Why is desalination the best solution for irrigation in agriculture against water stress?

The water supply can also be it will get worse in the coming months Between a decision of the Ministry of Ecological Transition and Demographic Struggle to increase the ecological flow of Tagus in Toledo and Aranjuez to 8.5 cubic meters, which would represent a loss of approximately 105 cubic meters of water if implemented Tajo to Segura transfer.

In this context, seeking irrigation and supply solutions, the newspaper, which was co-edited with BİLGİ ACCIONA Conference titled “Desalination for agriculture, a sustainable model”, a meeting where different experts analyze the current water situation and explain the advantages and disadvantages of desalination for agricultural use. Participated in the event Director, Manuel Navarro, ACCIONA’s Water Cycle; Joaquín Melgarejo, Director and Coordinator Water ChairDirector of the Institute of Water and Environmental Sciences at the University of Alicante (UA); Belén Castellano, manager Levante Irrigation; Y Juan Luis Paredes, Levante Irrigation Community – Segura’s right bank manager.

Reduction of 100 to 120 cubic hectometers per year

For ACCIONA’s Water Cycle director, reality shows that the proposed watershed hydrological plans in Spain for the period 2022-2027 cover the area affected by the Tajo-Segura transfer. a reduction of 100 to 120 cubic hectometers per year with the new requirements of the ecological flow, that is, “we have a five-year period to look for alternatives”. Therefore, he thought desalination is the best option currently existing as a complement to existing water resources.

“Desalination is the final frontier when other solutions have been exhausted. It is true that there are no technical guarantees to justify the increase in the ecological flow of the Tagus in Aranjuez, but this increase will be real and will mean water loss for the Spanish southeast. we have to find solutions Additionally, in an area where we are exploiting aquifers and cannot continue to compress,” noted Manuel Navarro. Therefore, he advocated the use of desalinated water for agriculture as a complementary response to mitigate the structural deficit of the Tajo-Segura transfer.

From a technical point of view, the expert provided: desalination is a mature application with a high energy efficiency component. Regarding its economic cost, he explained that the energy rate is responsible for 50% of the price of desalinated water. However, he reminded that companies buy energy in the long term, for a maximum of 15 years, and today the cost is 50 euros per MW/hour. “We can offer the farmer a secure supply and a stable price.”

A higher cost than water from the Tajo-Segura transfer, “but without water it would cost much more”, he pointed. Along this line, he argued, the ratio should be seen within the current set of water additives, such as those from the river, those that are reused. “Desalination water requires a mix of runoff and a mix of prices. I don’t want 100% of the cheapest water and 100% of the most expensive water. This is what we recommend to irrigation communities».

A complementary resource

Highlighting the current government’s decision to reduce the Tajo-Segura transfer, Joaquín Melgarejo “It is an ideological decision and has no technical basis”advocated the use of desalinated water as a supplement, but at the same time The main obstacle is the high economic cost for the farmer.energy as well. However, the expert was in favor of presenting this desalination process as a complementary resource. “to be used when necessary”Considering that the solution to using this desalinated water would be “to find a specific and private initiative that will give the farmer a price of about 40 cents per cubic meter”, as the ministry offers, something that is currently not viable.

Belén Castellano, director of Riegos de Levante, was most skeptical about the use of desalinated water in agriculture because “They still have 100% unresolved issues.” Among them, the first obstacle high levels of boron in water not removed by desalination and requires mixing with other types of nutritious water. Secondly, like other speakers, he reiterated that “it is impossible for the farmer to include the cost of this water in his daily expenses,” noting that today the Ministry has offered 0.526 euros instead of the subsidized price of 0.16 euros. cubic meters of transfer. “We cannot use this water exclusively.” was convicted.

“The market cannot afford the cost increase and the farmer eventually leaves. When we have no other choice, we will have to resort to it. desalination waterbut for now only some products like avocado can affect the cost of this water to the price. The cultivation here, like citrus, cannot do that,” he complained.

Juan Luis Paredes, manager of Segura’s Levante-Right Bank Irrigation Community, was more optimistic and was of the opinion: “If we include desalinated seawater in the array of additives we have (river, well, reused…), we eliminate the idea of ​​substitution and water it. integrating the solutions into the set, I think can be an interesting complement to the farmer and help alleviate the structural water deficit What we have in the Levante region».

In favor of high value-added agriculture

The future of agriculture in southeastern Spain It will depend on its transformation into a high value-added sector that can increase the price of its products.. According to the ACCIONA representative, the sector needs to take a step in the pursuit of professionalization to realize the transformation from traditional farmer to agricultural entrepreneur. In this way, it can offer the industry economically sustainable agriculture (to achieve profitability) and also environmental.

We are in a region that is the ‘orchard of Europe’ and Will not be replaced by North Africa. “We need time to adapt to the new prices,” he said.

Lower the price of desalinated water with Next Generation EU funds

The biggest barrier to the use of desalinated water in agriculture is its price, which is much higher than water from the Tajo-Segura transfer. For this reason, it is essential to reduce the price of cubic meters in order to use this resource in irrigation regularly. To minimize this cost, Manuel Navarro considered that there is a government subsidy for the construction of such infrastructures. in Next Generation EU funds An option that will allow farmers to access this water at a cost of around 30 cents per cubic metre.

«The future and complement of water for irrigation is desalination. There is no doubt. “What is in doubt is the time we will devote to making this change,” the ACCIONA representative said at the same time. “If the government subsidizes 50% of these infrastructure investments, the price of water from desalination plants could drop to 0.30 cents per cubic metre”

This grant will be for agricultural use only. In defense of this economic aid, Manuel Navarro recalled that these infrastructures will help ensure a water crossing in Spain by allowing less water to be used from rivers, increasing their flow and therefore having a direct and beneficial impact on the environment. «I believe that a partial subsidy for this type of work is justified, which will allow the cost of the price of water for the farmer to be reduced. There must be a transition period of 10 or 15 years for the new prices to be internalized. this will inevitably be higher than what is available for the Tajo-Segura transfer».

Advantages and disadvantages of desalination

• desalinated water manufacturers they can produce this good permanently and at fixed prices. Because companies like ACCIONA they can buy energy in the long run (15 years) at a price that is currently 50 MW/hr. This energy also comes from sustainable sources.

• The source of desalinated water is practically inexhaustible. The water of the seas is much wider than that of the rivers. In addition, production is not dependent on the weather. It is a resource that can make the agricultural industry self-sufficient.

• desalinated water The only solution and supplement to face the structural water deficit and permanent life in the Spanish southeast.

• Complex reverse osmosis installations requires a large electricity consumption. According to Melgarejo the energy cost is 3.4 KW/cubic meter, if you have to add 0.70 KW to add the interconnection, the cost can reach 5 KW per cubic meter compared to 1.1 KW for the transfer and post-transfer Tajo-Segura. .

• There is desalinated water high borontherefore it must be mixed with others that provide nutrients to be used for irrigation.

• desalinated water price It is more expensive for the farmer. The offer, which was (temporarily) subsidized by the Ministry, is EUR 0.562, which is considered unaffordable by the farmers.