FAQ Facts Questions and Answers
Where will A2WH work best?
The
A2WH system needs Sun to do it's
work. It can tolerate a wide range of humidity but generally
as
temperatures and relative humidity rise the cost per gallon produced
goes down. The system can work in areas
with daytime
humidity as low as 10% but the system gets heavier and more expensive
as humidity drops. We can substitute
wind to replace
some sun which can work even better in areas with very
low daytime
humidity. We can also substitute electricity for
the sun
but prefer not to do so.
A2WH systems are ideal in areas where no surface water is available and
where drilling wells are either abnormally expensive or where there is
a risk of non potable water or salt water coming out of the
wells. It can also be particularly
effective in
areas where it is difficult or expensive to dispose of the waste brine
streams produced by RO (Reverse Osmosis) desalination
systems.
The best areas in the gulf states are those who in a rain shadow or are
prone to extended droughts. Any location where the ground water is
saline is great.
The air to water system is generally less expensive than trucking in
water especially when long term labor and fuel costs are factored
in. All indications are that it
could compete
with RO desalination when the long term energy and
environmental
costs are factored in especially in the 10,000 to 100,000
gallon
systems which normally have high disposal costs for their brine
streams.
How will A2WH work in
Arizona where there is lots of
sun, low humidity and little Rain?
In
particular how much water can it produce near Tucson and Phoenix?
What really matters is the delta between the daytime and
nighttime humidity and strong sustained sun during the day. In
fact
our system will work better in Arizona that it does here near
Seattle. Our system absorbs moisture at night and reclaims it during
the
day. Even in Arizona the nighttime humidity swings much higher as
the air nighttime air cools.
I looked Tucson
up and spot checked a few days in August. The humidity ranged from
22%RH at
midnight up through 48% at 7:55. This is
more than
enough humidity
for our system to operate. I checked all of July
and
the conditions looked good with every night reaching humidity of at
least 48% and some nights as high as 75.
Under these conditions you would generally plan for 12 pounds of system
per
pound of water produced per day. This limit on production is really a
limit of space and cost. It may be feasible to
plan this
area with as little as
8 pounds of system per pound of water per day in these conditions but
it would be safer to plan on 12.
What
is the best time of year?
Our
system produces best during the
hottest part of the year when water is under most demand and hardest to
obtain.
The best time of year for
our system is the hottest part of the summer when there is the longest
sustained sunlight. Higher humidity also helps but the
design of
our
system is such that it can work in even the very dry locations like
Phoenix AZ and Las Vegas NV.
What
is the worst time of
year
Luckily
our bad part of the year Winter
coincides with times when people generally consume less water
and
when other water supplies are more plentiful.
We depend on solar heat and the system simply will not work without
sun. Here in the Pacific northwest during the winter there
is
insufficient sun and way too much cloud cover to allow the
system
to work optimally. There are days where it will work but only
on
days when it receives good sun. There are options
that use
grid power to augment solar heat but they add cost to the system and
increase operating costs.
We have been in greenhouses in Utah in the dead of January
when
it was 2F outside and 105F inside the greenhouse so the system could
work just fine in some winter locations especially those which receive
good sun and regularly rise above 35F during the day.
Another issue with winter use is that winter air contains
much
less moisture. That means we must process more air to get a
gallon of water. In some instances this can be over 40 times
more
air. This is a challenge because we receive less solar energy
to
drive the electrial blowers during the part of the year when we have to
work harder to get the moisture. This means the photo
voltaic
array must be larger for locations with dry winter air. Other
areas have very moist winter air and will work just
fine.
The default system is not designed to be freeze proof. Water
condenses in our system is a chamber which could eventually become
fully clogged with ice when the air is below freezing. The plastic used is flexible so it is unlikely to be damaged by
freezing but the system will not produce any
further water
until this chamber is melted. In addition the
water
leaving the condenser travels through drain lines which may freeze
solid and prevent the system from working until the next thaw. There are product options to mitigate these risks but they add to
the system cost.
What Quality of water does A2WH
produce?
The
water is
generally cleaner and has a lower TDS (Total dissolved
Solids) than any common source of surface or ground water. As a
result it
can
be used to dilute water from wells that have high loads which can
reduce downstream treatment costs. It is cleaner and safer
than
any
source of ground water.
The system produces water by extracting H2O from the air.
Before
this
happens the air has been filtered multiple times. It is
very close in
quality to single distilled water. Due to the solar
thermal
design
the air often reaches pasteurization temperatures before condensing
which
acts as a secondary sanitary mechanism.
What are the most popular uses
for the A2WH technology?
- Remote cabins without a
well. Most attractive where there
is no grid power and where water must be hauled in.
- Industry and packaging where
water shortages have caused work
stoppage or lost revenue.
- Hotels in water scarce
areas. Especially where they have
lost room stay nights and/or reputation due to water
shortages.
- Million $ homes which can be
developed on land that could
otherwise not be developed due to lack of water.
- Islands where overuse has
eroded the freshwater lenses and
destroyed wells. Especially islands with abnormally high
cost of
power.
- Municipalities where lack of
water supply is preventing issuance
of new building permits.
- Homes and business in the
hurricane zone who are at risk of
loosing power and or water supplies for extended periods of time.
- Well users in areas where
dropping aquifer have degraded water
quality and where drilling new wells has a low probability of success.
Is
the system good for agriculture use?
The
system can be viable for
high
value, high density crops such as citrus, tomatoes, grapes, herbs, etc.
It can be particularly valuable where it allows greenhouses
and
aquaculture to be established on land with a good growing season where
lack of water would otherwise prevent development.
Even when deployed at a scale of
several million gallons per day the water produced is expected to cost
over $800 per acre foot. This can be quite competitive with
desalination especially when long term energy costs are factored in but
it is sufficiently expensive that it would simply not be viable for use
in many bulk crops such as rice and wheat.
Are
systems available for home users?
Yes
but it is generally most attractive
for home users who have a fair amount of open yard space which receives
direct sun. The system is generally too heavy to
install
on residential roofs unless they have been reinforced and certified by
a local architect to take the additional weight. The
system units can be used to provide a partially shaded patio roof but
the supports must be locally engineered to meet code. The
units
do require periodic filter cleaning so it is best for them to be
installed where they can be easily accessed.
The smallest system produces 3 gallons per day during the prime
operating year. You must plan on the system
weighing 13 to
18 pounds per pound of water produced per day. This means a 3
gallon per day system will weigh about 375 pounds. We generally plan on 15 square foot per gallon per day.
This is generally rounded up to 20 sq foot per gallon per day
to
allow for service walk ways. This means a 3 gallon per day
system
will occupy about 60 square foot.
A 300 gallon per day system which is generally the minimum recommended
by most counties to service a home will weigh 37,500 pounds and will
occupy 6,000 square foot (0.14 acres). The system
can generally produce about 2,178 gallons per acre per day or
approximately 2.4 acre foot per year.
These numbers change based on location and time of year. We
generally size the system to deliver the rated water in the region from
June through Sept. Months with less sun or colder
temperatures will either deliver less water or will require larger
systems.
Is A2WH a Dew Catcher or Dew
Condenser?
No
dew condensers require a
nighttime temperature that is either at or very close to the dew
point. Our
first generation night radiant condenser systems extended this so we
could condense even when the dew point was 8F below the nighttime
ambient. Even with these enhancements we found that we simply
could not use that generation in a enough areas to
deliver the desired impact. Another issue
we found
with the dew condenser systems is that they would work well during part
of the year and then fail to deliver during the part of the year when
they are needed the worst.
The new solar thermal A2WH system was specifically designed to overcome
the deployment issues which limited success of the dew
condensers. As a result we can install it in a wide
range
of locations with a high degree of confidence that it would deliver
water when it is needed.
One of the benefits of this system is that it produces more water per
square foot in many locations so even in locations where the dew
condensers would work well the Solar thermal A2WH system will generally
deliver even better.
How does A2WH technology work?
A2WH
operate entirely from solar
energy. This
is mostly solar heat with a small amount of solar electricity used to
operate valves, sensors and the electronic control
system. This allows our system to operate much more efficiently which is
especially important in areas where electricity is expensive such as
islands where electricity is generated using imported
fuels.
Most Air to water systems use refrigeration to chill air to the dew
point that means that as the dew point drops the more the unit must do
more work to sufficiently chill the
air.
The A2WH system uses a desiccant to absorb moisture from the
air. The higher the humidity the more water our
desiccant
can absorb per pass which increases production.
We use solar heat to drive both the airflow for the absorption process
and to provide heat during the regeneration process which extracts the
moisture from the desiccant and allows us to capture the water in
liquid
form. Unlike radiant
condensation
systems this system actually produces during the dry months even when
there is no dew and it's production can go up in windy locations which
can prevent radiant chilling systems from working at
all. Our technology can work in conditions where the dew point is far below
the chilling level delivered by radiant chilling panels.
A
sophisticated micro controller based
sensor system determines when to
switch between absorption and regeneration modes. We use
different types and amounts of desiccants depending on the local
conditions to optimize the performance of the
system. A small Photo
Voltaic solar panel
provides power for the micro controller, sensors, various valves,
etc.
We have an optional enhancement that uses wind energy (wind over 4.5
MPH) to drive circulation at night when the relative humidity is
higher. To make this work best we increase the
weight of
the desiccant used in the system. In some areas
with good
nightly wind this allows the unit to work in areas with daytime
humidity as low as 10% We have optional enhancements which
allow
electric fans and heaters to augment or replace the solar heat.
The input air is filtered before it enters the absorption chamber where
the desiccant absorbs water out of it. The air is re-filtered
when heated for regeneration. A final stage of filtering is
used
as the air enters the condensation phase where the H2O is turned into
liquid water. As a result the output water is very
pure. We still recommend treatment using
a NSF 54
grade filter prior to consumption because we do not have any control
over the cleanliness of the storage tank.
Why should Cities and
Municipalities consider A2WH?
A2WH
delivers an
additional source of water that is reliable and less likely to be
affected by contamination or drought than any other
source. Increasing the diversity of water sources represents good planning and
delivers increased resilience during unplanned crises. Our
recommendation is for each municipal water source to look at their
absolute minimum potable water needs during a stage 4+ water
crisis. They
should implement sufficient A2WH to meet their minimum potable water
needs during the a crisis if two other major water sources became
unavailable.
Any city or municipality which delivers more than 40% of it's water
from Desalination is at serious risk of not delivering adequate potable
water if their desalination facility is off
line. Shutting down a large scale desalination plant is easier than
people realize. It can be caused by storm driven
sediment, chemical,
fuel, oil or sewage spills, electricity shortages,
earthquakes, floods or Homeland security
issues. A2WH represents an
ideal auxiliary
source which is unlikely to fail at the same time as the
desalination plants.
Any city at risk of having their imported water sources compromised by
earthquakes should consider A2WH. Those who import
water
through mountain especially those crossing fault lines are at even
higher risk. Earthquakes can break delivery
pipes in multiple locations which can take months to repair. Earthquakes can also make ground water sources unsafe or
unreliable at the worst possible time when imported water is not
available. A2WH represents an ideal auxiliary
source of
survival
water and is unlikely to be significantly affected by
earthquakes. A2WH can be installed in mountains above cities where gravity can be
used to deliver the water during power outages common after
earthquakes. As such it can pressurize the municipal water
system
even when the power is still out.
Sydney
Austrailia Atlanta
GA
Is it necessary to treat the
produced water
Even
with high quality water it is wise
to treat any water that will
be stored for a long period of time. We can not guarantee the
quality
of the intervening pipes and storage tanks so even if it leaves our
system clean it could be exposed to contaminates before it is delivered
to the ultimate consumer.
For private consumers a NSF 54 grade filter is recommended for any
water that has not been chlorinated. The cleanliness of our
water
can
make this grade of filter last a very long
time. RO
membranes
common in NSF 54 filters are most often clogged by minerals
and
other
contaminants in the water. Since our water has incredibly low
amounts
of minerals or contaminants the RO membranes can deliver a very long
life.
What about maintenance?
The
input air must be filtered to
remove dust. This is done using permanent electrostatic
filters. These filters require periodic washing or the amount of air passed will
diminish as they become clogged. Diminished airflow reduces
production.The washing interval varies depending on the
dust
load in
the area.
The solar panels decrease in efficiency as they become covered with
dust and dirt. It is a good idea to wash or blow them off on
a
periodic basis. They can get pretty dirty and still work just
like a
window but ultimately cleaning them is a good idea.
The electronics are designed to last the life of the system but can be
field replaced if needed. The same holds true for all the
mechanical
components.
The majority of the outer shell is made out of polycarbonate which is
incredibly tough and highly UV resistant. It can be
scratched but
even if scratched it can be simply painted or buffed.
What about contamination?
The
main point of contamination for
other water sources is completely avoided because our water is
extracted from the air. We filter the dust and the
basic
design is
highly robust. If the unit is flooded
with unclean
water it must be
sterilized and serviced before it can be safely used.
How will A2WH impact the
environment
Compared to electiric grid powered
units A2WH will reduce indirect carbon emissions by about 2 pounds per
gallon of water produced by the system.
In
general the system will have minimal
impact on the environment. The air moving through
the
system is purified and dried before being exhausted. This air
normally remixes with the ambient air with little impact.
Any area which receives significant off shore or in shore winds
has such a large amount of air movement that it will be
difficult
to measure the impact. In most cases the water is consumed
and
re-evaporates mixing back into the air so it has a net zero effect.
For very large systems such as 1 million acre foot per year a
research meteorologist should run the numbers because drawing
this much water out of the air could have impacts on the local
weather. For example it could reduce the humidity of downwind
communities. Dry air is heavier than the cold air which
means
this
volume of dry air could create dry wind rivers could do anything from
flush smog out of city valleys or stealing energy from forming
thunderstorms.
In some conditions dry stagnant air could eventually pool in the bottom
of bowl shaped valley's and eventually become sufficiently dry to
prevent the units located in the same valley from working at all.
A research
meteorologist should be able to develop models which can be
used
to predict the
impact for a given topography.
What is the difference between
A2WH and other units
available on market.
Most AWG systems are built around a refrigeration system which is very
similar to that used in small electric air conditioners. The
best
units consume 600 to over 3,000 watt hours per gallon of water they
produce. The industry average trends show consumption over 2,2000 watt hours per gallon which rise rapidly as
humidity drops.
A2WH functions with no external electricity. This saves 3,000
watts per gallon. Our novel design and control system allows it
to efficiently extract
water in a wide range of conditions including conditions where electric
AWG units become inefficient or do not work at all.
Our units can reduce carbon emissions by over 5 pounds of carbon per
gallon produced as compared to grid powered electric systems.
(2.2 pounds carbon per KWh saved * 3000 watts per gallon =
6.4
pounds of carbon per gallon of water). Even a small 6
gallon per day system this adds up to nearly 11,000 pounds reduced
carbon emissions per year.
Our most important difference is the compatibility of the core design
for scaling efficiently into millions of gallons per day at a
reasonable cost. It's other major benefit is compatibility
with
remote areas where grid power is either unavailable or
expensive. In some areas our units can be installed
in
mountains outside of towns and provide both water pressure and
electricity for the town. Rather than exaggerate summer power
shortages our system can actually help reduce these shortages.
How does A2WH compare
to Electric Refrigeration based AWG
units
Grid
or diesel powered AWG
Several
companies offer electric and
diesel powered AWG units of similar
capacity in range of $3,000 to $8,000 with energy costs of $0.20 to
$0.40 per gallon. Energy cost are higher with 50%
humidity. Our unit will
produce 21,900 gallons over a 10 year life so compared directly to a
grid powered electric system the value of the water @ $0.35 is $7,665.
If you add $5,000 unit price + $7,665 it yields a comparable of
$12,665.
Off
grid AWG
Our
unit would be most appropriate in
off grid scenarios
where power is either diesel or photo voltaic generated so the power
cost would be closer $11,497 which would yield an effective comparable
of $19,162. This does not factor in fuel or electric price increases
during the 10 year period which would raise our comparable value.
Bottled
Watter
In
bottled water where the kiosk is
cheap but you pay more for the bottled water. The last time I had water
delivered in Utah it was $6.70 per 5 gallon container after we paid the
delivery fees. This works out to $1.34 per gallon. Over our 10 year
life we would replace 21,900 gallons which at this rate would be worth
$29,346. The bottled watter was a hassle with
lifting the
jugs, storing the empties, etc so ours should get a bump in value for
convenience. In addition bottled water prices have been going up so it
is reasonable to expect a price over $10 per 5 gallon barrel before our
unit is end of life.
Where did you get 600 watt
hours for the electric refrigerant AWG
units?
We
quote 600 watt hours at the
low end for electric powered
units because we have seen claims from other companies that
they can deliver a gallon for 600 watts under ideal
locations. Those ideal conditions where not fully
documented but it seemed to be 85% humidity at 90F. In
reality we have not found any customer in the USA who claims to do
better than 1,800 watt hours per gallon. In most cases we
have
been hearing numbers that range from 2,800 to 4,500 watt hours per
gallon. We have also hear that many of these units fail to
work
at all when the humidity drops below 48%.
What is comparable sizing for
powering an electric refrigeration
AWG unit using PV (Photo Voltaic solar panels)?
These
numbers are only for comparison
purposes. Our nearest competitor is a electric refrigeration
AWG
powered by a Photo Voltaic system or a diesel
generator.
These
are quick calculations based on
statistics published for a Electric Refrigeration AWG unit sold out
of Europe. Please confirm these
with your solar
design engineer. We used this particular electric
refrigeration
AWG unit because one of our customer prospects contacted us after they
purchased the electric unit and still needed a better
solution.
The electric refrigeration AWG unit is rated at 24 liters (6.3) gallons
per day with a maximum power usage of 650
watts. Most
of the electric units are rated for 24 hour production so I used an
assumption of 1 liter per hour. Using
their max power
rating this came to a total of 15,600 Watt hours. Assuming
the
batteries charge at 75% efficiency and the inverter used is 90%
efficient this would require (15,600 / 0.75) / 0.90) = 23,111
Watt hours. Assuming
a 9 hour productive
solar day this equals 2567 continuous watts which if divided by 200
watts per panel equals 13 panels. These are conservative minimum sizing numbers. Best
practice is
generally to scale the system to160% of the minimum numbers to allow
for system operation during changing solar
conditions. If
you want
year round operation then you must adjust these numbers to reflect the
shorter effective winter solar day and the lower winter insolation.
I found 200 watt panels on the Internet for $1135 which brings the
panel cost to $14,755. Assuming a factor of 1.5 for
labor,
wires, mounting brackets, etc this would equal a total before batteries
of $22,132
Using the assertion that you need to operate electric
refrigeration AWG unit 24 hours per day to produce 6.3 gallons then you
need 24 hours - (9 hours of daylight) worth of storage = 15
hours
at 650 watts = 9750 Watt hours. Assuming you can
drain
your batteries to the 20% level (use 80% without damage) and a 90%
efficient inverter then you need a total of (9750 / 0.80) /
0.90)
= 13,541 watt hours of storage. Assuming a 12 volt battery
system
this would equal 1,128 amp hours. I found
PVX-1040T
which is capable of about 80 amp hours depending on discharge rate and
costs $285. Using
this estimate it would
require14 batteries at a cost $4,018 at a weight of about 910 pounds.
With batteries this would bring the power system cost to run the
Electric refrigeration AWG unit 24 hours per day to
$26,150
and it still would not work at under 45% RH. This
estimate
was based on published numbers from an external web site. They
did not specify production under different conditions but
other
Electric refrigeration AWG units do show these numbers and a rule when
relative humidity or temperature drop the energy cost per gallon goes
up. I have to assume that this was based
on their
best case rating so most consumers should plan on system sizes 150% to
250% of these sizes depending on their local environmental conditions.
Note:
It is possible modify this
configuration to eliminate the batteries by running 3 of the electric
refrigeration AWG units during the day. This would increase the power
production to 3 liters per hour for the 8 to 9 hour solar
day. The 3 units at 650 watts each and a
90%
efficient inverter the would require a minimum of 2166 watts of PV or
11 of the 200 watt panels. You would also need 2 of the
PVX-1040T
batteries to handle startup surges. The higher
grade 2.5KW
inverter with surge to 6,000 watts for motor starts would cost between
$1500-$2600 (islandearthsolar.com Part #08-53-010). You
would also need 2 additinoal AWG units at a cost of about $2,000 to
$3,500 each. The most interesting thing is that this system
could operate only during the day when the Relative humidity is lower
which is when the electric refrigeration units consume the most
power. In short it would generally be more cost effective to
add
more battery capacity to allow the electric AWG units to operate
between the hours of midnight and 8:00 am when the relative humidity is
highest. You also need some more
sophisticated
switching logic to only turn on the number of AWG units that you have
the energy to run or to switch off AWG units as the battery voltage
drops. It would probably be best to oversize the
power
system for daytime use to at least 160% of the minimum to ensure the
system can operate for the first 2 and last 2 hours of the solar day
when the solar production drops off due to changing solar angles.
Please
let me know how your real world
install compared to my calculations.
In
comparison our worst case price with
all the optimizations to allow our unit to operate in climates with
daytime humidity as low as 10% would cost less than just the power
system for the electric refrigeration AWG units. In addition
even
our worst case unit would weigh less than just the batteries for the PV powered system.
How
is A2WH
different from
desalination?
Desalination
accepts a salty input water such as Ocean water or Brackish salt
water. The salt is removed from the water using either a
Reverse Osmosis (RO) membrane or a Distillation
approach. The salt which is left is concentrated into a highly concentrated
brine stream which must be disposed of. A2WH produces no
waste brine so it has nothing to dispose of which can make obtaining
necessary permits easier and less expensive. In general A2WH
will compete favorably on a cost per liter basis when compared to
the capital + energy + membrane costs for operating a RO system over
it's 20 year life.
We
at A2WH feel
that Desalination and A2WH are ideally used
together. By
leveraging both technologies an ideal mix of reliability and cost can
be obtained. Spreading the investment for water
infrastructure across multiple unrelated technologies it can
improve the municipalities ability to withstand unanticipated
problems and natural disasters.
Here
are the main differences.
-
The
A2WH system starts with standard
air and extracts the water from it. It does not require a
source
water stream. This allows it be used hundreds of miles from
the
coast where land is much cheaper. It can be close
to the
point of consumption which reduces distribution costs.
-
Most
RO systems leave a residue of
salt behind. This generally runs under 400PPM to
900PPM. It
is rated as safe for human consumption but may be
undesirable. This level of salinity can result
in soil salt toxicity as the water is applied many times and allowed to
evaporate. The A2WH system starts from air which is
filtered and then the moisture extracted in a separate
phase. As a result the produced water has very low solids
essentially equal to single distilled water.
-
The
A2WH system is immune to damage
from local oil or chemical spills which can destroy coastal
desalination plants. The same holds true to storm and stilt
based clogging of the input manifolds. As a result
the A2W
system can continue producing when the RO system must shut
down. This makes the A2WH system an ideal pair with RO systems and increased
the power supply.
-
The
A2WH system does not produce any
brine stream which must be disposed of. Brine disposal is
becoming increasingly expensive and controversial. The
difficulty
in permitting and handling of the brine can prevent large scale
desalination by non governmental agencies. .
-
State
of the art desalination
facilities generally use grid power to operate high pressure pumps and
heating elements. State of the art RO systems can
consume
as little as 15 watts per gallon but this still results in the 10
million gallon per day RO plant consuming 150,000 KWh per day.
Consuming this amount of power in regions already under heavy demand
can increase electricity costs for all consumers.
At
150,000 KWh per day even the best RO plants end up emitting over
300,000 pounds of greenhouse gas.
-
The
desalination facility by nature
tend to be located close to the coast or close to their source water.
This can require pumping the water inland to the location where it is
needed. Pumping the water uphill requires additional
energy. The A2WH system can be located in mountains above the
towns where the water is consumed. This allows the A2WH
system to
pressurize the city water system which saves power and maintenance
costs. In some instances the A2WH water can generate
electricity
as it flows down from the point of generation to the storage
reservoirs.
Reference Sydney
Austrailia....
Atlanta
GA
.... .... ...
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