Description of the innovation
The WE4CC-II project has been testing the combination of technologies for using excess heat produced by industrial processes (e.g. electricity production) or specialized solar technologies such as Virtu® technology developed by Naked Energy Ltd. - that won the Venture Competition in October 2011 - in order to purify or desalinate water with the Memstill® technology developed by TNO. The cascading heat from these processes is intended to be used for heating & cooling, by using the Absorberbox® technology developed by TU Berlin. The combination of Virtu® and Memstill® technologies has been evaluated in the lab, while a demonstrator of the Absorberbox® is running in the Berlin Botanic Gardens. A demonstrator of the Memstill® technology is now successfully evaluated at the Electrabel/Laborelec power plant in Belgium, capturing waste heat from the electricity production process and purifying surface water from a river near the site, in order to make high pressure boiler feed water.
In the WE4CC-II project an advanced membrane distillation technology (Memstill®) is evaluated for the production of demineralised water and drinking water using low grade heat. Membrane distillation is a thermally driven separating process where water vapour passes through a hydrophobic membrane and high quality liquid water is retained. This process is triggered by the difference in water vapour concentration across the membrane. By using heat to drive the process (waste heat from power plants, renewable heat from solar PVT systems, etc.), electricity consumption for high quality water production is cut and no excess heat is wasted or discharged to the environment.
Two processes have been utilised to put membrane distillation into practice:
- Memstill®: partial use of waste heat Memstill® with additional heat envelop
- (MD-HEX): full use of waste heat WE4CC-II uses these membrane distillation technologies with the aim to commercialise the potential for waste heat / renewable heat - water cascades.
For air de-humidification, a market for future users of liquid desiccants (heat recovery, supply air drying and precise humidity control in buildings, dehumidification of greenhouses, drying of industrial goods) has to be prepared by developing a number of pilot projects, showing the technology and its specific contribution for power saving.
Furthermore, industrial waste heat suppliers will be needed for the regeneration part of the desiccants. Desiccant networks can be envisaged as a new way of energy storage and transport under use of today unexploited waste heat sources, especially as applications of air dehumidification and regeneration services will regularly not be found on the same place.
Waste heat is produced by a lot of processes that use energy. The biggest contributors to waste heat are industrial processes, domestic processes and energy production that occur in the urban environment. Often, this waste heat is lost to the ambient environment, contributing to a rise in global temperature. Storage and reuse of this waste heat contribute to improving energy efficiency and reduction of CO2 emissions in the city.