Non-Electric/Passive Atmospheric Water Harvesters

Non-Electric/Passive Atmospheric Water Generators (AWGs) are devices that generate water from the air without relying on electricity or active mechanical components. These systems operate using natural processes and require minimal or no external power sources. 

Here are the different types of Non-electric/Passive AWGs:

1) Dew Condensation: Dew condensation AWGs take advantage of temperature differentials to collect water. During the night, when the temperature drops, surfaces with a high dew point become cooler than the surrounding air. This temperature difference causes water vapor in the air to condense on the surface, forming droplets of water that can be collected. Examples of dew condensation AWGs include dew collectors, dew ponds, and dew traps.

2) Fog Harvesters: Fog harvesters are designed to collect water droplets from foggy environments. They typically consist of a mesh or netting structure that captures water droplets suspended in fog. As the fog passes through the mesh, the droplets condense and accumulate on the surface, eventually dripping into collection troughs or containers. Fog harvesters are often used in coastal or mountainous regions where fog is prevalent.

3) Rainwater Harvesting: Rainwater harvesting is a widely practiced method of passive water collection. It involves capturing and storing rainwater that falls naturally from the sky. This can be achieved through the use of rooftop catchment systems, gutters, downspouts, and storage tanks. Rainwater can be collected for various uses, including irrigation, domestic purposes, or replenishing groundwater.

4) Transpiration-Based AWGs: Transpiration-based AWGs utilize the natural process of transpiration by plants. These systems typically involve planting vegetation in a controlled environment or specially designed structures. The plants release moisture through their leaves via transpiration, and this moisture can be collected and condensed to obtain water.

5) Air Wells: Air wells are ancient structures that use the principle of condensation to collect water from the air. They typically consist of a below-ground chamber or cistern and an above-ground tower or structure. The underground chamber is usually cool and damp, while the tower is porous or made of a material that facilitates condensation. As warm air passes through the tower, it cools down, causing moisture to condense on the surface. The condensed water then drips down into the underground chamber where it is collected.

6) Coolers and Pot-in-Pot Systems: These passive AWGs make use of evaporative cooling to collect water. In coolers or Zeer pots, a smaller clay pot is placed inside a larger one, with a layer of sand or wet cloth in between. The outer pot is porous and allows water to evaporate from the sand or cloth, cooling the inner pot. As a result, moisture in the air condenses on the inner pot, and this condensed water can be collected. These systems are commonly used for small-scale water collection in arid regions.

7) Wicking AWGs: Wicking AWGs utilize the natural wicking properties of certain materials to collect water from the air. These systems typically involve a wick made of a porous material, such as cotton or synthetic fibers, that absorbs moisture from the air. The absorbed moisture then travels through the wick via capillary action and collects at a central point, where it can be collected and stored.

8) Biomimetic AWGs: Biomimetic AWGs draw inspiration from nature to passively collect water. These systems mimic the strategies used by certain organisms, such as desert beetles or cacti, to extract water from the air. They often involve specialized surface coatings or structures that promote condensation or water droplet collection. Biomimetic AWGs aim to replicate natural processes in an efficient and sustainable manner.

9) Bamboo Condensers: Bamboo condensers are passive AWGs that utilize the natural properties of bamboo to collect water. This method involves cutting a bamboo stalk horizontally and allowing the internal moisture to condense and drip into a collection container. The bamboo acts as a natural condensation surface, facilitating water collection.

10) Solar-Powered AWGs: While solar-powered AWGs do require electricity, they utilize solar energy as the primary power source. Solar panels capture sunlight and convert it into electrical energy to operate the refrigeration or condensation processes in the AWG. These systems are considered non-electric in the sense that they do not rely on grid electricity but rather use renewable solar power.

11) Wind-Powered AWGs: Wind-powered AWGs utilize the force of wind to drive the water collection process. These systems typically involve wind catchers or wind-driven turbines that create airflow. The moving air is directed towards condensation surfaces, where moisture in the air condenses and is collected for use.

12) Solar stills: Solar stills use the heat of the sun to evaporate water, which then condenses on a cool surface and drips into a collection area. This method involves a transparent cover that traps sunlight and allows evaporation to occur, while a cooler surface beneath collects the condensed water. Solar stills can be constructed using various materials such as glass, plastic, or metal.

13) Underground Dew Collectors: Underground dew collectors utilize the cooler temperatures present below the ground to collect dew. These systems typically involve burying a collection surface below the ground level. At night, when temperatures drop, the surface collects dew as moisture condenses on it.

14) Rock-Based AWGs: Rock-based AWGs make use of the thermal properties of rocks to collect water. These systems involve placing rocks in a strategic arrangement to create temperature gradients. Moisture in the air condenses on the cool rocks, and the condensed water is collected.

It's important to note that passive AWGs generally have lower water production capacities compared to active AWGs that utilize mechanical processes. Their effectiveness also depends on factors such as environmental conditions, humidity levels, and the specific design of the system. While they may provide a decentralized and sustainable method of water collection, their output may be limited and dependent on specific environmental conditions.