An energy efficient ambient moisture extraction system, which uses solar heat, heat pumping technology and solar photovoltaic panels to extract water from the air for industrial applications, is being promoted locally by an East London-based company.

Sifika Group director Lamile Sifika claims the machines are capable of producing between 20 Mℓ and 500 Mℓ a day and could eventually be manufactured in King William’s Town, but he admits that such an aspiration would be premised on commercial uptake.

The Sifika Air to Water Generator (SAWG) uses a desiccant to absorb moisture from the air pulled through a duct and into the extraction chamber, before reheating the desiccant and then cooling the air to condense released water vapour into liquid, which is then stored, Sifika’s Alice Ngomira says.

The system has two main processes, namely absorption and regeneration, and uses solar heat, a solar photovoltaic panel and, potentially, wind energy (in regions with sufficient wind) to move the air through the system and power the electronics. Heat pumping technology provides cooling and heating.

“We use heat to drive both the airflow for the absorption process and to provide heat during the regeneration process, which extracts the moisture from the desiccant,” she says.

However, questions remain about whether the system will be able to circulate enough air to produce sufficient quantities of water to supply industrial applications, as Sifika Group proposes.

Household air moisture extraction systems in the US reportedly produce between 19 ℓ and 25 ℓ (between five gallons and seven gallons) a day but draw power from the electricity grid.

To produce 20 Mℓ of water, the system would have to move about 650-million cubic metres of air through the system, if a water vapour content of 25 g/kg of air is assumed (in the tropics), at an assumed air density of 1.2252 kg/m3 (at 15 ºC and at sea level pressure) and if all the water in the air is captured.

Questions persist regarding the energy intensity of this system, but the group says it was designed to operate off-grid and in remote locations.

The company is seeking a partner on whose land it can erect a demonstration SAWG plant, which it would design, install, operate and maintain free of charge, with the part- ner only paying for water received, he concludes.