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\journal{Renewable Energy \; {\url{https://doi.org/10.1016/j.renene.2019.01.077}}}


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\begin{document}
\nolinenumbers
\begin{frontmatter}
  \title{Multidimensional Analysis of Groundwater Pumping for Irrigation Purposes: Economic, Energy and Environmental Characterization \\ for PV Power Plant Integration}
  % \tnotetext[mytitlenote]{Fully documented templates
  % are available in the elsarticle package on
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  %% Group authors per affiliation:
  % \author{Elsevier\fnref{myfootnote}}
  % \address{Radarweg 29, Amsterdam}
  % \fntext[myfootnote]{Since 1880.}
  
  %% or include affiliations in footnotes:
  \author[mymainaddress]{\'A. Rubio-Aliaga}
  \author[mysecondaryaddress2]{M.S. Garc\'ia-Cascales}
  \author[mysecondaryaddress1]{J.M. S\'anchez-Lozano}
  \author[mymainaddress]{\'{A}ngel Molina-Garc\'{i}a\corref{cor1}}
  \ead{angel.molina@upct.es}
  \cortext[cor1]{Corresponding author}  
  \address[mymainaddress]{Dept. of Electrical Eng. Universidad Polit\'ecnica de Cartagena, 30202 Cartagena, Spain.} 
  \address[mysecondaryaddress1]{Centro Universitario de la Defensa. Academ. General del Aire. Universidad Polit\'ecnica de Cartagena, San Javier, Spain.}
  \address[mysecondaryaddress2]{Dept. of Electronics, Technology of Computers and Projects. Universidad Polit\'ecnica de Cartagena, 30202 Cartagena, Spain.}
  
  \begin{abstract}
    Nowadays, the agriculture sector presents relevant opportunities
    to integrate renewable energy sources as an alternative solution
    to mitigate fossil-fuel dependence and decrease
    emissions. Moreover, this sector demands a detailed review of
    energy uses and other factors that are addressed as priority
    issues in most developed countries. In this framework, groundwater
    pumping energy requirements for agriculture irrigation emerge as a
    relevant topic to be improved in terms of power demand. Actually,
    this demand is currently supplied by diesel
      equipment solutions, with relevant drawbacks such as: $(i)$ a
      large energy dependence on fossil fuels for the agricultural
      sector and $(ii)$ a lack of participation in reducing CO$_2$
      emissions.


    This paper proposes a multidimensional
      characterization to evaluate photovoltaic (PV) solar energy
      integration into groundwater pumping requirements. Alternative
      solutions are compared under economic, energy and environmental
      aspects; thus providing an extensive scenario where the considerable
      influence of multiple factors such as water needs, irrigation
      area or aquifer depth are explicitly considered. Extensive
      results based on a real Spanish aquifer and discussion about the
      solutions are also included in the paper.
%
% REVIEWER: Reorient story. I think that Spain plays a relevant role
% in the paper. Although the methodology is more or less general, it
% is very Spanish oriented. This should be acknowledged in the
% title. Also, when describing the methodology it should be mentioned
% how the methodology could be applied to other countries/contexts.
  \end{abstract}
  \begin{keyword}
    PV systems, Solar pumping, Agricultural development, Optimization
    energy requirement, Characterization of energy
      alternatives, Economic-Energy-Environment (3E) Analysis.
  \end{keyword}
\end{frontmatter}	

\section{Introduction}\label{Introduction}        
Traditionally, the agriculture sector has depended heavily on fossil
fuels in a similar way to other activities have, with a low Renewable
Energy Source (RES) integration that can lead to suffering exhaustion
\cite{corominas2010agua}. {\color{black}{This fact also affects final prices, which
are highly dependent on energy cost fluctuations.  The high fossil
fuel dependence is especially remarkable in field crops, involving
aquifer over-exploitation problems \cite{narvarte2005lessons}.}} In
addition, this high energy dependence is one of the pollution sources
responsible for emissions and the greenhouse effect
\cite{faucher2006renewable}.  Recently, Spanish energy initiatives
\cite{IDAE1120}, European policies \cite{Regla2013,DPEEERR,PPE2014},
as well as environmental \cite{COP21} and agricultural matters
\cite{feader2014} have been aimed at raising awareness by promoting a
rational use of energy and an optimal water management in the
agriculture sector. These international policies involve sustainable
development proposals for renewable energy sources and energy
efficiency \cite{lara2007escenario}. They also provide alternative
solutions to mitigate the energy dependence on fossil fuels for the
agriculture sector and environmental concerns \cite{meah2008solar}.


\begin{figure*}[tbp]
  \centering
  %\includegraphics[width=0.95\linewidth]{../PAPER/figures/aguasubref.jpg}
  \subfloat[{\color{black}{Irrigation evolution in the Spanish agriculture}}]{\label{Fig1a}\includegraphics[width=0.725\linewidth]{Fig1_b.jpg}}\\
  \subfloat[{\color{black}{Irrigation sources}}]{\label{Fig1b}\includegraphics[width=0.425\linewidth]{Fig1_a.jpg}}
  \subfloat[{\color{black}{Energy requirement evolution}}]{\label{Fig1c}\includegraphics[width=0.425\linewidth]{Fig1_c.jpg}}  
  \caption{{\color{black}{Main indicators on energy demand for groundwater pumping agriculture in Spanish case \cite{del2002plan,tamames2014estructura}.}}}
  \label{fig:Groundwater_index_energy_spain}
\end{figure*}


During recent decades, irrigation techniques have progressively
required greater and greater energy needs. For example, the energy
demanded by this sector in Spain rose by 1800\% from 1950 to 2007
\cite{corominas2010agua}, covering 20\% of the total arable land and
representing 60\% of the final agricultural production
\cite{del2002plan}. The crop area irrigated with wells currently
presents a major percentage, also in Spain, where most energy
requirements are due to pumping extraction needs
\cite{redondo2006evolucion}, see
Figure \ref{fig:Groundwater_index_energy_spain}. This situation is
similar to that in other developed countries, where groundwater
pumping energy demand was mainly covered with diesel equipment, and
subsequently with a similar percentage of electricity-based
solutions. PV solar energy for irrigation purposes has been proposed
in the specific literature as an attempt to reduce both energy
consumption as well as CO$_2$ emissions in agriculture
\cite{odeh2006influence,abdourraziq2017photovoltaic}. {\color{black}{An
    evaluation of PV-based solutions was proposed by Purohit et al.
    {\cite{purohit2005renewable}}, as an alternative to decrease
    fossil fuel dependence and reduce its influence on final prices.}}
Other studies have focused on providing water as a basic resource in
isolated rural areas, mainly to cover human needs in
non-industrialised or under-developed countries
\cite{hammad1995photovoltaic,eshraa2013renewable} such as Nepal,
Kenya, Mauritania and Morocco \cite{hamidat2003small,CLOSAS201733}.
{\color{black}{Rural communities of under-developed countries with solar pumping
installations lower than 2 kW have been also discussed in other works,
such as Erbato et al. \cite{erbato2011development}.}}
%
%REVISOR1: An illustrative example, in page 2, "As an example, the
%energy demanded by this sector in Spain rose by 1800% from 1950 to
%2007 [1], covering 20% of the total arable land and representing 60%
%of the final agricultural production [12], see Figure 1." But Figure 1
%does not exactly reflect this. This type of misunderstandings are
%observable throughout the paper.
%
%ALVARO: La imagen se ha explicado mejor, y se han añadido imágenes
%que refuerzan el estado del arte referente a la situación agraria
%respecto de la energía.
%
PV solar pumping solutions for agriculture purposes have been analysed
from the technical and economic feasibility point of view
\cite{wies2010design,dadhich2017economic}. {\color{black}{The economic
    viability of PV solutions applied to irrigation has been widely
    discussed by Foster et al. {\cite{foster2014solar}} and Odeh et
    al. {\cite{odeh2006economic}}.  Approaches to the solar-PV system
    design in line with specific technical studies on solar radiation,
    mostly applied to areas with severe water scarcity, are provided
    by Setiawan et al. \cite{setiawan2014development}. According to
    Kelley et al. \cite{kelley2010feasibility}, PV systems are
    economically feasible for small systems (less than 4000 $m^3$ and
    less than 10 $ha$), whereas larger areas require a more detailed
    study. An extensive analysis is proposed by Cuadros et
    al. \cite{cuadros2004procedure} to determine the viability of PV
    solutions for water pumping purposes for olive trees irrigation in
    a specific area, including the influence of additional factors
    such as water depth dependence, solar radiation or crop growing.}}

% REVIEWER 1. State clearly the contributions. The review of the state
% of the art is very detailed and complete. However, I miss a
% parapragh, maybe together with some bullets, that states in which
% areas/topic your paper is contributing. The general contribution is
% there, but lacks precision. The readers misses the main objective of
% the paper.

In line with the specific literature, a comprehensive review of
alternatives is necessary to ensure that efficient irrigation systems
are achieved from different points of view: water, energy, economy and
environmental concerns; analysing the PV solar energy’s integration
under different configurations
\cite{wallace2000increasing,ould2010modelling}. Therefore, new
methodologies must combine the optimisation, sizing and viability of
irrigation systems based on solar technologies, including additional
factors such as energy costs, water management and CO$_2$ emissions
\cite{glasnovic2007model}.  Moreover, recent contributions affirm
that, before changing pumping diesel facilities into solar pumping
equipment, the influence of other factors must be studied and
characterized in detail. These include water depth, parcelling grouping,
crops, connection to grid or PV technologies
\cite{foster2014solar}. Global proposals are required to integrate
renewable energies into agriculture from an extensive manner,
optimising costs, reducing CO$_2$ emissions and minimising energy
requirements \cite{ould2010modelling}. Taking into account previous
contributions, this paper addresses a multivariable extensive
characterization for groundwater pumping irrigation purposes. The main
contributions of this paper to RES integration into the
agriculture sector are as follows:
  \begin{itemize}
  \item A proposal for characterizing a group of groundwater pumping
    alternatives that considers economic, energy and environmental
    points of view.
  \item An extensive visualization of dependences with relevant
    variables, such as aquifer depth, crop water requirements,
    irrigation area sizes and water storage options.
  \item A thorough comparison of the impacts of different resources
    for pumping groundwater requirements, in order to evaluate the
    suitability of each solution depending on different parameters.
  \end{itemize}
 Additionally, the proposed characterization is applied on a real
 Spanish aquifer and crops, providing a preliminary extended view to
 meet groundwater pumping requirements by introducing PV solar-based
 installations.


%suitable and reliable inputs for Multi-Criteria Decision Making
%(MCDM) methods, which can be applied in a subsequent analysis.
%REVISOR 2: 12- The significance of using the multidimensional
%analysis on the resource optimization should be highlighted and
%compared to one dimensional analysis such as energy, environment and
%economic. Such comparison would provide insightful informations,
%promote and encourage the decision makers to adopt these kind of
%analyses.
 
%ALVARO: Se ha explicado arriba la importancia el artculo, y como en
%la mayoria de los articulos hasta le momento, se han centrado en los
%aspectos energético y económico, y como en este artículo se ha
%unificado todas las variables, bajo un estudio multidimensional que
%ayude a comprender y comparar todas las variables que están implicdas
%en el problema.



 %REVISOR 3: I think it is better to show the conclusion of
 %multiple-criteria decision analysis (MCDA)in this study. Though it
 %is currently under study by the authors, the conclusion of MCDA can
 %make the paper a more complete research.

 %(ALVARO) SE HA QUITADO CUALQUIER REFERENCIA A UN PROCESO MCDM
 %POSTERIOR

%REVISOR 1: State clearly the contributions. The review of the state
%of the art is very detailed and complete. However, I miss a
%parapragh, maybe together with some bullets, that states in which
%areas/topic your paper is contributing. The general contribution is
%there, but lacks precision. The readers misses the main objective of
 %the paper.

 %ALVARO Se ha aclarado el objetivo del articulo

The rest of the paper is structured as follows: variables to be
considered for detailed analysis in the pumping irrigation problem are
discussed in Section {\ref{sec:Variables_Description}}. The method for the 
characterization and calculation of the alternatives taking 
complementary points of view to identify optimal and efficient
alternatives is proposed in Section
{\ref{sec:Methodology}}. The case study is described
  in detail in Section \ref{sec:Case_of_Study}, as well as the 
  alternatives and configurations that meet the constraints and
  requirements for the case study. The results are presented and
discussed in Section \ref{Results}. %including alternative characterisation as preliminary data for MCDM analysis.
Finally, Section \ref{Conclusions} details the conclusion and future works.
	
	
%REVISOR2: 2- Why the references of the manuscript are not updated with recent reference? the most recent ones are published in 2015.
%ALVARO: hay tres referencias de 2017
	
\section{Multivariable Extensive Proposal: General Overview}\label{sec:Variables_Description}
 
Considering the contributions previously discussed in Section 
\ref{Introduction}, a multidimensional group of variables is selected
to characterize the pumping irrigation problem in a reliable and
extensive framework. Indeed, multiple variables have a relevant
influence on the power demanded by the groundwater pumping systems and
thus, combinations of such variables provide an initial set of options
to be considered as a general guideline for groundwater pumping
purposes. Nevertheless, and due to the large number of possible
combinations, this paper aims to filter the most relevant alternatives
and practical solutions. Figure \ref{fig:General_scheme} shows the
identified groups of variables as well as the variables to be
considered as inputs of the problem: water needs, aquifer depth and
parcelling grouping. Additionally, the figure depicts the relations
among variables and the proposed characterization process to identify
possible alternatives in a multidimensional scenario.

% REVIEWER 1. Explain the methodology with more detail. Is there any
% model behind? Equations? The steps are blurry. Using bullets and/or
% subsections could help to explain the methodology. For example,
% although Figure 4 is useless, a similar figure, workflow oriented,
% shall add value to the paper.

% Quito esta parte
% as a
%preliminary step before the subsequent application of MCDM analysis.

\begin{figure*}[tbp]
  \centering
  \includegraphics[width=.65\linewidth]{Fig2.jpg}
  \caption{Groups of variables: identification and relations for characterization of initial alternatives.}
  \label{fig:General_scheme}
\end{figure*}


% REVISOR 1: Review figures. Figure 2 does not add value to the
% discussion as Figure 3 already contains that information. Figure 3 is
% fine, but a bit messy. I already commented my opinion about
% Figure 4. Figures must be self-explanatory and mainly reinforce the
% concepts that are explained in text. Besides the font size is often
% illegible.


%ALVARO: Las antiguas imágenes 2-3-4, se han fundido en una, con la
%intención que no fuera repetitiva a lo largo del paper, y que fuera
%más clara y legible.

%REVISOR 2: 4- Caption of figure 4 is not describing the figure in a proper way. Consider modifying it.


%ALVARO: La figura 4 ha sido fusionada dentro de la 2, junto a la 3. Y
%ha sido explicada mucho mas convenientemente, explicando los
%subgrupos.


From the initial group of general variables, the proposed methodology
to characterize pumping groundwater solutions involves the
identification of alternatives and the configurations discussed in the
following subsections.

\subsection{Pumping water options} %{\paragraph{Pumping Water Options}


Firstly, a relevant issue considered in the proposed characterization
process considers water storage options. Three configurations are
taken into account by the authors to meet the different perspectives:
annual water storage, seasonal water storage and direct pumping
(without water storage). The first option usually requires large water
reservoirs, with high costs and evaporation problems. However, it does
ensure the water supply demand and uniform irrigation throughout the year, 
albeit with a low power/year ratio. The seasonal water storage option is
based on pumping water during the months prior to the irrigation
period and throughout that period. Therefore, this requires a smaller storage reservoir
 to meet water requirements, with lower evaporation
problems. However, this option also demands high energy and initial
investments, being used for a short period of time according to the
hydraulic year. The third option to be considered is based on a direct
pumping solution. Water storage is still needed as a pressure surge
reservoir, although considerably lower than in the previous options. The
crop water demand is then mostly directly provided by the
aquifer. Consequently, the power demand presents a profile similar to
the water needs. This configuration involves higher power needs than
the other options, but significantly lower water storage and
negligible evaporation problems.


\subsection{Individual vs Cooperative facilities}


In order to determine an optimal configuration for irrigation pumping
systems, the proposed methodology considers both individual and
cooperative energy alternatives. According to the irrigation
requirements, different crop areas can be preliminarily defined. In the
case study, from 1 to 2000 $ha$ are estimated as initial solutions to be
analysed, see Section \ref{sec:Case_of_Study}. Nowadays, individual
systems are very common in agriculture, since they 
provide the farmers with greater independence in terms of the method and 
amount of irrigation. Cooperative solutions usually offer
significant size reduction in RES facilities, promoting RES
integration scenarios.
%
%facing individual installations have the advantage that they
%facilitate the integration of renewable energy sources and
%significantly reduce the size of the energy installation at the
%expense of turn-based irrigation planning. In turn, there is a
%reduction in investment costs in infrastructure and reduction of
%expenses in processes, thanks to its special configuration,
%controlling water consumption with fully automated processes.  They
%can allow joint emissions of CO$_2$ to the atmosphere to be mitigated,
%through the inclusion of improvements in energy efficiency and energy
%systems that are more respectful with the environment.  However, too
%large a size could incur high pressure losses in the distribution of
%water through the hydraulic network.}  ***cita
%
\subsection{Isolated or Connected installations}


Isolated installations have some advantages in terms of versatility
and easy implementation. However, these solutions must completely
cover the energy needs (mostly oversized) required by the groundwater
pumping. Installations connected to the grid allow us to reduce
facilities, since additional power demand or deficiencies can be
supplied by the grid. For crops on an annual scale (such as the case
study), connected installations might inject any excess energy into the
grid, thus being an economic profit for farmers in comparison to isolated
installations. The costs of power lines and additional grid facilities are 
further investments that must be taken into account for these connected
installations.


\subsection{Energy Solutions}


In relation to most of the usual solutions and renewable sources
currently promoted, four main resources have been considered: diesel,
isolated PV solar power plants, power directly provided by the grid,
and PV solar installations connected to the grid under net balance
conditions. Diesel is included due to its relevance in the current
agricultural sector, being used as a mature and reliable technology
for groundwater pumping actions and other agricultural applications in
most countries. In fact, this solution is mostly used for groundwater
irrigation purposes under individual diesel
configurations. %and presents relevant drawbacks,
  %such as high CO$_2$ emissions, fossil fuel dependence and the high
  %variability of prices. Nevertheless, it is based on a mature and
  %well-known technology with relatively low investment costs, but
  %which suffers from abundant thefts that happen relatively often. To
  %overcome economy of scale drawbacks, farmers usually promote
  %cooperative diesel solutions to reduce maintenance and save fuel
  %costs. However, this represents a more concentrated source of CO$_2$
  %emissions and, although the level of emissions is reduced, it causes
  %a relevant environmental impact.
  Isolated PV solar power plants emerge as a trending solution to supply power
  and reduce both energy dependence and emissions \cite{arab1999performance}.
  %A groundwater irrigation system with PV installations comprises a
  %pump, the pipeline, an irrigation reservoir (if any), and the
  %generation system that supplies power from the PV installation in
  %order to drive water from the aquifer to the crop
  %\cite{arab1999performance}.
  %This solution %is usually accepted by the agriculture sector; it
  These present some relevant advantages, such as minor energy
  dependence, relevant energy efficiency and, in most countries,
  important subsidies. Indeed, some authors affirm that diesel
  equipment installations can be currently turned into
  individual-isolated PV installations
  \cite{correa2012efficiency}. Moreover, combinations of individual PV
  installations require less power capacity and offer different
  opportunities to the farmers to significantly reduce CO$_2$
  emissions and optimise the integration of renewables into water
  pumping requirements. Its drawbacks include the large areas required
  for PV modules in comparison with diesel equipment, as well as power
  oscillations due to solar radiation fluctuations or partial
  shadings.  For those reasons, PV solar installations connected to
  the grid are assumed as an alternative of distributed generation
  applied to the agriculture sector \cite{lingfeng2012evaluation}. The
  power demanded by the pumps can be provided by both the PV
  installation and the grid. Subsequently, water can be used directly
  for irrigation purposes or stored in a reservoir. Actually,
  individual PV installations connected to the grid can be considered
  as a cooperative internal network with electricty suppliers and
  consumers \cite{guerrero2010distributed}.
%This
%solution can provide additional income to the farmers from the surplus
%energy sales.
Nevertheless, some countries differ in the laws and regulations regarding PV 
solar facilities and the power allowed to be injected into the grid. For
example, Spain provides some requirements for PV power plant
operations as well as taxes and fees currently applied on these
installations \cite{RD9002015}. With regard to cooperative irrigation
systems, PV solar pumping is also considered as a trade-off 
between large-scale renewable integration and groundwater pumping
requirement facilities. This approach must include additional costs
for power line infrastructures and grid distributed system
requirements \cite{atzeni2013noncooperative}. Finally, power directly
supplied by the grid and without additional renewables significantly
reduces costs, although farmers depend on the grid in terms of prices
and energy dependence. %If cooperative solutions
%are considered, new power line investments and power capacity must be
%taken into account to estimate costs and grouping
%constraints. \textcolor{black}{
This alternative thus provides substantial reductions of CO$_2$
emissions in comparison with diesel approaches. However, it does not
promote the integration of renewables with a consequent poor
participation in the decreasing of fossil fuel dependence.
% }


 \subsection{Specific Facilities Configurations}


 Finally, alternatives are also characterized and divided according to
 some facilities criteria. With regard to PV solar installations, we
 also distinguish:
%Other configuration options at a more specific level of each type of
%energy facility have been considered in the study.  With the aim of
%integrating renewable energy sources, PV solar installations are
%proposed as a suitable alternative to provide energy
%%requirements. Conventional solutions nowadays are mainly focused on
%diesel equipment.
 $(i)$ {\color{black}{different PV technologies, through a comparison of such
 technologies under economy, peak power requirements or emissions;}}
 this approach has also been discussed in the specific literature
 \cite{kato2001life,bekkelund2013comparative}. In our case, the most
 common commercial solutions currently available are considered:
 Silicon Monocrystalline (Mono-Si), Polycrystalline Silicon (Poly-Si)
 and Thin-Film modules. $(ii)$ different solar tracking technologies,
 such as fixed installations, one-axis and two-axes solar tracking
 solutions. %These systems have a clear advantage, the increase of
  %electric generation potential, which are able to obtain systems that
  %maintain an optimal solar orientation throughout the day. In this
  %way, the greater the potential that can be extracted, the smaller
  %the size of the solar installation will be. In contrast, the greater
  %the number of axes, the higher the maintenance cost of these facilities.
 $(iii)$ PV installations in islanding-mode or connected to the
 grid. In reference to this last option, a relevant factor to be
 characterized is the energy pumping requirements and energy fed into
 the grid ratio. In fact, some contributions discuss investments and
 benefits when a percentage of the electricity is injected into the
 grid \cite{lingfeng2012evaluation,romerospanish,RD9002015}. The
 proposed methodology then includes some scenarios depending on the
 percentage of participation with the grid: 25\%, 50\%, 75\% and 100\%
 of PV solar power injected into the grid.  Finally, energy pumping
 requirements directly supplied by the grid is a very realistic
 situation which is also included among our
 alternatives. {\color{black}{Different options are thus considered,
     depending on the distance between the crops and the power
     system. According to the case study describes in detail in
     Section \ref{sec:Case_of_Study}, three different distances
     between the crops and the grid have been considered for
     simulation purposes: 1 km, 3 km and 5 km. In fact, they are the
     most common distances by considering the aquifer real location,
     the crop layout and the power distribution system. Such
     alternatives are discussed and characterized in detail in the
     following section.}}


\section{Multidimensional Characterization of Alternatives}\label{sec:Methodology}



From the extensive group of variables described in Section
{\ref{sec:Variables_Description}}, a characterization of alternatives
is then proposed in the current section under different perspectives.
A global assessment of such alternatives is thus given by the proposed
methodology. An initial range of the variables to be characterized is
selected from specific crop areas, aquifer depths and water
requirements. Additional factors ---such as energy resources, water
storage options and cooperative levels, see
Figure \ref{fig:General_scheme}--- are also considered under realistic
scenarios \cite{kelley2010feasibility}\cite{SUDHAKAR198071}.



The proposed methodology considers simultaneously four perspectives
with the aim of characterizing the different alternatives: technical,
economic, energy and environmental perspectives. From this
complementary analysis, efficient and optimised
alternatives can be identified. Subsequently, representative solutions
of those combined factors are selected.
Figure {\ref{fig:analysis_variables_characterization_alternatives}}
summarises the proposed methodology to characterize the alternatives
based on the extensive group of variables and perspectives considered
in this work. A four-dimensional representation is proposed by the
authors to visualise the different perspectives.  Further information
and examples of this visualisation proposal can be found in Section
\ref{Results}.


\begin{figure}[tbp]
  \centering
  \includegraphics[width=0.5\linewidth]{Fig3.png}
  \caption{Analysis of variables and characterization of alternatives}
  \label{fig:analysis_variables_characterization_alternatives}
\end{figure}


%%sección calculos
%
%\textcolor{black}{The multidimensional calculation part (economic,
%  energy, environmental and water) of the alternatives has the
%  objective of estimating the values ​​associated with these dimensions
%  (euro/ha, kW/ha, TnCO$_2$/ha, m$^3$ evaporated/ha). The calculation
%  process is shown in (FIGURE).}

% 2018-06 QUITO LA NOMENCLATURA
%\begin{figure}[tbp]
%  \centering
%  \includegraphics[width=1 \linewidth]{../IMAGENES/nomenclatura1.jpg}
%  \caption{Situation of Case of Study. Aquifer 23. Castilla-La Mancha (Spain).} \\ {\scriptsize \textbf{Fuente:} Own Elaboration}
%  \label{fig:eq1}
%\end{figure}
%
%\begin{figure}[tbp]
%  \centering
%  \includegraphics[width=1 \linewidth]{../IMAGENES/nomenclatura2.jpg}
%  \caption{Situation of Case of Study. Aquifer 23. Castilla-La Mancha (Spain).} \\ {\scriptsize \textbf{Fuente:} Own Elaboration}
%  \label{fig:eq2}
%\end{figure}

%explicar calculos
	
According to
Figure {\ref{fig:analysis_variables_characterization_alternatives}},
% ECONOMIC
economic cost criteria are usually a relevant factor in the final
decision. This is in fact a crucial parameter to be considered, as
pointed out in \cite{Foster20141431,purohit2007financial}. The costs
of the initial investment depends on each alternative, considering
different water reservoir solutions \cite{mayer2015current}. Annual
benefits and costs of maintenance and operating expenses are also
considered. In fact, costs of equipment are included in accordance
with current prices \cite{clavier2013economic, barlow1993solar,
  IDAE1,Irena1}.
% ENERGY
Power requirements are mainly based on facilities for groundwater
pumping and water storage
\cite{roy2009water,moradi2007reservoir,GLASNOVIC2007904}.  The energy
perspective thus implies the comparison of different alternatives in
terms of installed power and required energy according to the
corresponding water requirements \cite{abu2011design}. Additionally,
water pumping for different depths under individual or cooperative
approaches also has an important impact on the energy needs
\cite{kelley2010feasibility}. An estimation of the total required
energy thus depends on the depth of the aquifer level and the crop
water demand
\cite{argaw1996evaluation,goyena2009sizing,markvart2006pv}. Other
factors, such as hydraulic system pressure
\cite{ould2010modelling,gallaher2009estimating} and hydraulic network
are also considered \cite{arab1999performance}. For a comparison
between alternatives, the power required by the pump is first
estimated ($P_p$),
\begin{equation}
  P_p = \frac{H_t \cdot Q_{mx} \cdot \rho \cdot g}{\eta_{MP}}
\end{equation}
{\color{black}{where $H_t$ is the total hydraulic head ($m$)}}, $Q_{MX}$ the maximum volume
flow rate ($m^3/s$), $\rho$ the water density ($kg/m^3$), $g$ the
earth gravitational acceleration ($m/s^2$) and $\eta_{MP}$ the pump
efficiency (\%). The rate power is then determined per hectare ($kW/ha$)
depending on the source. For a diesel equipment ($P_d$),
\begin{equation}
 P_d = \frac{P_p \cdot K_d}{\eta_d}
\end{equation}
{\color{black}{where $K_d$ is the coefficient majority diesel equipment (usually 1.2)}}
and $\eta_{d}$ the diesel equipment efficiency (\%). In a similar way,
for solutions connected to the grid ($P_g$),
\begin{equation}
 P_g = {P_p \cdot K_g}
\end{equation}
{\color{black}{where $K_g$ is the coefficient majority electric contract (usually 1.1).}} 
Finally, for PV solar installations ($P_{PV}$),
\begin{equation}
P_{PV} = \frac{E_{con} \cdot G_{CEM}}{G_{dm(\alpha,\beta)} \cdot PR}
\end{equation}
where $E_{con}$ is the energy consumption ($kWh/day$), $G_{CEM}$ is
assumed as 1$kW/m^2$, $G_{dm(\alpha,\beta)}$ is the average monthly
value of the daily irradiation on the horizontal surface
($kWh/m^2 \cdot day$) and $PR$ is the performance ratio of the PV
installation.


Emissions of CO$ _2$ for the different technologies are estimated
according to previous contributions
\cite{change2002ipcc,fthenakis2007greenhouse}. The alternatives are
the following: $(i)$ technologies based on fossil fuels (diesel);
$(ii)$ alternative exclusively supplied by the grid; and $(iii)$
isolated and connected to the grid PV power plants
\cite{raugei2005energy,fthenakis2006photovoltaics,kato2001life,sims2003carbon}. 
Emissions are determined in terms of averaged life cycle energy
consumption per hectare and considering a standard year
($TnCO_2/ha \cdot year$). According to the aim of this paper, initial CO$_2$
emissions for assembly and hydraulic network construction have been
excluded from the analysis.
%
% REVISOR3 Why the energy consumption and CO2 emissions for both the
% assembly and the construction process can be excluded? Could you
% please explain it in the paper? If possible, Life cycle energy
% consumption and CO2 emission will be more reasonable. (alvaro) Se
% han tenido en cuenta solamente las emisiones de CO2 de la
% infraestructura energética.
%
% WATER  - - - - - -
%
%The hydric aspect calculation has also been considered. In this case,
%the criterion that is taken into account is the evaporation of the
%surface of the systems that have an open accumulation deposit. The
%calculation process of this part has been carried out through the
%values ​​of the surface exposed in the deposits and the annual local
%evaporation data, taken daily. Obviously, the direct pumping
%alternative is more interesting in this case since its evaporation
%values ​​are zero, prior to any calculation.


%\begin{figure}[tbp]
%  \centering
%%  \includegraphics[width=0.95\linewidth]{../IMAGENES/calculos.jpg}
%  \caption{Multidimensional calculation process of energy alternatives for irrigation of groundwater. {\bf{FALTA!!!!!}} } % \\ {\scriptsize \textbf{Fuente:} Own Elaboration}}
%\label{fig:calculos_ecuaciones}
%\end{figure}


% REVISOR 1: Explain the methodology with more detail. Is there any
% model behind? Equations? The steps are blurry. Using bullets and/or
% subsections could help to explain the methodology. For example,
% although Figure 4 is useless, a similar figure, workflow oriented,
% shall add value to the paper.
%
% ALVARO En el apartado 2 se explica el modelo seguido, en el apartado
% 3 las ecuaciones se ha ordenado y aclardo tanto la metodologia usada
% como el procso de calculo, usando imagenes mas calras
%
%2018-07-20 HASTA AQUI Ok !!!!!!!!!!!!!!!

\section{Case Study}\label{sec:Case_of_Study}


The proposed methodology is a general-purpose solution which can be 
applied on different locations and crops. In order to evaluate the
suitability of this characterization, an agricultural area located in
the Region of La Mancha (Spain) has been selected. The irrigation of
this area depends on Aquifer 23 \cite{ac23a}, located in the
center of this region and in charge of providing water for residential
and irrigation purposes \cite{sanz1999irrigated}. The case study
covers an extensive area (over 5500 km$^2$) and subsequently, crops
and water requirements on the land vary significantly. Nevertheless,
different policies and actions have promoted a massive water
extraction for decades. Figure \ref{fig:Situation_Aquifer23_Spain} shows
the location and shape of this aquifer.




With regard to the agricultural potential, there is a large
concentration of vineyards, accounting for over 60\% of the
surface area. The rest of the crops are mainly based on different fruits and
vegetables in small orchards. The kind of crops has a relevant
influence on the amount of water to be extracted from the aquifer
\cite{moradi2007reservoir}. Therefore, it is assumed that the amount
of water demanded by each agricultural sector varies from 1500
$m^3/year$ for vineyards up to 8000 $m^3/year$ for fruits, cereals and
vegetables. In terms of climate, the region is considered to be semi-arid
Mediterranean Continental \cite{aemet2011atlas}, with high solar
radiation levels and an average annual precipitation ranging 
between 320 $mm/m^2$ (dry years) and 460 $mm/m^2$ (wet year). In
addition, the aquifer presents important depth variability between the
different aquifer zones, which significantly modifies the energy
requirements for each
crop. Figure \ref{fig:Average_Annual_Solar_Radiation_Level_Aquifer23}
summarises both the annual solar radiation values as well as the groundwater
level for the selected aquifer.


\begin{figure}[tbp]
  \centering
  \includegraphics[width=0.9995\linewidth]{Fig4.jpg}
  \caption{Situation of Case of Study. Aquifer 23. Castilla-La Mancha (Spain).} %\\ {\scriptsize \textbf{Fuente:} Own Elaboration}}
  \label{fig:Situation_Aquifer23_Spain}
\end{figure}


\begin{figure*}[tbp]
  \centering
  \includegraphics[width=0.95\linewidth]{Fig5.jpg}
  \caption{Average Annual Solar Radiation and Phreatic level of Aquifer 23. Castilla-La Mancha (Spain) \cite{ac23a}.}
  \label{fig:Average_Annual_Solar_Radiation_Level_Aquifer23}
\end{figure*}

As was discussed in Section \ref{sec:Case_of_Study}, the proposed
methodology includes both individual and cooperative alternatives to
minimize costs and optimise facilities. An initial matrix combining
water depth, agricultural cooperative areas and water requirements is
proposed to characterize energy, economic and environmental criteria
for each scenario. This multidimensional analysis allows us to
visualize each solution in a very extensive way, depending on the
specific characteristics of crops and the aquifer properties. In this
case, and according to the aquifer characteristics ---see
Figure \ref{fig:Average_Annual_Solar_Radiation_Level_Aquifer23}, four
different depth values are considered: 10, 25, 40 and 55 metres.  In
terms of cooperative scenarios, agricultural areas from 1 to 2000 $ha$
have been considered in this case study. Regarding water requirements 
(per averaged year), seven different values are selected: 1500, 3000,
4500, 6000, 7500, 9000 and 10500 $m^3/ha$. Ranges from these variables
are selected to analyze real scenarios according to the aquifer and
agricultural conditions. The methodology allows us to modifiy these
ranges depending on the specfic case study.

% ESTA PARTE LA QUITO Y PONGO UNA FRASE ANTES QUE RESUMA ESTE PUNTO.
%However, due to restrictions in the extraction of water and that some
%cases are difficult to reach due to agronomic and hydrogeological
%reasons (for example, it is difficult to occur for the extreme case of
%extracting 10,500 m$^3$/ ha, from a 40 m deep well , to irrigate 2,000
%ha) have been limited to the most feasible and easier to apply within
%the surface of the aquifer.




%REVISOR 2: 5- References for figure 5 and 6 are required to be incorporated in the figures captions. 
%ALVARO: YA TIENEN REFERENCIA O DE DONDE HAN SALIDO


%\begin{figure}[tbp]
%  \centering
%  \includegraphics[width=0.7\linewidth]{../IMAGENES/Modulos.jpg}
%  \caption{Characteristics of different PV-Solar Modules}
%  \label{fig:Characteristics of different PV-Solar Modules}
%\end{figure}



%2018-07-06 HASTA AQUI Ok !!!!!!!!!!!!!!!

       	
\section{Results}\label{Results}


By considering the proposed multidimensional analysis described in
Section \ref{sec:Methodology} as well as the case study
discussed in Section \ref{sec:Case_of_Study}, different alternatives
are characterised and compared in terms of economic, energy and
environmental criteria. 
%
% ESTO YA LO HAS DICHO ANTES
%Economic criteria involve costs, estimated incomes and expected
%expenses to determine the economic viability of each alternative. The
%energy analysis gives information regarding installations and grid
%requirements. From the environmental point of view, CO$_2$ emissions
%are estimated depending on the technology and source selected. Prices
%correspond to current investments for common facilities and equipment
%in Spain. Installations are also determined by considering Spanish
%requirements in terms of seismic, electrical and civil norms within
%the agricultural sector. Solar radiation data are taken monthly over a
%period of 10 years to forecast the solar resource.
%
%By considering the case study, the average agricultural surface is 3.2
%ha. These data are taken into account for the design of the hydraulic
%irrigation system. \textcolor{black}{
%
The characterization process only considers a reduced number of
alternatives and configurations, which are the most representative and
realistic scenarios according to the water crop requirements and the
aquifer characteristics. In terms of PV power plants, only results for
Mono-Si modules have been represented and 100\% participation is
considered for PV installations connected to the grid. For groundwater
pumping solutions directly connected to the grid, different power line
length scenarios have been estimated, including 1, 3 and 5 $km$ of power
lines. However, for the selected figures included in the paper, the 1 $km$
power line length is considered as representative of the case
study. Therefore, a complete characterisation of scenarios has then
been carried out by the authors, showing the most
representative alternatives in this section.
% QUITO ESTA MENCION A LOS MCDA - - - - - - - - - - - - - - - - - - -
%Nevertheless, the global group of solutions and options are available
%for subsequent works, such as MCDM or multiple-criteria decision
%analysis (MCDA) that is currently under study by the authors.


\begin{figure*}
  \centering
  \subfloat[Net Balance]{\scalebox{1.1}
    {\includegraphics{CostSeasonalNetBalance.pdf}\label{fig:CostSeasonalNetBalance}}
  }
  \subfloat[Diesel]{\scalebox{1.1}
    {\includegraphics{CostSeasonalDiesel.pdf}\label{fig:CostSeasonalDiesel}}
  }\\
  \subfloat[Islanding PV solar installation]{\scalebox{1.1}
    {\includegraphics{CostSeasonalPVIslanding.pdf}\label{fig:CostSeasonalPVIslanding}}
  }
  \subfloat[Connected to the grid]{\scalebox{0.45}
    {\includegraphics{CostSeasonalGrid.pdf}\label{fig:CostSeasonalGrid}}
  }
  \caption{Estimated Seasonal Pumping Cost (Euro). Comparison of sources}%
  \label{fig:cost_seasonal_pumping_euros}%
\end{figure*}


\begin{figure*}
  \centering
  \subfloat[Net Balance]{\scalebox{1.1}
    {\includegraphics{CostDirectNetBalance.pdf}\label{fig:CostDirectNetBalance}}
  }
  \subfloat[Diesel]{\scalebox{1.1}
    {\includegraphics{CostDirectDiesel.pdf}\label{fig:CostDirectDiesel}}
  }\\
  \subfloat[Islanding PV solar installation]{\scalebox{1.1}
    {\includegraphics{CostDirectPVIslanding.pdf}\label{fig:CostDirectPVIslanding}}
  }
  \subfloat[Connected to the grid]{\scalebox{0.45}
    {\includegraphics{CostDirectGrid.pdf}\label{fig:CostDirectGrid}}
  }
  \caption{Estimated Direct Pumping Cost (Euro). Comparison of sources}%
  \label{fig:cost_direct_pumping_euros}%
\end{figure*}


\begin{figure*}
  \centering
  \subfloat[Net Balance]{
    {\includegraphics[scale=0.25]{PowerSeasonalNetBalance.png}\label{fig:PowerSeasonalNetBalance}}
  }
  \subfloat[Diesel]{
    {\includegraphics[scale=0.25]{PowerSeasonalDiesel.png}\label{fig:PowerSeasonalDiesel}}
  }\\
  \subfloat[Islanding PV solar installation]{
    {\includegraphics[scale=0.25]{PowerSeasonalPVIslanding.png}\label{fig:PowerSeasonalPVIslanding}}
  }
  \subfloat[Connected to the grid]{
    {\includegraphics[scale=0.25]{PowerSeasonalGrid.png}\label{fig:PowerSeasonalGrid}}
  }
  \caption{Estimated Required Seasonal Pumping Power (kW). Comparison of solutions}%
  \label{fig:power_seasonal_pumping_kW}%
\end{figure*}


{\color{black}{Figure \ref{fig:cost_seasonal_pumping_euros} and
    \ref{fig:cost_direct_pumping_euros} depicts the different
    alternatives, in terms of costs (in Euro), depending on seasonal
    pumping or direct pumping. Ranges previously selected for aquifer
    depths (1 to 55 $m$ depth), water requirements (1.5 to 10.5
    $m^3/Ha \cdot 10^3$) and cooperative agricultural areas (1 to 2000
    $Ha$) have been considered, see Section
    {\ref{sec:Case_of_Study}}. From the results, the larger
    agricultural area and water requirements, the higher costs
    required by all sources. For example, and considering net balance
    and direct pumping, 5.4 $\cdot 10^6$ Euro is the cost for
    2000$Ha$, 1500 $m^3 /Ha \cdot 10^3$ and 40 $m$ depth; whereas 2.03
    $\cdot 10^6$ Euro is the cost for 1000$Ha$, 1500
    $m^3 /Ha \cdot 10^3$ and 40 $m$ depth.  An installation direclty
    connected to the grid ---without diesel solution neither PV power
    plant--- gives the lowest costs. However, this solution can't be
    implemented on remote areas whithout grid connection or when the
    power line length exceeds several km. The diesel equipment costs
    account for approximately half of the PV power plant costs, but
    the emissions are clearly higher as well as the energy dependence.
    Regarding seasonal and direct costs, the later are initially
    higher, though seasonal costs would be increased if additional
    installations related to reservoir purposes were included as
    well. Another relevant point for future works concerns the grid
    benefits and market potential generated through the sale of
    surplus electricity from the PV installations. This objective is
    beyond the scope of the present characterisation analysis and is
    currently under study by the authors.}}


\begin{figure*}
  \centering
  \subfloat[Net Balance]{
    {\includegraphics[scale=0.25]{PowerDirectNetBalance.png}\label{fig:PowerDirectNetBalance}}
  }
  \subfloat[Diesel]{
    {\includegraphics[scale=0.25]{PowerDirectDiesel.png}\label{fig:PowerDirectDiesel}}
  }\\
  \subfloat[Islanding PV solar installation]{
    {\includegraphics[scale=0.25]{PowerDirectPVIslanding.png}\label{fig:PowerDirectPVIslanding}}
  }
  \subfloat[Connected to the grid]{
    {\includegraphics[scale=0.25]{PowerDirectGrid.png}\label{fig:PowerDirectGrid}}
  }
  \caption{Estimated Required Direct Pumping Power (kW). Comparison of solutions}%
  \label{fig:power_direct_pumping_kW}%
\end{figure*}



{\color{black}{Figure \ref{fig:power_seasonal_pumping_kW} and
    \ref{fig:power_direct_pumping_kW} show the power required for the
    different alternatives ---seasonal pumping and direct pumping---
    in terms of aquifer depths (1 to 55 $m$ depth), water requirements
    (1.5 to 10.5 $m^3/Ha \cdot 10^3$) and cooperative agricultural
    areas (1 to 2000 $Ha$). These alternatives are characterised and
    compared taking into account real scenarios from the Spanish
    aquifer and the crops currently available in this area. In both
    cases (seasonal and direct pumping), diesel equipment requires
    less power than the rest of sources. As an example, and
    considering a direct pumping scenario, 782.2$kW$ is the diesel
    power for 1200$Ha$, 1500$m^3 /Ha \cdot 10^3$ and 25$m$ depth;
    whereas 1006.2$kW$ is the PV power plant required by the same
    conditions. Therefore, from an economic and power point of view,
    diesel solution would be initially the selected option. However,
    and as was previously discussed, relevant emissions and energy
    dependence should be also considered.  In a similar way to the
    previous cost estimation analysis, no additional facilities are
    considered for the seasonal scenario and grid benefits generated
    through the sale of surplus electricity from the PV installations
    are not also considered.}}

\begin{figure*}
  \centering
  \subfloat[Net Balance]{
    {\includegraphics{EmissionSeasonalNetBalance.pdf}\label{fig:EmissionSeasonalNetBalance}}
  }
  \subfloat[Diesel]{
    {\includegraphics{EmissionSeasonalDiesel.pdf}\label{fig:EmissionSeasonalDiesel}}
  }\\
  \subfloat[Islanding PV solar installation]{
    {\includegraphics{EmissionSeasonalPVIslanding.pdf}\label{fig:EmissionSeasonalPVIslanding}}
  }
  \subfloat[Connected to the grid]{
    {\includegraphics{EmissionSeasonalGrid.pdf}\label{fig:EmissionSeasonalGrid}}
  }
  \caption{Estimated Seasonal Pumping Emissions (Tonnes of CO$_2$). Comparison of sources}%
  \label{fig:emissions_seasonal_pumping_tnCO2}%
\end{figure*}


\begin{figure*}
  \centering
  \subfloat[Net Balance]{
    {\includegraphics{EmissionDirectNetBalance.pdf}\label{fig:EmissionDirectNetBalance}}
  }
  \subfloat[Diesel]{
    {\includegraphics{EmissionDirectDiesel.pdf}\label{fig:EmissionDirectDiesel}}
  }\\
  \subfloat[Islanding PV solar installation]{
    {\includegraphics{EmissionDirectPVIslanding.pdf}\label{fig:EmissionDirectPVIslanding}}
  }
  \subfloat[Connected to the grid]{
    {\includegraphics{EmissionDirectGrid.pdf}\label{fig:EmissionDirectGrid}}
  }  \caption{Estimated Direct Pumping Emissions (Tonnes of  CO$_2$). Comparison of sources}%
  \label{fig:emissions_direct_pumping_tnCO2}%
\end{figure*}

{\color{black}{Figure \ref{fig:emissions_seasonal_pumping_tnCO2} and
    \ref{fig:emissions_direct_pumping_tnCO2} summarise the CO$_2$
    emissions for the different alternatives. This environmental
    characterization allows us to visualise and compare how
    sustainable each solution is in terms of tonnes of CO$_2$. The
    diesel equipment obviously gives off the highest emissions,
    considerably greater than solutions based on PV installations or
    even for approaches which are connected to the grid. For example,
    for a seasonal pumping scenario, diesel equipment has 243.58
    Tonnes of CO$_2$ for 1200 $Ha$, 1500 $m^3 /Ha \cdot 10^3$ and 40
    $m$ depth; whereas the PV power plant has 9.0 Tonnes of CO$_2$ for
    the same conditions. Clearly, from the emissions and energy
    dependence, diesel equipment is not a suitable solution to be
    considered by the agricultural sector. However, from an economic
    analysis, the diesel solution is considerably cheaper than the
    other resources and, for this reason, an extensive and
    multidimensional characterisation is then necessary to be
    conducted before selecting an optimal solution. Consequently, the
    proposed framework provides an extensive characterisation of each
    alternative for each realistic scenario. As was previously pointed
    out, the proposed methodology can be applied to different
    locations and areas. Therefore, this alternative characterization
    aims to provide an extensive analysis of a more sustainable
    scenario with PV power plant integration.}}


{\color{black}{As an additional example, the proposed methodology has
    been applied on the Saiss aquifer located in the region of
    Fez-Meknes (Morocco). This aquifer is mainly supported by
    rainwater infiltration contributions. Nowadays, the aquifer
    provides an annual irrigation demand between 275 and 400 million
    $m^3/year$, suffering an intesive agriculture demand and covering
    relevant drinking water necessities since the 1980s. Subsequently,
    the aquifer presents a water deficit situation, without pumping
    constraints and an average water demand between 3500 $m^3/Ha$ and
    5600 $m^3/Ha$. Further information can be found in
    {\cite{acmaroc,Amraoui2005,ID3}}.
    Figure \ref{fig:Exempleapplicationesc} summarizes the application of
    the proposed methodology on this aquifer. In this case, the
    results for PV installations are depicted and compared for
    different water requirements, aquifer depths and agricultural
    areas. The proposed characterization also allows us to compare and
    estimate solutions with specific agricultural areas; providing
    both scalability and flexibility properties. With this aim, PV
    installation costs are compared for 1300 $Ha$ of crops. In this
    area, the aquifer depth is between 35 and 45
    $m$. Figure \ref{fig:Exempleapplicationmoroco} shows these costs for
    annual PV solar pumping requirements.}}


\begin{figure*}[tbp]
  \centering
  \includegraphics[width=.9\linewidth]{exampleaplicacion2.png}
  \caption{PV estimated installation: Saïss aquifer (Meknès, Morocco).} % \\ {\scriptsize 1250 ha of crops}.}% \\ {\bf{*** falta esta imagen}}}
  \label{fig:Exempleapplicationesc}
\end{figure*}	


\begin{figure*}[tbp]
  \centering
  \includegraphics[width=.9\linewidth]{saiss_ejem.png}
  \caption{Cost estimated for annual PV installation (1300 ha): Saïss aquifer (Meknès, Morocco).} 
  \label{fig:Exempleapplicationmoroco}
\end{figure*}


\section{Conclusion}\label{Conclusions}


A multidimensional economic, energy and environmental analysis is
proposed and assessed to characterise the groundwater pumping
problem. Different alternatives can be compared, including
conventional solutions based on diesel equipment, grid connection and
renewable promotion focused on PV solar integration. A real Spanish
aquifer mainly used for agricultural purposes has been used to assess
the proposed characterisation methodology. By considering current
crops, aquifer depths and agricultural water requirements the
alternative resources are characterised and visualised from two
scenarios: seasonal pumping requirements and direct pumping
requirements.
	

From the results, including seasonal and direct pumping scenarios for
the case of cooperative facilities, diesel equipment provides
considerably lower investment costs in comparison to the net balance
solution or islanding PV solar installation. In fact, the diesel
approach is currently one of the most commonly selected solutions by
the agriculture sector. However, diesel equipment presents very high
CO$_2$ emissions in comparison to the power system solution or PV
solar installations. Therefore, alternatives based on renewable energy
sources should be promoted by governments to decrease CO$_2$ emissions
and minimise fossil fuel dependence in the agriculture sector. This
analysis can be extended by including other additional variables, such
as investment costs in irrigation infrastructures (reservoir) and
annual electricity or fuel costs (diesel). According to the results
and the characterization of alternatives, this methodology presents a
low computational time cost and it is suitable to be aaplied on
different agricultural areas and scenarios.  In addition, an
estimation of the optimal areas for agro-energy cooperatives are also
provided by the proposed methodology based on different aquifer depths
and crop water requirements.


\section*{Acknowledgements}
This work is partially supported by projects Ref. TIN2014-55024-P from
the Spanish Ministry of Science and Innovation (including FEDER
funds), and SENECA Foundation 19882-GERM-15.

%\section*{References}

\bibliography{mybibfile_JM,mybibfile}

\end{document}

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