Atmospheric water generator
An Atmospheric water generator (AWG), or atmospheric condenser, produces pure drinking water from the humidity of the surrounding air. An AWG is essentially a dehumidifier: air is passed through a cooled coil, causing water to condense. The amount of water that can be produced depends on the humidity, the volume of air passing through the coils, and the size of the machine and the temperature.
The device is used in situations where pure drinking water is otherwise difficult to obtain.
In practical AWGs the air is filtered first, to reduce pollutants and bacterial contamination. Commercial systems use reverse osmosis as a final purification step. Some systems use ozone, or brass silver or copper as a long-lasting biocide in the coil and main tank. This reduces offensive smells and possible disease.
Principle of operation
An AWG uses refrigeration techniques optimized to condense water from air. Blower-driven air is drawn into the system through an electrostatic filter. In the machine's exterior housing, a compressor circulates refrigerant through a coil array located in the path of the air providing a temperature differential between the air and coil surface, resulting in condensation.
The condensation is funneled into a holding tank. A level switch in the holding tank controls the water making cycle.
Water in the tank must be purified. In some commercial systems, reverse osmosis removes pure water to a secondary tank, and brine is drained.
In other proposals, water in the tank is pumped through an ozone generating UV light chamber to kill bacteria and then through high and low density charcoal filters to remove solids and oxygenates. It is finally collected back in the holding tank. The water filtration cycle is both flow and time controlled. Water is dispensed by tap.
Copper and brass fittings are used in practical systems as copper poisons common bacteria, fungi and algae, but is proportionally less harmful to humans.
The actual amount of water produced depends on the relative humidity and ambient air temperature. Relative humidity measures the amount of water vapour present in the air at a given temperature. The higher the relative humidity and air temperature, the more efficient an AWG will be. A conventional AWG becomes inefficient when the ambient temperature is below 15.5°C (60°F) or the relative humidity is below 30%.
- Needs no water source, only air.
- Can generate from 20 litres to over 250.000 litres or more in 24 hours.
- Is designed for maximum cost efficiency.
- Contains no harmful minerals or chemicals
- Can be powered by solar, wind, dyno or aqua electrical generation systems.
A wide range of Atmospheric generators are available, from a home/office unit producing 28 litres a day, to 1200 litres and even more than 500.000 litres per day for industrial bottling plants.
The economy of an atmospheric water generator depends on the capacity of the machine and the air's humidity and temperature.
AWGs are normally powered by electricity. Some models operate from solar, wind, gas or oil. These which can be of great help for relief efforts.
The following is the cost per liter calculation for a typical 120 litres per day AWG with power consumption 2.6kW @ INR(Indian Rupee) 4.5 per kWh.
Total annual electric costs : 2.6kW × 24 hrs/day × 365 days/year ×INR 4.5 per kWh = Rs.1,02,492/year ≈ US$2,277.60/year (US$1 = INR45).......A
Total annual water production : 120 litres per day × 365 days/year = 43,800litres/year..........B
COST PER LITER = A ÷ B = US$0.05
The below listed methods are not AWGs but other alternative methods of water making.
- One company is using the desiccant lithium chloride to pull water from the air, after which the water must be boiled off and distilled.
Source: Sciperio Inc.
- Another company is involved in making a machine that extracts water from car exhausts. Although the machine is in a prototype stage with a lot of problems with water quality, it is another non-conventional means of water making.
Source: LexCarb LLC
- In popular culture: In the fictional Star Wars universe, atmospheric water generators were the source of livelihood for the Lars family.