A low-cost, compact system to generate drinking water

Abstract

A low-cost, low mass and very compact system capable of generating very pure water is a bi-product of producing healthy plant crops in space. The system could be deployed, for example, in disaster areas where normal water supplies are contaminated.

Description

In order to stimulate balanced growth in space crops, a minimum amount of water must be evaporated so as to allow sufficient ion transport within the plant. Since a crop chamber is a closed system, air humidity is mostly saturated and this strongly reduces the ion transport processes. To stimulate water evaporation by the crops, an air dehumidifier is installed, and dependent on the setting of the relative humidity, significant amounts of very pure water are condensed, up to 1-litre of water per day per plant, dependent on the plant size. In an experimental design developed for space, healthy tomato crops were grown, high-quality tomatoes were harvested and plenty of pure water was produced.

The system is composed of a hermetically closed airtight tent. Inside there is a single tomato plant (1.0-1.5 meter size) that feeds on a hermetically sealed waterproof Rockwool slab, filled with a specific nutrient solution. In addition there is a LED-light source that provides sufficient light for the plant to grow and a dehumidifier with adjustable relative humidity settings to stimulate evaporation.

Innovations and advantages of the offer

  • The water production system is low-cost, low-weight and very compact.
  • The resulting water is very pure (too pure for drinking water).
  • Waste or polluted water can be used as input.

Further Information

The system can be used in space (it is much smaller and lighter than the equivalent in ESA’s MELiSSA project), but also on Earth, for example in disaster areas, after a hurricane. In these situations, available water is often very polluted. In these situations the system would allow production of pure water quickly and reliably. Note that for drinking purposes the water actually is too pure, and some minerals must be added.

Application

Current application: Demonstration system for application in long-duration manned space missions

Potential application: Production of pure water as part of disaster relief and emergency assistance

Comments on the technology by the broker

At Groen Agro Control (GAC) the idea to develop a horticultural concept for space came up in 2011/2012, when future travel to the Moon and Mars was in the news. In May 2013 the R&D department of GAC looked at what exactly a plant absorbs from a variety of nutrients. This was found to be variable. Follow-up and contact with ESA was triggered by their participation in Space-MATCH in November 2013. Following this event, GAC started further research on their idea to produce water and crops more or less automatically, based on the ‘cockpit situation’ of a spaceship. Astronauts already have enough things to worry about and should not have to devote their attention to crop care.

Description of Space Heritage

GAC has developed this drinking water system as a spin-off of their activities to support and optimize crop production in Space. For long-duration human space missions, sustainable crop production will be a prerequisite. In the ‘Space Agro’ area, it is very important to deal with the available resources and stocks (especially water) efficiently. In the MELiSSA project ESA has made significant progress with regard to the circulation of water and minerals, defining the complete diet for astronauts, crop production and water purification. However, the resulting technology is still large-scale, heavy and expensive.

Based on their long experience in crop production on Earth GAC has developed this drinking water system as a low-cost alternative to the technology that is currently being used in the MELiSSA project.

Category
Other Technologies
Reference No.
TDO0209
Could this technology benefit your business? Please contact Len van der Wal TNO Space (Netherlands)
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