As part 1 of this article explained, demand for water is increasing rapidly. Some forecasts foresee €400-€500bn of investment per annum – just to keep up with this growing demand.
As a result desalination is seen as a potential solution to this challenge.
Traditionally desalination plants have been powered by fossil fuels, either directly drawing energy from the grid, or co-locating the plants close to coal- or natural gas-powered plants. It stands to reason that the global scale up of desalination technology driven by the use of fossils as the primary fuel source is both extremely expensive - leading to unaffordable increases in water cost to societies - and highly polluting.
So could the powering up of desalination plants with renewable energy sources be a logical next step in the development of seawater desalination?
Research over the past two years – undertaken by CambridgeIP – has shown steady progress in making the desalination technologies more energy efficient, as well as increasing the maturity of direct integration technologies.
Evidence of innovation and implementation
The integration of desalination processes with energy sources can be divided between those:
- Using mechanical power – for instance solar heat or industrial processes waste heat; or pressure from wind or wave power (so called direct integration), and;
- Using electricity generated from renewable sources to power the desalination plant (or ‘indirect integration').
In both these areas we have seen a steady acceleration of inventive activity and deployment of technologies, as follows:
Industrial processes integration
A number of companies have developed desalination technologies intended for direct integration with solar or waste heat using low-temperature thermal processes – such as multi-effect humidification (MEH) or solar multistage condensation evaporation cycle (SMCEC).
For instance US-based Altela Inc. has a modular off-grid product operating on solar thermal energy or waste heat. Examples of its application to date include the treatment of waste water from shale gas extraction.
Other companies such as Germany's TerraWater and France's TMW are developing similar systems for integration with solar thermal and waste heat energy.
Solar PV integration
Meanwhile, Swiss-based SwissInso has developed a solar-powered Reverse Osmosis (RO) water purification system capable of producing up to 100m3 p/day of pure drinking water from brackish water or seawater
The system has been deployed in rural or remote off-grid locations in West Africa and the Middle East, and can integrate off-the-shelf solar PV and Reverse Osmosis technologies. The container-based product is modular and mobile, and contains all the necessary components on delivery that can be assembled locally. It also contains a back-up diesel generator in case of solar PV failure or insufficient power.
And a research collaboration between MIT and King Fahd University in Saudi Arabia has developed a modular Solar PV – RO unit, which can be used in emergency relief operations or at the household level.
Wind power integration
Both Aerodyn and Enercon have in the past developed integrated wind energy and desalination units. The unit developed by Aerodyn works on mechanical vapour compression (MVC) technology, using the kinematical energy of the wind turbine directly to drive the compressor of the evaporation desalination plant.
And Germany-based engineering company Synlift Systems has implemented pilot wind-powered desalination units in the Gulf region, which integrate off-the-shelf wind turbines and RO desalination technology.
Wave power integration
The Australian wave energy company Carnegie Wave Energy Ltd has combined its wave energy technology with RO desalination by using the pressure generated from wave energy to drive the RO process. Carnegie's CETO 3 wave energy product has been shown to deliver sustained pressures capable of driving seawater reverse osmosis for commercial scale plants.
In addition to the technologies mentioned above, there are also a number of other desalination technologies under late stages of development which, once implemented, could be natural partners for renewable energy sources, and could even transform the economics of desalination. For instance, the crossover of membranes with nanotechnology is resulting in membranes that are more efficient and more durable, leading to further efficiency gains in RO desalination.
Looking even further afield, companies such as Canada-based Saltworks is looking to altogether more novel desalination processes that could result in up to 80% less energy requirement. Saltworks' patented technology is based on the concentration difference between salt water solutions through a thermo-ionic process.
Building from electrodialysis, Saltworks' stack uses ion exchange membranes to separate solutions and transfer salt. Low temperature waste heat from solar can help drive the system, but the system harnesses energy captured in concentrated salt solutions to initiate salt transfer.
Saltworks has already delivered a remote operated desalination unit to the Canadian Department of National Defence. And the technology will soon be tested by NASA Ames Research Centre, with hopes that it could be used on board the International Space Station (ISS).
The integration of renewable energy with desalination could transform the economics of water supply in coastal areas. This is already happening for remote/off-grid and “water-poor” island locations.
And while potable water is the primary usage of desalination, low-cost, sustainably-powered desalination raises the prospect of supporting agricultural development in previously unarable regions (such as through micro-irrigation), as well as improving the sustainability of water-intensive manufacturing operations such as in food and beverages.
This also provides renewable energy technology and project companies with a growing market niche, where the economics may be better than that of the mainstream electricity market, and which could allow market entry into the value chain of major industry players.
About the authors:
Ilian Iliev works for CambridgeIP. He is a serial entrepreneur and economist. Ilian has a wide experience in IP and technology strategy, innovation policy and innovation finance;
Helena van der Vegt is a Senior Associate with CambridgeIP and leads on projects in the energy and cleantech fields. She has worked with multinationals, SMEs, start-ups and public sector organisations, providing advice on R&D and IP strategy throughout technology and innovation lifecycles.
The company has worked with organisations like the International Renewable Energy Agency and the World Intellectual Property Office to build a patent and technology database of more than 4,500 desalination-related inventions (see Van der Wegt, Iliev et al. (2011), Desalination Technologies and the Use of Alternative Energies for Desalination) – as well as 900 inventions relating to the integration of desalination and renewables. Such technology information libraries can be used by inventors and acquirers of technology alike to identify cutting edge technologies, identify collaboration partners and also understand the scope for innovation in a sector. And it can also provide an early indicator of accelerating activity. The full report can be found here.