Desalination: new frontier for renewable energy?
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20 March/April 2012 | Renewable Energy Focus
focus:PerspectiveInsights on renewables
Demand for water is increasing rapidly. Some forecasts foresee 400-500bn of investment per annum - just to keep up with this growing demand.
Seawater desalination will form an increasingly important part of coastal water systems (where much of the population growth takes place) as an abundant source of water. And this is already happening: In recent years the use of desalination technologies
in extracting potable water from sea-water has spread beyond the affl uent and desert-surrounded locations in the Middle East - and a few loca-tions in California and Australia - to major population centres in Southern Europe, India, East Asia and Africa.
In Southern Europe for example, Barcelona, Malta and Cyprus already source the majority of their potable water from desalination treatment plants, while recent investments in
Israel have seen more than half the countrys water supply come from desalination sources.
Meanwhile, a desalination plant launched in 2010 in Chennai, India provides potable water for 2.5 million people.
What is the link to renewable energy?
The key challenge to deploy-ing desalination is in the cost of energy required. The current lead-ing desalination processes require large amounts of energy to either boil seawater (MFS technology), or push it through sophisticated membranes (RO technology). It is estimated that 28%- 50% of the total cost of running a seawater desalination facility is due to electric power useage, according to the WaterReuse Association (see http://www.watereuse.org/sites/default/ les/u8/Power_consumption_white_paper.pdf).
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 tech-nology driven by the use of fossils as the primary fuel source is both extremely expensive leading to unaff ordable increases in water cost to societies and highly polluting.
For instance in the United Arab Emirates (UAE), up to 3.5% of the total electricity produced goes towards desalination. And continued increases in power generation capacity are needed to keep up with the growing water demands of its growing popula-tion not to mention industrialisation. While thus far increased desalination electricity requirements have been met with natural gas power, the invest-ment and running costs are increasing rapidly. In Abu Dhabi alone the annual cost of building, maintaining and operating desalination plants is due to reach US$3.22bn by 2016 (see http://www.emirates247.com/business/economy- nance/uae-desalination-plant-spending-to -jump-300-2010-10-12-1.302849).
So could the powering up of desali-nation plants with renewable energy sources be a logical next step in the development of seawater desalination?
Desalination: new frontier for renewable energy?
WATER SYSTEMS around the world are under increasing pressure due to demands from continued industri-alisation and urbanisation; growing populations; and increasing pressure
on agricultural systems. This is driving the early stages of a revolution in the technologies and business models used in the water industry. Desalination is already part of this mix, but could the technologies high demand for energy open up a new market for renewable energy technologies?
In recent years the use of desalination technologies in extracting potable water from seawater has spread beyond the affl uent and desert-surrounded locations in the Middle East - and a few locations in California and Australia - to major population centres in Southern Europe, India, East Asia and Africa (image shows plant in the Caribbean).
Insights on renewables
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Until a few years ago the high cost of renewable energy and the energy ineffi ciency of the available desalina-tion technologies made such integra-tion unfeasible on a large commercial scale, even though it may have been possible on a smaller scale (island developments for example).
Yet in recent years, solar and wind power costs have come close to grid-parity precisely in some loca-tions where seawater is plentiful, and frequently where there is a freshwater shortage. At the same time, continued innovation in desalination technolo-gies is contributing to the improved effi ciency of desalination processes.
Research over the past two years undertaken by CambridgeIP - has shown steady progress in making the desalination technologies more energy effi cient, as well as increasing the maturity of direct integration technol-ogies (see box About CambridgeIP).
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 activ-ity and deployment of technologies, as follows:
Industrial processes integrationA number of companies have
developed desalination technologies intended for direct integration with solar or waste heat using low-tem-perature thermal processes - such as multi-eff ect humidi cation (MEH) or solar multistage condensation evapora-tion cycle (SMCEC).
For instance US-based Altela Inc. has a modular off -grid product operat-ing 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 Ger-manys TerraWater and Frances TMW are developing similar systems for integration with solar thermal and waste heat energy.
Solar PV integration Meanwhile, Swiss-based Swis-
sInso has developed a solar-powered Reverse Osmosis (RO) water puri ca-tion system capable of producing up
to 100m3 p/day of pure drinking water from brackish water or seawater (see http://www.swissinso.com/en).
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 neces-sary components on delivery that can be assembled locally. It also contains a back-up diesel generator in case of solar PV failure or insuffi cient power.
And a research collaboration between MIT and King Fahd Univer-sity in Saudi Arabia has developed a modular Solar PV - RO unit, which can be used in emergency relief opera-tions or at the household level.
Wind power integrationBoth Aerodyn and Enercon have
in the past developed integrated wind energy and desalination units. The unit developed by Aerodyn works on
About: Ilian Iliev works for CambridgeIP. He is a serial entrepreneur and economist. Ilian has a wide experience in IP and technol-ogy strategy, innovation policy and innovation nance.
About: Helena van der Vegt is a Senior Associate with CambridgeIP and leads on projects in the energy and cleantech elds. 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 Interna-tional Renewable Energy Agency and the World Intellectual Prop-erty Offi ce to build a patent and technology database of more than 4,500 desalination-related inven-tions (see Van der Merwe, Iliev et al. (2011), Desalination Technologies and the Use of Alternative Energies for Desalination) - as well as 900 inventions relating to the integra-tion of desalination and renewable - (see chart in this article). Such technology information librar-ies 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 http://www.cambridgeip.com/water (note readers can click on this link from the digital issue of the magazine).
Figure 1: Desalination technologies
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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 tur-bines and RO desalination technology.
Wave power integrationThe Australian wave energy com-
pany 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. Carnegies CETO 3 wave energy product has been shown to deliver sustained pressures capable of driving seawater reverse osmosis for commercial scale plants.
Future technologiesIn addition to the technologies men-
tioned 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 desalina