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Irrigation system with carbonated water from industrial CO2 captured

The present document summarizes the deliverable DC3.2 which corresponds to task C3, “Design and construction of an industrial CO2 capture prototype. Capture start-up and Irrigation tests”. It contains all the information related to the implementation of the irrigation head for irrigation with carbonated water with industrial CO2 captured from EATOMIZADO. As it has been explained in deliverable DC2. 1, irrigation tasks corresponding to action C3 take place in the plot under study nº 2 (P2).

C3 action corresponds to the injection and dissolution of the CO2 captured from EATOMIZADO in irrigation water. P2 is located in the town of Onda, at 800 m from EATOMIZADO’s facilities, and situated in plot 94 of the Industrial Estate 54. It has a total surface area of 8,751 m2 that is going to be divided into three areas: area AP2: control area where the current agronomic works are going to be carried out; area BP2: irrigation will be carried out with carbonated water with pure commercial CO2 together with fertilization; and area CP2: irrigation will be carried out with carbonated water with CO2 captured from EATOMIZADO, together with fertilization.

The aim is to be able to compare the obtained results from the 3 studied areas to assess the impact on the environment.

All the agronomic values for the correct implementation and the necessary adjustments in the irrigation head have been determined and are described in this report.

The present report on agronomic calculations is therefore drafted to determine crop irrigation needs in the selected area for irrigation with carbonated water. Water crop needs of the selected irrigation areas will determine the size and the design of the irrigation head. It is worth to mention that all the contents related to the design of experiments, sampling protocol, monitoring of the parameters as well as the results obtained from the CO2 fertirrigation will be gathered and shown in the corresponding deliverable, DC3.3, “Report of agronomic trials”.

Irrigation water needs is the difference between the crop water needs and effective precipitation, the latter being understood as the precipitation actually used by the plant for its growth or making it available for assimilation.

For the calculation of the water requirements of any crop and using the parameters of the FAO (Food and Agriculture Organization of the United Nations), parameters such as reference crop evapotranspiration (ETo) and the crop coefficient (Kc) are required.

Potential evapotranspiration (ETo) is calculated as a function of climatic variables, such as temperature, relative humidity, radiation, insolation, wind and evaporation; while the calculation of the crop coefficient (Kc) must take into account the crop itself, the phenological status at all times as well as its specific crop conditions and local climatic conditions.

The calculated annual evapotranspiration has a value of 619.22 mm/year and represents the amount of water that a crop can evaporate when it is in good water supply conditions and with the soil close to field capacity.

The actual precipitation calculated, based on the data observed at the Onda station, is 122.2 mm/month and represents the amount of soil infiltration water which remains available to the plant roots without drowning and without arriving to be lost by runoff or by deep filtration.

Thus, the net irrigation needs are obtained by the difference between the evapotranspiration of the crop and the effective precipitation and taking into account that for the type of irrigation installation used (by dripping), an efficiency in the application of irrigation of 90 % is considered, the annual irrigation needs value is of 590.6 l/m2. This value represents the amount of water that must be supplied by the irrigation system to ensure that the crop receives all the water it needs.

Finally, we have calculated the required water volumes according to the total needs for each type of irrigation surface and the surfaces of the same, obtaining that the average needs resulting, taking into account the crops is of 5,906 m3/ha and the total needs are up to 1723 m3 /year in each of the areas of the plot (control, pure injected CO2 and industrial CO2).

It must be noted that in this case, the water used for irrigation comes from a well, property of the owner’s P2 with a flow of 4500 l/h. The drip irrigation installation has two lines of self-compensating droppers per tree of 3.5 l/h per dropper and the separation distance between trees is of 1.25 m.

The irrigation head has been sized and designed according to the previous established water irrigation needs. The irrigation head has been installed in the area of study and contains the following elements:

  • Water pump
  • CO2 injection tank
  • Pumping equipment
  • Fertilizer injection system
  • Operating and control elements: solenoid valves, pH meter
  • Water Tanks

All the tests that are being performed with industrial CO2 dissolved in irrigation water are being carried out in a uniform way, that is to say, the dose of CO2 that is being injected is calculated so as not to reach pH values under 6, since lower values are not optimal for citrus crops, and may cause phytotoxicities in trees. The pH of irrigation water is being measured manually.

The pH of the well water used for irrigation has been measured obtaining a mean value of 7.70 pH units. The aim is to reach a pH value of 6 (pH target) after CO2 and fertilizers injection.

The procedure set for irrigation with industrial CO2 carbonated water is the following: 10 water tanks of 1 m3 will be filled with well water and transported to EATOMIZADO so as to inject the captured CO2. It must be noted that the plot is only 800 m distance from the ceramic installations.

The amount of CO2 to be injected will be calculated so as to reach a pH value of 6.5 in the carbonated water. Then, water tanks containing the carbonated water will be transported by a forklift electric truck, a sustainable means of transport, to the plot for irrigation of CP2 area. As in the case of commercial CO2, the amount to be injected would depend on the fertilizers addition requirements.