A system of floating roofs can save of 36 million euros for the field

In Spain are counted about 50,000 rafts of irrigation with a total surface area of approximately of 182 million m². The application of the system of photovoltaic floating roofs (SCFFV), patented by Celemin Energy, on the total of these irrigation ponds help water savings of 180 hm³ per year, taking into account evaporation annual average of 1.1 m³/m². Simplifying, this savings would amount to the annual consumption of water in a town of 2.45 million, based on an average spending of 200 litres per day per user. Or what is the same, almost all of the water that would be spent in the province of Valencia, with a census of 2.57 million citizens, according to the INE on 1 January of the year 2009. So says Jaime Sastre, CEO of Celemin Energy, for whom the secret lies in the ability of the SCFFV to prevent the evaporation of 90% of the water which, otherwise, would go up into the atmosphere. "Inhibition of the incident solar radiation on water surfaces that is obtained through the covering with the SCFFV system - argues - also implies a reduction of water losses through evaporation." "The water is heated less to be protected from solar radiation for this floating roof and thus reduces evaporation." According to the President of Celemin Energy, the national average evaporation round the 1,000 mm annually, i.e., 1,00 m³/m² of sheet of water and year. "The placement of the floating roof photovoltaic system reduces water losses in 90%." This would leave the rate of evaporation in 0.11 m³/m²", explains tailor." In addition, and based on a potential savings of water of 180 hm³ per year as well as an average price of water for irrigation of 0.20 EUR/m³, the Steering encrypts a cost savings for the agricultural sector close to the 36 million euros per year. "With this data, of course we consider that the SCFFV can play a vital role in the improvement of the economic balance of Spanish farmers", points out. The system, created for the installation of plants for production of photovoltaic energy prepared on any surface of water; that itself, free from strong swells.

Normally, the SCFFV is used to cover rafts and irrigation dams, resulting in more efficient than other systems of covering. The most widely used in Spain, in order to prevent the evaporation of the water, is the mesh of shading ready on rafts of small and medium-sized, through a grids of cables anchored to the perimeter of the raft. Mesh, made of black PE, are installed in double layer. "In the SCFFV, floats of black polyethylene that they cover all the raft of irrigation, with the exception of the perimeter of the shelter where PVC fabrics are available, they are equivalent to the mesh of hat." "Although in both cases we have a black cover, our floats are completely opaque, and in the mesh materials of shading not", justifies the director-general of Celemin Energy, to compare the benefits of both technologies. In addition, Sastre insists that the mesh of shading are available as high water covers: "This allows the existence of certain air currents by increasing the rate of evaporation". Something does not happen in the system of floating photovoltaic roofs, as coverage floats on the sheet of water.

The SCFFV, designed by the agronomist engineer Emilio Pons, provides a number of environmental and socio-economic benefits. With regard to the first, in addition to minimizing water losses by evaporation also it affects lower electricity consumption in the filtration of water. The spokesman of Celemin Energy explains why: "the installation of the cover of the raft, directly influences on the solar radiation received by the sheet of water." Absence or lesser amount of direct radiation on the surface of the water greatly helps reduce the appearance of algae and other microorganisms. Thus decreasing the number of filters-laundering operations and, thus, the electricity consumption derived from the same. "An estimated saving water and energy more than 20% in these operations." If this wasn't enough, this technology minimizes the emissions of carbon dioxide (43.8 tons of CO₂ equivalent per MW per year) and has an impact on the conservation of the vegetation cover curbing the risk of desertification, increase the quality of water for irrigationincreases the useful life of the waterproofing sheet to prevent their exposure to solar radiation as well as that of the useful life of the filters.

To avoid the direct radiation on the surface of the water slows the appearance of algae and other microorganisms.

In relation to the socio-economic benefits, since Celemin Energy ensures that this technology is a source of income for the community of irrigators, decreases costs in general, contributes to the sustainability of agriculture and the creation of jobs: suppliers, installers, maintainers, and so on. "Get generate income for the farming communities, either by sale of energy or subsistence." "However, all the benefits it brings, the main economic impact is given by revenues result from the sale of energy and water savings achieved by minimizing water losses by evaporation", points out. The directors also recognizes that still is "risky" make estimates on the economic influence that may be obtained when this technology is not introduced on a larger scale and become available data "first hand".

Taking into account the potential of installation for the whole country is 12,000 nominal MW - according to from Celemin Energy - and that the average productivity of the SCFFV at the national level can be quantified over 1350 kWh/kWpGets a production of 16,200 Gwh which can be allocated to the sale of energy, according to the regulations in force, or to the subsistence, which will make a stability in the price of the electricity tariff during the lifetime of installationsthat is to say 40 years. On the other hand, this technology is accessible to any agricultural producer. "As all photovoltaic installation will require some work of operation and maintenance of which is responsible for our company." In addition, this technology does not interfere with the normal use of the infrastructure of irrigation by farmers, but that these benefits by reducing evaporation and dirty water already commented. "In sum, is compatible with any community of regantes regardless of their technical capacity", notes Sastre.

To date, the first practical experience of a facility of this kind has been carried out on the raft 'El Negret' in the production Central energy photovoltaic our Lady of peace in Agost (Alicante). It's a very flexible, modular system that adapts to the morphology of any reservoir of water. "In fact, articulated joints that connect the various floats to form the floating deck, give this a similar behavior to that should cover these surfaces of water with a cloth", says by way of comparison. Although the structure can be applied to any community autonomous or even export to other countries, please choose areas with more solar radiation. "To get an idea, there is a correlation at the national level between the areas with the highest number of rafts of irrigation and the levels of solar radiation, concentrated irrigation ponds in the area of levante and Mainland South". Currently, Celemin Energy has already initiated efforts to launch this project at the international level, although its CEO gives some clues that would facilitate the production and mass marketing of this technology. "It would be good to have the support of the Government through the establishment of a tariff of specific remuneration for the sector, assessing not only the production of energy, but the indirect additional benefits that arise, especially in regards the management of water improvement".