Wind of Change: Water from Air

In September 2013, a Netherlands based company announced the successful pilot installation and validation of its 'water-from-air' technology at a site in Um Al Himam, Kuwait.

Istock 000032087958medium
Istock 000032087958medium

In September 2013, a Netherlands based company announced the successful pilot installation and validation of its 'water-from-air' technology at a site in Um Al Himam, Kuwait. So, how exactly does the technology work? What are the challenges involved in establishing it? And what are the prospects for rolling it out across the Middle East and elsewhere?

Andrew Williams reports.

As Wouter van Rooijen, business development manager at Dutch Rainmaker explains, the chief objective of the pilot installation is to validate the technology in the "difficult conditions of the Kuwaiti climate".

The facility has already successfully produced water out of air at the site - and the Kuwaiti Environmental Protection Agency (KEPA) intends to use it to supply its 'green wall' project, an ongoing government-backed scheme, which aims to plant 315,000 trees along the borders of Kuwait along a 420 km stretch within the next ten years.

The Dutch Rainmaker technology works by converting the mechanical energy of the rotating blades on a turbine to produce thermal energy.

According to van Rooijen, this 'highly efficient' conversion process is applied via a patented 'direct-drive' turbine, which uses compressors that generate heat. This heat is then used to cool down large amounts of incoming air, which is displaced by using vents.

"When air is cooled down it diminishes the capacity of water it can hold per cubic metre. This excess of water then condenses, in a similar fashion as it would when it starts to rain. Because this process takes place inside the Dutch Rainmaker installation it can 'catch' all of this water and use it as a resource," he adds.

In addition to the Kuwaiti installation, the company also operates a pilot plant at Leeuwarden in the Netherlands. Van Rooijen reveals that both facilities have successfully produced water out of air.

In his view, the fact that the two facilities are located at sites with 'very dissimilar' topographical and climatic conditions, serves as a validation of the technology - and suggests that it is viable "for all locations with conditions that lie between these two extremes".

Technology at scale

For Piers Clark, commercial director at Thames Water Utilities and strategy advisory board member at Dutch Rainmaker, the fact that the innovative idea has also been backed up with examples in the field provides substantial cause for optimism.

"The recovery of drinking water from air is not particularly new - just look at an air conditioning unit and you can see how it is technically possible to get water from air. The stand out feature from Dutch Rainmaker is that they are the first team to do this at scale, using robust technology, with a clear reliable cost benefit," he says.

"When I first saw the technology I knew that I was looking at something that had the ability to dramatically change how water is supplied to communities around the world.

"The fact that they have not one but two demonstration scale units in two starkly different parts of the world is also very impressive," he adds.

Remote Locations

Van Rooijen believes that the technology is especially suitable for remote locations - mainly because it does not need to be connected to an existing energy grid or water infrastructure, meaning it can be constructed "in the exact location where water is needed the most". This also provides an added advantage because it reduces the need for the transportation of water, which he points out is "very costly and environmentally unfriendly".

Clark adds: "Not only does it now mean that water can be produced at relatively cheap levels anywhere across the world, it also means that the need for long distance, progressively aging, distribution networks is reduced. With DRM water can be produced locally, even if there is not a reservoir or groundwater source nearby."

However, in spite of the vast potential of the technology, Van Rooijen admits that a number of challenges remain before it can be deployed at a global level.

In particular, he highlights the fact that locations where water scarcity is most pressing often also lack a 'serious' financial infrastructure - meaning that it is "sometimes difficult to establish projects at locations where it would add the most value".

In order to help in meeting these challenges the company recently introduced a hybrid version of the technology to guarantee a higher level of consistency in terms of output. It has also devised a Bottling Unit application, which can run alongside the AW75 to create a "self-sufficient water bottling line".

Looking ahead, van Rooijen is confident that locations across the Middle East could substantially benefit from the technological possibilities of Dutch Rainmaker "in securing sufficient drinkable water and resources for agricultural purposes".

Moreover, he confirms that the company has also received high levels of interest from South America, Africa, South East Asia and Australia.

"Warm, humid climates with remote or difficult to reach inhabited areas are specifically interesting for Dutch Rainmaker to work with," he says.

Currently, the company is focusing its efforts on finding "specific projects with a large capacity in terms of water-requirements".

Another intriguing possibility is the idea of installing the AW75 technology in wind farms, possibly in combination with existing wind turbines, to create "a completely self-sufficient area in terms of energy and water".

Construction Mill
When air is cooled it diminishes the capacity of water it can hold per cubic metre. This excess of water then condenses and is "caught" inside the rainmaker unit

"Perhaps less obvious are the island community opportunities, in particular in tourist areas, where seasonally fluctuating water demands mean that large quantities of potable water often need to be shipped in from mainland sources or produced on-island using very expensive techniques. Dutch Rainmaker can resolve these problems," says Clark.

"There are even some very neat industrial solutions. The water-water DRM unit produces demineralised water which is necessary for many industrial processes and needs to be produced via a fairly costly process from conventional water sources," he adds.

Rainmaker: the technology works by condensing heat generated by turbines into water. So far trials have taken place in Kuwait and the Netherlands

Beetle Mania

On the other side of the globe in Australia, a team of academics has also made great strides in researching how water can be efficiently collected directly from the atmosphere.

The group, which includes researchers from the University of New South Wales (UNSW) and the University of Sydney, is investigating the preparation of micro-patterned surface coatings to collect water from the atmosphere.

According to Dr Stuart Thickett, Vice-Chancellor's Post-Doctoral Research Fellow at the Centre for Advanced Macromolecular Design (CAMD) at UNSW, the project "covers everything from the fundamental science behind designing and preparing such surfaces, through to scale up and manufacturing of large devices over a metre squared in size".

"We consider the project important due to long-running sustainability issues related to water in Australia, in addition to providing alternatives to the typical centralized water collection and delivery methods in Australia's major cities," he says.

Snapshot Animatie
Water and wind harvest: the Rainmaker technology could be located with other wind turbines to create independent energy and water "farms"

The team was initially inspired by the stenocara, a Namib Desert beetle that lives in Southern Africa and survives on minimal surface water.

In 2001, the secret to Stenocara's success was revealed - namely that it possessed an exoskeleton consisting of water-loving hydrophilic bumps on a highly water-repellent background, and it was this unique surface structure that enabled it to collect water directly from the air, via condensation from fog.

Since this discovery, Thickett says there has been a lot of research worldwide into such 'biomimetic,' or nature copying, materials in an effort to try and replicate this phenomenon.

"We are trying to do the same, in particular with polymer surface coatings as the starting materials, which are particularly cheap, easy to manufacture and can be applied on a variety of surfaces and materials," he adds.

As Thickett explains, the reason why such a patterned surface is so successful is due to "continual condensation and water collection".

Compared to a flat surface, water can only condense on the bumps, which are approximately 0.5 mm in diameter in the case of a stenocara beetle.

In effect, water droplets are 'pinned' at these points, but continue to grow via condensation until they are so large that they detach from the surface, and roll off.

"This enables the Stenocara to have a drink, and we would envisage the droplets rolling off into a reservoir or collection vessel.

"Once the water droplets come off the surface, further water can condense, and the process can repeat itself," the CAMD's Vice Chancellor's Post-Doctoral Research Fellow.

Technological Challenges

In 2011, the team published a high impact paper in the journal Advanced Materials, which outlined its initial success in proving that the idea works at the laboratory scale.

Using a combination of a water-repellent polymer and a hydrophilic polymer, they created patterned surfaces that could capture significantly more water than corresponding flat films - an improvement in the range of - when cooled below the dew point.

The rate of water collection was measured to be close to three litres of water per hour per square metre of surface.

The team is now devoting its attention to working out how to overcome the technological challenges involved in making the process work at larger scales.

As Thickett explains, the main challenge at the moment is how to take a technology that is proven under laboratory conditions and translating it into a "true marketplace technology".

"The numbers I mention above sound impressive but our materials at the moment are only a few square centimetres in size, and we need to make equivalent surfaces on a much larger scale," he says.

"This will involve alternative techniques to cast and prepare our films, using cheap and robust substrates, as well as checking the viability of our materials under real-world conditions," he adds.

Andrew Williams is freelance contributor to WWi magazine and specialises in the areas of renewable energy, water and environmental issues. For more information on the article, contact:

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