Tuesday, 18 April 2023, 19:19
A desalination plant has become the great hope of the Axarquia to alleviate the ongoing extreme drought the area is suffering. With La Viñuela reservoir at just 10 per cent of its capacity with only 16 cubic hectometres stored and no rain forecast for the foreseeable future, the construction of a desalination plant has once again gained momentum. However, even that is unlikely to be ready until 2026.
Three projects have been put on the table so far, all of which are from private entities. The first came from the multinational company Acciona in July last year when it formally requested the Junta de Andalucía to grant a contract for irrigation and supply to towns through a treatment plant in Vélez-Málaga. This has been joined by two other proposals; one from Magtel and the other from an alliance formed by Trops, Grupo Cobra and the University of Malaga.
It is now down to Andalucía’s regional government to study the three proposals in terms of location, treatment capacity, energy costs, start-up times and the price per cubic metre.
The desalination plant planned by Acciona would be located on the right bank of the final stretch of the Vélez river, to the west of Torre del Mar, on a plot of land located to the south of the N-340 and next to Avenida Gerald Brenan. Its initial capacity would allow it to produce 25 cubic hectometres (Hm3) per year, although in a second phase it could be increased to 37.5. Of this initial volume, two thirds (17 Hm3) would be used for irrigation and one third (8 Hm3) for human consumption.
With an estimated investment of 100 million euros, which would be provided by Acciona without the need for external financing, the construction of the plant would take about two and a half years to build. The facilities would consist of the desalination plant, treated water tanks, an electrical substation connected to the Cala-Torremar line, a pipe in the sea and a discharge pipe to carry the treated water to the drinking water treatment plant at El Trapiche. The work would be complemented by the creation of a recreational area in the area adjacent to the river.
Acciona has not provided specific figures, but it does stress that desalinated water for irrigation should be seen as a complement, so that farmers would use a mixture of water from reservoirs, water regenerated in the treatment plants and desalinated water. As each has a different production cost, irrigation communities usually pay a 'mix' between the three tariffs.
On its own, generating one cubic metre of desalinated water costs around 0.6 euros. In this sense, Acciona does guarantee that the electricity will be 100 per cent renewable and at a defined price during the first 25 years of operation. In addition, it undertakes that if the government subsidises part of the investment, this reduction will be passed on in full to the final price paid by users and with the aim of achieving a circular economy and greater energy efficiency, the latest technological advances will be used to increase the conversion of treated water.
The project led by Trops, the Institute of Domotics and Energy Efficiency of the University of Malaga (UMA) and Tedagua (a Cobra Group company specialising in water treatment) is planned for the mouth of the Vélez river. Called Agua+S, the desalination plant devised by UMA researchers as a sustainable and ecological solution to the drought would have a generation capacity of 40 cubic hectometres, although this could be increased to 60 hectometres at a later date.
According to the proposal, the treated water would be channelled along the courses of the Vélez and Guaro rivers to the La Viñuela reservoir, from where it would supply domestic consumption and irrigation to the whole of the Axarquía, taking advantage of the existing infrastructure.
The total estimated budget is 144 million euros, including the creation of an innovative floating photovoltaic plant on the waters of the reservoir itself. A solar park that would occupy 15 per cent of the surface and would generate 250 megawatts of energy, which would not only guarantee self-sufficiency for the entire desalination system (some 80 megawatts for a production of 40 Hm3 per year) but would also allow the rest to be sold, ensuring in exchange a stable and competitive price that would make it possible to reduce production costs, which is the main issue of desalination.
With this same objective in mind, a second source of income is also proposed through the sale of the brine, which is used for the production of green hydrogen and chlorine, instead of returning it to the sea. Thanks to this cheaper energy and the profitability of the brine, the developers estimate that the price per cubic metre could be between 0.20 and 0.30 euros.
Apart from the price, the other big advantage of this business alliance is time, because they say that they could be producing in just three months after obtaining permits and that the definitive plant would be fully operational in a year's time.
Furthermore, the developers claim that this installation model would be perfectly reproducible in all geographical locations in Andalucía where there is a reservoir near the coast, as is the case in 15 other locations.
The desalination plant proposed by Magtel would be next to the Vélez-Málaga sewage treatment plant, to the south of the A7 motorway and west of the El Ingenio shopping centre, on land far enough away from residential areas but also close to the mouth of the River Vélez. With an investment of around 100 million euros, the plant is designed for an initial capacity of 40 Hm3 (with a future expansion to 60 if necessary), of which 10 would be used for domestic supply and the remaining 30 for irrigation. Moreover, production could be adjusted to the needs of the moment, so that the system would be structured in steps of 10 Hm3/year.
In principle, the volume reserved for domestic consumption would be transported to an existing drinking water reservoir, while for irrigation a solution is being worked on to incorporate the resources into the system by taking advantage of the existing infrastructure, including La Viñuela reservoir itself.
Magtel has said that it is committed to signing a long-term electricity supply contract that ensures a stable and reasonable price. Although this could also be optimised with self-consumption solutions through the installation of solar panels, which the company has been working on for some time now and which could provide a competitive advantage in terms of the final price. With the weighted price of this 'mix' of all the different sources of resources (reservoir, flowing, aquifers, regenerated and desalinated) and the cost of each one of them, the company claims that the availability of water needed for agriculture in the region would be guaranteed at less than 0.30 euros per cubic metre.
In the event of winning the concession, Magtel hopes to obtain all the necessary permits to begin work in December 2023. Since construction would take two years, the desalination plant could be producing water by the beginning of 2026.
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