renewable energy drives desalination processes in remote or arid regions

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Membrane Technology August 2008 FEATURE 8 Renewable energy drives desalination processes in remote or arid regions Lack of water causes great distress among the population in large parts of Africa and Asia. Small decentralised water treatment plants with an autonomous power supply can help solve this problem – they transform sea water or brackish water into pure drinking water. Complex technology Large industrial plants for the desalination of sea water deliver 50 million m 3 (around 13.2 billion gallons) of fresh water every day – par- ticularly in the coastal cities of the Middle East. However, the technology is complex and con- sumes large amounts of energy. It is not suitable for the arid and semi-arid regions of Africa and India, though these are the very places where it is becoming increas- ingly difficult to supply drinking water, particu- larly in rural areas. ‘The regions have a poor infrastructure. Quite often there is no electricity grid, so conventional desalination plants are out of the question,’ said Joachim Koschikowski of the Fraunhofer Institute for Solar Energy Systems (ISE), based in Freiburg, Germany. Decentralised plants In various projects funded by the European Union (EU) over the past few years, Koschikowski and his team have developed small, decentralised water desalination plants that produce fresh drinking water with their own independent solar power supply. ‘Our plants work on the principle of mem- brane distillation,’ explained Koschikowski. ‘In our plant, the salty water is heated up and guided along a microporous, water-repellent membrane. Cold drinking water flows along the other side of the membrane. The steam pres- sure-gradient resulting from the temperature difference causes part of the salt water to evapo- rate and pass through the membrane. The salt is left behind, and the water vapour condenses as it cools on the other side. It leaves us with clean, germ-free water,’ added Koschikowski. Own energy supply The researchers have so far built two different systems, both with their own energy supply. ‘Our compact system for about 120 litres (32 gallons) of fresh water per day consists of 6 m 2 (65 ft 2 ) of thermal solar collectors, a small photovoltaic module to power a pump, and the desalination module itself,’ explained Koschikowski. In the dual-circuit system, on the other hand, several desalination modules are connected in parallel, enabling several cubic metres of water to be treated every day. A single cubic meter of drinking water (1000 litres) will cost about 10. ‘When you think how much the inhabitants currently have to pay for the same amount of bottled water or soft drinks, the plant will pay for itself very quickly,’ claimed Koschikowski. Test plants in Gran Canaria and in Jordan have been operating successfully for some time. The researchers are planning to market the plants through a spin-off concern known as ‘SolarSpring’. Windmill drives sea-water desalination ‘Drinking with the wind’ is a project that is being run at Delft University of Technology (TU Delft) in The Netherlands. The project combines desalination and wind energy to produce safe and reliable drinking water for remote areas, where there is a shortage of fresh water and sufficient wind power available. The concept behind the system – a combina- tion of a windmill and reverse osmosis (RO) unit – that has been developed by TU Delft is relatively straightforward. It is based on a tradi- tional windmill which is used to drive a pump. In this case, it involves a high-pressure pump that pushes water through a RO membrane at a pressure of approximately 6 MPa (60 bar). The membrane produces fresh water directly from brackish water or sea water. The windmill can be located near a small village in an isolated, dry coastal area. Storing electricity Systems that are made up of a combination of a windmill and a desalination installation are already being used. The electricity produce by these windmills from wind power is stored and subsequently used to power a high-pressure pump that drives the RO installation. However, the storage of electricity in particular is expen- sive, and throughout the conversion processes energy losses occur. To minimise these energy losses a system that uses a direct connection between the windmill and a high-pressure pump has been developed. The RO installation operates intermittently, because of the variable character of the wind, and product water is stored. The desalina- tion installation is operated mechanically and hydraulically. Driven directly by wind power In the TU Delft installation, the high-pressure pump is driven directly by wind power, and water is stored to make up for any shortfall that may occur during calm periods. A windmill that is normally used for irriga- tion purposes can be used for this application. These turn relatively slowly and are also robust. On the basis of the windmill’s capacity (at varying wind speeds) it is estimated that such a system is capable of producing 5–10 m 3 of fresh water per day – essentially enough Lack of water causes great distress among population groups living in rural areas or in arid and semi-arid regions of the world. This brief article shows that small, decentralised water treatment plants, powered by renewable energy, can help solve this problem. It covers work that is being done at the Fraunhofer Institute for Solar Energy Systems, where systems have been developed that pro- duce fresh drinking water using their own independent solar-power supply. In addition, it provides a summary of a project at Delft University of Technology that combines desalination and wind energy to create a safe and reliable source of drinking water for small communities.

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Page 1: Renewable energy drives desalination processes in remote or arid regions

NEWS

8Membrane Technology August 2008

FEATURE

8

Renewable energy drives desalination processes in remote or arid regions

Lack of water causes great distress among the population in large parts of Africa and Asia. Small decentralised water treatment plants with an autonomous power supply can help solve this problem – they transform sea water or brackish water into pure drinking water.

Complex technologyLarge industrial plants for the desalination of sea water deliver 50 million m3 (around 13.2 billion gallons) of fresh water every day – par-ticularly in the coastal cities of the Middle East. However, the technology is complex and con-sumes large amounts of energy.

It is not suitable for the arid and semi-arid regions of Africa and India, though these are the very places where it is becoming increas-ingly difficult to supply drinking water, particu-larly in rural areas.

‘The regions have a poor infrastructure. Quite often there is no electricity grid, so conventional desalination plants are out of the question,’ said Joachim Koschikowski of the Fraunhofer Institute for Solar Energy Systems (ISE), based in Freiburg, Germany.

Decentralised plantsIn various projects funded by the European Union (EU) over the past few years, Koschikowski and his team have developed small, decentralised water desalination plants that produce fresh drinking water with their own independent solar power supply.

‘Our plants work on the principle of mem-brane distillation,’ explained Koschikowski.

‘In our plant, the salty water is heated up and guided along a microporous, water-repellent membrane. Cold drinking water flows along the

other side of the membrane. The steam pres-sure-gradient resulting from the temperature difference causes part of the salt water to evapo-rate and pass through the membrane. The salt is left behind, and the water vapour condenses as it cools on the other side. It leaves us with clean, germ-free water,’ added Koschikowski.

Own energy supply The researchers have so far built two different systems, both with their own energy supply.

‘Our compact system for about 120 litres (32 gallons) of fresh water per day consists of 6 m2 (65 ft2) of thermal solar collectors, a small photovoltaic module to power a pump, and the desalination module itself,’ explained Koschikowski.

In the dual-circuit system, on the other hand, several desalination modules are connected in parallel, enabling several cubic metres of water to be treated every day. A single cubic meter of drinking water (1000 litres) will cost about �10.

‘When you think how much the inhabitants currently have to pay for the same amount of bottled water or soft drinks, the plant will pay for itself very quickly,’ claimed Koschikowski.

Test plants in Gran Canaria and in Jordan have been operating successfully for some time. The researchers are planning to market the plants through a spin-off concern known as ‘SolarSpring’.

Windmill drives sea-water desalination‘Drinking with the wind’ is a project that is being run at Delft University of Technology (TU Delft) in The Netherlands. The project combines desalination and wind energy to

produce safe and reliable drinking water for remote areas, where there is a shortage of fresh water and sufficient wind power available.

The concept behind the system – a combina-tion of a windmill and reverse osmosis (RO) unit – that has been developed by TU Delft is relatively straightforward. It is based on a tradi-tional windmill which is used to drive a pump. In this case, it involves a high-pressure pump that pushes water through a RO membrane at a pressure of approximately 6 MPa (60 bar). The membrane produces fresh water directly from brackish water or sea water. The windmill can be located near a small village in an isolated, dry coastal area.

Storing electricity Systems that are made up of a combination of a windmill and a desalination installation are already being used. The electricity produce by these windmills from wind power is stored and subsequently used to power a high-pressure pump that drives the RO installation. However, the storage of electricity in particular is expen-sive, and throughout the conversion processes energy losses occur.

To minimise these energy losses a system that uses a direct connection between the windmill and a high-pressure pump has been developed. The RO installation operates intermittently, because of the variable character of the wind, and product water is stored. The desalina-tion installation is operated mechanically and hydraulically.

Driven directly by wind powerIn the TU Delft installation, the high-pressure pump is driven directly by wind power, and water is stored to make up for any shortfall that may occur during calm periods.

A windmill that is normally used for irriga-tion purposes can be used for this application. These turn relatively slowly and are also robust. On the basis of the windmill’s capacity (at varying wind speeds) it is estimated that such a system is capable of producing 5–10 m3

of fresh water per day – essentially enough

Lack of water causes great distress among population groups living in rural areas or in arid and semi-arid regions of the world. This brief article shows that small, decentralised water treatment plants, powered by renewable energy, can help solve this problem. It covers work that is being done at the Fraunhofer Institute for Solar Energy Systems, where systems have been developed that pro-duce fresh drinking water using their own independent solar-power supply. In addition, it provides a summary of a project at Delft University of Technology that combines desalination and wind energy to create a safe and reliable source of drinking water for small communities.

Page 2: Renewable energy drives desalination processes in remote or arid regions

FEATURE

August 2008 Membrane Technology9

The inaugural ‘Singapore International Water Week’, held on 23–27 June 2008 at Suntec Singapore International Convention and Exhibition Centre, was run under the theme ‘Sustainable Water Solutions for Cities’. Some 8500 delegates and trade visitors attended the event to discuss the latest challenges, best prac-tices and technologies in the water industry.

The annual event – organised by Singapore International Water Week Pte Limited, a company set up by Singapore’s Ministry of Environment & Water Resources and Singapore’s national water agency Public Utilities Board (PUB) – features the Water Leaders Summit, Water Convention, Water Expo, Business Forums and Water Festival, as well as the presentation of the Lee Kuan Yew

Water Prize for innovative contributions to solving the world’s water problems.

Deals and agreementsAccording to the event’s organiser, govern-ments, utilities providers and water compa-nies signed agreements totalling more than SG$367 million (US$270 million) during the first Singapore International Water Week. In addition, a water fund was launched to attract SG$435 million (US$320 million) in invest-ments for water projects in Asia.

Deals worth US$1 million or more were concluded by exhibitors such as Hydranautics, Koch Membrane Systems, Nalco Pacific and EIMCO Water Technologies.

Among other business deals concluded was one worth an estimated SG$272 million (US$200 million) over the next three years for Singapore-based Ayser-Technische Corporation and Acuatico. The two companies signed a Memorandum of Understanding (MOU) to set up a joint venture to design, construct and operate private water infrastructure projects in Indonesia. They also teamed up to provide and run central water treatment facilities for all future developments by Bakrieland, the largest developer listed on the Indonesian Stock Exchange.

Black & Veatch, a global engineering, construc-tion and consulting company, clinched projects in Singapore, Australia and Hong Kong worth about SG$46 million (US$34 million), while US-based Marmon Water, one of the world’s largest manufacturers of residential and commer-cial water treatment systems, is set to build the SG$24-million (US$18-million) Marmon Water Manufacturing Plant in Singapore to produce filtration systems and components for the world-wide residential water-treatment market place.

Singapore-based technology start-up company AridTec found distributors for its patent-pending atmospheric ‘water harvesting’ systems, which

drinking water for a small village of around 500 inhabitants.

System safeguards are also performed mechanically (so that no electricity is needed) in the event of the installation running dry, or to balance either a low or high number of revolutions.

A prototype has been built and tested at a location close to the A13 motorway near Delft. Further tests are being carried out on the island of Curaçao in the southern part of the Carribbean Sea.

SupportThe ‘Drinking with the wind’ project has been supported financially and in other ways by a number of organisations in The Netherlands.

Initial financial support was given by G.N.M. Grootscholten. While running his own company, Grow Group Plantenkwekerij G.N.M. Grootscholten BV, he became inter-ested in RO. He decided to raise money to help solve the problem of drinking-water shortages in developing countries and asked TU Delft to design a small-scale installation for this purpose.

Hatenboer-Water, a company that spe-cialises in complete systems, products and services for the water industry, supported the project from the beginning, not only financially, but also by offering its expertise and the use of its facilities. The Aqua for All Foundation, which is keen to tackle the scar-city of drinking water and sanitary facilities in developing countries in a structural way,

contributed by acting as a ‘hinge’ between all parties involved.

SenterNovem, an agency of the Dutch Ministry of Economic Affairs that promotes sustainable development and innovation also supported the project.

Contacts:

Joachim Koschikowski, Fraunhofer Institute for Solar

Energy Systems (ISE), Heidenhofstrasse 2, 79110

Freiburg, Germany. Tel: +49 761 4588 5294

Email: [email protected]

Bas Heijman, Faculty of Civil Engineering and

Geosciences, Delft University of Technology, Stevinweg

1, 2628 CN Delft, The Netherlands. Tel: +31 15 278

5440, Email: [email protected],

www.drinkingwiththewind.nl

Singapore’s first Water Week – a global platform for technologies, products and initiativesThe ‘Singapore International Water Week’ – described as a global platform for technologies, products and services for the water industry – brings together policy-makers, industry leaders, experts and practitioners to address challenges, discover opportunities and celebrate achievements in the water world. This feature covers some of the highlights of this event, which was held for the first time this year. It provides a summary of com-mercial transactions, agreements and initiatives, and key points associated with the fast-growing water market in China.