Data centers directly and indirectly use water; however, they also have significant impacts on watersheds and the hydrologic cycle replacing natural open space with 7-8 football fields of building surrounded by cleared, compacted and paved land. Data centers also deliver contaminants into our waters.
We all know that data centers use huge amounts of
electricity to power their millions upon millions of chips. One data center can
require 50 times the electricity of a typical office building, according to the
U.S. Department of Energy. That electricity has a water footprint.
The electric power sector uses a large amount of water,
primarily for cooling (though there is hydroelectric use. In Virginia we use
hydroelectric for power storage. The Bath County Pumped Storage
Station uses two reservoirs to create a hydroelectric power storage
battery which is reportedly the largest battery in the world with a maximum
generation capacity of 3,003 MW and a total storage capacity of 24,000 MWh.
The most significant use of water is in power generation.
Thermoelectric power plants (including natural gas, nuclear, and coal plants)
boil water to create steam, which spins a turbine to generate electricity. The
steam leaving the turbine must be cooled back into water to be used to generate
more electricity. Plants withdraw water from nearby rivers, lakes, or oceans
and pass that water through the steam leaving the turbine. That process cools
and condenses the steam back into water, but a certain amount evaporates. In
2021, 73% of the utility-scale electricity generated in the United States came
from thermoelectric power plants.
The electric sector’s water-withdrawal intensity—the amount
of water withdrawn per unit of electricity generated—depends on the power
generation mix and technology used. It has been falling as we move away from
coal since natural gas uses less water. Nationally, water used in power
generation was 11,595 gal/MWh in 2021.
While the Virginia power mix has been migrating away from
coal and towards natural gas, nuclear and renewables, Virginia does not
generate enough power to supply our current and growing need for power. The
shortfall in power is supplied by PJM generation coming predominantly from West
Virginia and Pennsylvania.
Dominion Energy in Virginia predicts that by 2035 the data
center industry in Virginia will require 11,000 megawatts from them, nearly
quadruple what it needed in 2022, or enough to power 8.8 million homes.
Northern Virginia Electric Cooperative recently told PJM that the more than 50
data centers it serves account for 59% percent of its energy demand. It expects
to need to serve about 110 more data centers by July 2028.
Data centers also use large amounts of water directly for cooling systems, which ensure that the heat produced by these massive facilities is controlled.Data Centers are cooled using either air conditioning (electricity) or evaporative cooling (water). Evaporative cooling is more efficient and effective.
In a water-cooled system, water-cooled chillers and cooling
towers located on top of the data center roofs produce chilled water, which is
delivered to computer room air conditioners for cooling the entire building.
Some of this water can be recycled through the system more than once.
So, how much water do data centers use,. The industry treats
it as a trade secret. In 2021, when Prince William County looked at water
consumption for its 25 operational data centers at the time it found that water
use varied by season and ranged from about 0.2 to 0.5 gallons per square foot
per day. Of course, the total square footage of the data centers was not
disclosed. The data
centers that Prince William looked at were all relatively small 100,00-250,000
square feet- nothing like the hyper centers being built now. Today, data
centers seem to start at a million square feet and move up from there with
multiple building campuses. How water use scales up in multi-story
data centers is unknown. The heat island effect is likely to increase water
needs for cooling.
Loudoun County has a larger data set. Loudoun County built a
reclaimed water system to supply data centers more cheaply with water. However
the expansion of data centers required more than that system could provide. The
water from the Broad Run Waste Water Treatment plant was inadequate to serve
all data centers.
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| from Loudoun Water ICPRB presentation data centers that they know about |
According to Loudoun County, Data center water use will have grown to an average 4 million gallons a day of potable water and 4 million gallons a day of reclaimed water by the end of this year- since in northern Virginia we drink the reclaimed water from UOSA and returned upstream to the Potomac, that is enough water to supply 100,000 people.
As reflected in the Loudoun Water data, some of the data
centers do reuse water by recirculating the same water through their cooling
systems multiple times while replenishing what evaporates. According to Google,
this practice saves up to 50% of water when compared with “once-through”
cooling systems. However, eventually this reused water needs to be replaced
with new water, due to mineral scale formation which could damage the cooling
equipment or once the conductivity of the water is too high which could damage
the IT equipment.
The need for new water results from the build-up of calcium,
magnesium, iron, silica, and salt which become concentrated by evaporative
cooling cycles. The amount of water data centers consume also fluctuates based
on seasonal weather conditions. Facilities typically use less water during the
winter months and more during the summer months as can be seen in the potable
water data from Loudoun County.
Data center wastewater is largely comprised of blowdown; the
portion of cooling water removed from circulation and replaced with freshwater
to prevent excessive concentration of undesirable components like salt can the
concentrated impurities. In general data centers recycle their water until the
concentration of dissolved solids (which is essentially salts) is roughly five
times the supplied water. This blowdown is sent to the waste water treatment
plant which is not designed to remove salts. This exacerbates the problem of salinization
that is a growing problem in our region
and water resources.
In Loudoun the reclaimed water distribution system in
Ashburn receives reclaimed water from Loudoun Water helping to save money. Purchasing reclaimed water is cheaper than purchasing an
equal amount of potable drinking water. To provide the reclaimed/ recycled
water, Loudoun uses the effluent water from the Board Run wastewater treatment
facility near Ashburn. That water is ultimately returned to the Potomac River,
saltier than it started upstream from the Leesburg, Fairfax Water and
Washington Aqueduct intakes for their drinking water treatment plants.
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| from Loudoun Water presentation to ICPRB |
Prince William county believes that most data center water comes from potable water supplies. Though Amazon has a permit to withdraw upto 2.5 million gallons of water a day from groundwater wells it has in Manassas, most data centers in Virginia are not required to permit and monitor their water use. In Prince William County the treated sewage from UOSA is already used by Fairfax Water (upto 40 millions gallons a day) to supplement water supply to the Occoquan Reservoir for our drinking water supply.
Though we do not generally think of it that way, a data center is an industrial use, not a commercial use in its need for square footage and power with a very large carbon footprint, diesel generators and fuel storage tanks treated under regulations as separate sources of above ground fuel storage and potential release. The actual buildout of the physical properties of data canters is also impacting the availability of and quality of water. Impacting to future sustainability and availability of water for our region.
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