SRP will ensure that its facilities are designed, constructed and operated to minimize environmental
The advanced technologies of today's natural gas facilities mean that such facilities are one of the
cleanest ways to produce electricity. The turbines powering this plant will be equipped with emissions
controls. The technology being used minimizes nitrogen oxide (NOx) formation and controls carbon monoxide
Permitting process and requirements
Multiple environmental requirements apply to the construction and operation of a natural gas generating
The Pinal Energy Projects will be developed and operated in compliance with all applicable federal, state
and local environmental laws. The new plants will operate with the cleanest and most efficient fossil-fuel
technology available, using natural gas to generate electricity and will contain state-of-the-art
Together with permitting and regulatory requirements, the plants will be fully protective of local and
regional air quality.
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Air quality issues
The plants will incorporate modern technology and clean-burning natural gas to meet air quality standards
that protect public health and the environment. The plants are subject to federal, and local air quality
regulations, which primarily relate to combustion byproducts.
The advanced technologies of today's natural gas facilities mean that simple-cycle facilities, like the
one proposed for the Abel site, are one of the cleanest ways to produce electricity. The turbines powering
this plant will be equipped with emissions controls. The technology being used minimizes NOx formation and
controls CO emissions. Sulfur dioxide (SOx) emissions are also a consideration although they are far less
than NOx or CO at natural gas plants.
The technology under consideration for the Pinal Central location is called combined-cycle generation.
Find out more about intermediate load and combined-cycle
units. Combined cycle turbines have much the same air quality considerations as simple-cycle
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Water use and disposal at the plants
As a major steward of Arizona's water for more than 100 years, SRP is sensitive to the need to use and
release water responsibly. That said, natural gas power plants do use some water. In some types of plants,
the cooling tower evaporation process is the primary consumer of water to improve performance and/or to
The chemicals used to treat water at these types of plants are comparable to those used in a swimming pool.
All water released from the new plant will meet state and federal regulations for the protection of groundwater quality.
The Abel site is located in the Phoenix Active Management Area (AMA). SRP has been storing CAP water in
two recharge facilities (Granite Reef Underground Storage Project and New River - Aqua Fria Underground
Storage Project) for several years. This renewable water supply can be used at SRP's existing Kyrene and
Santan generating station locations, but could also be used as a source of supply for the Abel site. SRP
also is exploring the option of direct use of CAP water.
The Pinal Central and Eloy sites are located in the Pinal AMA, where the use of groundwater is closely
regulated. SRP is currently delivering Central Arizona Project water to several irrigation districts in
the Pinal AMA to reduce the districts' use of groundwater, thereby creating a "water credit" that can be
used later by SRP for power generation. SRP is being proactive to ensure that its future use of
groundwater has no impact to the aquifer.
Water use at simple-cycle plants
Water use by simple-cycle plants is low compared to base load and intermediate load facilities such as
coal-fired power plants and combined cycle natural gas fired plants. This is because simple-cycle plants
do not have a steam cycle, which is where most water in power production is used (in the form of cooling
water to condense the steam). In addition, simple-cycle plants run substantially fewer hours in a year,
which limits their water use.
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Water use at combined-cycle plants
At a combined-cycle plant, the primary use of water is for condensing steam. Cooling water is circulated
through a heat exchanger, where the heat of the steam is transferred to cooling water. As the steam cools,
the cooling water increases in temperature. This cooling water is circulated through a cooling tower,
which reduces the temperature of the water primarily by evaporation. The cooled water is then recirculated
to the steam condenser. The evaporation of water in the cooling tower is the primary source of water
consumption at a combined-cycle plant.
In some locations, primarily where water is physically not available, alternatives to entirely wet cooled
systems are possible. One such system is an air-cooled condenser. In such a system, large fans are used to
blow air over finned tubes carrying the steam to condense the steam.
In addition, some facilities have been constructed with various forms of hybrid systems, which are
generally combinations of wet-cooled technology and air-cooled technology.
In either case, the air-cooled equipment is physically very large (typically it will be the largest
structure on a combined-cycle plant site). Application of this kind of technology has tradeoffs.
Generally, in hot arid climates like Arizona, increases in water savings are accompanied by decreases
in plant output, decreases in fuel efficiency, and increases in construction costs. So for any particular
site, the water constraints of the location must be balanced against these factors in determining the
appropriate cooling technology for the plant.
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Consideration of renewables
Renewable projects need a back-up source of power, when the sun isn't shining or the wind isn't blowing.
Building simple-cycle gas turbines provides an important source of back-up power that will facilitate the
development of renewable energy. SRP already offers and continues to explore numerous renewable energy
opportunities, which could include projects within Pinal County.
SRP has an aggressive program for incorporating renewable resources and energy conservation efforts into
its Resource Plan. The SRP Sustainable Portfolio currently provides 6% of SRP's retail sales and is
scheduled to meet 15% of load by 2025. SRP has a wide variety of renewable resources including solar, wind,
geo-thermal, biomass, landfill gas and fuel cell. With the exception of biomass, these resources are
essentially carbon-free. Renewable resources typically are location specific, i.e., wind projects must be
located where wind is abundant, or solar must be located where abundant, low- cost land is available.
Each option is carefully considered to determine the most economical method of meeting not only our
customer's power requirements, but also electrical system requirements and environmental considerations.
SRP will continue to evaluate these options over the next several years as these projects are developed to
ensure we provide power in the most economical and environmentally friendly manner possible.
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