rally of the Great March for Climate Action, May 10, 2014.
5. “How Energy Drains Water Supplies”, New York Times, September 16, 2011,
by Kate Galbraith. Retrieved May 18, 2014.
6. “Fracking And Water Consumption”, SourceWatch, The Center for Media and
Democracy, (undated). Retrieved June 16, 2014.
7. “Burning Our Rivers: The Water Footprint Of Our Electricity”, Report by
River Network, April, 2012, by Wendy Wilson, Travis Leipzig, and Bevin
Griffiths-Sattenspiel. Retrieved May 15, 2014.
8. Calculations are based on data from PNM, “PNM 2014-2033 Integrated
Resource Plan (IRP)”, handout at PNM IRP meeting, September 26, 2013.
Water consumed for electricity generation is shown in that handout on the
page for Slide 8, “Water Use Intensity For Existing Rate-Based Generation”.
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