Harnessing the Power of the Sun and reducing our dependence upon Greenhouse Gasses

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Harnessing the Power of the Sun and reducing our
dependence upon Greenhouse Gasses For centuries
innovative and resourceful designers and builders
have recognized that the most fundamental
efficient renewable sustainable energy is the
direct energy of the sun. They have used the
heating factor of the sun both passively and
actively to heat a house or building. The
earliest example I have seen of a solar thermal
collector was in a house in Western Upstate New
York that was built in 1735. Exactly when the
solar thermal collector was installed, I do not
know. The designer installed iron pipes in a
series of tubes on the zinc standing seam metal
roof. The pipes were on the south side facing
roof. The interior dimension of these pipes was
approximately 1 and the series of pipes was more
than 100 feet. In the basement he had a
100-gallon tank of water which was kept heated
with a fire. This supplied a closed loop radiator
system that provided heat for the house. Since
then, many different variations of flat plate
solar collectors have been utilized that absorb
the heat from the sun using pipes full of liquid
to provide domestic hot water and water source
heating for the house. In the past two decades
solar thermal collectors have advanced
significantly and become more than 80 more
energy efficient in capturing and using the heat
of the sun than flat plate collectors. This has
been advanced through the technology of Evacuated
Tube Solar Thermal Collectors (ETSC) As this
system has improved and the demand for thermal
energy has increased so has the price decreased
to make it a much more viable option than flat
plate solar collectors. Furthermore, the usable
energy of the sun is 53 more energy efficient
than the best technology Solar Voltaic
Collectors. The highest energy consumption for
residential use is in heating and cooling a
house. So the first approach to addressing this
issue is in lowering the houses thermal load by
making the envelope of the structure more
resistant to heat loss or gain. The next step is
to design a highly energy efficient heating and
cooling system that most effectively uses the
suns energy at the lowest cost for that
exchange in energy both in initial cost and
lifetime costs. So most would assume that the
options would be in the question of using Solar
Voltaic Collectors which generate direct
electricity from the sun or Solar Thermal
Collectors which capture heat energy? For many
the comparison in cost between installing an
Evacuated Tube Solar Thermal Collector or
installing a Solar Photo- Voltaic Collector (PV)
to do the same basic task of providing quiet,
clean water source heating and continuous
domestic hot water is all you care to know. A
well- built, highly energy efficient house to
best justify the initial cost of these systems is
the same given. For a 1500-2000 square foot
house the average cost of a Solar Photo-Voltaic
Generator with inverters and back-up batteries is
30000. For one third of the face surface to
operate a heat and cooling system using
Photo-Voltaic generators you can install an
Evacuated Tube Solar Thermal Collector which can
heat and cool your home. In both applications
the surface space is usually on the roof. For
both the optimal location is where you have the
longest solar exposure throughout the day and
throughout the year. The
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roofmay be the place for these installationshowev
er,it is not always the best.In most cases the
roof is not the best place for Photo-Voltaic
Generators because the radiant heat from the roof
affects its optimal function and shortens its
life expectancy. So for PV Collectors the
circulation of air over and under the unit is
best and its average life expectancy is 11-17
years, depending upon what PV technology is
utilized. The lithium batteries must be replaced
on an average of every five years. The
production and disposal of these batteries is a
big long term question concerning
sustainability, which I will address in a future
blog post. For Evacuated Tube Solar Thermal
Collectors, the radiant heat from the roof
improves its thermal function and has no effect
on its lifetime function.An Evacuated Tube Solar
Thermal Collector will put out consistent direct
solar thermal energy for at least 25 years.
Usually, the only thing you may need to replace
in such units are the evacuated tubes that might
break or lose their vacuum seal. This involves
the simple task of unscrewing an affected tube
and screwing in a new tube. Now back to
addressing the costsdifferences between a Solar
Photo- Voltaic generator to produce the energy
needed to heat and cool your house and the costs
of Evacuated Tube Solar Thermal Collectors to do
the same thing. The installation costs for such a
unit including storage tanks and liquid
circulators for 1500-2000 square foot home is
8500. What a difference! Such a small investment
for a lifetime of free thermal energy from the
sun. So, what is an Evacuated Tube Solar Thermal
Collector (ETSC)?
The aim of Solar thermal collectors is to absorb
as much solar heat energy as possible and to
retain that heat in a liquid medium. In other
words, solar collectors convert solar radiation
into
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thermal energy and reduce energy loss. ETSCs
improve this energy efficiency over flat plate
absorption collectors by using glass or plastic
cylindrical clear tubes that have within them
copper tubes with a reflective backing that
absorbs the radiant heat from the sun. These
absorption tubes maintain their radiant energy by
being sealed inside a clear vacuumed tube. This
acts as a diathermic wall. The internal absorber
is a copper heat pipe that contains a vaporized
fluid that makes it possible for the heat
transferred fluid to reach temperatures that
exceed 250 degrees (F). This means that this heat
has the possibility of running a steam electric
generator or hydrolyzing hydrogen from water to
be collected in pressurized tanks to operate an
electric generator instead of being dependent on
back up batteries which when spent has to be
disposed of as hazardous waste. I see the future
of truly renewable sustainable energy as a
micro-grid for individual residential use or for
a system that may power a neighborhood or a city
as in a hybrid approach of using the direct
energy of the sun in ETSC, PV, and wind
generators with the end goal of the most
efficient means to power hydrogen fuel cells
which can produce electricity to power whatever
size grid during low light conditions. It is my
opinion that the most cost efficient and energy
efficient route to this end is using direct
thermal energy from the sun. In moderate
climates the most efficient use of this thermal
heat is in direct heating water as the vaporized
liquid. This provides direct heat for domestic
hot water and for water source heating for the
home either through radiant tubes or hot water
run through coils in the air handler to heat the
home. In climates especially that have a high
gradient temperature between day and night or
climes which have many days without sun or
temperatures below freezing, then a liquid like
glycol is the absorbent liquid. The vaporized
liquid rises to the condenser and the heat
manifold and turns back to liquid and falls back
to the solar exposed space. In such a system
there is a built-in storage tank that maintains
this cycle with natural thermal convection. In
most closed loop systems, the heated fluid
circulates through a water heater and through a
system of radiant tubes either in direct radiant
heat or through coils in the air handler and
returns to the ETSC using a circulating pump to
supply domestic hot water and for water source
heating for the home. We recommend a dedicated
low wattage circulating pump supplied by a
photo-voltaic generator. Since the heat
absorption tubes are protected within the
evacuated tubes that prevent the loss of thermal
energy and maintain the maximum heat absorption
and because the evacuated clear tubes are
cylindrical this system works effectively from
sunrise to sunset and even on overcast days.
Furthermore, the vacuum seal makes the system
impervious to energy loss on cold days or the
flow of air around the tubes. This system using
cylindrical tubes optimizes the total
thermalsurface area for collecting thermal
energy. The vacuum seal also prevents corrosion
from the effects of the environment or from
collection of condensation. This translates into
continuous production of thermal energy every
day, every season for a lifetime. This means
this system saves you inenergy costs
consistently for many years directly using the
free thermal energy of the sun.
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Now with solar thermal collectors surrounded by a
clear cylindrical vacuum tubes consistently
provides heat for heating water for domestic hot
water and for heating the home is a no brainer
for this purpose, but it can also be utilized for
a cooling systemthrough desiccant cooling as
well. A desiccant cooling system uses a material
that removes moisture from the air with resulting
cooling of the space where the relative humidity
is extracted. A common readily accessible and
inexpensive desiccant could be silica gel. Here
is how a desiccant cooling system would work in
conjunction with Evacuated Tube Solar Thermal
Collectors. The ETSC provides consistent heat
through the heated liquid medium which is
produced by direct thermal energy of the sun.
This heat is transferred to a desiccant wheel or
rotor. The desiccant wheel rotates between the
air flow and the heated fluid, which allows the
desiccant material to absorb the moisture from
the air. As the desiccant absorbs the moisture
from the air it releases latent heat, which cools
the air passing over it. The cooled dehumidified
air provides effective cooling for your living
space. In all our eco-sustainable plans we
integrate the use of Evacuated Tube Solar Thermal
Collectors as an integrated part of our heating
and cooling system because it captures the
direct thermal energy of the sun as a highly
consistent, energy efficient and inexpensive
heating and cooling system year round.