The combination of wind and water attracted quite a crowd at the recent International Desalination Association (IDA) conference in Abu Dhabi. Commanding all the attention was one of the latest innovations in desalination technology.
the wind-powered desalination plant.
Judging by the interest shown, its German developers have produced a product which should find a ready market in the Gulf.
The new plant is the brainchild of SEP, based in Ismaning, near Munich. It is specifically tailored to supply water to remote areas, enabling outlying communities to be independent of the national grid.
Besides the obvious ecological attractions of tapping the power of the wind, the plant only needs a modest investment and has low maintenance costs.
Work on the wind-powered desalination plant started 10 years ago, says SEP managing partner Ulnich Plantikow.
Drawing on experience gained from working on Germany’s state-sponsored wind energy programme, Plantikow was all too aware of the difficulties involved in harnessing the wind to generate electricity efficiently. ‘Wind energy is a complicated business, because of the character of the wind: it can change in strength from 1 metre a second to 15 metres a second in a very short space of time,’ he says. The extreme fluctuations make wind power very volatile and any plant exploiting wind energy needs expensive batteries to use as storage facilities.
Water works In his search for a solution to the problem, Plantikow’s attention turned to water. ‘I thought that the best way to use wind energy was to produce something that could be easily stored and the cheapest form of storage system is for water,’ he explains. ‘The desalination plant would also act as a control system for the energy produced from the wind.’ Plantikow recognised the need to provide a facility that could deliver a constant supply of water, regardless of the weather conditions. This means that wind energy has to be supplemented by a conventional generator. ‘The important aspect is that the two forms of energy are combinable,’ he says. ‘The equipment is intelligent enough to draw on an external system, when needed.’ The central element of the plant is an evaporator-condenser unit, consisting of a vertical tube bundle for the evaporation of seawater and the condensation of the compressed vapour. It operates by drawing seawater into a closed evacuated container which is partly filled with warm seawater. The steam above the seawater is then compressed by the wind energy generator. The compressed steam in turn is condensed in a heat exchanger, which heats the incoming sea water.
The system can also be used to purify brackish or contaminated water.
The plant designs were completed in the early 1990s and SEP moved quickly to turn the concept into a reality. In March 1995, a demonstration plant, with a capacity of 15 cubic metres an hour (cm/h) of water, went into operation on the Baltic island of Ruegen. Last July, SEP signed an agreement with Thyssen Stahlunion which is to manufacture the plant and act as its agent and distributor.
Remote possibilities The two partners are currently working out a detailed marketing strategy. Rather than target large urban centres the aim is to establish units in remote coastal communities, where the cost of supplying water from the national grid can be prohibitively expensive and fossil fuels may be in short supply. In a northern European setting, it is estimated that a plant the size of the Ruegen facility can satisfy the domestic requirements of 1,200-1,500 people.
In the long run, the aim is to double or even triple the current design capacity.
However, for the time being, the SEP/Thyssen team is set on marketing the smaller version. A unit similar to the Ruegen facility is expected to have a price tag of DM 2.5 million-3 million, which excludes site preparation and transportation costs. While delivery times are expected to range up to eightmonths, erection will only take about a week.
In view of the Middle East’s topography, declining renewable water resources and strong dependence on desalination, the region is viewed as a key market for the product. Thyssen reports that the response from initial discussions with regional customers has been promising.
‘The political and industrial reaction to the plant has been very positive,’ says one official. ‘It offers a unique solution to solving the water problems in many parts of the region, especially at a time of growing concerns about the environment.’ AH