Extracting water from the air is one method that can be used in providing a water supply.
In this guide, we look at the pros and cons of atmospheric water generation and harvesting water from air.
Summary – Pros & Cons Of Atmospheric Water Generation (& Harvesting Water From Air)
Firstly, there’s a difference between water harvesting from air as a general method of water supply, and atmospheric water generators themselves.
Harvesting water from air (the atmosphere) includes all active and passive water- from-air harvesting methods. For example, one passive method includes fog nets and fog fences.
Atmospheric water generators are specific devices/units that run actively on a power supply to extract water (using one of several extraction methods – such as a cooling rod/coil, or desiccants) from humid ambient air. There’s now several brands that sell these types of devices, each with different features and capabilities.
Some of the potential benefits of atmospheric water generation and harvesting water from air might include diversification of water supply, water independence, being able to generate water off grid and in remote or isolated areas, and having one more way to address water scarcity/stress related issues.
Some of the potential drawbacks of atmospheric water generation and harvesting water from air might include cost effectiveness, reliance on power for AWG units, use of non green sources of energy for power (in some instances), being able to generate quantities of water at the largest scales needed, and that AWG technology might only work effectively in a select range of air conditions.
Although there are some great benefits in generating water from air, it doesn’t appear to be a ‘perfect’ or ‘magic bullet’ type of water supply option – at least not yet.
*Note – the type of water-from-air method used, the technology (and brand) used, the conditions and situation it’s used in, the availability of alternatives, and other factors play a part in the overall pros and cons of AWG and harvesting water from air.
The pros and cons below are some generalized points.
Pros Of Atmospheric Water Generation (& Harvesting Water From Air)
Can Produce Water From Air – it’s unique in that no other water supply source does this.
Several Different AWG Technologies Exist – such as air passing over a cool coil (causing water to condense), or, liquids and wet desiccants that pull water from the air. Some technologies even use solid desiccants.
Can Provide Direct Drinking Water – when used with purification and filtration technology (and UV treatment). Some AWGs also produce ice in addition to drinkable water.
Rate Of Water Production Can Be Increased – depending on variables such as the ambient air temperature, relative humidity, the volume of air passing over the coil, and the machine’s capacity to cool the coil or the size of the compressor (wikipedia.org)
Both Small, & Large AWGs Exist – there are smaller domestic and household style units. But, large wet desiccation unit mounted on trailers, are said to produce up to 1,200 US gallons (4,500 l) of water per day, at a ratio of up to 5 gallons of water per gallon of fuel (wikipedia.org)
Large AWG Units Have Shown Development In Becoming More Environmentally Friendly – a variation of the large wet desiccation technology has been developed that is more environmentally friendly, primarily through the use of passive solar energy and gravity (wikipedia.org). Roof top solar hydro panels can also use solar power and solar heat during the day to generate drinking quality water (wikipedia.org)
Provides Water Independence, & Accommodates Off Grid Living – independent from other water sources, and public utilities. Facilitates off grid living in some ways.
Diversifies Water Supply – can be used alongside other water sources like rain water harvesting, desalination, water recycling, ground water and surface water withdrawal, and so on. Can be used as part of a diversified water strategy.
Can Help Address Water Scarcity Issues – being able to generate water from another source – the atmosphere – helps address water quantity problems in some areas.
Can Be Portable – in the case of smaller AWG units.
Some Methods Of Collecting Water From Air Are Passive & Don’t Need External Energy – passive methods rely on natural processes. A fog fence or a fog net is an example of this, and air wells are another (passively collecting moisture from the air). Fog nets and fences though need specific conditions in order to collect enough water – ‘[high humidity], high wind speeds and an adequate temperature change are required to harvest enough water from the atmosphere [for fog nets]’
Brackish Water Can Increase Drinking Water Generation Capacity – with some EWGs, where there are low humidity ambient air conditions, the evaporative cooler, along with a brackish water supply can increase air humidity neat to dew point collection (wikipedia.org)
Some Environments Are Great For AWGs – such as greenhouses where the air inside can be hotter and more humid than outside. The same can be said for climates and region with moist air.
Might Be Used In Emergencies, Or Isolated Locations – where other water supply options other than bottled water aren’t available. Examples include natural disasters, recovery efforts, and in rural or non urban (remote) locations.
New Systems Are Being Developed – that will allow AWGs to function differently and have different features in the future.
There’s Usually No Waste – some AWG units have neither water waste, or waste products that are produced. This is compared for example to desalination that does involve waste.
No Installation Required With Some AWGs – they are shipped ready to be plugged in and start operating straight away.
Can Be More Economical Than Some Other Water Sources – such as bottled water, home distilled water, and water tanks (GENAQ provides a chart of these costs)
Cons Of Atmospheric Water Generation (& Harvesting Water From Air)
Can Require A Lot Of Energy – Some units can take 310 Wh to make 1 litre of water (wikipedia.org)
Can Have A High Carbon Footprint – when coal is used as an energy source for electricity. Some estimates say it exceeds reverse osmosis seawater desalination by three times (wikipedia.org). It can be one of the worst water sources environmentally in this instance.
May Not Be Fully Renewable Or Sustainable In Some Instances – depending on how much electricity is used, the energy source used for the electricity, and the eco impact of the EWG technology.
Cost Effectiveness Can Be An Issue – cost-effectiveness of an AWG depends on the capacity of the machine, local humidity and temperature conditions and the cost to power the unit [or, the cost of electricity/power in a city or town] (wikipedia.org). The upfront cost of an AWG machine and the alternative cost of water from other sources can also play a part. AWG technology can sometimes be more expensive than other water supply options such as home purified water, desal water, surface water, and ground water (GENAQ provides a chart of these costs)
Can Be Inefficient (Input To Output) – it demands more than four times as much water up the supply chain than it delivers to the user (wikipedia.org)
Largest Quantities/Scales Of Water Generation Can Be An Issue – AWG technology may not be suitable for uses like agriculture due to the sheer quantity of water required for irrigation and other uses. It might only produce enough water for activities like drinking, cooking, cleaning, and general human use and consumption.
Might Not Work Effectively In Some Environments – EWG technology might work better when relative humidity and air temperature is higher. It might not work efficiently when temperature is below 18.3°C (65°F) or the relative humidity drops below 30% (wikipedia.org). EWG technology may also not be good in region and countries with very dry climates and dry air (as there is no moisture to extract in the air) – although some brands like GENAQ say they make units for arid climates over 50ºC (122F) and relative humidity lower than 20%. Each model of AWG by different brands might work ideally in different conditions – so you have to check the specifications and product details for optimal working temperature and relative humidity.
Cleanliness, Healthiness & Safety Of Collected Water Can Be An Issue – in the case of passive ‘water harvesting from air’ methods that don’t rely on patented technology that come with water purification and filtration devices. Even in the case of AWG units, you have to consider factors such as purification of the air (which might be poor quality), and the final mineral content of the water.
Peltier Semi Conducting Material Units Have Pros & Cons – their solid state nature makes them suited to being portable units, but have low efficiency of condensing water at commonly experienced humidity, which is compounded by high power consumption
Not All Countries Can Afford ‘Water From Air’ Technology & Systems – both AWG units, and passive devices like fog nets cost money. Very poor regions can’t afford them unless there is external funding.
Distribution Of Water Can Be An Issue – is there the ability of the water to be distributed properly to where and who it needs to go to, from wherever the AWG unit or air from water passive systems are set up? Even if bottles are used – there’s the issue of generating more plastic, which might end up becoming waste.
Noise Can Be An Issue – some AWG machines can be noisy whilst in operation.
AWGs Can Be Heavy – for example, a 1000 gallon a day unit can weigh 90,000lbs (total including PowerStation and panels) (solarcoldbox.com). Although, Watergen makes a light model for home use (the GENNY model).
Can Be Additional Requirements & Costs For Heated Water – as indicated by GENAQ in their economics of water for human consumption chart. Although, Watergen makes a hot and cold water dispenser model for home use (the GENNY model).