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Wind power as it applies to water desalination

Report Prepared for ASTF (Arab Science and Technology Foundation)

Water Desalination by Solar Energy Project

Cipriano Marín

July 2006

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INDEX 1. INTRODUCTION ............................................................................. 2 2. WIND POWER STATUS ...................................................................... 3 3. WIND POWER – RO ...................................................................... 6 4. WIND-POWERED DESALINATION OPTIONS ....................... 9

4.1 ONGRID ...................................................................................... 9

4.2 ONGRID ISOLATED YSTEMS Hydro-wind-storage hybrid .......................................................10 4.3 OFFGRID Stand Alone Systems.................................................................11

5. REFERENCE CASES ....................................................................13

5.1 ONGRID SYSTEMS.....................................................................13

5.2 ONGRID-ISOLATED SYSTEMS..................................................17

5.3 OFFGRID SYSTEMS Stand Alone Systems. Seawater desalination with an autonomous wind energy system ...............................19

5.4 OFFGRID SYSTEMS

Stand Alone Systems optionally connected to small grids ...........................................................26

5.5 Demonstration Projects of reference .......................................28

6. MAIN CONCLUSIONS...................................................................30

7. REFERENCES.................................................................................31

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1. INTRODUCTION In the last years wind power has become one of the most advanced energy key vectors that would define desalination strategy in the forthcoming years, especially within seawater desalination. Wind energy coupling desalination is at present one of the most hopeful possibilities within the binomial RES energy-water. Each RES vector has different possibilities which determine its degree of application in desalination. The selection of the appropriate RES desalination technology depends on a number of factors. These include desalination technology, feed water salinity, remoteness, electricity grid availability and size, technical infrastructure, characteristics of demand, and the type and potential of the local renewable energy resources. Among the several possible combinations of desalination and renewable energy technologies, some seem to be more promising in terms of economic and technological feasibility than others. Some RET or their combinations are more appropriate for large size plants, whereas some others are better suited for small scale application. One challenge to be overcome in coupling a renewable energy source (RES) to a desalination process is the variability of the power output of the RES and the availability in terms of time, basically when we refer to solar (both thermal and PV) and wind. Biomass and geothermal sources should be considered as basic sources not subject to variations. Wind can be used to supply either electricity or mechanical power. Wind Energy Converters (WEC) have progressively pointed to electricity as usual output. Today, wind turbines can be supplied in any capacity from a few kW to 5 MW. They come in a variety of configurations, but a fundamental feature is that market and technological development are oriented to big wind turbines. Within the framework of new wind powered desalination alliances, it is worth emphasizing that coastal areas, especially in dry regions, and islands are places where often optimum wind conditions are found. Coastal areas normally are subject to constant winds and in several occasions average wind speed is stronger than 6 m/s allowing new wind turbines functioning at their nominal load for more than 2000 h/year. An interesting synergy exists between the technologies in relation to coastal geographies.

Clearly desalination plants processing seawater gain from being situated close to the water, both for easy access to feed water as well as easier disposal of the briny concentrate. While wind systems certainly gain from relatively consistent coastal winds, the real advantage comes from the recent development of offshore wind technologies. WEC possibilities are limited to two energy output vectors (mechanical or electricity). This reduces the range of efficient applications to the following desalination processes: Reverse Osmosis (RO), Electrodialysis (ED), and Vapour Compression (VC). Figure 1.

Figure 1. Options of desalination powered by wind. Since electricity is the commonest output, most options are at present pointing to windpower-RO coupling because of its high efficiency.

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2. WIND POWER STATUS The wind energy scene has radically changed in only one decade. WEC (Wind Energy Converters) technology has mainly pointed at specialization within the segment of wind turbines for electricity generation. We can state that we are now before an absolutely mature technology stabilized in the market. In contrast to what was happening a few decades ago, wind turbines can operate continuously, unattended, with low maintenance, and some 120,000 hours of active operation can be expected over a design lifetime of 20 years. By comparison, a typical car engine has a design lifetime of the order of 6,000 hours. Since the early 1980s, the capacity of an individual turbine has increased by a factor of over 200. Generation costs have declined by 80%. Modular and quick to install, wind turbines range in size from a few kilowatts to 5,000 kW. Wind turbines are highly reliable, with operating availabilities (the proportion of the time in which they are available to operate) of 98%. No other electricity generating technology has a higher availability at present. Figure 2 shows the exponential evolution of wind energy installed capacity during the last years. Wind power has the potential to make a major contribution to the world’s increasing energy demand. Wind Force 12, a publication by the

Global Wind Energy Council (GWEC), EWEA and Greenpeace, shows that 12% of the world’s electricity can be supplied by wind power in 2020 if political and policy changes are being pursued, so that technical, economic or resource limitations are minimised.

Figure 3. Wind Power Prospects to 2020. Source: «Wind Force 12», GWEC, EWEA, Greenpeace The impressive increase in wind power installed capacity in the whole world went in parallel with the increase in power and size of wind turbines, which in only ten years passed from 300 kW to 5 MW. This growth was caused by factors related to technological optimization, market, material innovation and operational simplification, which allowed a steady reduction of generation costs. Figure 3 shows the significance of this increase.

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Figure 2. Cumulative Wind Energy Installed Capacity. Source EWEA (European Wind Energy Association).

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An important consideration deduced from the evolution of wind energy technologies, is that because of a progressive specialization in higher power ranks, smaller wind turbines (<200 kW), show generation costs increasingly phased out if compared with bigger solutions. This is particularly important in specific applications such as small-scale desalination. Other factors that determine to a great extent wind energy penetration capacity are related to technological and market barriers to their implementation: grid connection, pricing and energy accounting systems, where conventional energies prevail. Figure 4. Growth in Size of Commercial Wind Turbine Designs. Source EWEA.

Figure 5. Average Wind Turbine Size Installed Each Year. Source EREC (European Renewable Energy Council). Figures 4 and 5 show the evolution in size of wind turbines in the last years, as well as the average installed power of each turbine. This evolution allowed a constant reduction of price per unit of power installed of wind turbines, as well as reduction of generation prices. Figure 6 shows how, under favourable wind conditions, (>6.5 m/s) the wind kWh starts to be competitive compared to conventional sources, being this fact absolutely unthinkable only a few years ago. As shown in Figure 7 total wind energy cost per unit of electricity produced has lowered below the barrier of 0.5 €/kWh (0.6 US$) in wind farms with turbines bigger than 1 MW. Nevertheless, it is very important to emphasize the fact that these costs can reach 0.4 €/kWh (0.48 US$) in coastal areas.

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Figure 6. Prices for Different Generation Technologies. Source EWEA.

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Figure 8 shows the large difference existing between the cost of wind power related with the number of hours when wind speed allows wind turbines working at their nominal power and the discount rate. Once more it can be observed the favourable situation of an important part of coastal areas. Figure 7. Total wind energy costs per unit of electricity produced, by turbine size (constant 2001 prices). EWEA.

Source EWEA

Figure 8. Cost of Wind Power as a Function of Wind Speed and Discount Rate Source: EWEA (European Wind Energy Association). Market and provider distribution is unbalanced, as shown by Figure 9 and 10, favouring certain countries, several of them of the European Union. Germany heads the leading countries, followed by USA, Spain, Denmark and India. An important gap exists between this group of countries and the rest. In practice the distribution of providers follows the same trend of power installed in each country, although the case of Denmark stands out among them. Wind power geography is absolutely different than PV, except the case of Germany.

Figure 9. The Top-10 Markets in the World. Source: EREC.

Figure 10. The Top-10 Suppliers in the World. Source: EREC 5 MW wind turbine.

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3. WIND POWER - RO Since electricity is the generalised energy vector in modern Wind Energy Converters (WEC), it seems wiser to prioritize wind power applications to desalination limitedly to those technologies compatible with this vector: Reverse Osmosis (RO), Vapour Compression (VC) and Electrodialysis. Taking also into account the evolution of electricity consumption, in relation with the different desalination technologies, we confirm that the best option at present, in terms of energy efficiency, is the Reverse Osmosis (RO), especially after the introduction of the energy recovery systems based on turbines or isobaric chambers. Figure 11 shows that the best evolution towards more energy efficient systems corresponds to the Reverse Osmosis option. To this panorama we should add the fact that nowadays most desalination plants are moving towards RO solutions (Figure 12).

Figure 11. Evolution of energy consumption per m3 desalinated seawater. Source: Canary Islands Water Centre. M. Hernández.

Figure 12. Distributin of installed plant capacity according to desalination process (2004). Source: 2004 IDS Woldwide Desalting Plants Inventory Report nº 18.

The recent experience in seawater desalting plants shows that energy consumption of big plants (> 50000 m3/d) is around 3.1 kWh/m3. This figure includes all operational inputs of the plant. Consumption is lower in average or medium-sized plants, their energy demand reaching 2.5 kWh/m3 in plants producing between 1,500 and 15,000 m3/d. These consumption figures correspond to the present situation of RO systems which are provided with isobaric chambers, and are similar to RO systems provided with last generation turbines (Figures 13, 14).

Figure 13. Energy recovery in RO plants with isobaric chambers. Source: Canary Islands Water Centre. M. Hernández.

Figure 14. Energy recovery in RO plants with turbines. Source: Canary Islands Water Centre. M. Hernández.

Figure 15. View of isobaric chambers installed in a desalinating plant in the Canary Islands. Photo by M. Hernández.

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In spite of the steady increase of RO desalination efficiency, energy is still a very important factor within the cost of water production. Table 1 shows the cost analysis of a medium-sized plant in the Canary Islands in 2001, confirming that energy costs represent 44% of the total.

Table 1. Desalination costs in medium and large plants on Tenerife (2001). Source: Manuel Hernández (Canary Islands Water Centre).

During the same years, wind power-RO desalination comparative studies emphasized the importance of the different factors at the time to decide in favour of this option instead than conventional systems. Table 2, summarizes the impact of the different factors.

RO-Desalination plant. WP-RO project. Cape Vert. Source: C.marin.

Parameter Effect on the LC

RO plant:

Plant capacity 5 Specific energy consumption 3–4 Availability 3 Membrane replacement costs 2 O&M (without energy consumption) 4

Wind energy resources: Average wind speed 4 Weibull distribution shape parameter 2–4

Wind farm: Wind farm cost (turbine and O&M) 2–3 Wind turbine model 2–3 Economics: Real discount rate 4–5

Table 2. Influence on levelized cost of product. 2002. 5: very high, 4: high, 3: medium, 2: low, 1: very low. Source: L. García-Rodríguez, V. Romero Ternero, C. Gómez-Camacho. Dpto. Física Fundamental y Experimental, Universidad de La Laguna. Energy efficiency has been a fundamental factor in the evolution of desalinated water production costs, and their drop incidentally coincided with a similar trend of wind power generation costs. Table 3 shows the evolution of power consumption and average seawater desalinations costs in Spain during the last three decades.

Year kWh/m3 €/m3 Tech 1970 22 2.103 MSF

1980 18 1.803 MSF

1985 15 1.112 VC

1988 13 0.102 VC

1989 8.5 0.961 VC

1990 6.2 0.751 RO

1992 5.8 0.721 RO

1994 5.5 0.691 RO

1996 5.3 0.661 RO

1998 4.8 0.528 RO

1999 4.5 0.521 RO

2000 4.0 0.504 RO

2001 3.7 0.492 RO

2002 3.5 0.468 RO 2003 3.1 0.431 RO

Table 3. Evolution of power consumption and seawater desalination costs in Spain Source: 20 years Evolution of Desalination Costs in Spain. Jose A. Medina. MMA. 2005.

Concept Cost € Water pumping to plant (50m) 0.026 Energy 3.1 kWh/m3 0.225 Pre-treatment (sodium bisulphite, anti-incrustation) 0.006

Post-treatment 0.008 Personnel 0.066 Substitution of membranes 0.006 Substitution of filters 0.009 Maintenance of pumps and other equipment 0.012

0.079 SUBTOTAL 0.437

Industrial benefit plant operator (15%) 0.066

TOTAL (not including plant amortisation) 0.503

Plant amortisation 0.060

TOTAL (including plant amortisation) 0.563

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A few years later we can refer to the study carried out by the Canary Islands Water Centre for 2005, which takes into account verified wind power generation costs. At present, fixed costs of big desalting plants, which include maintenance, exploitation, labour and conservation of surrounding infrastructures, are around 8%. Variable costs, which include pre-treatment, post-treatment membrane maintenance and replacement, are around 47%. Energy costs are around 35%, taking as a reference an energy cost of 0.049 €/kWh (wind power supply), that would lead to a final cost of desalinated water of 0.435 €/m3 for the reference case of the Canary Islands (M. Hernández, Canary Islands Water Centre). This figure shows that the wind power-RO binomial, in grid-connected systems is absolutely competitive compared to traditional systems. Computed costs are subject to the following variations: • Prices of chemical products may greatly vary

inn relation with the type of installation and water source, especially antiscales (-40%).

• Filter cartridge replacement would depend (±15%) on the maintenance programme of each case.

• Washing and replacement of membranes may also vary (±20%) according to the pre-treatment system performance.

• Membrane replacement costs would also depend (±15%) on the membrane type and maintenance programme.

• Energy consumption corresponds to the new plant design and includes little pumping between (from/to) plant and storing reservoirs.

At the time of evaluating the viability of autonomous systems non-connected to the grid, figures substantially vary in function of wind power generation costs, specific typology of the plant (e.g. variable regime) and operational and maintenance costs.

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4. WIND-POWERED DESALINATION OPTIONS

4.1 ONGRID

Within this category we can differentiate three kind of solutions, referred: a) Combined systems of large RO plants and wind farms connected to large grids. These are alliances established between wind power and water utilities. Wind farms and desalting plants do not necessarily have to belong to the same operator or being close to each other. The reference case 5.1.1. falls within this profile. In the Perth project (Australia) a 140.000 m3/d seawater RO-desalination plant is associated to an 80 MW wind farm. The second reference case is of a larger size than the previous one. It consists of six desalting plants on the Spanish Mediterranean coast, to be built soon as a response to the debatable Ebro River water transfer. The total amount of desalinated water that the plants would jointly produce is about 880,000 m3/d (10.19 m3/s). This operation would require 84.380 RO membranes de RO, which are equivalent to a filtering surface of 314 ha. Energy consumption of the six planned plants sum to about 860,000 MWh/year. The energy input required by the project has been evaluated to be of around 230 MW of wind power to be installed. In the first case, unitary costs of produced water are around 0.88 US$/m3, while in the second project case should be of about 0.64 US$/m3, being the difference mainly attributed to the different wind quality, the electric pricing system that favours renewables in Spain, and to the inclusion of aspects related to the integral water cycle (treatment) in the case of Perth. b) Water producers (medium-sized RO plants < 15.000 m3/d) which operate wind farms covering their power supply needs. These solutions are adapted to medium-size grids non-connected to continental large grids (islands or regions which are electrically isolated). In this case, the additional costs supported for conventional power generation, often make this solution a competitive one. As in the previous cases, the size of the local grid (in terms of installed power and minimum load) is a lot bigger than the installed wind farms.

In the analyzed reference cases (5.1.2 - 5.1.3), unitary costs of produced water are slightly higher than option a), but still competitive in their segment, being between 0.7 y 0.9 US$/m3.

Cases related to these applications generally correspond to small municipalities which wish guaranteeing drinking water supply at appropriate prices, tourist resorts, and agricultural companies or associations working in intensive crops, in areas characterized by high water prices water shortage problems. In both previous cases the grid is big enough and no special controls are applied to the wind generators or the desalting plants. Although some authors consider it debatable if this constitutes a wind desalination coupling (in a technical sense), it is out of doubt that in the forthcoming years the most important WP-RO development would be of this kind. c) WP-RO in small size autonomous electricity grids. This type concerns the coupling of the wind generators and the desalting plant on a small size autonomous electricity grid. Several demonstration projects falling within this type have been developed with variable levels of success. The small autonomous grids are usually powered by diesel generators. The larger is the size of the local grid (installed power and minimum load) the easier to implement such a configuration. If the wind turbine and the

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desalting plant size are comparable to the size of the local grid, then special controls are required. Depending on the relative sizes of wind, desalination and diesel as well as the control applied to it, the system may be considered as a wind desalination system with diesel backup or as a hybrid system. One variant of this application is when the desalination project is an integral part of the electrification project. In this case diesel engines are the basic energy supply as well as the regulation system of the grid. Figure 16 shows the functioning of the wind/diesel system with a desalination plant coupled.

Figure 16. Main parts in a wind/diesel system. Source VESTESEN. The reference cases 5.2.1., 5.2.2. and 5.2.3. correspond to the first variant of this category, as well as the option of grid connection in the case 5.4.1. The example of Punta Jandia (5.3.7.) is presented as a reference of the second variant of this option.

Unitary costs of water production vary between 1.2 US$ and 2.1 US$, depending on the, on the grid and plant size and quality, on the complexity of the system and of the control system. 4.2 ONGRID ISOLATED SYSTEMS Hydro-wind-storage hybrid Since one of the big problems of wind power is its high variability, water production through desalination could be a way to store wind energy excess for its future re-conversion into hydropower or just for consumption. It is an innovator integrated view where desalination is part of an isolated, medium-sized electric grid, and fulfils the double function of guaranteeing both potable and irrigation water and, at the same time is the vector for storing wind power in order to guarantee an uninterrupted supply in absence of wind and maintain stability to the whole system. This project, conceived as a hydro-wind-storage hybrid supported by a desalination plant (RO), is being carried out on El Hierro island (Canary Islands, Spain, reference case 5.2.1.), which in the near future would be the first energy self-sufficient island 100% RES in the world non connected to the grid, and through this project it would also cover autonomously the water deficit historically suffered by the island. Figure 17 shows a schematic view of the system. Under acceptable wind conditions, the wind farm guarantees the electricity supply of the island, including the desalination plant needs. The desalting plant is oversized in order to achieve two objectives: meeting drinking and (partially) agricultural water needs, and provide desalinated water for the functioning of the hydraulic system. Wind power excess would be used to pump part of the desalinated water produced to an upper reservoir. In absence of

Figure 17. Source: SYNLIFT Systems.

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wind, this stored water would feed the turbines to maintain the electricity supply of the whole system.

Figure 17. Hybrid-hydro-wind-storage-RO Source: El Hierro 100% RES Project. M. Hernández. The wind farm has a total installed power of 12 MW, the reservoir has a capacity of 300,000 m3 and the desalination plant has an output of 1,500 m3/d. All the system would supply water and energy to a population of around 11,000 inhabitants. The project conditions (being carried out at present) establish a reduction of present generation costs (diesel power plant) of about 20%, with a direct repercussion on the estimated water cost of about 10% (final cost: 0.7 €/m3). The project is co-financed by the European Commission and the El Hierro island Government (Canary Islands). This model represents a good integrated solution for isolated system and areas with a similar profile. If the necessary altitudinal variation is not available, other complementary accumulation systems are under study on islands such as Porto Santo (Madeira), where a similar solution use hydrogen production for energy storing.

4.3 OFFGRID Stand Alone Systems In the last two decades, a large part of the R&D projects aiming at coupling RET with different desalination systems, have mainly worked on Stand Alone Systems. It is important to emphasize that, with regard to the relationship wind power-desalination, both fields have gone through very fast technological developments, although separately, conditioning the final results of these projects (Demonstration Projects of Reference, 5.5.). Understanding electricity as the fundamental vector within this alliance, we can notice how on the one side the most efficient systems, including small-scale ones, RO-desalination has been the most praised. On the other side, wind turbines have evolved in efficiency and reliability to very high standards, higher than those requested by small-scale autonomous systems. Purely mechanic WEC had a limited development, almost at an experimental level, in their different applications, including desalination. Nevertheless, technologically speaking, an acceptable level of coupling can be reached using desalination units with an output bigger than 250 m3/d. With regard to wind turbines, the best designs start at 300 kW. With regard to autonomous systems, the following solutions can be differentiated: a) WEC with mechanical coupling to a desalination plant. Mechanical coupling of rotor with shaft driven pumps. The simplest scheme is based on a multivaned WEC with better mechanical efficiency and adapted to low and medium-speed winds. One or several multiplication phases allow starting the desalination pump. The RO-desalination plant works under variable regimen. These are very small units (10-20 m3/d) which are characterized for their toughness, technological and maintenance simplicity, adapted for very isolated solutions. Production costs in these cases are around 2.3-2.5 $/m3 (Reference cases 5.3.2., 5.3.4.). A project, more evolved, following this principle, has been developed by DeSalter. Also in this case, kinematical energy of a WEC directly to drive the compressor of an evaporation plant or the high-pressure pump of a reverse osmosis plant, that is, has two different configurations: RO y MVC. In this

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case it is a more evolved WEC, with blades aerodynamically designed adapted to these working conditions, with the peculiarity that all functional elements, such as seawater reservoir, filtering installation, pump units, desalination units, compressor, heat exchanger or drinking water storage tank should be integrated in the WEC tower (reference case 5.3.6.). b) Wind generator with hydraulic coupling to a desalination plant. The hydraulic power transmission system is produce by means of a set turbine and a displacement oil pump. The oil-hydraulic system, which acts as a control system, allows the desalination plant to work under nominal conditions. This scheme has been used for the AERODESA project, which, in its commercial production phase, expects decreasing water production costs to 2 US$ (reference case 5.3.3.). b) Electrical wind turbine coupled to a RO desalination plant. It is a more common solution for isolated systems, with a wide range of experiences and projects tested for plants from 20 to 1,200 m3/d. Nevertheless, the analysis of the different options shows that optimum costs start from 300 m3/d. At a small scale, there are some outstanding projects such as AGROGEDESA, based on electrical coupling from small commercial wind turbine operating RO plant under a constant regime and managing the storage and available wind energy use through a battery bank. The battery bank guarantees that the washing system is filled with seawater, thus guaranteeing a longer working life of the membranes. (reference case 5.3.5.).

The resulting water cost in this project is 2.3 US$/ m3. For commercial systems bigger than 250 m3/d the project managers (ITC) computed an estimated cost of 1.3 US$/ m3. Another option is represented by Enercon-type modular systems, based on a different idea, with plants functioning in variable regime. Their basic elements are a synchronous machine (WEC), flywheel, battery and diesel generator. The system allows supplying and storing energy and water according to demand. Actually it is a hybrid system supported by diesel generators that can be optionally connected to the grid (reference cases 5.4.1., 5.4.2.). Reference costs are not available, but, according to the experience carried out on Syros and Tenerife (ITER) costs are around 1.3 $US/m3. Figure 18 shows a typical chart of optimization of a system defining maximum wind power penetration in function of wind speed.

ENERCON SWRO Stand Alone plant. Source: Enercon.

Figure 18.

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5. REFERENCE CASES

5.1 ONGRID SYSTEMS

5.1.1. The Perth seawater desalination plant - RO, 140.000 m3/d, 80 MW Wind Farm. Kwinana, Australia. 2006.

It is the biggest experience of a wind-powered desalination project at present. Then desalinating plant will be the largest of its kind in the southern hemisphere, and will be powered by a 80 MW grid connected wind farm. This new plant will ultimately supply 17% of Perth's needs and make Western Australia the country's first state to use desalination as a major public water source. With an initial daily capacity of 140,000m³ and the inbuilt potential for expansion to 250,000m³/d, the plant will be the largest single contributor to the area's integrated water supply scheme, providing an annual 45GL and serving a population of 1.5 million. In addition to the design, construction and operation of the plant itself, the project also involves the provision of a seawater intake, pre-treatment and product water facilities, a pipeline and a new pumping station. The total project cost is AU$387 million (291 millon US$), with annual running costs of less than AU$20 million (15 million US $). By 2004, these combined initiatives had added nearly 40GL of water to the municipality's integrated supply system. To safeguard the future of supply in the longer

term, the Water Corporation have adopted what they have termed a 'security through diversity' strategy. This approach comprises seven key platforms - water trading with irrigators, water recycling, enhanced catchment management, demand management, new groundwater, new surface water and the construction of the new desalination plant. The Cockburn Sound is an area of environmental sensitivity and the potential impact of the new plant on this water has been the subject of extensive consideration. The background of this project is based on the growing concern over the dwindling natural supplies of water across the region in the wake of the hotter, drier shift in the climate acted as the main driver on the project. The winter of 2001 saw the poorest inflow of water to the reservoirs serving the Perth metropolitan area since 1914 and by 2002 it was clear that the region was suffering the worst two-year drought on record. In 2005, it was confirmed that in the eight years from 1997 stream flows had dropped to an annual average of 115GL compared with the 161GL/yr over the previous 23 years (1974 to 1997). The initial response was to implement a medium-term drought recovery plan, which included restrictions on sprinkler use, obtaining a temporary increase in groundwater allocation and the provision of $142 million to further augment supply capacity. a. Technical Description The plant will operate continuously, drawing water with an input salinity of 35,000mg/L to 37,000mg/L at 16°C to 24°C via the new intake structure. This will amount to under 0.02% of the water in the sound being removed per day, which will first pass through a pre-treatment filter to protect the pores of the membranes, before being forced through the spiral wound membrane elements of the RO treatment trains.

A Degrémont membrane array use in the new seawater reverse osmosis (SWRO) plant which, when completed. Electricity for the desalination plant - which has an overall 24MW requirement and a production

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demand of 4.0kWh/kL to 6.0kWh/kL - will come from the new 80MW Emu Downs Wind Farm. The wind farm, which will consist of 48 wind turbines and be located 30km east of Cervantes, is being developed by Stanwell Corporation, a power generation corporation owned by Queensland Government and Western Australia's Griffin Energy.

Schematic of the RO process, which uses a spiral-wound membrane module. The power supply arrangement between the Water Corporation and Western Power as energy suppliers will ultimately make the desalination plant the largest facility of its kind in the world to be powered by renewable energy. The plant provides a third water source for Perth, parts of the South-West and towns serviced through the Goldfields Pipeline to Kalgoorlie Boulder and complement existing dams and groundwater schemes. The client and plant owner is the Water Corporation of Western Australia. The main contractor is the Multiplex-Degrémont JVC and the plant operators will be Degrémont over the 25-year life of the contract. McConnell Dowell Constructors have the subcontract for the mechanical installation works. Western Power are the energy suppliers, using renewable power from the wind farm developed by Stanwell Corporation and Griffin Energy.

c. Key Data Plant type RO

Capacity 140,000m³/d

Design expansion capacity

250,000m³/d

Annual output 45GL

Population supplied 1.5 million

Seawater temperature 16°C to 24°C

Salinity 35,000mg/L to 37,000mg/L

Power demand 24MW

Process energy requirement

4.0 kWh/m3 to 6.0 kWh/m3

Power supply Emu Downs wind farm.

Anticipated water cost AU$1.17/m3 (0.88 US$)

Annual running costs <AU$20 td million<>

Project cost AU$387 million 291 US$

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5.1.2. Solaires Canarias. Vargas. Gran Canaria. Spain.

Power production of a wind farm with consumption associated for desalinated seawater for agriculture. It is a strictly private project that joins a wind farm with a seawater desalinating plant for intensive agriculture water supply. a. Technical Description Capacity: 5,000 m3/d (RO) Wind Farm Installed Power: 2.64 MW Wind Farm production (2003): 10,210,109 kWh Self-consumption (2003) Wind Farm: 1,547,244 kWh Electricity consumption from the grid (2003): 681,101 kWh Total consumption (2003): 2,228..45 kWh Energy Consumption: 2.8 kWh/m3

Desalinating plant, wind farm and intensive crops. b. Cost Data Average price 2003: 0.68€ /kWh (0.81US $). Desalinated water selling price: 0.6€ /m3 (0.72 US$). Electricity average selling price (2003): 0.07€ /kWh (0.08 $). c. Lessons learnt This is a demonstration case of viability of wind power-water desalination system when the following circumstances are met: - Appropriate price to sell the excess of electricity produced to the utility. - Satisfactory cost of water production in comparison with the traditional system. In this case pumping costs of saline wells make water price rise above the desalinating system normal price.

The desalinating plant 5.1.3 AGRAGUA – Parque Eólico

Montaña Pelada (Gáldar). Gran Canaria. Spain.

Power production of a wind farm with consumption associated for desalinated seawater for agriculture.

Because of the drought affecting in the late 80’s, many crops of north-eastern Gran Canaria disappeared. A group of farmers of the Gáldar area joined to constitute a corporation named AGRAGUA, in order to build a desalinating plant that allowed them keep on their flower and banana crops, which started working in 1997. After three years, the farmers’ association decided to promote a wind farm in order to reduce the electricity costs through self-production and selling the excess of production to the utility through the grid. a. Technical Description Wind Farm: 4.62 MW (MADE wind turbines - 660 kW). Capacity: 15,000 m3/d (RO). Energy Consumption: 2.9 kWh/m3 (extraction + desalination + pumping)

Year Production (m3)

Consumption (kWh)

Wind Farm (kWh)

1998 1,221,355 6,128,080

1999 4,763,621 24,959,620

2000 4,979,812 25,708,620

2001 4,910,820 15,987,179 10,275,528

2002 4,782,721 14,119,484 12,264,045

2003 4,691,509 13,987,581 11,907,931

2004 3,615,784 10,289,804 8,656,732

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b. Lessons learnt Market conditions for self-producers of electricity from renewable energy sources, availability of good wind resources, prices marked by water scarcity and the type of intensive crops allowed this alliance between wind power and desalination, originating a new kind of mixed entrepreneurs (agriculture, water production and energy production). Spanish legislation establishes a compensation of 0.023 € (0.027$)/kWh generated from renewable energy sources in installations producing more than 100 kW.

AGRAGUA pumping station.

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5.2 ONGRID-ISOLATED SYSTEMS

5.2.1. Wind Powered Desalination

Hybrid-hydro-wind-storage El Hierro 100%RES project. It is an innovator integrated view where desalination is part of an isolated, medium-sized electric grid, and fulfils the double function of guaranteeing both potable and irrigation water and, at the same time is the vector for storing wind power to give stability to the whole system. The island of El Hierro, Canary Islands (Spain) has an area of 276 km², a population of approximately 8,000 inhabitants and is not connected to a continental electricity grid. El Hierro has been the first island that has been declared a Biosphere Reserve by the UNESCO in the new millennium. This acknowledgement was basically due to the need to preserve the particular natural and cultural values of the island, but it involved the support to the island’s Sustainable Development Plan that had been officially approved in 1997, where an ambitious and innovator strategy of future already endorsed by several sustainable development projects started since the 80’s was defined. Both the basic objectives of the island’s declaration as a Biosphere Reserve and the Sustainable Development Plan contain the commitment to turn El Hierro to an island with 100% RES supply. It is the first declaratory commitment among all territories declared Biosphere Reserves by UNESCO that includes a new replication dimension forRES application in more than 400 areas internationally recognised with this title. The Sustainable Development Plan of El Hierro relies on several ways and projects to achieve this objective. · Electricity supply from RES · Water deficit cover as a complementary and integral part of the 100% RES project (water-energy binomial). a. Technical Description The originality of the El Hierro project is to consider water as a storing system for the excess of wind power, in order to guarantee a regular power supply based on the demand. The system has two circuits: 1. The energy generation circuit: that includes the wind park, the turbine and the diesel generator. 2. The hydraulic circuit: that includes the pumping station, turbines, desalination plants,

the upper reservoir, the lower reservoir and the penstock. The loads of the system are: the electricity demand of the island, the desalination plants and the pumping station. The basic scheme of the system is showed in the image below.

Elements of the system: • Wind farm: 9.35 MW • Pumping station: 7 x 800 kW + 2 x 275 kW • Minihydro power station (Pelton turbines): 2 x 3.3 MW • Diesel power station (existing one): 9,745 MW • Desalination plant (RO): 1000 m3/d • Upper reservoir: 225,000 m3 • Lower reservoir: 225,000 m3 • Penstock • Distribution system

b. Cost Data The project is being developed and carried out at present. Therefore final costs will not be known until it starts functioning. Nevertheless, according with the projections made, electric production costs would be close to present average fares, therefore reducing actual generation costs up to 30%. This involves that desalinated water production would fall around the admissible parameter of 0.5 €/m3 (0.6 US$).

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b. Lessons learnt The integrated idea joining RE power supply and water production in isolated areas is upheld as an important niche of future for wind-powered desalination. Within the framework of the project financed by EC’s DG-TREN, at least 40 viable replication cases on islands and coastal areas have been identified. 5.2.2. Utila Island case Utila island is another case inspired on the same RES-water complementarity. The Tennessee Valley Infrastructure Group (TVIG) has secured US$1.89mn debt financing for the first phase of a power and water purification project on Honduras' Utila Island, TVIG said in a statement Tuesday. The US$2.9mn first phase consists of installing 1.5MW diesel generation and the desalination of 15,000 gallons/day seawater, TVIG marketing VP Robert Blenker told BNamericas. Through the Utila Power Company (UPCO), TVIG and partners will provide the balance of the financing. A second phase will add 1.2-1.8MW wind power, which apart from being able to meet 100% of the island's power demand will also provide sufficient power to raise the desalination capacity to 40,000-60,000 gallons/day, representing 100% of local water demand, Blenker said. El Hierro 1100%RES project

5.2.3. Rottnest Island Rottnest Island is about 20 kilometres off the coast from Perth and has its own diesel fuelled power station which supplies electricity to the popular holiday accommodation and tourist services on the island. Perth is one of the windiest cities in the world, and wind energy will soon supply a significant percentage of the electrical load on Rottnest Island. In the island one has settled a new power station incorporating a single 600kW wind turbine (ENERCON). The wind turbine was installed in December 2004. Work on the new power station will be undertaken during 2005. The Excess wind energy is used to power a water desalination plant. Diesel fuel savings of 37%. a. Technical data • 2.14MW diesel & 600kW wind – 40%

average penetration • Single 600kW ENERCON E40 variable

speed turbine • Two LLD/DGI 320kVA combination sets • Full power system automation & control over

RO desalination

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5.3 OFFGRID SYSTEMS Stand Alone Systems Seawater desalination with an autonomous wind energy system

5.3.1. SDAWES Project - Sea Water Desalination (SWD) by means of an Autonomous Wind Energy System. ITC - Canary Islands [27].

The project has been co-financed with the European Commission through the JOULE Program; the ITC is the co-ordinator of the project. The other partners of the project were: the University of Las Palmas of Gran Canaria (ULPGC); ENERCON; the research centre "Instituto de Energías Renovables" of Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (IER-CIEMAT), and the Centre of Renewable Energy Systems Technology (CREST), and National Engineering Laboratory (NEL).

a. Technical Description The system is made up by two synchronous wind turbines, connected in parallel and isolated from the electrical grid, with 230 kW of nominal power each one. These wind turbines supply the necessary power for the operation of the different desalination plants associated to the project: 8 Reverse Osmosis desalination plants (with a total capacity of 200 m3/d) a vapour compression plant (with a capacity of 50 m3/d) and an electrodialysis plant (with a capacity of 192 m3/d). Working of the system When the start-up signal is given, the system measures the wind speed and decides if there is enough wind to start up the isolated system (minimum average of 6 m/s during 5 minutes or similar). Under these conditions, one of the wind turbines starts to accelerate the flywheel until it reaches 48 Hz, then the synchronous machine is activated to generate a three phase grid of 400 V which is detected as a reference

by the wind turbine (WT). Then the WT introduces energy to the only connected load: the flywheel, until it reaches the upper speed limit of 52 Hz. From that moment the normal loads can be connected; the WT will change the blade angle to adapt the supplied power to the consumed power. If the wind speed decreases, the control system will detect the reduction of the frequency and request a reduction in the consumption by disconnecting plants or modifying the working point until reaching the nominal frequency (52 Hz); if the wind is very weak, all the loads will be stopped. The system has two control modes: from the wind farm (in case of excess of wind) and from the loads control (in case of shortage of wind). As a general assessment at this point of the project (more than four years since the beginning) it can be said that as a original R&D, several unexpected difficulties have appeared, which have forced the partners to create original solutions. It has meant, on the one hand, a cost in time and in money; and on the other hand, a very interesting learning experience. b. Lessons learnt Checking the stability of the system The stability is possible due to the double control: from the wind, by changing the blade angle in case of excess of wind; and from the control system, by reducing the power consumption in case of lack of wind. Determination of the pressure control in the RO feed pipe Depending on the number of the connected RO plants, the flow changes and varies the pressure; several tests were performed to determine the control of the pressure.

Flywheel and synchronous machine Optimisation of the system (wind farm with RO) A simulation model has been used to identify the optimal installation of RO plants connected to an off grid wind farm. It has been decided to

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use only RO plants because it is the most suitable desalination system for seawater with the smallest specific consumption. These desalination systems are easily transferable to developing countries. Due to their simple, robust and reliable operation, and low maintenance, they are adaptable to the varying conditions of target locations. The production of water depending on the number of RO plants installed; the production of water increases with the plants and the rejected energy decreases, because with less loads it is more difficult to adapt the consumption to the available power.

c. Cost Data Production costs vary between 0.817 and 0.835 €/m3 (1 US$).

5.3.2. AERODESA I Project. Wind generator with mechanical coupling to a desalination plant. Pozo Izquiertdo. ITC - Canary Islands [27].

The project has been financed by the Government of the Canary Islands, and has been carried out by ITC. Low-tech wind generator with a rated power of 15 kW, specially designed to be coupled to a seawater RO desalination plant (with a capacity of 10 m3/d) with a mechanical coupling system

and seawater as a control fluid. The unit has been designed for both ordinary and low maintenance conditions, which is essential in isolated areas or developing countries.

WEC –mechanical coupling a. Technical Description The rotor is made up by three 4.5 meter long blades, built with fibber-glass in polyester in the traditional way. The driving gear consists of a main low rotation shaft in the wind turbine nacelle, a first multiplication for bevel gear, a vertical prop shaft made of different units elastically attached, and, finally, a multiplication for the desalination pump. The desalination module is made up by four osmotic membranes, set in series, with a low recovery rate, according to the operation requirements of the system. The control system, supported by a pressure accumulator, uses seawater as a control fluid. The desalination plant works under variable regimen, according to the technical limits established by the membrane's manufacter (from 45 to 70 bars). This variable regimen is regulated by the seawater valves system, that act as a control system. c. Cost Data Water cost m3 (prototype): 3.78 €/m3 (4.5 $/m3) Water cost m3 (fabrication cost - estimated): 1.89 €/m3 (2.3 $/m3)

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5.3.3. AERODESA II. Windgenerator with hydraulic coupling to a desalination plant. Pozo Izquiertdo. ITC Canary Islands [27].

Wind generator with a rated power of 15 kW, specially designed to be coupled to a seawater R.O. desalination plant of two modules (with a rated capacity of 15 m3/d) with a oil-hydraulic mechanical coupling system, thus allowing a high automation of the system. The project has been financed by the Government of the Canary Islands-ITC.

View of the WEC. a. Technical Description It is a horizontal axis wind turbine with a passive downwind orientation system and two hinged blades. It has also an overspeed brake system and a hydraulic power transmission system by means of a set turbine and a displacement oil pump. The oil-hydraulic system, which act as a control system, allows the desalination plant to work under nominal conditions. Relation surface/water production: 55 m2/ m3-d (m3 means 1 m3 of desalted water per day). b. Cost Data Water cost m3 (prototype): 4.2 €/m3 Water cost m3 (fabrication cost): 2.03 €/m3 c. Lessons learnt The project can be installed in any part of the world with a medium wind speed.

Nevertheless, the unit has been designed for both ordinary and low maintenance conditions, which is essential in isolated areas or developing countries, so that these kind of areas seem to be its natural market.

Oil-hydraulic system 5.3.4. Desalination of Brackish Water

with Wind-Powered Reverse Osmosis. Oahu, Hawaii.

A prototype system was constructed on Coconut Island off the windward coast of Oahu, Hawaii. This system consists of a 30-ft tall multivaned windmill/pump a Filmtec ultra low pressure RO membrane, a flow/pressure stabilizer, and a prefilter. A feedback control mechanism was developed for this project and installed in the prototype system. This control mechanism enhances the system performance by allowing continuous operation under varying ambient wind conditions.

a. Technical Description A schematic of a wind-powered RO desalination prototype system is shown in the following image. Proper operation of the RO module requires that feed water pressure be maintained within a small pre-set range. For the membrane used in this prototype system, the feed water pressure must be maintained in a

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range of 85 - 105 psi. Feed water pressure equals the water pressure inside the stabilizer, which is continuously monitored by a pressure sensor located on top of the stabilizer. When this pressure is below the minimum value or above the maximum value required for the operation of the RO module, the datalogger sends a signal to a solenoid valve to shut down the operation. The pressure in the stabilizer depends on the rates of inflow and outflow. Inflow is generated by the wind pump, an input variable that cannot be controlled. The outflow from the stabilizer is the RO feed water, which is separated into flows of brine and permeate.

5.3.5. AEROGEDESA Project. Windturbine electrical coupled to a desalination plant. Pozo Izquiertdo. ITC - Canary Islands.

Electrical coupling from a 15 kW commercial windturbine to a Reverse Osmosis desalination plant (with a desalination capacity of 18 m3/d), operating under a constant regime and managing the storage and available wind energy use through a battery bank. The battery bank guarantees that the washing system is filled with seawater, thus guaranteeing a longer working life of the membranes. The whole system is fully automated. a. Technical Description Wind turbine with a rated power of 15 kW, a three-phase self exciting induction generator for a static condenser battery, a charger and a three-phase sine wave inverter, both micro-processed. It also has a battery storage with an autonomy of 20 minutes. A Reverse Osmosis desalination plant of 18 m3/d adapted to a frequent start/stop configuration is coupled to the system. It is an electric coupling from a commercial wind turbine of 15 kW to a Reverse Osmosis desalination plant, operating on a constant basis

and managing the storage and use of the available wind energy through a battery bank. The whole system is fully automated. The control and data acquisition systems are made up by a Programmable Logic Controller (PLC) receiving all the signs from the sensors in the plant and making decisions in relation to the start/stop configuration in the installation. It will also monitor the safety devices by using two microprocessors exclusively used to control and manage the available energy in the electric system. The Reverse Osmosis desalination plant has a brine washing system for stop configurations, so that the plant service life and reliability is maintained. The battery bank (with an autonomy of 20 minutes) will guarantee that the washing system is always full with desalted water. b. Cost Data Water cost m3 (prototype): 3.11 €/m3 (3.7 US$/ m3) Water cost m3 (fabrication cost): 1.91 €/m3 (2.3 US$/ m3) Water cost m3 (optimised system with energy recover and bigger desalination plant about 300 m3): 1.12 €/m3 (1.3 US$/ m3) b. Lessons learnt The project can be installed in any part of the world with an average wind speed and no grid connection because of economic reasons.

View of the reverse osmosis plant (18 m3/d)

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5.3.6. Wind Powered Desalination - Mechanic, coupled MVC/RO. WINDDESALTER.

The core of the WindDeSalter Technology is to use the substantial part of the available kinematical energy of a WEC directly to drive the compressor of an evaporation plant or the high-pressure pump of a reverse osmosis plant. Furthermore, all functional elements such as seawater reservoir, filtering installation, pump units, desalination units, compressor, heat exchanger or drinking water storage tank should be integrated into the WEC (Wind Energy Converter). a. Technical Description The WEC converts air movement into rotational energy by means of the rotor blades, which are mounted pitchable on the rotor hub, allowing to influence the characteristic curve of the WEC by changing the pitch angle via the blade pitch system. The rotational speed of the drive shafts is transmitted via the gearbox driven by the hub on the rotor side. An auxiliary generator is driven by this fast-rotating drive shaft. The electrical energy produced by the auxiliary generator required for driving the auxiliary aggregates is temporarily stored by a group of batteries that also supplies the control device. These components are located in the nacelle of the WEC, which is continually aligned with the changing wind direction via the yaw system. The integrated clean water tank with a man access and pipe duct in the centre works as a reservoir for the valuable produced liquid. This duct enables man ascent for maintenance or repair work. The lower part of the tower can be accessed through the entrance door. Located in the foundation part of the WEC is a seawater reservoir with a pre-filter, pretreatment installation and feeding pump. In the future when offshore WEC are common it can be advantageous if larger plants are realised offshore and installed directly within the sea to save the investment in a separate intake. The tower is connected to the foundation part via the bottom flange. The tower is composed of the lower tower segment with the drinking water tank and the upper tower segment with the filtering and pre-treatment unit. Both tower parts are connected to each other with the connecting flange. The main idea of this solution is that the entire functional unit is directly integrated into the WEC. Only a water pipe needs to be led to shore to supply the end user.

b. Lessons learnt It is a still developing solution. In theory it would perform maximum energy optimization for small-scale in-situ applications. Lack of pilot projects prevents evaluating its feasible reach.

WindDeSalter RO

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WindDeSalter MVC 5.3.7. PUNTA JANDIA Project.

Wind-diesel system for water and electricity supply in the island of Fuerteventura.

The project has been cofinanced with the European Commission through the VALOREN Program; Town council of Pájara (Fuerteventura), Fuerteventura Water

Association, Industry Council (Government of the Canary Islands) and the Institute of Renewable Energies (IERCIEMAT). The partners involved were the University of Las Palmas de Gran Canaria (ULPGC) and the Institute of Renewable Energies (IER-CIEMAT). This project is focused on the basic elements for living in a community, which are the following: • water • energy • improvement of the economic infrastructure of the population The difficulties of a fishermen's community, without power mains (the electricity grid ends 20 km before the village), have turned, by means of this project, into an increase of the living standards through a full self-supply of: • drinkable water, through a Reverse Osmosis plant powered by wind energy, with the possibility of water processing. • energy self-supply through a wind-diesel system isolated from the grid. • improvement of the economic conditions of the fishermen with an ice generation plant and a cold-storage plant to freeze fish. These plants are also powered by a wind-diesel system. Before the project each house had a diesel generator for their own energy consumption. The water was supplied by a truck, therefor the water price was very high because they had to pay for the water price plus the driver fees and the truck diesel; so the water price was nearly 3 €/m3. This area will hold, according to the local bylaws, a small housing development up to a maximum of 450 summer visitors, 60 permanent inhabitants and 500 occasional visitors per day. a. Technical data Planned drinkable water supply: 60 l/d (with low consumption toilets) Power supply (Kph/person/year): unlimited Desalination capacity: 56 m3 per day Water storage tank: 2 x 500 m3. Cold-storage room for: 1200 Kg of fish at 0"C Ice production: 500 Kg/day Peak power demand: 100 KW Windturbine: Vestas, V27m 225 KW Diesel equipment: 2 x 60 KW Control system: flywheel, dump loads and PC with AT Bus. b. Lessons learnt It is an excellent laboratory for the development of an integrated view of a joint solution of energy and water needs for a small isolated community.

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5.3.7. WDS2 A/S – Desalination Systems- RO.

Vestesen A/S, previous Danvest Energy is also a part of – WDS2 A/S – specialize in Wind/Diesel/Desalination Systems. The WDS2 A/S desalination systems are designed as containerised modules with production capacities from 10 to 3.800m3/d/unit. The desalination modules are based on Reverse Osmosis processes. The complete RO system can include water intake system, pretreatment, RO-desalination and post-treatment. The RO system has variable capacity and is specially designed for WD operation. Turnkey solutions – WDS2 designs the total system and in consortium cooperation with – acknowledged manufacturers for wind turbines (Vestas Wind Systems), desalination equipment (Provital A/S). The stations are delivered in 20 foot and 40 foot standard containers and the complete stations are build of container modules: Generator module, service module. Capacity : Electric Power 100 - 5.000 kW/h Fresh water 100 – 60,000 m3/d Standard module 3,800m3/d a. Cost data Manufacturers do not offer any production cost data to make comparisons.

MTorres project (Spain). Off-shore desalinating plant integrated on wind platform. 2007.

Renewable Energy Use for Potable Water Supply in Remote Villages of Depressed Region in Kazakhstan. UNEP. 2003.

Wind Power Project on Sir Bani Yas Island

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5.4 OFFGRID SYSTEMS Stand Alone Systems

optionally connected to small grids 5.4.1. ENERCON’S SWRO

Enercon has been developing since several years the modular wind energy converter (WEC) - reverse osmosis (RO) sea water desalination concept. The concept targets essentially applications in remote, often off-grid, areas with small and medium local water demand. The first actual experiences regarding the development of this system date to 2002 and were carried out on the islands of Tenerife (ITER) and Syros. a. Technical Description The seawater desalination plant’s primary power supply is generated by an wind energy converter. In combination with other system components, such as a synchronous machine, flywheel, battery and diesel generator, the system supplies and stores energy and water precisely according to demand. These plants are characterised by the absence of fixed operating point. The water production can range between max. 12.5% and 100% of the nominal capacity by adjusting the piston speed according to demand. This has two main advantages: Firstly, operation is possible with a fluctuating energy supply, and secondly, output can be adjusted flexibly to water demand without shutting down the plant. Only about 25% of the energy in the reverse osmosis process is used to produce drinking water, so without a recovery method, about 75% would go to waste. The energy recovery system comprises a low-pressure pump (max. 20 bar) and a three-piston system, which raises the pressure up to 70 bar and simultaneously re-uses the remaining energy. There is no need for a second (high-pressure) pump. The ENERCON’S SWRO system has two configurations: a) Stand-alone grid system to guarantee a continuous, stable supply of energy and water to consumers in remote areas far away from the public grid. Its basic elements are a synchronous machine, flywheel, battery and diesel generator. The system design supplies and stores energy and water precisely according to demand. b) On grid system. The seawater desalination plant’s primary power supply is generated by an wind turbine. During strong winds, the surplus energy can be fed directly into the public grid. When there is insufficient wind the desalination plant can be powered from the grid.

Both the plant and its mentioned components are modular. Each 20-foot container contains a separate part of the plant. This design enables easy worldwide transport and set-up logistics and also guarantees optimal protection of the plant from climatic influences.

The manufacturer provides the below production chart that is in line with advanced conventional plants’ consumptions.

b. Cost data The manufacturer, in spite of the modular nature of the system, does not provide any cost figures. b. Lessons learnt There are no available data of consolidated installation that allow establishing operativity guarantee levels and actual costs of this solution.

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5.4.2. Modular desalination: development and pilot-operation of a family of second generation modular wind powered sea water desalination plants. FP-4 Project - Joule and Prodesar. Tenerife and Syros. These projects were the start and testing ground for the present Enercon's SWRO concept. They have been co-financed by the European Commission, Directorate General XII within the framework of the JOULE III programme in 1997 (ITER-CIEMAT-CREST-NEL). a. Technical Description. Syros-Greece Greece: E-40 wind generator (500 kW), with a RO unit with 8 membranes, drinking water production between 60 and 900 m³/day. The WEC and the RO unit are installed at two different sites, about 1.5 km distant, and linked via a medium voltage grid line. The WEC machine has a synchronous ring generator and a grid management systemwhich allows for output frequency and voltage control and self-adaptation of the WEC to weak electric grids. The energy is buffered in the storage system before it is fed into the RO unit and the electric grid.

The RO unit contains 8 identical RO membranes. Since the maximum power consumption of the RO unit is only 200 kW where as the nominal power of the WEC is 500 kW, a large fraction of the generated electricity is fed into the island's electric grid. The RO unit is installed in five 40' containers. The main container houses the purification plant and the rinsing system, as well as the main electrical connection and the main control. Each of the two RO containers houses four RO membranes. The tank container is identical to its counterpart in the plant on Tenerife. The collection container houses the connection pipes to the island's water distribution system and to the RO and tank containers as well as two pumps: a pre-pressure pump supplies the RO containers with sea water and another pump feeds the produced

drinking water into the water distribution system. b. Technical Description. Tenerife. ITER. Instituto Tecnológico y de Energía Renovables. The WEC which is used in the pilot WEC-RO plant on Tenerife is an ENERCON E-12 machine, a newly developed WEC with a permanent magnet synchronous generator, 30kW nominal power and a passive yaw system. The E-12 grid management system first rectifies the AC output of the generator and then, depending on the application, transforms the generated current into an AC current of specific voltage and frequency. In case of a grid connection, the AC current is fed into the grid via a transformer at a voltage and frequency according to the requirements and standards given by the utilities. When using an electric motor as a load such in the case of a RO plant, the output of the management system has a variable frequency and voltage. The pilot plant in Tenerife does not include the optional energy storage system and contains only a single RO block with a water desalination capacity between 60 and 110m3/day. PRODESAL: It is the follow-up of the previous project, in this case using a 200 kW E-30 turbine. The energy consumption is 3.5 kWh/m3, with a production of 252 m3/d and an efficiency of 25 %. Operational problems and low efficiency obliged destining this plant to research, and ITER was then provided with a new plant of 70 m3/d, with an energy consumption of 2.5 kWh/m3, connected to the RE-Park local grid.

The new plant

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5.5 Demonstration Projects of reference Loughborough Univ., U.K. CREST, U.K, 2003 Wind / RO Plant Capacity: 0.5 m3/h (12 m3/day) Feed water: seawater Nominal power: 2.5 kW W/G, Unit Water Cost: 1.78 €/m3

Mykonos, 1999. A 300-kW (NEG Micon) induction wind turbine connected to the desalination plant of Mykonos Island (THERMIE Programme). The aim is to couple a medium-size wind turbine to a desalination plant and to have the option of operating it as a standard grid-connected machine, if necessary. Mykonos Island, 1999. A 300-kW induction wind turbine connected to the desalination plant of Mykonos Island (THERMIE Programme). The aim is to couple a medium-size wind turbine to a desalination plant and to have the option of operating it as a standard grid-connected machine, if necessary. Therasia Island, 1998. Autonomous Wind-Desalination system on the island of Therasia (APAS Programme). The project concerns the installation of an autonomous wind powered small desalination system in Therasia. Therasia is a small island in the Aegean Sea, very close to the island of Santorini. The desalination system is based on Reverse Osmosis technology with a nominal water production capacity 5m3 per day. The wind turbine, manufactured by Vergnet SA, has a rated power of 15 kW.

Purpose of the project was to demonstrate the feasibility of developing off-grid autonomous wind desalination units in remote areas. Island of Rügen, 1995 The wind turbine was rated at 300 kW and the MVC unit at a maximum 12.5 m/h. Again a resistance heating is used for auxiliary power when required. The energy consumption ranges between 9 and 20 kWh/m3. The cost for such a system is around 1.48 million €. The operation costs were calculated between 3.03 €/m3 and 3.69 Euro/m3. If the system is operated on a grid connected basis, the costs would reduce to 2.38 Euro/m3. Drepanon, Petras. 1992. The project, including a 35 kW wind turbine, was initiated in 1992, and completed in 1995. The project called for full design and construction of the wind generator turbine (blades, etc.), plus installing two RO units with a production capacity of 5 m3/d and 22 m3/d. Since 1995, operational results have been poor due to the low wind regime. Currently, only the first RO unit is operating, driven by a diesel engine generator. Borholm, 1991 A pilot plant was installed at the German island where a wind turbine with a nominal power of 45 kW was coupled to a 48 m3/day Mechanical Vapour Compression (MVC) evaporator. The compressor required was of 36 kW. The system was controlled by varying the compressor speed, and assisted by a resistance heating when the compressor run at its speed limit. Halling, 1985 A WEC-RO plant was erected at Hallig Süderoog´s Island in the North Sea, Germany. The 14 kVA WEC is a two blades synchronous generator. The seawater is pumped to a well. From this flow through a Filter with a low-pressure pump. Then the feed flow is pumped with a high-pressure (60 bar) pump against two RO membranes. The system has a drinking water production capacity of 0.2 m³ per hour with an average specific electrical consumption of 19 kWh per m³. From a water salt concentration equivalent to 27.000 ppm, a drinking water quality of 334 ppm is obtained. Lastours, 1985 5 kW wind turbine provides energy to a number of batteries (1500 Ah, 24 V) and via an inverter to an RO unit with a nominal power of 1.8 kW. The energy consumption is around 20 kWh/m3.

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Island of Planier, 1982. As early as 1982, a small system was set at Ile du Planier. A WEC-RO plant was carried out by CEA - Cadarache Research Center in association with Aerowatt Company for seawater desalination on the island of Planier, near Marseille. The RO unit with a production capacity of 0.5 m³/h is supplied by a 4kW WEC without batteries. The plant employed a Pelton turbine for energy recovery, retrieving 1.2 kW from the outgoing brine flow. The major problem reported was the frequent start up and shut down cycles particularly when the wind speed was in the cut in speed region. When operating at a wind speed higher than 7 m/s was observed a specific energy consumption of 7.8 kW/m³ with an averaged recovery ratio of 25%. Helgoland Island, 1988 The wind turbine in this case was rated at 1.2 MW and used to drive two RO units, 480 m3/day each, with seawater feed. Reports indicate that some time later the turbine was dismantled, and other supplementary sources were used.

ENERCON SWRO plant

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6. MAIN CONCLUSIONS

Fast technological evolution of wind energy technologies, based on the development of bigger and more efficient wind turbines, allow glimpsing an important alliance between desalination and wind energy sector for grid-connected medium and large-sized systems (basically RO).

Competitive wind zones, with average wind speeds of around 7 m/s and turbines operating for at least 2300 hours/year, are frequent in coastal areas, exactly where water needs and seawater desalination possibilities are higher.

At a large scale, this alliance between energy operators and water companies is already a reality in some important cases, such as Perth (Australia), or the "AGUA" programme in the Spanish Levante, where it is expected that wind power supply will cover a fundamental share of the water-energy binomial for the foreseen increase in desalination capacity of more than 900,000 m3/day, that means an estimated energy consumption of 861 GWh/year. Two sorts of criteria have been consolidating in alliances of this kind. The first one corresponds to viability in terms of electricity generation costs for big wind farms, connected to important electric grids which guarantee interconnection stability, and in appropriate market conditions and rates. In large desalinating plants, energy still represents about 35% of total cost of produced water (≈ 3 kWh/m3). The second criterion corresponds to standards of sustainability or convergence with Tokyo commitments to be implemented within some countries’ development polices. Increase in energy demand for desalination will be a factor to take into account in the forthcoming years.

The alliance between wind power and RO desalination has shown to be competitive also for systems connected to smaller electric grids (islands and coastal areas which are not well interconnected), where conventional generation costs are slightly higher. Although for somewhat smaller plants (between 5,000 and 25,000 m3/d) RO energy efficiency is higher (≈ 2.5 kWh/m3), when wind conditions are appropriate, and with relation to wind energy penetration into the grid, this solution showed to be competitive even for irrigation.

The wind power-RO desalination binomial opened new possibilities for small isolated areas with a small electric grid (5-15 MW of installed power), which were unthinkable until a few

years ago. The El Hierro 100% project shows how it is possible that desalinated water fulfils the double function of drinking water supply and it is a vector of energy storage at the same time. It is a wind-hydraulic system that allows guaranteeing water and energy supply, achieving a stable electric system based on renewable energy sources. Conventional generation costs, using a fuel-powered thermal power station, are quite higher in this case. This combination opened spaces for very competitive projects. A second, very important advantage of these solutions lies in the guarantee of energy and water supply, where self-sufficiency must be highly valued as opposite to the continuous risk of shortage.

All the previously mentioned cases presuppose the availability of good wind conditions. Efficiency and competitivity are remarkably reduced when turbines operate for less than 2,000 hours/year and average wind speed is lower than 6 m/s, since the power of wind turbines is exponentially related to wind speed, and most of them are designed to reach their nominal power with medium and high wind speed.

For wind powered-RO Stand Alone Systems (off-grid) the panorama starts changing considerably. A good example is given by the modular wind energy converter WEC- reverse osmosis system launched by Enercon, designed for plants ranging between 200 and 1200 m3/d. Technically speaking, the idea is greatly attractive, since it joins together the modular concept and a flexible system with variable power, working together with diesel generator. Previous experiences, however, as well as the few existing pilot projects of reference, make it impossible to demonstrate that the so-publicized production curves of this company and of other ones that develop similar autonomous systems, are really adjusted to real experiences. Furthermore there are no reliable data available about production costs for different wind and water situations. Experience showed that, at least in principle, these solutions are more viable when they are connected to the small local grids, of course depending on their quality and stability. Nevertheless the experience done in a few R&D projects, such as SDAWES (ITC-Canarias), advances production costs of about 1 US$/m3, as average cost in different types of small plants (≈ 200 m3/d), and estimations for commercial production are even lower.

Another theoretically promising system for isolated areas is based on direct mechanical coupling to drive the compressor of an

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evaporation plant or the high-pressure pump of a reverse osmosis plant, incorporating the desalination system within the WEC or separated from it (through hydraulic transmission, for instance). Experiences are in this case still being developed or in a project phase, so it is not possible yet to make appropriate projections in the short term.

Finally, in very small plants (50-100 m3/d), the wind power option is clearly less competitive and viable if compared with PV. This is due to the higher operative and maintenance complexity, as well as to the supplementary storage requirements (batteries). Even in PV-wind hybrid systems, wind contribution is not extremely efficient, as it gives the system more complexity and vulnerability. One of the problems carried by smaller solutions lies in the fact that wind energy technology has mainly evolved towards big wind turbines, so the lower power segment is out of step, except for very few manufacturers such as Vergnet.

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