Sustainable Energy Transition in Island Systems with substantial RES
and Electricity Storage
EMMANUEL KARAPIDAKIS1, SOFIA YFANTI2, CHRISTOS KOUKNAKOS3
1Energy, Environment and Climate Change Institute,
Hellenic Mediterranean University,
Estavromenos Campus 71410 Heraklion,
GREECE
2 Department of Mechanical Engineering
Hellenic Mediterranean University
Estavromenos Campus 71410 Heraklion
GREECE
3Department of Electrical and Computer Engineering
Hellenic Mediterranean University
Estavromenos Campus 71410 Heraklion
GREECE
Abstract: - A sustainable power system will require an extensive reliance on renewable energy sources (RES).
Taking into account the fact that a significant share of RES has already been deployed, either on large or a
small scale, today’s most crucial issue is their further participation in an extensive and secure power generation
expansion to cover the large future energy demand. Although there is the needed capacity of RES that could
cover the corresponding demand, the current power system structure and operation emerge limitations, which
hold back their further exploitation. The introduction of energy storage systems, such as pump storage and
batteries can help the further exploitation of the needed RES by balancing the current load demand and the
intermittent power flow of photovoltaics and wind turbines. This paper analyses a recently interconnected
island power system operation, as a representative case study, and demonstrates benefits, such as CO2
emissions reduction, and obstacles emerged by ultra-high penetration of RES. This ultra-high share of RES is
technically feasible, through strong interconnections and electricity storage systems.
Key-Words: - Energy Planning, Energy Transition, Renewable Energy Sources, CO2, Sustainability, Electricity
Storage.
Received: March 29, 2023. Revised: October 25, 2023. Accepted: December 19, 2023. Published: December 31, 2023.
1 Introduction
Ensuring energy security and reducing energy
dependency has been an integral part of the
European Union, as it steadily moves towards a
sustainable energy transition, through legislative and
funding schemes, such as the European Green Deal
[1], the Paris Agreement or the latest European
Climate Law, where energy-related issues are
closely linked to the climate agenda, [2]. Hence, as
the EU rethinks its goals of decarbonizing the
economy and energy transition, [3], a significant
part of this transition is associated with the
challenging task of transforming the energy sector,
because it is one of the most important emitters of
environmental pollutants, [4]. Climate change
objectively requires the attainment of sustainability.
Thus, reducing too many negative impacts such as
CO2 emissions is a way to achieve the energy
transition. Energy production and consumption are
considered cornerstones for the reduction of
greenhouse gas emissions. Nevertheless, reducing
the carbon intensity of the energy sector could be
achieved through the implementation of measures
such as increasing energy efficiency or expanding
the use of renewable energy sources, [5].
Thereupon, the transformation of the power
systems sector requires the change of existing
energy balance as well as the introduction of new
technologies and architectures, [6], [7].
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Indicatively, advanced renewable energy
harvesting technologies are under investigation,
more often with an emphasis on solar and wind
energy as prime movers, [8], while enhancements to
the power grid are also mandated to host massive
amounts of such energy sources, [9], [10], [11],
which are usually distributed into the grid in
contrast to the legacy technology of centralized
large power plants. Alternatively, and since the
enhancement of the power grid may correspond to
an expensive or geographically infeasible task,
novel architectures and control methodologies for
power systems are investigated in the context of
distributed networks and smart grids, whose smart
operation can potentially alleviate such bottlenecks,
[12], [13], [14].
An additional consideration lies in the
electrification of other energy carriers, such as the
heating and transportation sectors, to neutralize their
footprint, as they are considered important polluters
as well (Table 1).
Table 1. Sources of Green House Gas Emissions
(C2es.org & Statista.com)
Emissions (%)
Sources
2013
Electricity & Heat
31
Transportation
15
Agriculture
11
Manufacturing
12
Further development of these sectors is expected
to vastly increase the load that the electric power
system needs to accommodate. However, energy use
produced by non-renewable resources causes carbon
dioxide (CO2) emissions to increase, [15]. And even
though a reduction in energy consumption may
affect CO2 emissions, [16], it may also hinder
economic growth, [17], [18], as any discussion of
changes in CO2 emissions is interconnected with
economic changes, and economic growth, [19].
Hence appropriate policies are needed for energy
efficiency like energy security, [20] and
sustainability. As the energy security issues
attracted the attention of global policymakers, they
agreed that energy consumption pattern requires an
energy transition, [21], [22]. Thereupon, both smart
grids function for effectively managing the power
system operation, but also increase renewable
energy production for neutralizing the
environmental footprint of the energy production
process, which are crucial in this context.
According to the above arguments, the increase
in renewable energy production in a power system is
of crucial importance. Hence, a challenge arises in
calculating the hosting capacity (HC) of each area in
a power system, so that the amount of renewable
energy sources (RES) that can be interconnected is
known to the corresponding regulators and
operators, [8], [23]. Traditionally, the main reasons
limiting the RES hosting capacity have to do with,
i) conventional power plant operation,
ii) thermal and short circuit limitations at the
distribution network and
iii) voltage and frequency regulation, [24].
To quantify the above-expressed problem,
various techniques have been proposed, with most
of them focusing on iterative simulation, [23], while
others also consider streamlined and stochastic
approaches, [24], [25], [26]. Moreover, as voltage
violations are one of the main hosting capacity
limitations functions, the capability of voltage-
related ancillary services provision by smart
inverters has been reviewed in [11], [26]. As it is
evident, in most of the projects, the hosting capacity
is tackled from the distribution system operation
point of view, which of course is reasonable due to
the weaker operation of the grid as well as the
underlying spatial issues. Nevertheless, important
considerations could be also concluded from the
transmission system operation point of view. In this
regard, [27], discussed the transmission side HC
based on transient stability considerations, while
short circuit currents have also been discussed in
[28], [29]. Moreover, transmission and distribution
system co-simulations were performed in [30], to
take into consideration the limitations that arise
from the transmission system operation.
European Islands, based on the previous
statements and considering their geographical and
natural position represent a key actor with specific
characteristics in the implementation framework of
a sustainable energy policy. More precisely, three
main dimensions have been identified by the
European Commission for successful energy
planning, which is security of supply, sustainability,
and competitiveness. Furthermore, several obstacles
and technical restrictions are evident in an island's
energy sector, such as higher total costs, fluctuations
in the price, and insecurity of supply. However,
these disadvantages can be outweighed by inherent
advantages, especially by the utilization of
renewable energy technologies, thanks to their
relatively high wind and sun exposure, [31]. This
potential should be further exploited to investigate
the operation and planning limitations and estimate
the possible solutions, [32].
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2 Materials and Methods
Renewable energy sources for electricity generation
have several advantages over conventional
generation technologies. Reduction of greenhouse
gases (GHG) that contribute to global climate
change and local air quality is one of the major
advantages of RES utilization. Additionally, they
reduce the risk of fossil-fuel price fluctuations,
spread the energy mixture, and decrease the
electricity sector dependency. These advantages can
enhance an island’s efforts for sustainable power
generation.
Greece’s national target, according to the EU
Directive on Renewables, of 18% of renewables in
the final energy consumption in 2020 has been
exceeded by almost 4 pp (21,7% in 2020), while the
share of renewable electricity was set at 40% (36%
achieved in 2020) [33]. Under its National Energy
Climate Plan (NECP), the country targets a 35%
share of renewables in final energy consumption in
2030, including 60% for electricity, 40% for heating
and cooling, and 14% for transport. In the NECP, a
target of 2 GW of offshore wind is set for 2030 [33],
transforming the islands’ areas to the mean for its
achievement.
According to the literature, [34], [35] isolated or
weak connected power systems are considered all
the small and medium-size power systems where no
interconnection exists with conterminous and/or
continental systems. These power systems face
increased problems related to their operation and
control, [36], [37]. In most of these systems,
dynamic performance is a major concern, since
mismatches in generation and load and/or unstable
system frequency control might lead to system
failures, easier than in interconnected systems.
Renewable Energy Sources and especially wind
power exploitation appear particularly attractive.
However, the integration of a substantial amount of
wind power in isolated systems needs careful
consideration, to maintain a high degree of
reliability and security of the system operation, [38],
[39]. The main problems identified concern
operational scheduling (mainly unit commitment)
due to high production forecasting uncertainties, as
well as steady-state and dynamic operating
problems. These problems may considerably limit
the amount of wind generation that can be
connected to the island’s systems, increasing the
complexity of their operation. Thus, next to the
more common angle and voltage stability concerns,
frequency stability must be ensured. This depends
on the ability of the system to restore balance
between generation and load following a severe
system upset with minimum loss of load.
In this study, the recently interconnected power
system of Crete Island has been selected as a
representative model for long-term energy planning
estimation in case of a significant high share in
power and energy balance from renewable energy
sources. Crete possesses ample wind and solar
resources having wind parks and photovoltaic plants
with total nominal power of 210 and 120 MW,
respectively, and a small hydro power plant with 0.6
kW nominal power. Technically more than 1.2 GW
could be harnessed to produce electricity at a
reasonable cost if control and management
restrictions are excluded. The dispersion of RES
installations and the variability of electricity
production must be successfully managed by the
electricity grid. Generally, the dispersed generation
changes distribution networks from passive
networks, with power flows from higher to lower
voltage levels, into active networks with multi-
directional power flows, [40]. Furthermore,
transmission and distribution infrastructures require
specific economic regulations, [41].
This work investigates the feasibility of further
utilization of RES till 2030, in Crete. Real
operational data of the examined power system is
used as a baseline for the assessment of generation
capacity expansion and the optimal energy balance
till 2030, taking into consideration previous studies.
2.1 Case Study
Crete is the largest Greek island and one of the
largest in the Mediterranean Sea. Its population is
currently more than 615,000 inhabitants and it
exceeds 2.3 million during the summer. There has
been a stable annual electricity demand of
approximately 3TWh during the last twelve years,
as shown in Figure 1.
Fig. 1: Evaluation of Annual Load
Additionally, comparing the mean hourly load
demand variation all year round, there is a
considerable electricity generation diversification
between months and seasons, as shown in Figure 2.
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However, even during the low consumption
periods, the minimum load demand is greater than
the current system technical minimum
(approximately 120 MW). Island's electricity
generation system is based mainly on three (3) oil-
fired thermal power units, located as it is shown in
Figure 3. The nominal capacity of the local power
plants is 742 MW in total, although the actual power
is considered to be 721 MW for winter and 674 MW
for summer operations, [42].
Fig. 2: Monthly Variation of Load (2021)
Fig. 3: Examined Power System
The annual peak load demand occurs on a
summer day and within July in this case.
Furthermore, the overnight loads can be assumed to
be approximately equal to 25% of the corresponding
daily peak loads. More precisely, Figure 4 depicts
the minimum and the maximum of the daily load
demand for one year.
Fig. 4: Daily variation range
The steam and diesel units mainly supply the
base-load demand. The Gas turbines normally
supply the daily peak load or the load that cannot be
supplied by the other units in outage conditions.
These units have a high running cost that
significantly increases the average cost of the
electricity being supplied. The annual duration
curve is composed of each generation unit share and
is presented in the following Figure 5, where
“Conv” represents the total production from all the
conventional power units of the island, “RES” the
local renewables, and “Link” the AC
interconnection with the mainland of Greece.
Fig. 5: Crete’s annual load duration curve (2021).
Currently, there are 30 Wind Parks (WPs)
installed with a nominal power of 210MW in
appropriate regions of the island. These WPs are
connected to the grid through MV/HV substations
of 20kV/150kV and they are located all over the
island as shown in Figure 6.
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Fig. 6: Geographical allocation of WPs (Green) and
PVs (Red) [source: geo.rae.gr]
Elaborating and analyzing all the official
(provided by local TSO) recorded data of the load
demand and the corresponding RES production of
the year 2021, a few interesting figures emerged. In
Figure 7 the RES production as a share of the
overall generation on a monthly basis is presented.
The maximum energy share of RES in a month was
33%, which is considered a significantly high share.
In 2021 the RES penetration was varying between
19% and 33% of the total power supply.
Fig. 7: Load and RES penetration per month
Furthermore, the day (7/8/2021) with the highest
share of RES on a daily base is depicted in Figure 8
where the RES power production share reached
almost 70%. More precisely, the energy supplied by
RES on that day was equal to 3,640 MWh, while the
RES penetration varied between 36% and 69% of
the total power supply without any significant
operation difficulty. Consequently, these are
considered significant RES penetration values,
especially for an island system such as Crete's
network. In the next Figure 9, the hourly average
values in the daily base of the wind power and the
corresponding penetration of the year 2021 are
presented.
Fig. 8: Highest recording share of RES in the
examined island power system
In Figure 9, the annual energy balance of 2021 is
depicted. The larger share remains on local oil-fired
power plants with a significant share of imports
through the new interconnection equal to 12.8%.
However, a substantial energy share of more than
33% belongs to the already installed RES on the
island. Therefore, according to the current condition
of RES and their operation for the year 2021, Crete
deals even now with a significant dispersed
generation and considerably high penetration of
RES. This could be a fine baseline case for
extensive new WPs and PV installations, and an
even higher RES share till 2030, taking into
consideration the prospects and the potential
opportunities.
Fig. 9: Energy Balance of 2021
2.2 Future Prospects
The annual electricity consumption in Crete for
2021 was 3.07 TWh, which can be considered as a
representative year of load demand, considering the
Covid pandemic. During previous years the annual
increase in electricity consumption was significant,
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varying between 4% and 6%. In this study, two
cases of the annual electricity demand evolution up
to the year 2030 have been considered, as they are
depicted in Figure 10 and Figure 11, considering a
confidence interval equals to 95%. The second and
most moderate scenario of load demand augment,
considering both the slight population growth and
the energy saving that should be achieved by 2030.
Regarding the specific forecast, which is based on
the Greek National Energy and Climate Plan
(NECP), the annual energy needs of 2030 will vary
from an average value of 3.37TWh to a maximum
of 4.45TWh.
In addition to the previously mentioned RES
power that is already installed, there are current
plans for an extra 48 MW new WPs. This fact will
lead shortly to even higher wind power up to
258MW. Furthermore, 140MW of new small-scale
PVs are planned to be installed by 2030, adding up a
total of 250MW of PVs.
Fig. 10: Annual Energy demand evolution
estimations
Thereupon, in this study three (3) main scenarios
groups of sustainable expansion were investigated
concerning the maximization of WPs and PVs
capacity till 2030, as presented in Table 2. The
study has considered hourly-based operation and the
corresponding technical limitations of the power
system. In the first two (2) scenarios, the local RES
is increasing, finding the best mix between PVs and
WPs, till the point where their rejection, due to
power system constraints reaches 5% of their total
annual production. This approach tends to go safely
beyond the targets of Greek NECP for the island.
The next scenarios assume a quite extensive
installation of electricity storage systems (ESS) up
to 600MW and 4.8GWh of energy capacity [43].
This approach is considered to support an even
higher expansion of RES on the island by 2030.
Fig. 11: Peak Load demand evolution estimations
Table 2. Scenarios of RES power expansion in 2030
Scenar
io
Peak
Load
Energy
2030
Description
A1
726
MW
3.37
TWh
Max WPs & PVs
A2
901
MW
4.45
TWh
Max of WPs & PVs
B1
726
MW
3.37
TWh
Max of WPs & PVs with
ESS
B2
901
MW
4.45
TWh
Max of WPs & PVs with
ESS
C1
726
MW
3.37
TWh
Max of WPs & PVs with
ESS and DC Link
C2
901
MW
4.45
TWh
Max of WPs & PVs with
ESS and DC Link
2.3 Methodology
This paper presents a program with an algorithm
that is developed to optimally expand the local RES
potential of an area (an interconnected island in the
examined case) without risking the normal operation
of the specific power system. Additionally, the
impacts of different scenarios of generation
expansion planning have been taken under
consideration in the Cretan Power System operation.
The previously mentioned scenarios focus on the
future energy demand, in particular the energy
demand by 2030, and the corresponding energy
balances.
Different energy balances have been calculated
by taking into account both the current way of
generation expansion, the possible use of electricity
storage systems, and the future implementation of a
new larger interconnection. All these schemes have
been investigated and their impact on CO2 emission
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mitigation and RES production rejection have been
estimated. The constructed model incorporates a
range of energy demand on hourly base (8760
values of each parameter), taking into consideration
the transmission limitations. In conclusion, four (4)
representative approaches have been carried out to
expand RES generation till 2030, where the main
objective is the minimization of local oil-fired
electricity production, whereas the main constraint
is the RES rejections to be less than 5%:
a. In the first two scenarios of medium (A1) and
high (A2) load demand increment till 2030, the
energy penetration of RES technologies will be
increased till the total RES rejection on the
island is less than 5%, without BESS
installation.
b. In the second two scenarios of medium (B1)
and high (B2) load demand increment till 2030,
the energy penetration of RES technologies
will be increased till the total RES rejection on
the island is less than 5%, but in these cases,
BESS installation is considered.
c. In the second two scenarios of medium (C1)
and high (C2) load demand increment till 2030,
the energy penetration of RES technologies
will be increased till the total RES rejection on
the island is less than 5%, but in these cases,
both BESS installation and new DC link are
considered.
2.4 Carbon Intensity of Electricity
Carbon intensity of electricity measures the
amount of CO2 that is produced per unit of
electricity. It is measured as the grams of CO2
produced per kilowatt-hour (kWh). Electricity
nonetheless comes from various sources such as
fossil fuels (coal, oil, and gas summed together),
nuclear power, or RES.
The CO2 emissions in this analysis are
determined by the product of Energy Consumption
(E) with the Emission Factor (EF) as shown in the
following equation, [44]:
CO2Emissions = E x EF
Therefore each region’s carbon intensity of
electricity differs based on its Energy Balance and
thus this study takes under consideration the
transformation of energy into CO2 emissions the
depicted annual energy balance of Crete as
presented in Figure 9. As countries or researchers do
not compile their Emission Factors (EFs) in the
same way, one should use the EF which can
represent the average emissions rate for a specified
activity occurring at a national or regional scale and
thereby may represent a range of specific
technologies and practices (e.g., national steel
production). Taking that under consideration in this
study Greece’s yearly CO2 Emission Factor was
used for the analysis of the data presented in Figure
19.
2.5 Algorithm Flow Charts
In the following Table 3, the used abbreviations are
explained. This methodology uses an algorithm that
is developed to simulate and estimate the impacts of
different future generation expansion scenarios in
Cretan Power System operation.
Table 3. Abbreviations Description
LOAD
Load Demand per hour
PV
Photovoltaics production per hour
WT
Wind park production per hour
RES
The total renewables production
(PV+WP)
LINK
Energy flow through the island
interconnection
SURPLUS
Renewable energy surplus (RES -
LOAD)
LINKCAP
Interconnection power flow capacity
CONV
Local oil-fired power plant
ESS
Energy flow of the island energy storage
systems
ESSCAP
ESS capacity
REJECTION
RES production rejection by systems’
technical limitation
In Figure 12, the flowchart of the proposed
algorithm that uses the parameters, which are
described in Table 3, is presented.
The second to last step is to calculate the Link
with the continental grid. Taking for granted that the
Link limit is 200 MVA and already know the RES-
NET from the previous equation, it is possible to
find the Link (diagram 1.5).
The last step is to find how much energy
Thermal (diagram 1.6) has to be produced from the
power plants to cover the rest of the load that can’t
be covered by RES, batteries, and Link together.
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Fig. 12: Proposed algorithm calculations flowchart
In Figure 13 a screenshot of the developed
program is presented. The dashboard of the program
shows the results of each scenario, such as
generation sources installed capacity, annual energy
balance and relevant energy shares, energy
exchanges through interconnections, and detailed
information on local energy storage systems.
Fig. 13: Developed program interface
The Generalized Reduced Gradient (GRG)
method has been used in this study to find the
optimal solution for the proposed approach. The
GRG method is an extension of the reduced gradient
method to accommodate nonlinear inequality
constraints. In this method, a search direction is
found such that for any small move, the current
active constraints remain precisely active. If some
active constraints are not precisely satisfied because
of the nonlinearity of the constraint functions, the
Newton–Raphson method is used to return to the
constraint boundary. Thus, the GRG method can be
considered somewhat similar to the gradient
projection method, [45].
3 Results
In Figure 14, the results of the baseline state (year
2020), where the island was non-interconnected, are
presented. That year, all its energy needs were
covered by local power plants and renewables (PVs
and WPs), which were 120 MW of PVs and 210
MW of WTs on the island.
Fig. 14: Operation Analysis of the Power System in
2020
In Figure 15, the results of the current state (year
2023) of the power system with a 200MVA
interconnection, are presented. In particular, 22.7%
of the annual load demand had been covered by
RES, 14.3% by the interconnection, and 63.0% by
local oil-fired power plants. If we compare these
numbers with those of 2020 (Figure 14), we observe
that the production of power plants was reduced by
14.3%, because Crete’s system did not any
interconnection with the mainland of Greece. This
translates into a reduction of 3.86 million tons of
CO2 assuming that 1MWh emits 0.27tones of CO2
equivalent.
In the first group of scenarios, as depicted in
Figure 16, RES installed power is maximized to the
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point that annual RES production
rejections/curtailments are maintained at lower than
5%. More precisely, the algorithm calculated that
the maximum new PVs installed power can be
between 248MW and 326MW without any serious
curtailments in their annual production. In the same
manner, the maximum new WP installed power can
be between 633MW and 831MW. In that case, the
local power plant production share is reduced by
52.4%, whereas the RES share increases up to 81%.
Fig. 15: Operation Analysis of the Power System in
2023
In the second group of scenarios, the utilization
of electricity storage systems is considered in the
examined energy balance. In this way, it is possible
to manage even higher values of RES power without
rejecting large amounts of energy. The goal of RES
energy rejections of less than 5% remains in these
scenarios, too. Following the results of our
previously conducted research, the planned capacity
for future energy storage systems in the specific
island is considered to be 4.8GWh at 600MW
charge and discharge rate, [43].
Fig. 16: Operation Analysis of Scenario A1 with
further expansion of RES in 2030
The results, as depicted in Figure 17, show an
even higher RES penetration up to 90% in the
annual energy balance and an even lower share of
oil-fired power plants equal to 4.5%. It is worth
mentioning that BESS systems have a significant
share of 4.4% in the energy balance, which is the
main factor of the high-RES share in these
scenarios. Regarding the new RES power capacities,
in these cases, they vary between 339MW and
405MW for new PVs, and between 722MW and
1058MW for new WTs.
In the third group of scenarios, besides storage, a
new interconnection is constructed and it will be in
operation by 2025. In that way, the system can have
the maximum possible RES capacity, which can
supply all the needs of the island, in collaboration
with the local BESS. The goal is once again that the
annual RES energy rejection should be less than
5%.
More precisely, the algorithm calculated that the
maximum new PVs installed power can be between
538MW and 591MW without any serious
curtailments in their annual production, whereas the
maximum new WPs installed power can be between
2125MW and 2562MW. In that case, as shown in
Figure 18, the local power plant production share is
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zero, whereas the RES share increases up to 96%
with the BESS contribution to be 3.8%.
Fig. 17: Further expansion of RES using ESS of
600MW/4.8GWh by 2030
In conclusion, the extracted results of all the
scenarios are presented in Table 4, where the
forecasted energy needs and the relevant power
peaks are depicted, in parallel with the
corresponding new PVs and WTs that can be
installed without being rejected more than 5% in the
annual base.
Table 4. Results of all the examined scenarios
Scenario
Peak
Load
Energy
2030
New
PVs
New
WPs
Local
Thermal
A1
726MW
3.37TWh
248MW
633MW
357.4GWh
A2
901MW
4.45TWh
326MW
831MW
668.0GWh
B1
726MW
3.37TWh
339MW
722MW
152.0GWh
B2
901MW
4.44TWh
405MW
1058MW
392.6GWh
C1
726MW
3.37GWh
538MW
2125MW
-
C2
901MW
4.44GWh
591MW
2562MW
-
Fig. 18: Further expansion of RES using both ESS
and new DC interconnection by 2030
Following the previously presented results of
new PVs and WTs that can securely be installed in
the examined power system, an estimation of the
resulting CO2 emission reductions is presented in
Figure 19 below, taking into account Greece’s EF
factors per 1 kWh thermal energy production.
Fig. 19: Total CO2 Emissions per year and Scenario
estimation
WSEAS TRANSACTIONS on ENVIRONMENT and DEVELOPMENT
DOI: 10.37394/232015.2023.19.130
Emmanuel Karapidakis,
Sofia Yfanti, Christos Kouknakos
E-ISSN: 2224-3496
1443
Volume 19, 2023
Figure 19 outlines the significant mitigation of
CO2 emissions not only between the year 2020,
when Crete was not connected with the main grid,
and 2021 when the first Link was achieved, but also
within Table’s 4 scenarios. From 2020 to 2021
Crete achieved a reduction of 98.2 5% just by
connecting with the national grid. This reduction is
also noticeable even between the A2 scenario and
Crete’s current energy production (8% from 2021).
Nonetheless one cannot ignore CO2 mitigation even
between the scenarios, as a reduction of 50.7% for
A1; 79% for B1, and 45.86% for B2 is estimated to
be achieved.
4 Conclusions
This paper investigates RES's contribution in the
energy balance and CO2 eq. emissions of Crete’s
grid. A methodology has been introduced that
optimizes the penetration level, maximizing local
RES production, increasing the self-sufficiency of
the island, and keep RES energy
rejection/curtailments below 5%. Although there is
the needed capacity of RES that could cover the
corresponding demand, the current power system
structure, and operation emerge limitations, which
hold back their further exploitation. The
introduction of energy storage systems, such as
pump storage and batteries can help the further
exploitation of the needed RES by balancing the
current load demand and the intermittent power
flow of photovoltaics and wind turbines. This paper
analyses a recently interconnected island power
system operation, as a representative case study, and
demonstrates benefits, such as CO2 emissions
reduction, and obstacles emerged by ultra-high
penetration of RES. This ultra-high share of RES is
technically feasible, through strong interconnections
and BESS, resulting in significant CO2 mitigation.
Considering our national multi-level efforts for
the achievement of the new National Energy
Planning goals, Greece’s new national production
structure should be Green (based on sustainability),
Smart (using artificial intelligence and other digital
achievements and applications), Fair (in social and
spatial level), Inclusive (so as not to leave out the
weak) and with National Added Value (through the
creation of adequate permanent jobs).
The scenarios’ results confirmed that the high
RES technologies penetration significantly affects
the mitigation of CO2 emissions. Thus the
combination of grid enhancement along with the
utilization of RES technologies would not only
reduce greenhouse gas emissions [5], mitigating
climate change, but it would also benefit Crete on
social and economic levels, as new job opportunities
would appear, [46] and energy poverty would be
also moderated, [47], [48].
Based on the results of this research, several
paths of future work can be outlined for exogenous
factors such as pandemics (e.g. COVID-19), wars
(e.g. Ukraine war) and natural disasters (e.g.
earthquakes) to be investigated in the energy
emissions model combined with the application of
energy forecasting models that use actionable
parameters, [48]. Including such variables could
reveal an energy dependency which could lead to
the modification of energy policy of EU countries
towards energy self-sufficiency, [5].
In conclusion, a sustainable power generation
expansion planning, which combines grid
enhancement, advanced operation control,
substantial PVs, and WPs exploitation in
collaboration with adequate electricity storage
systems, overcoming current technical and
operational limitations, could lead to a realistic
environmentally neutral power system by the end of
2030, attaining much earlier the EU green deal goals
in local scale, along with providing solutions in
problems such as the lack of fresh water and energy
independence in remote islands [50]. In the future,
further research of the interaction from the
introduction of this concept to Local Regional
Authorities could further optimize RES penetration
level, [51] and CO2 emissions reduction, [52].
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Sofia Yfanti, Christos Kouknakos
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Contribution of Individual Authors to the
Creation of a Scientific Article (Ghostwriting
Policy)
Conceptualization, E.K., and C.K.; methodology,
E.K.; software, E.K. and C.K.; validation, C.K., and
S.Y.; formal analysis, S.Y.; investigation, E.K. and
C.K.; resources, E.K.; data curation, S.Y.; writing—
original draft preparation, C.K.; writing—review
and editing, E.K and S.Y..; supervision, E.K.;
project administration, E.K.. All authors have read
and agreed to the published version of the
manuscript.
Sources of Funding for Research Presented in a
Scientific Article or Scientific Article Itself
No funding was received for conducting this study.
Data Availability Statement: The used data can be
found at Hellenic Energy Exchange Market,
https://www.enexgroup.gr/ (Last Access
21/12/2022).
Conflicts of Interest
The authors declare no conflict of interest.
Creative Commons Attribution License 4.0
(Attribution 4.0 International, CC BY 4.0)
This article is published under the terms of the
Creative Commons Attribution License 4.0
https://creativecommons.org/licenses/by/4.0/deed.en
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WSEAS TRANSACTIONS on ENVIRONMENT and DEVELOPMENT
DOI: 10.37394/232015.2023.19.130
Emmanuel Karapidakis,
Sofia Yfanti, Christos Kouknakos
E-ISSN: 2224-3496
1447
Volume 19, 2023