No w ada ys, the agriculture sector presen ts relev an t opp ortunities to in tegrate renew able energy sources as an alternativ e solution to mitigate fossil-fuel dep endence and decrease emissions. Moreo v er, this sector demands a detailed review of energy uses and other factors that are addressed as priorit y issues in most dev elop ed coun tries. In this framew ork, groundw ater pumping energy requiremen ts for agriculture irrigation emerge as a relev an t topic to b e impro v ed in terms of p o w er demand. A ctually , this demand is curren tly supplied b y diesel equipmen t solutions, with relev an t dra wbac ks suc h as: (i) a large energy dep endence on fossil fuels for the agricultural sector and (ii) a lac k of participation in reducing CO 2 emissions. This pap er prop oses a m ultidimensional c haracterization to ev aluate photo v oltaic (PV) solar energy in tegration in to groundw ater pumping requiremen ts. Alternativ e solutions are compared under economic, energy and en vironmen tal asp ects; th us pro viding an extensiv e scenario where the considerable in uence of m ultiple factors suc h as w ater needs, irrigation area or aquifer depth are explicitly considered. Extensiv e results based on a real Spanish aquifer and discussion ab out the solutions are also included in the pap er. Keywor ds: PV systems, Solar pumping, Agricultural dev elopmen t, Optimization energy requiremen t, Characterization of energy alternativ es, Economic-Energy-En vironmen t (3E) Analysis. 1. In tro duction T raditionally , the agriculture sector has dep ended hea v- ily on fossil fuels in a similar w a y to other activities ha v e, with a lo w Renew able Energy Source (RES) in tegration that can lead to suering exhaustion [1]. This fact also aects nal prices, whic h are highly dep enden t on energy cost uctuations. The high fossil fuel dep endence is es- p ecially remark able in eld crops, in v olving aquifer o v er- exploitation problems [2]. In addition, this high energy dep endence is one of the p ollution sources resp onsible for emissions and the greenhouse eect [3]. Recen tly , Spanish energy initiativ es [4], Europ ean p olicies [5, 6, 7], as w ell as en vironmen tal [8] and agricultural matters [9] ha v e b een aimed at raising a w areness b y promoting a rational use of energy and an optimal w ater managemen t in the agricul- ture sector. These in ternational p olicies in v olv e sustain- able dev elopmen t prop osals for renew able energy sources and energy e ciency [10]. They also pro vide alternativ e solutions to mitigate the energy dep endence on fossil fuels for the agriculture sector and en vironmen tal concerns [11]. Corresp onding author Email addr ess: angel.molina@upct.es (Ángel Molina-García)During recen t decades, irrigation tec hniques ha v e pro- gressiv ely required greater and greater energy needs. F or example, the energy demanded b y this sector in Spain rose b y 1800% from 1950 to 2007 [1], co v ering 20% of the total arable land and represen ting 60% of the nal agricultural pro duction [12]. The crop area irrigated with w ells cur- ren tly presen ts a ma jor p ercen tage, also in Spain, where most energy requiremen ts are due to pumping extraction needs [14], see Figure 1. This situation is similar to that in other dev elop ed coun tries, where groundw ater pumping energy demand w as mainly co v ered with diesel equipmen t, and subsequen tly with a similar p ercen tage of electricit y- based solutions. PV solar energy for irrigation purp oses has b een prop osed in the sp eci c literature as an attempt to reduce b oth energy consumption as w ell as CO 2 emis- sions in agriculture [15, 16]. An ev aluation of PV-based solutions w as prop osed b y Purohit et al. [17], as an al- ternativ e to decrease fossil fuel dep endence and reduce its in uence on nal prices. Other studies ha v e fo cused on pro viding w ater as a basic resource in isolated rural ar- eas, mainly to co v er h uman needs in non-industrialised or under-dev elop ed coun tries [18, 19] suc h as Nepal, Ken y a, Mauritania and Moro cco [20, 21]. Rural comm unities of under-dev elop ed coun tries with solar pumping installa- Pr eprint submitte d to R enewable Ener gy https: // doi. org/ 10. 1016/ j. renene. 2019. 01. 077 May 3, 2020 (a) Irrigation ev olution in the Spanish agriculture (b) Irrigation sources (c) Energy requiremen t ev olution Figure 1: Main indicators on energy demand for groundw ater pumping agriculture in Spanish case [12, 13]. tions lo w er than 2 k W ha v e b een also discussed in other w orks, suc h as Erbato et al. [22]. PV solar pumping solu- tions for agriculture purp oses ha v e b een analysed from the tec hnical and economic feasibilit y p oin t of view [23, 24]. The economic viabilit y of PV solutions applied to irriga- tion has b een widely discussed b y F oster et al. [25] and Odeh et al. [26]. Approac hes to the solar-PV system de- sign in line with sp eci c tec hnical studies on solar radia- tion, mostly applied to areas with sev ere w ater scarcit y , are pro vided b y Setia w an et al. [27]. A ccording to Kelley et al. [28], PV systems are economically feasible for small systems (less than 4000 m3and less than 10 ha ), whereas larger areas require a more detailed study . An extensiv e analysis is prop osed b y Cuadros et al. [29] to determine the viabilit y of PV solutions for w ater pumping purp oses for oliv e trees irrigation in a sp eci c area, including the in uence of additional factors suc h as w ater depth dep en- dence, solar radiation or crop gro wing. In line with the sp eci c literature, a comprehensiv e re- view of alternativ es is necessary to ensure that e cien t irrigation systems are ac hiev ed from dieren t p oin ts of view: w ater, energy , econom y and en vironmen tal concerns; analysing the PV solar energy's in tegration under dier- en t con gurations [30, 31]. Therefore, new metho dologies m ust com bine the optimisation, sizing and viabilit y of irri- gation systems based on solar tec hnologies, including addi- tional factors suc h as energy costs, w ater managemen t and CO 2 emissions [32]. Moreo v er, recen t con tributions a rm that, b efore c hanging pumping diesel facilities in to solarpumping equipmen t, the in uence of other factors m ust b e studied and c haracterized in detail. These include w a- ter depth, parcelling grouping, crops, connection to grid or PV tec hnologies [25]. Global prop osals are required to in tegrate renew able energies in to agriculture from an extensiv e manner, optimising costs, reducing CO 2 emis- sions and minimising energy requiremen ts [31]. T aking in to accoun t previous con tributions, this pap er addresses a m ultiv ariable extensiv e c haracterization for groundw ater pumping irrigation purp oses. The main con tributions of this pap er to RES in tegration in to the agriculture sector are as follo ws:  A prop osal for c haracterizing a group of groundw ater pumping alternativ es that considers economic, energy and en vironmen tal p oin ts of view.  An extensiv e visualization of dep endences with rele- v an t v ariables, suc h as aquifer depth, crop w ater re- quiremen ts, irrigation area sizes and w ater storage op- tions.  A thorough comparison of the impacts of dieren t re- sources for pumping groundw ater requiremen ts, in or- der to ev aluate the suitabilit y of eac h solution dep end- ing on dieren t parameters. A dditionally , the prop osed c haracterization is applied on a real Spanish aquifer and crops, pro viding a preliminary extended view to meet groundw ater pumping requiremen ts b y in tro ducing PV solar-based installations. 2 The rest of the pap er is structured as follo ws: v ariables to b e considered for detailed analysis in the pumping ir- rigation problem are discussed in Section 2. The metho d for the c haracterization and calculation of the alternativ es taking complemen tary p oin ts of view to iden tify optimal and e cien t alternativ es is prop osed in Section 3. The case study is describ ed in detail in Section 4, as w ell as the alter- nativ es and con gurations that meet the constrain ts and requiremen ts for the case study . The results are presen ted and discussed in Section 5. Finally , Section 6 details the conclusion and future w orks. 2. Multiv ariable Extensiv e Prop osal: General Ov erview Considering the con tributions previously discussed in Section 1, a m ultidimensional group of v ariables is selected to c haracterize the pumping irrigation problem in a reli- able and extensiv e framew ork. Indeed, m ultiple v ariables ha v e a relev an t in uence on the p o w er demanded b y the groundw ater pumping systems and th us, com binations of suc h v ariables pro vide an initial set of options to b e consid- ered as a general guideline for groundw ater pumping pur- p oses. Nev ertheless, and due to the large n um b er of p os- sible com binations, this pap er aims to lter the most rel- ev an t alternativ es and practical solutions. Figure 2 sho ws the iden ti ed groups of v ariables as w ell as the v ariables to b e considered as inputs of the problem: w ater needs, aquifer depth and parcelling grouping. A dditionally , the gure depicts the relations among v ariables and the pro- p osed c haracterization pro cess to iden tify p ossible alterna- tiv es in a m ultidimensional scenario. F rom the initial group of general v ariables, the prop osed metho dology to c haracterize pumping groundw ater solu- tions in v olv es the iden ti cation of alternativ es and the con- gurations discussed in the follo wing subsections. 2.1. Pumping water options Firstly , a relev an t issue considered in the prop osed c haracterization pro cess considers w ater storage options. Three con gurations are tak en in to accoun t b y the au- thors to meet the dieren t p ersp ectiv es: ann ual w ater storage, seasonal w ater storage and direct pumping (with- out w ater storage). The rst option usually requires large w ater reserv oirs, with high costs and ev ap oration prob- lems. Ho w ev er, it do es ensure the w ater supply demand and uniform irrigation throughout the y ear, alb eit with a lo w p o w er/y ear ratio. The seasonal w ater storage option is based on pumping w ater during the mon ths prior to the irrigation p erio d and throughout that p erio d. Therefore, this requires a smaller storage reserv oir to meet w ater re- quiremen ts, with lo w er ev ap oration problems. Ho w ev er, this option also demands high energy and initial in v est- men ts, b eing used for a short p erio d of time according to the h ydraulic y ear. The third option to b e considered is based on a direct pumping solution. W ater storage is stillneeded as a pressure surge reserv oir, although consider- ably lo w er than in the previous options. The crop w ater demand is then mostly directly pro vided b y the aquifer. Consequen tly , the p o w er demand presen ts a pro le simi- lar to the w ater needs. This con guration in v olv es higher p o w er needs than the other options, but signi can tly lo w er w ater storage and negligible ev ap oration problems. 2.2. Individual vs Co op er ative facilities In order to determine an optimal con guration for irri- gation pumping systems, the prop osed metho dology con- siders b oth individual and co op erativ e energy alternativ es. A ccording to the irrigation requiremen ts, dieren t crop ar- eas can b e preliminarily de ned. In the case study , from 1 to 2000ha are estimated as initial solutions to b e anal- ysed, see Section 4. No w ada ys, individual systems are v ery common in agriculture, since they pro vide the farm- ers with greater indep endence in terms of the metho d and amoun t of irrigation. Co op erativ e solutions usually oer signi can t size reduction in RES facilities, promoting RES in tegration scenarios. 2.3. Isolate d or Conne cte d instal lations Isolated installations ha v e some adv an tages in terms of v ersatilit y and easy implemen tation. Ho w ev er, these so- lutions m ust completely co v er the energy needs (mostly o v ersized) required b y the groundw ater pumping. Instal- lations connected to the grid allo w us to reduce facilities, since additional p o w er demand or de ciencies can b e sup- plied b y the grid. F or crops on an ann ual scale (suc h as the case study), connected installations migh t inject an y excess energy in to the grid, th us b eing an economic pro t for farmers in comparison to isolated installations. The costs of p o w er lines and additional grid facilities are fur- ther in v estmen ts that m ust b e tak en in to accoun t for these connected installations. 2.4. Ener gy Solutions In relation to most of the usual solutions and renew able sources curren tly promoted, four main resources ha v e b een considered: diesel, isolated PV solar p o w er plan ts, p o w er directly pro vided b y the grid, and PV solar installations connected to the grid under net balance conditions. Diesel is included due to its relev ance in the curren t agricultural sector, b eing used as a mature and reliable tec hnology for groundw ater pumping actions and other agricultural appli- cations in most coun tries. In fact, this solution is mostly used for groundw ater irrigation purp oses under individ- ual diesel con gurations. Isolated PV solar p o w er plan ts emerge as a trending solution to supply p o w er and reduce b oth energy dep endence and emissions [33]. These presen t some relev an t adv an tages, suc h as minor energy dep en- dence, relev an t energy e ciency and, in most coun tries, imp ortan t subsidies. Indeed, some authors a rm that diesel equipmen t installations can b e curren tly turned in to 3 Figure 2: Groups of v ariables: iden ti cation and relations for c haracterization of initial alternativ es. individual-isolated PV installations [34]. Moreo v er, com- binations of individual PV installations require less p o w er capacit y and oer dieren t opp ortunities to the farmers to signi can tly reduce CO 2 emissions and optimise the in- tegration of renew ables in to w ater pumping requiremen ts. Its dra wbac ks include the large areas required for PV mo d- ules in comparison with diesel equipmen t, as w ell as p o w er oscillations due to solar radiation uctuations or partial shadings. F or those reasons, PV solar installations con- nected to the grid are assumed as an alternativ e of dis- tributed generation applied to the agriculture sector [35]. The p o w er demanded b y the pumps can b e pro vided b y b oth the PV installation and the grid. Subsequen tly , w a- ter can b e used directly for irrigation purp oses or stored in a reserv oir. A ctually , individual PV installations con- nected to the grid can b e considered as a co op erativ e in ter- nal net w ork with electrict y suppliers and consumers [36]. Nev ertheless, some coun tries dier in the la ws and regula- tions regarding PV solar facilities and the p o w er allo w ed to b e injected in to the grid. F or example, Spain pro vides some requiremen ts for PV p o w er plan t op erations as w ell as taxes and fees curren tly applied on these installations [37]. With regard to co op erativ e irrigation systems, PV solar pumping is also considered as a trade-o b et w een large-scale renew able in tegration and groundw ater pump- ing requiremen t facilities. This approac h m ust include ad- ditional costs for p o w er line infrastructures and grid dis- tributed system requiremen ts [38]. Finally , p o w er directly supplied b y the grid and without additional renew ables sig- ni can tly reduces costs, although farmers dep end on the grid in terms of prices and energy dep endence. This alter- nativ e th us pro vides substan tial reductions of CO 2 emis- sions in comparison with diesel approac hes. Ho w ev er, it do es not promote the in tegration of renew ables with a con- sequen t p o or participation in the decreasing of fossil fuel dep endence.2.5. Sp e ci c F acilities Con gur ations Finally , alternativ es are also c haracterized and divided according to some facilities criteria. With regard to PV solar installations, w e also distinguish: (i) dieren t PV tec hnologies, through a comparison of suc h tec hnologies under econom y , p eak p o w er requiremen ts or emissions; this approac h has also b een discussed in the sp eci c lit- erature [39, 40]. In our case, the most common commer- cial solutions curren tly a v ailable are considered: Silicon Mono crystalline (Mono-Si), P olycrystalline Silicon (P oly- Si) and Thin-Film mo dules. (ii) dieren t solar trac king tec hnologies, suc h as xed installations, one-axis and t w o- axes solar trac king solutions. (iii) PV installations in islanding-mo de or connected to the grid. In reference to this last option, a relev an t factor to b e c haracterized is the energy pumping requiremen ts and energy fed in to the grid ratio. In fact, some con tributions discuss in v estmen ts and b ene ts when a p ercen tage of the electricit y is injected in to the grid [35, 41, 37]. The prop osed metho dology then in- cludes some scenarios dep ending on the p ercen tage of par- ticipation with the grid: 25%, 50%, 75% and 100% of PV solar p o w er injected in to the grid. Finally , energy pump- ing requiremen ts directly supplied b y the grid is a v ery realistic situation whic h is also included among our alter- nativ es. Dieren t options are th us considered, dep ending on the distance b et w een the crops and the p o w er system. A ccording to the case study describ es in detail in Section 4, three dieren t distances b et w een the crops and the grid ha v e b een considered for sim ulation purp oses: 1 km, 3 km and 5 km. In fact, they are the most common distances b y considering the aquifer real lo cation, the crop la y out and the p o w er distribution system. Suc h alternativ es are dis- cussed and c haracterized in detail in the follo wing section. 4 Figure 3: Analysis of v ariables and c haracterization of alternativ es 3. Multidimensional Characterization of Alterna- tiv es F rom the extensiv e group of v ariables describ ed in Sec- tion 2, a c haracterization of alternativ es is then prop osed in the curren t section under dieren t p ersp ectiv es. A global assessmen t of suc h alternativ es is th us giv en b y the prop osed metho dology . An initial range of the v ariables to b e c haracterized is selected from sp eci c crop areas, aquifer depths and w ater requiremen ts. A dditional factors suc h as energy resources, w ater storage options and co- op erativ e lev els, see Figure 2 are also considered under realistic scenarios [28][42]. The prop osed metho dology considers sim ultaneously four p ersp ectiv es with the aim of c haracterizing the dif- feren t alternativ es: tec hnical, economic, energy and en vi- ronmen tal p ersp ectiv es. F rom this complemen tary analy- sis, e cien t and optimised alternativ es can b e iden ti ed. Subsequen tly , represen tativ e solutions of those com bined factors are selected. Figure 3 summarises the prop osed metho dology to c haracterize the alternativ es based on the extensiv e group of v ariables and p ersp ectiv es considered in this w ork. A four-dimensional represen tation is prop osed b y the authors to visualise the dieren t p ersp ectiv es. F ur- ther information and examples of this visualisation pro- p osal can b e found in Section 5. A ccording to Figure 3, economic cost criteria are usu- ally a relev an t factor in the nal decision. This is in fact a crucial parameter to b e considered, as p oin ted out in [43, 44]. The costs of the initial in v estmen t dep ends on eac h alternativ e, considering dieren t w ater reserv oir solu-tions [45]. Ann ual b ene ts and costs of main tenance and op erating exp enses are also considered. In fact, costs of equipmen t are included in accordance with curren t prices [46, 47, 48, 49]. P o w er requiremen ts are mainly based on facilities for groundw ater pumping and w ater storage [50, 51, 52]. The energy p ersp ectiv e th us implies the com- parison of dieren t alternativ es in terms of installed p o w er and required energy according to the corresp onding w ater requiremen ts [53]. A dditionally , w ater pumping for dif- feren t depths under individual or co op erativ e approac hes also has an imp ortan t impact on the energy needs [28]. An estimation of the total required energy th us dep ends on the depth of the aquifer lev el and the crop w ater de- mand [54, 55, 56]. Other factors, suc h as h ydraulic system pressure [31, 57] and h ydraulic net w ork are also considered [33]. F or a comparison b et w een alternativ es, the p o w er re- quired b y the pump is rst estimated ( Pp ), Pp=HtQmxg MP(1) whereHt is the total h ydraulic head ( m ),QMX the maxim um v olume o w rate ( m3=s ), the w ater densit y (kg=m3),g the earth gra vitational acceleration ( m=s2) and MP the pump e ciency (%). The rate p o w er is then de- termined p er hectare ( kW=ha ) dep ending on the source. F or a diesel equipmen t ( Pd ), Pd=PpKd d(2) whereKd is the co e cien t ma jorit y diesel equipmen t (usu- ally 1.2) and d the diesel equipmen t e ciency (%). In a similar w a y , for solutions connected to the grid ( Pg ), Pg=PpKg (3) whereKg is the co e cien t ma jorit y electric con tract (usu- ally 1.1). Finally , for PV solar installations ( PPV ), PPV=EconGCEM Gdm( ; )PR(4) whereEcon is the energy consumption ( kWh=day ),GCEM is assumed as 1 kW=m2,Gdm( ; ) is the a v erage mon thly v alue of the daily irradiation on the horizon tal surface (kWh=m2day ) andPR is the p erformance ratio of the PV installation. Emissions of CO 2 for the dieren t tec hnologies are esti- mated according to previous con tributions [58, 59]. The al- ternativ es are the follo wing: (i) tec hnologies based on fossil fuels (diesel); (ii) alternativ e exclusiv ely supplied b y the grid; and (iii) isolated and connected to the grid PV p o w er plan ts [60, 61, 39, 62]. Emissions are determined in terms of a v eraged life cycle energy consumption p er hectare and considering a standard y ear ( TnCO 2=hayear ). A ccord- ing to the aim of this pap er, initial CO 2 emissions for assem bly and h ydraulic net w ork construction ha v e b een excluded from the analysis. 5 Figure 4: Situation of Case of Study . A quifer 23. Castilla-La Manc ha (Spain). 4. Case Study The prop osed metho dology is a general-purp ose solution whic h can b e applied on dieren t lo cations and crops. In order to ev aluate the suitabilit y of this c haracterization, an agricultural area lo cated in the Region of La Manc ha (Spain) has b een selected. The irrigation of this area de- p ends on A quifer 23 [63], lo cated in the cen ter of this re- gion and in c harge of pro viding w ater for residen tial and ir- rigation purp oses [64]. The case study co v ers an extensiv e area (o v er 5500 km2) and subsequen tly , crops and w ater requiremen ts on the land v ary signi can tly . Nev ertheless, dieren t p olicies and actions ha v e promoted a massiv e w a- ter extraction for decades. Figure 4 sho ws the lo cation and shap e of this aquifer. With regard to the agricultural p oten tial, there is a large concen tration of viney ards, accoun ting for o v er 60% of the surface area. The rest of the crops are mainly based on dieren t fruits and v egetables in small orc hards. The kind of crops has a relev an t in uence on the amoun t of w a- ter to b e extracted from the aquifer [51]. Therefore, it is assumed that the amoun t of w ater demanded b y eac h agricultural sector v aries from 1500 m3=year for viney ards up to 8000 m3=year for fruits, cereals and v egetables. In terms of climate, the region is considered to b e semi-arid Mediterranean Con tinen tal [65], with high solar radiation lev els and an a v erage ann ual precipitation ranging b et w een 320mm=m2(dry y ears) and 460 mm=m2(w et y ear). In addition, the aquifer presen ts imp ortan t depth v ariabil- it y b et w een the dieren t aquifer zones, whic h signi can tly mo di es the energy requiremen ts for eac h crop. Figure 5 summarises b oth the ann ual solar radiation v alues as w ell as the groundw ater lev el for the selected aquifer.As w as discussed in Section 4, the prop osed metho dol- ogy includes b oth individual and co op erativ e alternativ es to minimize costs and optimise facilities. An initial matrix com bining w ater depth, agricultural co op erativ e areas and w ater requiremen ts is prop osed to c haracterize energy , eco- nomic and en vironmen tal criteria for eac h scenario. This m ultidimensional analysis allo ws us to visualize eac h so- lution in a v ery extensiv e w a y , dep ending on the sp eci c c haracteristics of crops and the aquifer prop erties. In this case, and according to the aquifer c haracteristics see Fig- ure 5, four dieren t depth v alues are considered: 10, 25, 40 and 55 metres. In terms of co op erativ e scenarios, agri- cultural areas from 1 to 2000 ha ha v e b een considered in this case study . Regarding w ater requiremen ts (p er a v er- aged y ear), sev en dieren t v alues are selected: 1500, 3000, 4500, 6000, 7500, 9000 and 10500 m3=ha . Ranges from these v ariables are selected to analyze real scenarios ac- cording to the aquifer and agricultural conditions. The metho dology allo ws us to mo di y these ranges dep ending on the sp ec c case study . 5. Results By considering the prop osed m ultidimensional analysis describ ed in Section 3 as w ell as the case study discussed in Section 4, dieren t alternativ es are c haracterised and compared in terms of economic, energy and en vironmen tal criteria. The c haracterization pro cess only considers a re- duced n um b er of alternativ es and con gurations, whic h are the most represen tativ e and realistic scenarios according to the w ater crop requiremen ts and the aquifer c haracteris- tics. In terms of PV p o w er plan ts, only results for Mono-Si mo dules ha v e b een represen ted and 100% participation is considered for PV installations connected to the grid. F or groundw ater pumping solutions directly connected to the grid, dieren t p o w er line length scenarios ha v e b een esti- mated, including 1, 3 and 5 km of p o w er lines. Ho w ev er, for the selected gures included in the pap er, the 1 km p o w er line length is considered as represen tativ e of the case study . Therefore, a complete c haracterisation of sce- narios has then b een carried out b y the authors, sho wing the most represen tativ e alternativ es in this section. Figure 6 and 7 depicts the dieren t alternativ es, in terms of costs (in Euro), dep ending on seasonal pumping or direct pumping. Ranges previously selected for aquifer depths (1 to 55 m depth), w ater requiremen ts (1.5 to 10.5 m3=Ha103) and co op erativ e agricultural areas (1 to 2000 Ha ) ha v e b een considered, see Section 4. F rom the re- sults, the larger agricultural area and w ater requiremen ts, the higher costs required b y all sources. F or example, and considering net balance and direct pumping, 5.4 106 Euro is the cost for 2000 Ha , 1500m3=Ha103and 40 m depth; whereas 2.03 106Euro is the cost for 1000 Ha , 1500m3=Ha103and 40m depth. An installation direclt y connected to the grid without diesel solution neither PV p o w er plan t giv es the lo w est costs. Ho w ev er, this solu- tion can't b e implemen ted on remote areas whithout grid 6 Figure 5: A v erage Ann ual Solar Radiation and Phreatic lev el of A quifer 23. Castilla-La Manc ha (Spain) [63]. 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103)Water requirements (m3/Ha·103)Aquifer depth (m)100% PV-Mono-Si and 1km power line length 00.511.522.533.544.55·106 (a) Net Balance 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103)Water requirements (m3/Ha·103)Aquifer depth (m)Diesel 00.511.522.533.544.55·106 (b) Diesel 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103)Water requirements (m3/Ha·103)Aquifer depth (m)100% PV-Mono-Si and non-connected to the grid 00.511.522.533.544.55·106 (c) Islanding PV solar installation 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103) Water requirements (m3/Ha·103)Aquifer depth (m)Without PV power plant and 1km power line length connected to the grid 0.40.50.60.70.80.91·105 (d) Connected to the grid Figure 6: Estimated Seasonal Pumping Cost (Euro). Comparison of sources 7 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103)Water requirements (m3/Ha·103)Aquifer depth (m)100% PV-Mono-Si and 1km power line length 00.10.20.30.40.50.60.70.80.91·107(a) Net Balance 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103)Water requirements (m3/Ha·103)Aquifer depth (m)Diesel 00.10.20.30.40.50.60.70.80.91·107 (b) Diesel 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103)Water requirements (m3/Ha·103)Aquifer depth (m)100% PV-Mono-Si and non-connected to the grid 00.10.20.30.40.50.60.70.80.91·107 (c) Islanding PV solar installation 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103) Water requirements (m3/Ha·103)Aquifer depth (m)Without PV power plant and 1km power line length connected to the grid 0.40.50.60.70.80.911.1·105 (d) Connected to the grid Figure 7: Estimated Direct Pumping Cost (Euro). Comparison of sources (a) Net Balance (b) Diesel (c) Islanding PV solar installation (d) Connected to the grid Figure 8: Estimated Required Seasonal Pumping P o w er (k W). Comparison of solutions 8 connection or when the p o w er line length exceeds sev eral km. The diesel equipmen t costs accoun t for appro ximately half of the PV p o w er plan t costs, but the emissions are clearly higher as w ell as the energy dep endence. Regard- ing seasonal and direct costs, the later are initially higher, though seasonal costs w ould b e increased if additional in- stallations related to reserv oir purp oses w ere included as w ell. Another relev an t p oin t for future w orks concerns the grid b ene ts and mark et p oten tial generated through the sale of surplus electricit y from the PV installations. This ob jectiv e is b ey ond the scop e of the presen t c haracterisa- tion analysis and is curren tly under study b y the authors. Figure 8 and 9 sho w the p o w er required for the dieren t alternativ es seasonal pumping and direct pumping in terms of aquifer depths (1 to 55 m depth), w ater require- men ts (1.5 to 10.5 m3=Ha103) and co op erativ e agricul- tural areas (1 to 2000 Ha ). These alternativ es are c har- acterised and compared taking in to accoun t real scenarios from the Spanish aquifer and the crops curren tly a v ailable in this area. In b oth cases (seasonal and direct pump- ing), diesel equipmen t requires less p o w er than the rest of sources. As an example, and considering a direct pump- ing scenario, 782.2 kW is the diesel p o w er for 1200 Ha , 1500m3=Ha103and 25m depth; whereas 1006.2 kW is the PV p o w er plan t required b y the same conditions. There- fore, from an economic and p o w er p oin t of view, diesel solution w ould b e initially the selected option. Ho w ev er, and as w as previously discussed, relev an t emissions and energy dep endence should b e also considered. In a similar w a y to the previous cost estimation analysis, no additional facilities are considered for the seasonal scenario and grid b ene ts generated through the sale of surplus electricit y from the PV installations are not also considered. Figure 10 and 11 summarise the CO 2 emissions for the dieren t alternativ es. This en vironmen tal c haracteriza- tion allo ws us to visualise and compare ho w sustainable eac h solution is in terms of tonnes of CO 2 . The diesel equipmen t ob viously giv es o the highest emissions, con- siderably greater than solutions based on PV installa- tions or ev en for approac hes whic h are connected to the grid. F or example, for a seasonal pumping scenario, diesel equipmen t has 243.58 T onnes of CO 2 for 1200Ha , 1500 m3=Ha103and 40m depth; whereas the PV p o w er plan t has 9.0 T onnes of CO 2 for the same conditions. Clearly , from the emissions and energy dep endence, diesel equip- men t is not a suitable solution to b e considered b y the agricultural sector. Ho w ev er, from an economic analysis, the diesel solution is considerably c heap er than the other resources and, for this reason, an extensiv e and m ultidi- mensional c haracterisation is then necessary to b e con- ducted b efore selecting an optimal solution. Consequen tly , the prop osed framew ork pro vides an extensiv e c haracter- isation of eac h alternativ e for eac h realistic scenario. As w as previously p oin ted out, the prop osed metho dology can b e applied to dieren t lo cations and areas. Therefore, this alternativ e c haracterization aims to pro vide an extensiv e analysis of a more sustainable scenario with PV p o w erplan t in tegration. As an additional example, the prop osed metho dology has b een applied on the Saiss aquifer lo cated in the re- gion of F ez-Meknes (Moro cco). This aquifer is mainly sup- p orted b y rain w ater in ltration con tributions. No w ada ys, the aquifer pro vides an ann ual irrigation demand b et w een 275 and 400 million m3=year , suering an in tesiv e agricul- ture demand and co v ering relev an t drinking w ater neces- sities since the 1980s. Subsequen tly , the aquifer presen ts a w ater de cit situation, without pumping constrain ts and an a v erage w ater demand b et w een 3500 m3=Ha and 5600 m3=Ha . F urther information can b e found in [66, 67, 68]. Figure 12 summarizes the application of the prop osed metho dology on this aquifer. In this case, the results for PV installations are depicted and compared for dieren t w ater requiremen ts, aquifer depths and agricultural areas. The prop osed c haracterization also allo ws us to compare and estimate solutions with sp eci c agricultural areas; pro- viding b oth scalabilit y and exibilit y prop erties. With this aim, PV installation costs are compared for 1300 Ha of crops. In this area, the aquifer depth is b et w een 35 and 45m . Figure 13 sho ws these costs for ann ual PV solar pumping requiremen ts. 6. Conclusion A m ultidimensional economic, energy and en vironmen- tal analysis is prop osed and assessed to c haracterise the groundw ater pumping problem. Dieren t alternativ es can b e compared, including con v en tional solutions based on diesel equipmen t, grid connection and renew able promo- tion fo cused on PV solar in tegration. A real Spanish aquifer mainly used for agricultural purp oses has b een used to assess the prop osed c haracterisation metho dol- ogy . By considering curren t crops, aquifer depths and agri- cultural w ater requiremen ts the alternativ e resources are c haracterised and visualised from t w o scenarios: seasonal pumping requiremen ts and direct pumping requiremen ts. F rom the results, including seasonal and direct pumping scenarios for the case of co op erativ e facilities, diesel equip- men t pro vides considerably lo w er in v estmen t costs in com- parison to the net balance solution or islanding PV solar installation. In fact, the diesel approac h is curren tly one of the most commonly selected solutions b y the agriculture sector. Ho w ev er, diesel equipmen t presen ts v ery high CO 2 emissions in comparison to the p o w er system solution or PV solar installations. Therefore, alternativ es based on renew able energy sources should b e promoted b y go v ern- men ts to decrease CO 2 emissions and minimise fossil fuel dep endence in the agriculture sector. This analysis can b e extended b y including other additional v ariables, suc h as in v estmen t costs in irrigation infrastructures (reserv oir) and ann ual electricit y or fuel costs (diesel). A ccording to the results and the c haracterization of alternativ es, this metho dology presen ts a lo w computational time cost and it is suitable to b e aaplied on dieren t agricultural areas and scenarios. In addition, an estimation of the optimal 9 (a) Net Balance (b) Diesel (c) Islanding PV solar installation (d) Connected to the grid Figure 9: Estimated Required Direct Pumping P o w er (k W). Comparison of solutions 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103)Water requirements (m3/Ha·103)Aquifer depth (m)100% PV-Mono-Si and 1km power line length 02004006008001,0001,2001,400 (a) Net Balance 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103)Water requirements (m3/Ha·103)Aquifer depth (m)Diesel 02004006008001,0001,2001,400 (b) Diesel 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103)Water requirements (m3/Ha·103)Aquifer depth (m)100% PV-Mono-Si and non-connected to the grid 02004006008001,0001,2001,400 (c) Islanding PV solar installation 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103)Water requirements (m3/Ha·103)Aquifer depth (m)Without PV power plant and 1km power line length connected to the grid 02004006008001,0001,2001,400 (d) Connected to the grid Figure 10: Estimated Seasonal Pumping Emissions (T onnes of CO 2 ). Comparison of sources 10 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103)Water requirements (m3/Ha·103)Aquifer depth (m)100% PV-Mono-Si and 1km power line length 02004006008001,0001,2001,400(a) Net Balance 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103)Water requirements (m3/Ha·103)Aquifer depth (m)Diesel 02004006008001,0001,2001,400 (b) Diesel 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103)Water requirements (m3/Ha·103)Aquifer depth (m)100% PV-Mono-Si and non-connected to the grid 02004006008001,0001,2001,400 (c) Islanding PV solar installation 00.511.522.530369120 −10 −25 −40 −55 Agricultural Surface (Ha·103)Water requirements (m3/Ha·103)Aquifer depth (m)Without PV power plant and 1km power line length connected to the grid 02004006008001,0001,2001,400 (d) Connected to the grid Figure 11: Estimated Direct Pumping Emissions (T onnes of CO 2 ). Comparison of sources Figure 12: PV estimated installation: Saïss aquifer (Meknès, Moro cco). 11 Figure 13: Cost estimated for ann ual PV installation (1300 ha): Saïss aquifer (Meknès, Moro cco). areas for agro-energy co op erativ es are also pro vided b y the prop osed metho dology based on dieren t aquifer depths and crop w ater requiremen ts. A c kno wledgemen ts This w ork is partially supp orted b y pro jects Ref. TIN2014-55024-P from the Spanish Ministry of Science and Inno v ation (including FEDER funds), and SENECA F oundation 19882-GERM-15.