Why
should I consider gas A/C?
Currently, why is electric cooling used more
than gas cooling?
Are there
different types of gas cooling systems? If so,
what are they?
How
much does gas cooling cost?
Are there incentives or special rates that are
applicable when using gas cooling?
Is there gas
cooling equipment available that would suit my needs?
What are
“ideal” applications for a large gas chiller system?
Is
gas cooling only applicable to large cooling system applications?
Does
it make sense to have both electric and gas cooling?
Where
do I go for more help on gas cooling?
1. Why should I consider gas A/C?
Some of the key reasons for using gas cooling
are as follows:
·
Lower operating costs as compared to electric
cooling
·
A hedge against the uncertainties of electric
industry restructuring
·
Non-ozone depleting chlorine-free cooling
technology (gas absorption cooling)
·
Availability of an abundant fuel that is 95%
domestically produced
·
Increase in cooling requirements in a facility
where the electrical system cannot be easily upgraded
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2.
Currently, why is
electric cooling used more than gas cooling?
In the United States, most cooling needs in the
1930s and 1940s were provided by gas. By the
1960s, electric chillers began making inroads into the cooling market due to lower cost
equipment, low electric rates, and higher efficiency machines. In the 1970s, the use of gas was restricted and
electric cooling use continued to increase. By
1990, only 5% of all air conditioning in the United States was provided by gas. However, during the 1980s in Japan, efforts (backed
by the Japanese government) were being made to accelerate the development of gas cooling. By 1991, nearly 30% of Japan’s air
conditioning was provided by gas chillers.
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3.
Are there
different types of gas cooling systems? If so,
what are they?
Yes, there are three basic types of gas
cooling systems; absorption, engine-driven and desiccant.
In Southern California, the most popular systems are double-effect
absorption (either direct-fired or steam) and engine-driven gas cooling units. Absorption cooling systems are similar to vapor
compression or mechanical systems in that they utilize a cycle of evaporation and
condensation of a fluid or refrigerant to produce cooling.
However, absorption cooling differs from the vapor compression cycle by
using heat as a thermochemical “compressor” rather than a mechanically-driven
compressor. The source of heat can be from a
direct-fired gas burner, from steam or from hot water.
On the other hand, engine-driven gas cooling systems utilize a vapor
compression cycle similar to an electric chiller. The
primary difference is that the compressor (reciprocating, screw, or centrifugal) is driven
by a high-efficiency natural gas engine rather than an electric motor.
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4.
How much
does gas cooling cost?
The operating cost (for fuel and maintenance)
of a gas cooling system can be as much as 25% to 50% less than an electric system. However, the first cost of gas cooling equipment is
generally higher than electric equipment. Both
the operating costs and the equipment costs are project and site specific. Therefore, the economics of gas cooling require a
life cycle cost analysis, or at minimum, a simple payback analysis to best estimate the
actual economics of your facility.
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5.
Are
there incentives or special rates that are applicable when using gas cooling?
Yes and No.
Some gas companies offer special incentives for the installation of certain
gas A/C systems.
In some cases, special rates are
also available for residential customers.
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6.
Is there gas
cooling equipment available that would suit my needs?
Yes. Absorption equipment is
available from all of the major manufacturers of A/C equipment, Carrier,
Trane, York,
McQuay, and Dunham-Bush as well as Yazaki, Broad, and Robur,
Cention, Energen, Energy
Concepts and Thermax. Engine-driven
equipment is available from York, Tecogen, Trane and
Alturdyne. Desiccant equipment is available
from AIL Research, Inc., Bry-Air, Concepts and Designs,
Drykor, Kathabar Systems Division,
Munters Corporation, NovelAire, Seasons 4 and SEMCO. Residential equipment
is available from Ambian, Cooltec, Robur and Novelaire.
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7.
What are
“ideal” applications for a large gas chiller system?
The “ideal” application for a large
gas cooling installation would be for a project or facility that has many of the following
attributes:
·
Cooling load of 200 tons or more
·
Built-up chilled water system
·
In preliminary planning/design phase
·
Electric power has high demand charges and/or
high on-peak rates
·
Majority of the cooling load is during periods
of peak electric rates
·
Higher emphasis on life-cycle cost than first
cost
As noted above, the economics of a project
are site specific and do need to be evaluated accordingly
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8.
Is gas cooling
only applicable to large cooling system applications?
No. Unitary
or packaged gas cooling
is available in both direct expansion (DX) as well as chilled water systems. Equipment range in size from 3 tons to 500 tons and larger. This equipment is suitable to most residential and
light commercial/industrial applications.
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9.
Does it make sense to
have both electric and gas cooling?
In many cases, the optimal cooling system would incorporate both electric and gas
chillers. In a “hybrid” plant, the
gas chillers may be used for the “base load” and the electric chillers would be
used only during the peak cooling periods. In
general, this is a more economic and more reliable solution than a thermal energy storage
system. In addition, the ability to have
“dual” fuels for your plant may give you added reliability and a
“hedge” against future fuel prices in a more unstable restructured energy
environment.
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10.
Where
do I go for more help on gas cooling?
Contact your Gas Company Account Executive or representative who will assist you in
evaluating your facility or project to determine if gas cooling
makes sense for you. |
