Water From the Air

The atmosphere contains about as much water as the terrestrial fresh water supply. That’s a lot of water! Wouldn’t it be nice if we could extract water directly from the air instead of having to depend on rainfall or groundwater?

98% of atmospheric water is invisible water vapor. The other 2% is condensed water that appears as clouds. The water vapor in the air is also known as humidity. For weather forecasting purposes they measure relative humidity.  Relative humidity is the comparison between the maximum amount of water vapor that the air can hold at the ambient temperature and the actual amount of water vapor present. For example, a relative humidity of 30% means that the air contains 30% percent of the maximum amount of vapor the air can hold without condensing out. Higher temperature air can contain more water vapor.

The temperature at which water condenses out of the atmosphere is called the dew point. The dew point temperature is higher as humidity increases.  Lowering the air temperature to below the dew point will cause the water to condense out. This is the basis for air wells and most atmospheric water generators.

Air wells are passive systems that need no external energy source and have no moving parts. There have been, historically, two kinds of air wells – the mass air well and the radiative air well.

The first ones were mass air wells and they did not perform very well. They consisted of massive stone buildings that, because of their mass, stayed cooler than the surrounding air thus accumulating condensed water on cool stone surfaces within the structure. The water would run down the stone surfaces into catch basins. A big one was built in the early 1900’s that was 45 feet high and made of stone. It only manages to capture five gallons of water per night. That’s really a lot of work to get only that small amount of water. The main problem with these, besides the fact that they are huge structures, is they also heated up during the day and could not cool down enough at night to produce more water.

Another ancient water collecting method was to create dew ponds. As it turns out, they produced most of their water from moisture in the soil or by collecting rainwater. Very little, if any, of the water collected in dew ponds actually came from dew.

The radiative air well uses night sky radiation to produce a cool surface for water to condense on. The thermal properties of night sky radiation are the reason frost sometimes occurs on roofs even if the air temperature is above freezing.  This phenomenon is now being explored for whole house cooling that doesn’t require air conditioners or evaporative coolers.

The material used to collect moisture has to be very low mass so it can’t hold heat. It also has to be insulated from the heat held by the ground. The material also has to be hydrophobic (water repellent) so that the water runs quickly off and into a storage container before it can evaporate. Typically, radiative air wells consist of a thin plastic film backed by insulation and placed far enough above the ground to mitigate heat coming from the ground. Most of the research and development on radiative air wells has occurred in the last 40 years. New thin-film materials are being designed that maximize the collection of the condensation. The best new materials have bumps on them to increase the surface area. 

You can make your own radiative air well using a sheet of polyethylene suspended at about a 30 degree angle with a trough at the lower end to collect the water and direct it into a storage container. I am thinking black polyethylene would work better than clear. That’s worth an experiment I think. You will want a filter between the collector and the storage container to keep out dust, etc.

How much water you can collect will depend on the humidity and how cold it gets at night. If you regularly get dew on your car windshield then a radiative air well could work for you.

There is a commercially available system that collects water from fog. The Warka Water system is being tested in Africa. http://www.vittori-lab.com/introductionwarka  Since the sides of the collecting fabric are vertical I don’t think it would work very well capturing water vapor.  They are interesting looking!

The radiative air wells are capable of producing more water than the mass air wells but not a lot of water. Larger surface areas produce more water. They can produce enough to provide drinking water under the right conditions - high humidity and a large temperature differential between day and night. Where I live, in central Arizona, humidity is very low most of the year so collecting water from the air would be difficult.

Atmospheric Water Generators (AWG) are active systems that use the same technology as air conditioners. They produce the most water of all and under a wider variety of atmospheric conditions. They contain cold surfaces and the water condenses on them. These are energy intensive appliances so are not practical in applications where cheap energy is not available. There are home systems that you can plug into house current. The use between 400 and 1000 watts which is a lot of you are off-grid. It may be worth it if clean water is not available and you have enough energy to run the equipment.

Some commercial AWG systems are being designed with their own renewable energy sources to provide the refrigeration necessary for atmospheric water generators to work. An example of this is the Eole Water Generator. http://www.eolewater.com/gb/our-products/range.html  This generator runs on wind power and also generates a considerable amount of extra electricity that can be used.

You could probably make your own AWG using an air conditioner. You would have to reconfigure the placement of the condenser so that water can be collected from it. I think you could use  a much slower fan, if you need a fan at all since the goal is to collect the condensation rather than deliver cool air into your house. To get a reasonable amount of water with AWG systems the humidity should be above 30% and the temperature should be above 65 degrees Fahrenheit during the day.

 

There is another method to get the water out of the air that involves hygroscopic liquid salts (desiccants) that absorb water vapor. These salts are then heated to boiling and the water evaporates and is collected and condensed.  It sounds like these might use less energy than the condensation systems although toxic salts don’t sound like something I want to fool with.

Even if collecting water from the air does not produce a lot of water via the above methods, the water produced is very clean. We really don’t use that much water for drinking so it might be enough for that purpose. It can also be a fun thing to experiment with. May someone will discover a new method to get more water from the air without using too much energy.

Planting Time Again

Spring has come early to Northern Arizona. It feels like we didn’t have winter at all. In the 23 years I have lived in this area I don’t remember a single winter without at least some snow. But we got no snow at all this year and barely any rain. Since mid-November we had one storm with measurable rainfall and that was 0.7 inches. I guess the Midwest is getting all the winter!

Our average last freeze each year is May 1 so it’s now time to plant some of the cooler weather crops in our little garden. I bought spinach, romaine, broccoli, and beet seeds and planted them yesterday. I only planted a five foot row of each, small enough that our portable row covers can go over them if we have a cold snap.

We tried growing these same vegetables the first year we were here but that was before we built the full cage that surrounds our garden now. The first year everything came up beautifully and then, one day, it was all gone. Critters had eaten everything. Not this year, though. We have it protected against everything except insects.

Last November we thought we’d try planting a winter crop of garlic. It is working out wonderfully. They survived the winter (minimal though it was) and they look great! We didn’t pick most of the onions we grew last year and they have come back looking really good.

In two or three weeks I will plant some veggies that are a bit more sensitive to frost and see how they do. Then, in the beginning of May, we will plant the pumpkins.  We will also plant tomatoes, chili peppers, and cilantro once a freeze is unlikely.  Last year we made pico de gallo completely out of what we grew in our garden.

If you want to eat home-grown food in the middle of winter,  plant pumpkins at the beginning of summer.  Pumpkins last a long time in storage. We cut open a pumpkin from last year in February and it was fine. We cut, steamed, and mashed it, and it is now in our freezer waiting to become pumpkin bread or maybe pie.

We are excited about our garden this year. We learned a lot in our first attempts out here and are looking forward to having even more fresh food grown in our own yard. Delicious!

Way Off-Grid at Paddock

Other than living in a converted school bus for half a year, my first experience living off grid was at a remote homestead that went by the name of Paddock. It was an old ranch headquarters that mostly operated as a dude ranch. The first building there was a one-room log cabin that was built about 1920. In the late 40’s or early 50’s a kitchen, two bedrooms, and a bathroom were added on. This was our house.

The Paddocks owned an ice-cream company. They would bring drug store owners up to their mountain ranch to entertain them and hopefully get them to buy ice cream and supplies. In those days, drug stores were the largest wholesale buyers of ice cream. The ranch managers lived in the old cabin. At the west end of the property was another, larger, cabin. This was where the ranch owners lived when they visited.

The ranch was sold, in the 70's I think, to a wealthy guy who liked to buy ranches. He has several. In order to prevent the unoccupied property from deteriorating he rented it out to my friend, Jack. The total rent was $250/month. My share was half that. What an awesome deal! It is a beautiful spot in the pines at a 6000 foot elevation with a spring and a series of meadows.

We lived in this picturesque cabin

We were way off-grid there. The dirt road to the place was 25 miles long and often not in good condition. It was a 50 mile drive to town. The 32-acre property was completely surrounded by national forest. The nearest neighbor was a ranch about three miles away.  We had no electricity or phone. Cell phones didn’t work there either. The mail was delivered three times a week but only in good weather. There was a propane refrigerator and cook stove. That was the extent of our modern conveniences. Lighting was provided by oil lamps and candles. Eventually we scored a 10-watt solar panel so we could listen to the radio during the day. That was our big move into the modern world.

There was a wood burning cook stove that also served to heat the kitchen and the bedrooms. We closed off the living room in the winter and used it as a walk-in cooler so we didn’t even need the refrigerator during the cold months. We would set a couple one-gallon plastic bottles filled with water out on the front porch each night and, in the morning, they were frozen solid. We used these in a series of ice chests that we kept in the living room. In the summer, the living room was the coolest place in the house.

solar water heater

Living this way inspired us to speculate and experiment with ultra-low-tech ideas for making our lives comfortable. We spent many a candle-lit evening discussing the finer points of passive solar design and how to design functional energy systems that were simple, cheap, and durable. We did not have the luxury of consulting the internet. We had an old set of Encyclopedia Britannica from the 60’s if we wanted to research anything. Jack spearheaded this experimentation and built a solar water heater on the roof and a clever solar heat box on the wall of his bedroom. These were made using mostly free materials and they worked well, and were very simple to understand and build. He wrote a book recently about the devices that he experimented with. It is called Magic Machines in a Magic House and is available at Amazon.com

The old pump motor

Our water was from a hand-dug well that was only twelve feet deep. We used an ancient Wisconsin single cylinder gas motor that was connected to a Jacuzzi pump and used this to fill a concrete and stone cistern up on a hill behind the house. We would run the pump every month or so to fill the cistern and the water would gravity feed to the house. The pump motor was so old that it was difficult to get started. We had to take it apart and clean the magneto several times. One time we just couldn’t get it started. Jack called the manufacturer to see if he could get parts. When he told them the model and serial number of the motor, they were amazed it was still in service and wanted to know if it was for sale. They wanted it for their museum! They were not able to help us fix it but we managed to get it going again without their help.

 

The stone cistern stored our water

We diverted the kitchen sink drain to deliver water to the garden. The bathroom sink drained out into the yard. Our septic system was questionable. We couldn’t figure it out. We had no idea where the flush toilet drained to. There were no clean-outs. For all we knew it just went into a big hole in the ground and we didn’t know where that hole was. Wherever it all went, eventually it filled up and the toilet would no longer work. We removed it and replaced it with a simple composting toilet consisting of a five-gallon bucket under a plywood bench with a hole in it. A toilet seat was mounted over the hole. It was just like an outhouse only it was in our indoor bathroom.

It was a simple system. We would put a couple of coffee cans full of dirt from the yard and a can full of cedar sawdust in the bottom of a five-gallon plastic bucket and put it under a toilet seat bench. Each time we used it we would dump a can of dirt and saw dust on top. When the bucket was about ¾ full we took it out to the yard.

One of our scenic toilet spots

We had a line of maybe ten five-gallon plastic buckets in service to the toilet. It took at least a couple of months to go through the whole line. We would put the newly filled bucket at the end of the line. The bucket at the front of the line was now old enough, and the contents sufficiently decomposed, that we could dump it in the garden, rinse it out and then put that bucket under the toilet seat. It was an efficient cycle. 

In the winter, the line of buckets was kept in a greenhouse so they would be warm enough for the bacteria to turn the poop into soil. In the summer the line was under a big tree. We had to make sure to water the buckets to keep the contents moist. The system was so effective that we built a couple more toilet benches and put them outdoors in scenic places. I would often use the scenic toilets. I could sit and watch elk in the meadow while taking care of business.

 

We tried various clothes washing techniques. The best one was to just put the clothes in a plastic 5-gallon bucket with a lid along with water and soap and roll it around the yard for a while before rinsing, wringing, and line drying. It wasn’t as effective as a washing machine but it wasn’t much work either.

This one-room cabin was used as a guest room

We did several small construction projects while I lived there. Since we had no electricity, power tools were useless. We had to cut the lumber with hand saws. We used hand crank drills. It’s hard to imagine how tough people must have been a hundred years ago to be able to build entire houses without power tools.

I moved to town near the end of 1997 but the place is still functioning pretty much the same these days. There are a few more solar panels and the old gas-powered well pump motor has been replaced by a solar powered electric pump. The composting toilet bucket system is still functioning well and oil lamps are still the preferred lighting method.

Our current off-grid situation is luxuriously modern compared to my time at Paddock. Here we have solar panels, a washing machine, flush toilets, satellite internet, and a nice wood stove. Still, I have fond memories of what an adventure it was.

The west cabin.

A Long Way to Town

We live forty miles from town and sixteen of those miles are on a dirt road. A round trip plus all the scurrying around doing errands often adds up to 100 miles of driving by the time I get back home. Because of this we try to limit our trips to town as much as we can. I have a big truck which I need for my work as a metal sculptor. Big trucks get poor gas mileage. Mine gets about 17 mpg which makes a trip to town cost about $20 for gas (at $3.50/gallon). If I had a regular five-day-a-week job in town it would cost me over $500 each month just for the gasoline. Fortunately I don’t have to go to town every day. I try to keep it down to twice a week.

Because of the dirt road I go through tires faster than city people and my truck’s front end needs alignment more often.  I am sure there is other accelerated wear and tear on my truck that can be attributed to living out in the wild.

Living on a long dirt road also limits what kind of vehicle you can have. We would love to have a little car that gets 40 mpg but there would be so many times when it would not be big enough to carry all the stuff we need to transport and there would be times when the dirt road would be too muddy to drive a little car. We can’t afford to have a different car for every purpose. We have to compromise and pick the most useful vehicles for our circumstances. For us that means a full-size pickup and a minivan.

Then there is the time.  It is two hours round trip for a drive to town. When we lived in town we could easily go out several times a day for various things. That is just not practical where we live now. My wife and I make lists of the errands that need to be done on each trip to town. We have counted the errands and some days we have had more than fifteen stops. The bank, the post office, library, dumping trash (no trash pickup out here in the woods!), groceries, and gasoline are almost always on the list. I often need to buy steel and welding supplies for my work and meet with clients in town. We try to schedule multiple meetings on the same day or, when there is an unavoidable appointment, we make that the day for our town errands. We try to cram as much as we can into a day in town. I keep a little notebook with me to keep track of the errands and shopping lists.

I have become quite a connoisseur of public restrooms as a result of living so far out. By the time I get to town I have to go! I have my favorite spots - the hardware store has a big, clean bathroom that is rarely occupied and so does the supermarket. We don't miss the opportunity to go if we are at a restaurant either. Out here in the woods I just pee on the ground but they frown on that in town.

The weather can make our road pretty nasty. I have nearly gotten stuck sliding around on our muddy road. The truck gets covered in mud, too. It is important to clean it as well as I can when that happens. The mud covers the undercarriage with a crust that can cause problems. There is a sensor on the tail of my truck’s transmission that got so covered in mud that it failed. I had to chip off the hardened mud to find it. It turned out that it was full of mud and all I had to do is clean it. Still, that’s an extra thing to pay attention to if you live on a muddy road.

The distance to town limits our social activities. There are often events, social gatherings, etc. going on that would be fun to attend but, if they are not on one of our already scheduled days to go to town, we just don’t do it. In the winter our trips to town have to end early enough in the evening for us to get home with enough time to fire up the wood stove and get the house warm before we go to bed.

 

Since I only go to town twice a week and my wife tries to only go once a week, the trip becomes kind of special. Out here we can wear our worst clothes. Nobody sees us so who cares? When we go to town we make sure we are clean and wear nice clothes. “Put on your best, Honey! We’re goin’ to town!”

Living remote is great, don’t get me wrong, but there are downsides and if you are considering living in a remote location, it is good to have some idea what they might be. A long drive to town has its problems. An upside is that most of the time it's a beautiful drive.

Javelina Babies

On Monday a herd of javelina made their way through our yard digging and playing. There were babies, too. Most notable was the appearance of twin babies that must have just been born. They were only six or seven inches tall! So cute we could hardly stand it. We see them fairly often out here.

Javelina are also known as collared peccaries. They look like wild pigs but are technically not pigs. They are distantly related, though. There are three known species of peccary in the Americas. Two of them live in South America, the white-lipped peccary and the chacoan peccary. javelina habitat ranges from Central America up to the southwest U.S.A. Apparently their may be another species, called the giant peccary, that has been recently spotted in the Brazilian rainforest but this has not yet been confirmed, according to Wikipedia. The first appearance of javelina in Arizona was not that long ago. They migrated north from Central America and their habitat is still spreading, mostly toward the north and west.

Adult males generally weigh about 60lbs with the females being slightly smaller. Javelina have lived as long as 24 years in captivity but in the wild their lifespan is more like 7 or 8 years. We have seen herds of approximately 20 animals here even though the official literature says their groups are more like 9 or 10 animals. They breed year-round with most births occurring in July and August.

They mostly seem to eat plants but they also do a lot of digging. Maybe they are digging up roots or grubs? Gardeners in the Prescott area all have to do something to keep them out. They can decimate a garden in a single night. They mostly ignore humans but can become aggressive if cornered. I have surprised quite a few of them while hiking. It seems that they don't see well. If you are downwind you can get pretty close.

Some people hunt them. There are a couple of seasons for this. Right now it is archery season for javelina. Last year some hunters gave us a couple of livers. My wife liked them but they tasted too strong for me. Mostly we tell the critters to run if we see hunters coming for them! We like seeing them running around. Fortunately our garden is well fenced.

I shot some video of the javelina and their cute babies and pieced it together in a 30-second piece that you can view here.