Spanish experience in desalination for agriculture - Valoriza Agua

D. Zarzo et al. / Desalination and Water Treatment 5Table 1Comparison of economic benefits in a farm using water from different sourcesWater originSuperficial (Tajo-SeguraRivers transfer)Brackish waterfrom wellsPermeate fromBWRO plantWater price (e/m 3 ) 0.1322 0.054 a 0.2284 (including payback)Incomes (fruit sales) (e/year) 15,037 7,519 b 16,539 cExpenses (e/year) 3,885 3,885 4,273Benefit (e/year) 11,152 3,634 12,268Note: economic data were supplied by the farmer, participant in the study.a With well in property.b In this case the fruit production is below 50% compared to irrigation with superficial water.c Increased incomes due to the higher production.Downloaded by [Domingo Zarzo] at 23:54 18 July 2012mations. According to the Ministry of Agriculture,Food and Environment these rates are intended torecover the annual costs of operation, operation andmaintenance of the aqueduct, as well as to amortizethe investments made by the Government. The tariffshave been reduced more than 30% this year from0.174 to 0.124 e/m 3 . On the other hand, some environmentalorganizations, such as world wide fund fornature in Spain, have complained that the calculationof the new rates for the use of the Tajo-Segura aqueductseems to have not included the environmentalcosts. Really these prices are fixed by the governmentand we do not know the real cost. We must bear inmind also that according with the EU Water FrameworkDirective is mandatory the full-price waterrecovery by 2010.Anyway, water transfer between different regionsis sometimes conflictive by political and economicalreasons and it is deeply affected by the weather conditions.It is generally admitted that water costs are areduced percentage of the overall cost of crop production,around 5%, although some authors reported thatthis could range between 5 and 25%, depending onwater price and even more than 45% for crops with ahigh water requirement (as oranges or lemons) [10].Other interesting data could be the differences for thesame product (e.g. tomatoes) when we compare productionin greenhouses or in an open field, as shownin Table 2 [9].Table 2Effect of water price over the overall production cost oftomatoes (expressed as increase in % of total cost)Water price (e/m 3 ) Greenhouses (%) Open field (%)0.12 2.2 50.54 9.3 19.3Source: Ref. [9].In an interesting report from the Spanish Ministryof Environment [11], the economic recovery of waterfor agricultural products was calculated. The resultsshowed that greenhouse products (horticultural, flowersand ornamental plants) provide greater addedvalue per unit of irrigated water with 5.79 e/m 3 onaverage in Spain. Far from these values, with intermediateproductivity are vineyards and fruit trees (1.08and 0.68 e/m 3 , respectively). On the other hand, thecereal grain reach an average productivity of around0.06 e/m 3 , which being the main crop in Spain, producesan average of 0.41 e/m 3 for all the products.In a study made in 2008 [12] by the community ofusers of water in the area of Nijar, Almeria, someinteresting data here supplied about the productivityof water in agriculture (Table 3):In this case, water consumption per hectare was5,600 m 3 , with a total consumption of 150 hm 3 andwater productivity of 11.41 e/m 3 . The water costssupplied [12] were 0.22 e/m 3 for brackish water,0.44 e/m 3 for desalinated water and 0.33 e/m 3 forresulting blended water.Another problem to evaluate the cost of water,mainly from desalination, is the energy price. Inrecent years, it has been increasing very fast, and dueto this, the main cost in a desalination production, thewater costs are continuously increasing (although thisTable 3Almeria and its production under plastic. Relationshipwater-harvestCrop Type Hectares Production value (inthousands of Euros)Greenhouses 26,833 1,714,969Lettuces 4,260 90,248Extensive (not lettuces) 3,277 97,852Total 34,370 1,903,069Source: Ref. [12].