Solar Power www.ConcentratingSolarPower.com
advertise on this site, call or email
The Renewable Energy Institute
Solar Power ("CSP") project
development services - from
project inception, design
and engineering, to financing permitting and installation.
solar power and energy project services include: Solar
Water Heating Systems, Solar Electric Power Systems, Solar CHP, Solar
Cogeneration and Solar Trigeneration power and energy systems. We
also offer energy-saving technologies including;
Absorption Chillers, Adsorption
Chillers, Automated Demand
Response, Cogeneration, Demand
Response Programs, Demand Side
Management, Energy Master
Planning, Engine Driven
Chillers, Trigeneration and Energy
Energy Systems is a subsidiary of Cogeneration Technologies located in
Houston, Texas. We provide the following power and energy project
Engineering Feasibility & Economic Analysis Studies
Procurement and Construction
Engineering & Permitting
Funding & Financing Options; including Equity Investment, Debt
Financing, Lease and Municipal Lease
Savings Program with No Capital Investment from Qualified Clients
Party Ownership and Project Development
Tag (Renewable Energy Credit, Carbon Dioxide Credits, Emission
Reduction Credits) Brokerage Services; Application and Permitting
provide Net Energy Metering project development services as well as
"turnkey" products and services in the areas of "Renewable
Energy Technologies" and in developing clean power/energy
projects that will generate a "Renewable
Energy Credit," Carbon
Dioxide Credits and Emission
Reduction Credits. Through our strategic partners, we offer
"turnkey" power/energy project development products and
services that may include; Absorption
Chillers, Adsorption Chillers,
Automated Demand Response, Biodiesel
Refineries, Biofuel Refineries,
Biomass Gasification, BioMethane,
Canola Biodiesel, Coconut
Biodiesel, Cogeneration, Concentrating
Solar Power, Demand Response
Programs, Demand Side
Conservation Measures, Energy
Master Planning, Engine Driven
Chillers, Solar CHP, Solar
Cogeneration, Rapeseed Biodiesel,
Solar Electric Heat Pumps, Solar
Electric Power Systems, Solar
Heating and Cooling, Solar
Trigeneration, Soy Biodiesel, and Trigeneration.
most companies, we are equipment supplier/vendor neutral. This means we
help our clients select the best equipment for their specific
application. This approach provides our customers with superior
performance, decreased operating expenses and increased return on
For more information: call us at: 832-758-0027
We provide Solar
Power and Energy systems, including
Concentrating Solar Power project development services. Concentrating
Solar Power is an "ecogeneration™" solutions that produce
cooler, cleaner, greener power and energy for our customers and our
This solar thermal power plant located in the
in Kramer Junction,
, is one of nine such plants built in the 1980s. During operation,
oil in the receiver tubes collects the concentrated solar energy
as heat and is pumped to a power block (in background) for
solar dish engine is an electric generator that "burns"
sunlight instead of gas or coal to produce electricity. The dish,
a concentrator, is the primary solar component of the system,
collecting the energy coming directly from the sun and
concentrating it on a small area. A thermal receiver absorbs the
concentrated beam of solar energy, converts it to heat, and
transfers the heat to the engine/generator.
U.S. Department of Energy (DOE) researches and develops a clean,
large-scale solar thermal technology known as concentrating solar
power (CSP). This research and development (R&D) focuses on
three types of concentrating solar power
technologies: trough systems, dish/engine systems, and power
towers. These technologies are used in concentrating solar power
plants that use different kinds of mirror configurations to
convert the sun's energy into high-temperature heat. The heat
energy is then used to generate electricity in a steam generator.
solar power plant's relatively low cost and ability to deliver
power during periods of peak demand—when and where we need
it—mean that concentrating solar power can be a major
contributor to the nation's future needs for distributed sources
Solar Energy Technologies Program works in concentrating solar
power R&D to provide clean, reliable, affordable solar
thermal electricity for the nation. The program's goal is to
ensure that solar thermal technologies like concentrating solar
power make an important contribution to the world's growing need
solar power plants produce electric power by converting the sun's energy
into high-temperature heat using various mirror configurations. The heat
is then channelled through a conventional generator. The plants consist
of two parts: one that collects solar energy and converts it to heat,
and another that converts heat energy to electricity.
solar power systems can be sized for village power (10 kilowatts) or
grid-connected applications (up to 100 megawatts). Some systems use
thermal storage during cloudy periods or at night. Others can be
combined with natural gas and the resulting hybrid power plants provide
high-value, dispatchable power. These attributes, along with world
record solar-to-electric conversion efficiencies, make concentrating
solar power an attractive renewable energy option in the Southwest and
other sunbelt regions worldwide.
resource for generating power from concentrating solar power systems is
plentiful. For instance, enough electric power for the entire country
could be generated by covering about 9 percent of Nevada—a plot of
land 100 miles on a side—with parabolic trough systems.
solar resources for generating power from concentrating solar
power systems is plentiful. For instance, enough electric power
for the entire country could be generated by covering about 9
percent of Nevada – a plot of land 100 miles on a side – with
parabolic trough systems.
amount of power generated by a concentrating solar power plant depends
on the amount of direct sunlight. Like concentrating photovoltaic
concentrators, these technologies use only direct-beam sunlight, rather
than diffuse solar radiation.
southwestern United States potentially offers the best development
opportunity for concentrating solar power technologies in the world.
There is a strong correlation between electric power demand and the
solar resource due largely to air conditioning loads in the region. In
fact, the Solar Electric Generating System plants operate for nearly
100% of the on-peak hours of Southern California Edison.
Does It Work?
three kinds of concentrating solar power systems—troughs,
dish/engines, and power towers—that are classified by how they collect
The sun's energy is concentrated by parabolically curved, trough-shaped
reflectors onto a receiver pipe running along the inside of the curved
surface. This energy heats oil flowing through the pipe, and the heat
energy is then used to generate electricity in a conventional steam
collector field comprises many troughs in parallel rows aligned on a
north-south axis. This configuration enables the single-axis troughs to
track the sun from east to west during the day to ensure that the sun is
continuously focused on the receiver pipes. Individual trough systems
currently can generate about 80 megawatts of electricity.
designs can incorporate thermal storage—setting aside the heat
transfer fluid in its hot phase—allowing for electricity generation
several hours into the evening. Currently, all parabolic trough plants
are "hybrids," meaning they use fossil fuel to supplement the
solar output during periods of low solar radiation. Typically a natural
gas-fired heat or a gas steam boiler/reheater is used; troughs also can
be integrated with existing coal-fired plants.
What is a Power Tower and How Does it Work?
A power tower converts sunshine into clean electricity for the world’s
electricity grids. The technology utilizes many large, sun-tracking
mirrors (heliostats) to focus sunlight on a receiver at the top of a
tower. A heat transfer fluid heated in the receiver is used to generate
steam, which, in turn, is used in a conventional turbine-generator to
produce electricity. Early power towers (such as the Solar One plant)
utilized steam as the heat transfer fluid; current designs (including
Solar Two, pictured) utilize molten nitrate salt because of its superior
heat transfer and energy storage capabilities. Individual commercial
plants will be sized to produce anywhere from 50 to 200 MW of
What are the Benefits of Power Towers?
Solar power towers offer large-scale, distributed solutions to our
nation’s energy needs, particularly for peaking power. Like all solar
technologies, they are fueled by sunshine and do not release greenhouse
gases. They are unique among solar electric technologies in their
ability to efficiently store solar energy and dispatch electricity to
the grid when needed — even at night or during cloudy weather. A
single 100-megawatt power tower with 12 hours of storage needs only 1000
acres of otherwise non-productive land to supply enough electricity for
50,000 homes. Throughout the sunny Southwest, millions of acres are
available with solar resources that could easily produce solar power at
the scale of hydropower in the Northwest U. S.
What is the Status of Power Tower Technology?
Power towers enjoy the benefits of two successful, large-scale
demonstration plants. The 10-MW Solar One plant near Barstow, CA,
demonstrated the viability of power towers, producing over 38 million
kilowatt-hours of electricity during its operation from 1982 to 1988.
The Solar Two plant was a retrofit of Solar One to demonstrate the
advantages of molten salt for heat transfer and thermal storage.
Utilizing its highly efficient molten-salt energy storage system, Solar
Two successfully demonstrated efficient collection of solar energy and
dispatch of electricity, including the ability to routinely produce
electricity during cloudy weather and at night. In one demonstration, it
delivered power to the grid 24 hours per day for nearly 7 straight days
before cloudy weather interrupted operation.
The successful conclusion of Solar Two sparked worldwide interest in
power towers. As Solar Two completed operations, an international
consortium, led by U. S. industry including Bechtel and Boeing (with
technical support from Sandia National Laboratories), formed to pursue
power tower plants worldwide, especially in Spain (where special solar
premiums make the technology cost-effective), but also in Egypt,
Morocco, and Italy. Their first commercial power tower plant is planned
to be four times the size of Solar Two (about 40 MW equivalent,
utilizing storage to power a 15MW turbine up to 24 hours per day).
This industry is also actively pursuing opportunities to build a similar
plant in our desert Southwest, where a 30 to 50 MW plant would take
advantage of the Spanish design and production capacity to reduce costs,
while providing much needed peaking capacity for the Western grid. The
first such plant would cost in the range of $100M and produce power for
about 15˘/kWh. While still somewhat higher in cost than conventional
technologies in the peaking market, the cost differential could be made
up with modest green power subsidies and political support,
jump-starting this technology on a path to 7˘/kWh power with the
economies of scale and engineering improvements of the first few plants.
It would, at that point, provide clean power as economically as more
Boeing/Stirling Energy Systems DECC project will evaluate the
performance of the “critical” parts of the Stirling engine
and develop the next-generation of the 25 kW Dish-Stirling
is a Solar Dish-Engine System?
A Solar Dish-Engine System is an electric generator that “burns”
sunlight instead of gas or coal to produce electricity. The major parts
of a system are the solar concentrator and the power conversion unit.
Descriptions of these subsystems and how they operate are presented
which is more specifically referred to as a concentrator, is the primary
solar component of the system. It collects the solar energy coming
directly from the sun (the solar energy that causes you to cast a
shadow) and concentrates or focuses it on a small area. The resultant
solar beam has all of the power of the sunlight hitting the dish but is
concentrated in a small area so that it can be more efficiently used.
Glass mirrors reflect ~92% of the sunlight that hits them, are
relatively inexpensive, can be cleaned, and last a long time in the
outdoor environment, making them an excellent choice for the reflective
surface of a solar concentrator. The dish structure must track the sun
continuously to reflect the beam into the thermal receiver.
POWER CONVERSION UNIT includes the thermal receiver and the
engine/generator. The thermal receiver is the interface between the dish
and the engine/generator. It absorbs the concentrated beam of solar
energy, converts it to heat, and transfers the heat to the
engine/generator. A thermal receiver can be a bank of tubes with a
cooling fluid, usually hydrogen or helium, which is the heat transfer
medium and also the working fluid for an engine. Alternate thermal
receivers are heat pipes wherein the boiling and condensing of an
intermediate fluid is used to transfer the heat to the engine.
Science Application International Corporation/STM Power Inc. 25
kW Dish-Stirling System is operating at a Salt River Project
site in Phoenix, AZ.
engine/generator system is the subsystem that takes the heat from the
thermal receiver and uses it to produce electricity. The most common
type of heat engine used in dish-engine systems is the Stirling engine.
A Stirling engine uses heat provided from an external source (like the
sun) to move pistons and make mechanical power, similar to the internal
combustion engine in your car. The mechanical work, in the form of the
rotation of the engine’s crankshaft, is used to drive a generator and
produce electrical power.
addition to the Stirling engine, microturbines and concentrating
photovoltaics are also being evaluated as possible future power
conversion unit technologies. Microturbines are currently being
manufactured for distributed generation systems and could potentially be
used in dish-engine systems. These engines, which are similar to (but
much smaller than) jet engines, would also be used to drive an
electrical generator. A photovoltaic conversion system is not actually
an engine, but a semi-conductor array, in which the sunlight is directly
converted into electricity.
small photovoltaic solar dish conversion system is being developed
by Concentrating Technologies, LLC.
are the markets for Solar Dish-Engine Systems?
Solar dish-engine systems are being developed for use in emerging global
markets for distributed generation, green power, remote power, and
grid-connected applications. Individual units, ranging in size from 9 to
25 kilowatts, can operate independent of power grids in remote sunny
locations to pump water or to provide electricity for people living in
remote areas. Largely because of their high efficiency and
“conventional” construction, the cost of dish-engine systems is
expected to compete in distributed markets.
Advanced Dish Development System is a 10 kW water pumping system
developed by WG Associates for use by Native Americans in the
are emerging for the deployment of dish-engine systems in the Southwest
U.S. Many states are adopting green power requirements in the form of
“portfolio standards” and renewable energy mandates. While the
potential markets in the U.S. are large, the size of developing
worldwide markets is immense. The International Energy Agency projects
an increased demand for electrical power worldwide more than doubling
installed capacity. More than half of this is in developing countries
and a large part is in areas with good solar resources, limited fossil
fuel supplies, and no power distribution network. The potential payoff
for dish-engine system developers is the opening of these immense global
markets for the export of power generation systems.
gained with Solar Two has established a foundation on which
industry can develop its first commercial plants.
(Joe Flores, Southern California Edison)
and Market Opportunities
With one of the best direct normal insolation resources anywhere on
earth, the southwestern states are poised to reap large and as yet
largely uncaptured economic benefits from this important natural
resource. California, Nevada, Arizona, and New Mexico are each exploring
policies that will nurture the development of their solar-based
addition to the concentrating solar power projects under way in this
country, a number of projects are being developed in India, Egypt,
Morocco, and Mexico. In addition, independent power producers are in the
early stages of design and development for potential parabolic trough
power projects in Greece (Crete) and Spain. Given successful deployment
of one or more of these initial markets, additional project
opportunities are expected in these and other regions.
competitive advantage of concentrating solar energy systems is their
close resemblance to most of the power plants operated by the nation's
power industry. Concentrating solar power technologies utilize many of
the same technologies and equipment used by conventional central station
power plants, simply substituting the concentrated power of the sun for
the combustion of fossil fuels to provide the energy for conversion into
electricity. This "evolutionary" aspect—as distinguished
from "revolutionary" or "disruptive"—results in
easy integration into today's central station–based electric utility
grid. It also makes concentrating solar power technologies the most
cost-effective solar option for the production of large-scale
predict the opening of specialized niche markets in this country for the
solar power industry over the next 5 to 10 years. The U.S. Department of
Energy estimates that by 2005 there will be as much as 500 megawatts of
concentrating solar power capacity installed worldwide.
Does It Cost?
solar power technologies currently offer the lowest-cost solar
electricity for large-scale power generation (10 megawatt-electric and
above). Current technologies cost $2–$3 per watt. This results in a
cost of solar power of 9˘–12˘ per kilowatt-hour. New innovative
hybrid systems that combine large concentrating solar power plants with
conventional natural gas combined cycle or coal plants can reduce costs
to $1.5 per watt and drive the cost of solar power to below 8˘ per
in the technology and the use of low-cost thermal storage will allow
future concentrating solar power plants to operate for more hours during
the day and shift solar power generation to evening hours. Future
advances are expected to allow solar power to be generated for 4˘–5˘
per kilowatt-hour in the next few decades.
information about how concentrating solar power technologies compare
financially with one another, see page 3 of "Overview Of Solar
Thermal Technologies" (PDF
information about how concentrating solar power technologies compare
financially with other renewable energy electricity technologies, see
page 3 of "Project Financial Evaluation" (PDF
the Cord" to Your Electric Company and
Dis-connect from Expensive Dirty-Power!
GO GREEN WITH OUR
SOLAR ELECTRIC POWER &
SOLAR HEATING AND COOLING SYSTEM!
THERE IS NO
CLEANER, GREENER, CHEAPER
POWER AND ENERGY SYSTEM THAN OURS!
INCENTIVES, GREEN TAGS
AND TAX CREDITS AVAILABLE
Solar Electric Power Systems Combined with our
Solar Heating and Cooling system will eliminate your electric bills
Cooling, Heating and Power is Here!
Homes, Schools, Office Buildings,
most any other building or facility can now have
Clean, Green, Power and Energy
Solar electric power systems transform
sunlight into electricity. Sunlight is an abundant resource.
Every minute the sun bathes the Earth in as much energy as
the world consumes in an entire year.
Solar cells employ special materials called
semiconductors that create electricity when exposed to
light. Solar electric systems are quiet and easy to use, and
they require no fuel other than sunlight. Because they
contain no moving parts, they are durable, reliable, and
easy to maintain.
How It Works
Solar cells, also known as photovoltaic
(PV) cells, do the work of making electricity. Several types
of solar electric technology are under development, but
four—crystalline silicon (a form of refined beach sand),
thin films, concentrators, and thermophotovoltaics—are
illustrative of the range of technologies. Solar cells are
connected to a variety of other components to make a solar
electric power system.
Crystalline silicon solar cells are used in
more than half of all solar electric devices. Like most
semiconductor devices, they include a positive layer (on the
bottom) and a negative layer (on the top) that create an
electrical field inside the cell. When a photon of light
strikes a semiconductor, it releases electrons (see
animation). The free electrons flow through the solar cell's
bottom layer to a connecting wire as direct current (DC)
Some solar cells are made from polycrystalline silicon,
which consists of several small silicon crystals.
Polycrystalline silicon solar cells are cheaper to produce
but somewhat less efficient than single-crystal silicon.
A simple silicon solar cell can power a watch or
calculator. However, it produces only a tiny amount of
electricity. Connected together, solar cells form modules
that can generate substantial amounts of power. Modules are
the building blocks of solar electric systems, which can
produce enough power for a house, a rural medical clinic, or
an entire village. Large arrays of solar electric modules
can power satellites or provide electricity for utilities.
Solar Electric Power System Components
In addition to modules, several components
are needed to complete a solar electric power system.
Many systems include batteries, battery chargers, a
backup generator, and a controller so that people in
solar-powered homes and buildings can turn on the lights at
night or run televisions or appliances on cloudy days.
Grid-connected systems don't require batteries or backup
generators because they use the grid for backup power. Some
remote system applications, such as those used to pump
water, do not require a backup power source.
Components of a typical
standalone PV system using crystalline silicon
technology. (Source: Solar Electric Power
Solar electric power systems can incorporate inverters or
power control units to transform the DC electricity produced
by the solar cells into alternating current (AC) to run AC
appliances or sell to a utility grid. Complete systems
usually include safety disconnects, fuses, and a grounding
circuit as well.
Solar electric thin films are lighter, more
resilient, and easier to manufacture than crystalline
silicon modules. The best-developed thin-film technology
uses amorphous silicon, in which the atoms are not arranged
in any particular order as they would be in a crystal. An
amorphous silicon film only one micron thick can absorb 90%
of the usable solar energy falling on it. Other thin-film
materials include cadmium telluride and copper indium
diselenide. Substantial cost savings are possible with this
technology because thin films require relatively little
Thin films are produced as large, complete modules, not
as individual cells that must be mounted in frames and wired
together. They are manufactured by applying extremely thin
layers of semiconductor material to a low-cost backing such
as glass or plastic. Electrical contacts, antireflective
coatings, and protective layers are also applied directly to
the backing material. Thin films conform to the shape of the
backing, a feature that allows them to be used in such
innovative products as flexible solar electric roofing
Concentrators use optical lenses (similar
to plastic magnifying glasses) or mirrors to concentrate the
sunlight that falls on a solar cell. With a concentrator to
magnify the light intensity, the solar cell produces more
electricity. Today, most solar cells in concentrators are
made from crystalline silicon. However, materials such as
gallium arsenide and gallium indium phosphide are more
efficient than silicon in solar electric concentrators and
will likely see more use in the future. These materials are
now used in communications satellites and other space
Concentrators produce more electricity using less of the
expensive semiconductor material than other solar electric
systems. A basic concentrator unit consists of a lens to
focus the light, a solar cell assembly, a housing element, a
secondary concentrator to reflect off-center light rays onto
the cell, a mechanism to dissipate excess heat, and various
contacts and adhesives. The basic unit can be combined into
modules of varying sizes and shapes. Concentrators only work
with direct sunlight and operate most effectively in sunny,
dry climates. They must be used with tracking systems to
keep them pointed toward the sun.
Thermophotovoltaic (TPV) devices convert
heat into electricity in much the same way that other PV
devices convert light into electricity. The difference is
that TPV technology uses semiconductors "tuned" to
the longer-wavelength, invisible infrared radiation emitted
by warm objects. This technology is cleaner, quieter, and
simpler than conventional power generation using steam
turbines and generators.
TPV converters are relatively maintenance-free because
they contain no moving parts. In addition to using solar
energy, they can convert heat from any high-temperature heat
source, including combustion of a fuel such as natural gas
or propane, into electricity. TPV converters produce
virtually no carbon monoxide and few emissions. They may be
used in the future in gas furnaces that generate their own
electricity for self-ignition (during power outages) and in
portable generators and battery chargers.
Solar electric systems offer many
advantages. Standalone systems can eliminate the need to
build expensive new power lines to remote locations. For
rural and remote applications, solar electricity can cost
less than any other means of producing electricity. Solar
electric systems can also connect to existing power lines to
boost electricity output during times of high demand such as
on hot, sunny days when air conditioners are on.
Solar electric systems are flexible. Solar electric
modules can stand on the ground or be mounted on rooftops.
They can also be built into glass skylights and walls. They
can be made to look like roof shingles and can even come
equipped with devices to turn their DC output into the same
AC utilities deliver to wall sockets. These advances mean
individual homeowners and businesses can relieve pressure on
local utilities struggling to meet the increasing demand for
More than 30 states offer grid-connected solar electric
system owners the chance to save money on their energy bills
by feeding any excess power their solar electric system
produces into the utility grid—an arrangement called net
Solar power systems require minimal maintenance. They run
quietly and efficiently without polluting. They are easy to
combine with other types of electric generators such as
wind, hydro, or natural gas turbines. They can charge
batteries to make solar electricity continuously available.
For utilities, large-scale
solar electric power plants can help meet demand for new
power generation, especially in distributed applications. A
solar electric power plant is created from multiple arrays
that are interconnected electronically. Solar electric
plants are easier to site and are quicker to build than
conventional power plants. They are also easy to expand
incrementally—by adding more modules—as power demand
Solar electric power systems are good for the
environment. When solar electric technologies displace
fossil fuels for pumping water, lighting homes, or running
appliances, they reduce the greenhouse gases and pollutants
emitted into the atmosphere. The use of solar electric
systems is particularly important in developing nations
because it can help avert the expected increases in
emissions of greenhouse gases caused by the growing demand
for electricity in those countries.
Solar electric technologies also benefit the U.S. economy
by creating jobs in U.S. companies. Exporting solar electric
technologies to developing nations expands U.S. markets
while protecting the global environment.
Although solar electric systems make
financial sense in remote areas that lack access to power
lines, they are usually more expensive than fossil fuels for
This disadvantage is significant for utilities
considering large-scale solar electric power plants.
Although solar electricity costs considerably more than
electricity generated by conventional plants, regulatory
agencies often require utilities to supply electricity for
the lowest cash cost.
Utilities view solar electric power plants differently
than they view conventional power plants. Solar electric
modules produce electricity intermittently—only when the
sun shines. Their output varies with the weather and
disappears altogether at night. Integrating solar
electricity into a utility system requires creative
A combination of solar electric
arrays and pool-heating solar collectors were used
to provide power and heat to the Georgia Tech
University Aquatic Center, site of the 1996 Olympic
swimming competition. (Credit: Heliocol)
Solar electricity has powered satellites
since the dawn of the space program. It has run remote
communications outposts high in the mountains and turned on
the lights, kept medicines cold, and pumped water in rural
areas for more than 30 years. Small solar cells are used to
power wristwatches, calculators, and other electronic
gadgets. More recently, solar electric systems have been
used to provide supplemental power to homes and commercial
buildings in cities.
Solar electric technology has important roles to play in
both the developing and developed worlds. From the farmer
irrigating his crops in rural Mexico to an innovative
lighting system for an Olympic sports arena, solar electric
Electric utilities harness solar electricity for
distributed applications—near substations or at the end of
overloaded power lines, for example, to avoid or defer
costly line upgrades. They use solar electricity during hot,
sunny periods when the demand for air conditioning stretches
conventional power generation to its limit. The Sacramento
Municipal Utility District, for example, uses large
solar electric arrays as part of its power generation mix.
Utilities also rely on solar electricity to power remote,
standalone monitoring systems.
Consumers and builders are integrating solar electric
modules into their homes and offices. Innovative solar
electric technologies can replace conventional roofing and
facade materials in new buildings. Solar electric roofing
shingles, for example, are being used in some new
residences. In grid-connected applications, solar
electricity supplies some of a consumer's energy needs; the
local utility provides the rest.
Standalone solar electric systems power a variety of
applications far from the reaches of the power grid. These
applications include remote communications systems such as
television and radio transmitters and receivers, telephone
systems, and microwave repeaters. Standalone solar electric
power is also used to prevent corrosion of metal pipes,
tanks, bridges, and buildings.
Many remote residences worldwide use solar electricity as
their source of power. For instance, more than 100,000
vacation homes in Scandinavia rely solely on solar electric
technology to run lights and appliances.
Villages around the world are building solar electric
systems to bring electricity to their homes and local
industries, often for the first time. To make the maximum
use of available resources, village power is typically
produced by a hybrid power system that combines solar
electricity with diesel backup generators and sometimes
another renewable energy technology such wind power.
Villages also use standalone solar electric systems for
pumping water—an application shared by rural farmers and
ranchers in the United States.
For more information, visit the following Web sites:
Our Solar Heating and Cooling
System - Uses the "free" Power of the Sun to Heat and Cool
your Commercial Business or Home for Free!
Cooling and heating your building (home, office, school,
hospital, etc.) costs you up to 60%, or more, every month you receive
your electric bill. You can eliminate the heating and cooling portion of
your electric bill forever, and cool and heat your home with the sun's
power with our Solar Heating and Cooling system!
Our Solar Heating and Cooling system is the cleanest,
greenest, and lowest cost method to cool and warm your home or
commercial office or other buildings. Our Solar Heating and
Cooling system will eliminate your energy costs for heating and cooling
your home, office, school, or any other commercial facility for *free:
Requires the purchase of our Solar Heating and Cooling system. Minimum
size is 10 tons. You must be located in a qualified geographic location,
which means our system must be located to receive direct sunlight.
For qualified customers, we will install the system with little to no
money down and you pay for the system with the savings our system
Solar Absorption Cooling. Solar heat can be used to displace electricity used for
cooling. Absorption chillers use a heat source, such as natural gas or
hot water from solar collectors, to evaporate the already-pressurized refrigerant from an
absorbent/refrigerant mixture. Condensation of vapors provides the same cooling effect
as that provided by mechanical cooling systems. Although absorption
chillers require electricity for pumping the refrigerant, the amount is very small compared to that
consumed by a compressor in a conventional electric air conditioner or refrigerator.
Solar Absorption Cooling systems are typically sized to carry the full air conditioning load during sunny periods.
How Does an Absorption Chiller Work?
What is an Absorption Chiller?
chillers use heat instead of mechanical energy to provide cooling. A
thermal compressor consists of an absorber, a generator, a pump, and a
throttling device, and replaces the mechanical vapor compressor.
the chiller, refrigerant vapor from the evaporator is absorbed by a
solution mixture in the absorber. This solution is then pumped to the
generator. There the refrigerant re-vaporizes using a waste steam heat
source. The refrigerant-depleted solution then returns to the absorber via
a throttling device. The two most common refrigerant/ absorbent mixtures
used in absorption chillers are water/lithium bromide and ammonia/water.
with mechanical chillers, absorption chillers have a low coefficient of
performance (COP = chiller load/heat input). However, absorption chillers
can substantially reduce operating costs because they are powered by
low-grade waste heat. Vapor compression chillers, by contrast, must be
motor- or engine-driven.
steam-driven absorption chillers are available in capacities ranging from
100 to 1,500 tons. Absorption chillers come in two commercially available
designs: single-effect and double-effect. Single-effect machines provide a
thermal COP of 0.7 and require about 18 pounds of
15-pound-per-square-inch-gauge (psig) steam per ton-hour of cooling.
Double-effect machines are about 40% more efficient, but require a higher
grade of thermal input, using about 10 pounds of 100- to 150-psig steam
single-effect absorption machine means all condensing heat cools and
condenses in the condenser. From there it is released to the cooling
water. A double-effect machine adopts a higher heat efficiency of
condensation and divides the generator into a high-temperature and a
Is It Right for You?
Absorption cooling may be worth considering if your site requires cooling,
and if at least one of the following applies:
You have a combined heat and power CHP)
unit and cannot use all of the available heat, or if you are
considering a new CHP plant
Waste heat is available
A low-cost source of fuels is available
Your boiler efficiency is low due to a
poor load factor
Your site has an electrical load limit
that will be expensive to upgrade
Your site needs more cooling, but has an
electrical load limitation that is expensive to overcome, and you have
an adequate supply of heat.
short, absorption cooling may fit when a source of free or low-cost heat
is available, or if objections exist to using conventional refrigeration.
Essentially, the low-cost heat source displaces higher-cost electricity in
a conventional chiller.
In a plant where low-pressure steam is currently being vented to the
atmosphere, a mechanical chiller with a COP of 4.0 is used 4,000 hours a
year to produce an average 300 tons of refrigeration. The plant's cost of
electricity is $0.05 a kilowatt-hour.
An absorption unit requiring 5,400 lbs/hr of 15-psig steam could replace
the mechanical chiller, providing annual electrical cost savings of:
Savings = 300 tons x (12,000 Btu/ton / 4.0) x 4,000 hrs/yr x $0.05/kWh x
kWh/3,413 Btu = $52,740
Actions You Can Take
the cost-effectiveness of displacing a portion of your cooling load with a
waste steam absorption chiller by taking the following steps:
Conduct a plant survey to identify
sources and availability of waste steam
Determine cooling load requirements and
the cost of meeting those requirements with existing mechanical
chillers or new installations
Obtain installed cost quotes for a waste
steam absorption chiller
Conduct a life cycle cost analysis to
determine if the waste steam absorption chiller meets your company's
Absorption Chiller Refrigeration
The basic cooling cycle is
the same for the absorption and electric chillers. Both systems use a
low-temperature liquid refrigerant that absorbs heat from the water to be
cooled and converts to a vapor phase (in the evaporator section). The
refrigerant vapors are then compressed to a higher pressure (by a
compressor or a generator), converted back into a liquid by rejecting heat
to the external surroundings (in the condenser section), and then expanded
to a low- pressure mixture of liquid and vapor (in the expander section)
that goes back to the evaporator section and the cycle is repeated.
The basic difference
between the electric chillers and absorption chillers is that an electric
chiller uses an electric motor for operating a compressor used for raising
the pressure of refrigerant vapors and an absorption chiller uses heat for
compressing refrigerant vapors to a high-pressure. The rejected heat from
the power-generation equipment (e.g. turbines, microturbines, and engines)
may be used with an absorption chiller to provide the cooling in a CHP
The basic absorption cycle
employs two fluids, the absorbate or refrigerant, and the absorbent. The
most commonly fluids are water as the refrigerant and lithium bromide as
the absorbent. These fluids are separated and recombined in the absorption
cycle. In the absorption cycle the low-pressure refrigerant vapor is
absorbed into the absorbent releasing a large amount of heat. The liquid
refrigerant/absorbent solution is pumped to a high-operating pressure
generator using significantly less electricity than that for compressing
the refrigerant for an electric chiller. Heat is added at the
high-pressure generator from a gas burner, steam, hot water or hot gases.
The added heat causes the refrigerant to desorb from the absorbent and
vaporize. The vapors flow to a condenser, where heat is rejected and
condense to a high-pressure liquid. The liquid is then throttled though an
expansion valve to the lower pressure in the evaporator where it
evaporates by absorbing heat and provides useful cooling. The remaining
liquid absorbent, in the generator passes through a valve, where its
pressure is reduced, and then is recombined with the low-pressure
refrigerant vapors returning from the evaporator so the cycle can be
Absorption chillers are
used to generate cold water (44°F) that is circulated to air handlers in
the distribution system for air conditioning.
absorption chillers use steam, hot water or hot gases steam from a boiler,
turbine or engine generator, or fuel cell as their primary power input.
Theses chillers can be well suited for integration into a CHP system for
buildings by utilizing the rejected heat from the electric generation
process, thereby providing high operating efficiencies through use of
otherwise wasted energy.
systems contain natural gas burners; rejected heat from these chillers can
be used to regenerate desiccant dehumidifiers or provide hot water.
chillers can be single-effect or multiple-effect. The above schematic
refers to a single-effect absorption chiller. Multiple-effect absorption
chillers are more efficient and discussed below.
In a single-effect
absorption chiller, the heat released during the chemical process of
absorbing refrigerant vapor into the liquid stream, rich in absorbent, is
rejected to the environment. In a multiple-effect absorption chiller, some
of this energy is used as the driving force to generate more refrigerant
vapor. The more vapor generated per unit of heat or fuel input, the
greater the cooling capacity and the higher the overall operating
A double-effect chiller
uses two generators paired with a single condenser, absorber, and
evaporator. It requires a higher temperature heat input to operate and
therefore they are limited in the type of electrical generation equipment
they can be paired with when used in a CHP System.
Triple-effect chillers can
achieve even higher efficiencies than the double-effect chillers. These
chillers require still higher elevated operating temperatures that can
limit choices in materials and refrigerant/absorbent pairs. Triple-effect
chillers are under development by manufacturers working in cooperation
with the U.S. Department of Energy.
* Geothermal Energy... Power from the Depths
The Earth's crust is a bountiful source of energy—and fossil fuels
are only part of the story. Heat or thermal energy is by far the more
abundant resource. To put it in perspective, the thermal energy in the
uppermost six miles of the Earth's crust amounts to 50,000 times the
energy of all oil and gas resources in the world!
The word "geothermal" literally means "Earth" plus
"heat." The geothermal resource is the world's largest energy
resource and has been used by people for centuries. In addition, it is
environmentally friendly. It is a renewable resource and can be used in
ways that respect rather than upset our planet's delicate environmental
Geothermal power plants operating around the world are proof that the
Earth's thermal energy is readily converted to electricity in geologically
active areas. Many communities, commercial enterprises, universities, and
public facilities in the western United States are heated directly with
the water from underground reservoirs. For the homeowner or building owner
anywhere in the United States, the emergence of geothermal heat pumps
brings the benefits of geothermal energy to everyone's doorstep.
There's a relatively simple concept underlying all the ways geothermal
energy is used: The flow of thermal energy is available from beneath the
surface of the Earth and especially from subterranean reservoirs of hot
water. Over the years, technologies have evolved that allow us to take
advantage of this heat.
In fact, electric power plants driven by geothermal energy provide over
44 billion kilowatt hours of electricity worldwide per year, and world
capacity is growing at approximately 9% per year. To produce electric
power from geothermal resources, underground reservoirs of steam or hot
water are tapped by wells and the steam rotates turbines that generate
electricity. Typically, water is then returned to the ground to recharge
the reservoir and complete the renewable energy cycle.
Underground reservoirs are also tapped for "direct-use"
applications. In these instances, hot water is channeled to greenhouses,
spas, fish farms, and homes to fill space heating and hot water needs.
Geothermal energy use extends beyond underground reservoirs. The soil
and near-surface rocks, from 5 to 50 feet deep, have a nearly constant
temperature from geothermal heating. As a homeowner or business owner, you
can use the Earth as a heat source or heat sink with geothermal heat
pumps. According to the U.S. Environmental Protection Agency (EPA),
geothermal heat pumps are one of the nation's most efficient—and
therefore least polluting—heating, cooling, and water-heating systems
available. In winter, these systems draw on "earth heat" to warm
the house, and in summer they transfer heat from the house to the earth,
which ranges in temperature from 50° to 70°F (10° to 21°C) depending
A Clear Advantage
Geothermal energy delivers some powerful environmental and economic
benefits. If you live in an area that uses geothermal resources for
electricity production, you're quite fortunate. Consider Lake County,
California, which is home to many of the geothermal power plants at our
nation's best-developed geothermal resource, The Geysers. It's no
coincidence that the Lake County air basin is the first and only one in
compliance with all of California's stringent air quality regulations.
Perhaps you own a greenhouse and need to cut exorbitant energy bills in
order to stay in business. If you are located near a geothermal resource,
you should know that most greenhouse growers estimate that direct use of
geothermal resources instead of traditional energy sources reduces heating
costs by up to 80%. This can save about 5% to 8% in total operating cost.
Assume you're a home or business owner who has installed a geothermal
heat pump. You're not only doing your part to help make the world a
cleaner place to live and breathe, you're rewarded with low operating and
maintenance costs, and, usually, lowest life-cycle costs. (Life-cycle cost
is the total cost of the equipment spread over the useful life of the
equipment.) In practical terms, your heat pump investment may cost you $15
per month more in mortgage payments, but it may save you $30 per month on
your electric bill.
In all three of these cases, domestic, not foreign, resources are being
used—a practice that has merits all its own. Nearly half of our nation's
annual trade deficit would be obliterated if we could displace imported
oil with domestic energy resources. A nation's trade deficit represents a
permanent loss of wealth for the citizens of that nation. Keeping the
wealth at home translates to more jobs and a robust economy. And not only
does our national economic and employment picture improve, but a vital
measure of national security is gained when we control our own energy
Types of Geothermal Resources
The center of the Earth is 4000 miles (6400 kilometers) deep. How hot
is this region? Our best guess is 7200°F (4000°C) or higher. Partially
molten rock, at temperatures between 1200° and 2200°F (650° to 1200°C),
is believed to exist at depths of 50 to 60 miles (80 to 100 kilometers).
Heat is constantly flowing from the Earth's interior to the surface.
Most types of geothermal resources—hydrothermal, geopressured, hot dry
rock, and magma—result from concentration of Earth's thermal energy
within certain discrete regions of the subsurface.
Hydrothermal resources are reservoirs of steam or hot water,
which are formed by water seeping into the earth and collecting in, and
being heated by fractured or porous hot rock. These reservoirs are tapped
by drilling wells to deliver hot water to the surface for generation of
electricity or direct use. Hot water resources exist in abundance around
the world. In the United States, the hottest (and currently most valuable)
resources are located in the western states, and Alaska and Hawaii.
Technologies to tap hydrothermal resources are proven commercial
Geopressured resources are deeply buried waters at moderate
temperature that contain dissolved methane. While technologies are
available to tap geopressured resources, they are not currently
economically competitive. In the United States, this resource base is
located in the Gulf coast regions of Texas and Louisiana.
Hot dry rock resources occur at depths of 5 to 10 miles (8 to 16
kilometers) everywhere beneath the Earth's surface, and at shallower
depths in certain areas. Access to these resources involves injecting cold
water down one well, circulating it through hot fractured rock, and
drawing off the now hot water from another well. This promising technology
has been proven feasible, but no commercial applications are in use at
Magma (or molten rock) resources offer extremely
high-temperature geothermal opportunities, but existing technology does
not allow recovery of heat from these resources.
Earth energy is the heat contained in soil and rocks at shallow
depths. This resource is tapped by geothermal heat pumps.
Geothermal Power Plants—from Water to Light
Flip a switch and light up a room—what could be easier? Push a button
on the TV remote control and be entertained. It all seems so simple that
we are often unaware of the true environmental and social cost of these
conveniences—and who would want to give them up even if we had to
account for every penny?
But rather than thinking in terms of giving things up, let's think
positively: in the United States, right now, the installed generating
capacity for geothermal stands at about 2700 megawatts. That's the
equivalent of about 58 million barrels of oil, and provides enough
electricity for 3.7 million people. The cost of producing this power
ranges from 4˘ to 8˘ per kilowatt hour. The geothermal industry is
working to achieve a geothermal life-cycle energy cost of 3˘ per kilowatt
hour. And remember, this is clean energy produced from domestic resources.
How clean? In terms of air emissions, geothermal power plants have an
inherent advantage over fossil fuel plants because no combustion takes
place. Geothermal plants emit no nitrogen oxides and very low amounts of
sulfur dioxide—allowing them to easily meet the most stringent clean air
standards. The steam at some steam plants contains hydrogen sulfide, but
treatment processes remove more than 99.9% of those emissions. Typical
emissions of hydrogen sulfide from geothermal plants are less than 1 part
per billion—well below what people can smell. The low levels of air
emissions produced are mostly carbon dioxide, which many people believe
acts as a greenhouse gas to trap heat within Earth's atmosphere. Even so,
geothermal plants emit minimal amounts of carbon dioxide—1/1000 to
1/2000 of the amount produced by fossil-fuel plants.
Geothermal water sometimes contains salts and dissolved minerals. In
the United States, the geothermal water is usually injected back into the
reservoir from where it came, at a depth well below groundwater aquifers,
after its heat energy has been extracted. This recycles the geothermal
water and replenishes the reservoir. However, some geothermal plants also
produce some solid materials, or sludges, that require disposal in
All U.S. geothermal power plants are located in the states of
California, Nevada, Utah, and Hawaii—home to some of the most majestic
scenery on Earth. It's fortunate, then, that these plants consume only a
small amount of land, and can coexist with numerous other land uses,
including agriculture, with minimal impact on the surrounding beauty.
They're reliable and efficient, too. Taken as a group, geothermal power
plants are available to generate power 95% or more of the time; they are
seldom off-line for maintenance or repair. And, they have the highest
capacity factors of all types of power plants. Capacity factor is the
ratio of the amount of electricity a plant produces to how much
electricity it is capable of producing.
Dry Steam Power Plants were the first type of geothermal power
plant (in Italy in 1904). The Geysers in northern California, which is the
world's largest single source of geothermal power, is also home to this
type of plant. These plants use the steam as it comes from wells in the
ground, and direct it into the turbine/generator unit to produce power.
Flash Steam Power Plants, which are the most common, use water
with temperatures greater than 360°F (182°C). This very hot water is
pumped under high pressure to equipment on the surface, where the pressure
is suddenly dropped, allowing some of the hot water to "flash"
into steam. The steam is then used to power the turbine/generator. The
remaining hot water and condensed steam are injected back into the
Binary Cycle Power Plants operate on the lower-temperature
waters, 225° to 360°F (107° to 182°C). These plants use the heat of
the hot water to boil a "working fluid," usually an organic
compound with a low boiling point. This working fluid is then vaporized in
a heat exchanger and used to turn a turbine. The geothermal water and the
working fluid are confined to separate closed loops, so there are no
emissions into the air.
Because these lower-temperature waters are much more plentiful than
high-temperature waters, binary cycle systems will be the dominant
geothermal power plants of the future.
Developing and commercializing geothermal power technologies
contributes not only to a cleaner environment, but to a healthy U.S.
industrial base, as well. Around the developing countries of the world,
demand for electric power is burgeoning—and nearly half of these
countries have geothermal resources. These markets have proven
particularly receptive to clean energy produced with indigenous resources,
creating attractive export options for geothermal technologies and
expertise. In fact, U.S. geothermal companies have signed contracts worth
more than $6 billion in the past few years to build geothermal power
plants in some of these developing countries.
Direct Use of Geothermal Energy
If you've ever soaked in water from a natural hot spring, you're one of
the millions of people around the world who has enjoyed the direct use of
geothermal energy. And while this naturally occurring hot water may be the
perfect tonic for frayed nerves and sore muscles, it's capable of much
more. In the United States alone, direct geothermal applications (not
including geothermal heat pumps) have an installed capacity of 500 thermal
megawatts, which is roughly equivalent to saving half a million barrels of
oil per year. This includes approximately 40 greenhouses, 30 fish farms,
190 resorts and spas, 125 space and district heating projects, and 10
The resource required for these applications is widespread across the
western third of the United States. This is water in an underground
reservoir, at low-to-moderate temperatures usually ranging from 68° to
302°F (20° to 150°C). The consumer of direct-use geothermal energy can
count on savings in energy costs—as much as an 80% reduction from
traditional fuel costs, depending on the application and the industry.
Direct-use systems typically require a larger initial investment, but have
lower operating costs and no need for ongoing fuel purchases, therefore
reducing life-cycle costs.
In a typical application, a well brings heated water to the surface; a
mechanical system—piping, heat exchanger, controls—delivers the heat
to the space or process; and a disposal system either injects the cooled
geothermal fluid underground or disposes of it on the surface.
The direct use of geothermal energy offers some heartening
possibilities. Imagine an entire community of people having their homes
heated geothermally. Sound like something way off in the future? Not at
all. In 1893, the citizens of Boise, Idaho, put their pioneering spirit to
work and built the world's first geothermal district heating system by
piping water from a nearby hot spring. Within a few years, the system was
providing heat to 200 homes and 40 downtown businesses—and the system
continues to flourish today.
There are now 18 district heating systems in the United States
(including one in Klamath Falls, Oregon, that melts snow from the city's
downtown sidewalks), and the potential for more is tremendous. A recently
updated resource inventory of 10 western states identified 271 communities
located within 5 miles (8 kilometers) of a geothermal resource.
Greenhouse operators are taking advantage of geothermal direct use in
growing numbers, with nearly 40 greenhouses (many of which are several
acres in size) producing vegetables, flowers, houseplants, and tree
seedlings in eight western states. Operators of fish farms are profiting
from the lower energy costs and improved fish growth rates that geothermal
energy delivers. Other industrial and commercial applications that match
well with geothermal direct use include food dehydration, laundries, gold
processing, milk pasteurizing, and swimming pools and spas.
The Heat Pump Solution
The geothermal heat pump doesn't create electricity—but it greatly
reduces consumption of it. If you would like to reduce the cost of heating
and cooling your home, you might want to consider installing a geothermal
heat pump, an economical and energy-efficient technology for space heating
and cooling and water heating. Nationwide, more than 350,000 of these
systems are in operation in homes, schools, and businesses. And the
geothermal heat pump industry expects to be installing 40,000 systems per
year by 2000.
In winter, heat pump systems draw thermal energy from the ambient
temperature of the shallow ground, which ranges between 50° and 70°F (10°
to 21°C ) depending on latitude. In summer, the process is reversed to a
cooling mode, using the ground as a sink for the heat contained within the
building. The system does not convert electricity to heat; rather, it uses
electricity to move thermal energy between the building and the ground and
condition it to a higher or lower temperature according to the heating or
cooling requirements. Consumption of electricity is reduced 30% to 60%
compared to traditional heating and cooling systems, allowing a payback of
system installation in 2 to 10 years. And these low-maintenance systems
have long lives of 30 years or more. Some systems are also capable of
producing domestic hot water at no cost in summer and at small cost in
An analysis by the EPA found these systems to be among the most
efficient space-conditioning technologies available—with the lowest
environmental cost of all that were analyzed. But this might be the most
compelling statistic: Surveys show that the number of satisfied geothermal
heat pump customers stands at 95% or higher.
About Solar Heating and Cooling
It is possible to use solar thermal energy or solar electricity to operate or power an
HVAC or heating and cooling system. The following is a brief description of "active" solar cooling and refrigeration technologies. Active solar energy systems use a mechanical or electrical device to transfer solar energy absorbed in a solar collector to another component in the "system." It is possible to also cool a building or structure by using the natural processes of solar heat transfer (conduction, convection, and radiation). This is often referred to as "passive solar cooling," and is primarily an architectural technique. This brief focuses on active solar cooling systems. The American Solar Energy Society (ASES, see Source List below) is one source of information on passive solar cooling techniques.
Absorption Cooling and Refrigeration
Absorption cooling is the first and oldest form of air conditioning and refrigeration. An absorption air conditioner or refrigerator does not use an electric compressor to mechanically pressurize the refrigerant. Instead, the absorption device uses a heat source, such as natural gas or a large solar collector, to evaporate the already-pressurized refrigerant from an absorbent/refrigerant mixture. This takes place in a device called the vapor generator. Although absorption coolers require electricity for pumping the refrigerant, the amount is small compared to that consumed by a compressor in a conventional electric air conditioner or refrigerator. When used with solar thermal energy systems, absorption coolers must be adapted to operate at the normal working temperatures for solar collectors: 180° to 250°F (82° to 121°C). It is also possible to produce ice with a solar powered absorption device, which can be used for cooling or refrigeration.
Does an Engine Driven Chiller Work?
Packaged natural gas
engine-driven water chillers and direct expansion (DX) units are now
available. Commercially proven custom and packaged engine-driven
refrigeration units offer excellent reliability and economic advantages
for ice rinks, refrigerated warehouses and other applications. The
industry is also focusing on developing small, engine-driven heating and
cooling systems suitable for small commercial applications.
cooling systems employ a conventional vapor compression cycle. Their main
components are the compressor, condenser, expansion valve and evaporator.
Advantages: The main difference
between a natural gas and conventional electric system is the replacement
of the electric motor with a gas engine. This change results in
variable-speed operation capability; higher part-load efficiency;
efficient high-temperature waste-heat recovery for water heating, process
heating, or steam generation; and an overall reduction in operating
* Requires no more room
than conventional electric chillers
* Lowest operating cost of
any available chiller
* Depending on electric
rates and natural gas rates, an engine driven chiller may operate at up to
1/2 of the cost of direct-fired absorption chillers
Like absorption chillers, engine driven chillers reduce on-peak
electric demand charges.
* Depending on your
electric and/or natural gas supplier, there may be rebates available for
purchasing a new absorption chiller or engine driven chiller from your
* Environmentally friendly.
more information on absorption chillers, call
us at: 832-758-0027
* Some of the above information from the Department
of Energy website with permission.