Keywords

1 Introduction

Greenhouse gases (GHG) from human activities are the most significant drivers of observed climate change since the mid-twentieth century (US—EPA 2017). From 1970 to 2012, the GHG emissions increased steadily from 24.3 to 46.4 Gton CO2eq/year (Janssens-Maenhout et al. 2017).

In the past years, the awareness of the impacts of human activities on climate has led to the definition of various environmental policies aimed at reducing GHG emissions (e.g. Kyoto Protocol, Paris climate conference—COP21, etc.).

Among the human activities responsible for GHG, the energy sector (including power generation and energy consuming sectors, i.e. buildings, industry, transport and agriculture) represents by far the largest source of emissions. In detail, it accounts for two-thirds of global GHG and 80% of CO2 emissions (IEA 2014a, 2016, 2017). Therefore, effective actions in the energy sector are essential to tackling the climate change problem (Beccali et al. 2007). Mitigation scenario studies carried out by IPCC indicate that, within the energy system, the electricity sector can play an important role in deep GHG emissions cut, as the decarbonization of electricity generation can be achieved at a much higher pace than in the rest of the energy system (IPCC 2014). A variety of mitigation options exists in the electricity sector, including renewable, nuclear power plants or fossil fuel power stations equipped with carbon capture and storage (CCS) technologies (Bruckner et al. 2014). Many climate change mitigation policies are focused on replacing fossil fuel with renewable energy sources (RES) (Dandres et al. 2012).

In this framework, the European Union (EU) has set ambitious targets for 2030 in the field of GHG emissions and renewable energy generation (European Commission 2011). In detail, the 2030 EU energy and climate objectives aim at cutting GHG emissions by 40% if compared to 1990 levels, and at increasing the share of renewables to at least 27% of EU energy consumption (European Commission 2014). In order to match such objectives, all Member States should contribute to the attainment of these common objectives and targets to different extents (European Commission 2016). In this context, the authors focused their attention on the electricity sector, and carried out a scenario analysis for its generation in Sicily in 2030, considering a high exploitation of RES. The authors followed a life cycle approach in order to assess the potential contribution of Sicily in the achievement of European energy and climate targets. Moreover, as replacing fossil fuels with RES could cause negative impacts, e.g., in terms of resources depletion, they carried out an environmental evaluation of the scenarios, including the assessments of a wide range of environmental impacts.

2 Scenario Analysis

In the following steps, the methodology employed in the definition of the electricity generation scenarios in 2030 is briefly described:

  • Step 1—Electricity production in Sicily: analysis of electricity production in Sicily from 2009 to 2014 in order to characterize the electricity mix and the RES penetration in the system.

  • Step 2—Identification of the renewable energy technologies that can change their capacity production (increase or decrease) in response to a change in the demand for electricity (renewable energy marginal technologies).

  • Step 3—Electricity generation scenarios: definition of two electricity scenarios considering a decrease (−0.2%/year) of the electricity demand by 2030 in the first one and an increase (+0.6%/year) in the second one. Both forecasted scenarios are characterized by an increase in electricity produced by RES.

2.1 Electricity Production in Sicily

In Sicily, electricity is generated by thermal power plants, hydroelectric plants, wind turbines, and photovoltaic (PV) systems (Region of Sicily 2015). Figure 1.1 shows the evolutions of the Sicilian electricity mix per type of plant and energy source from 2009 to 2014 (TERNA 2017; GSE 2017).

Fig. 1.1
figure 1

Share of electricity production per type of plant and of energy source in Sicily from 2009 to 2014 (*CHP: combined heat and power plant; **other fuel (solid): coke, brown coal briquettes, etc.; ***bioenergy: biogas, bioliquid and biomass) (own elaboration from TERNA and GSE data) [the production of electricity in pumped storage units from water previously pumped uphill is not included, as indicated in (European Commission 2009)]

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2014 was assumed as reference scenario (RS14) due to the highest availability of data: the annual total electricity production was equal to 22,536 GWh: 75.3% was generated by fossil fuel thermal power plants and 24.7% by RES (TERNA 2017). Concerning RES only 2.1% was generated by hydroelectric plants (1.4% hydropower at reservoir; 0.6% hydropower run of river), 8.4% by PV systems, 13.0% by wind turbines, and 1.2% by bioenergy.

The amount of electricity generated by RES in 2014 was assumed as a reference for the estimation of RES exploitation in the 2030—scenarios, as described in Sect. 1.2.3.

2.2 Identification of the Renewable Energy Marginal Technologies

In order to contribute to the EU energy and climate goals, the future electricity production sector should be characterized by an increase of the RES. Then, the potential capacity production of each renewable energy technology should be identified. A technology that can change its capacity production in response to a change in demand in an energy system (increase or decrease) is defined as a marginal technology (Weidema et al. 1999). It is an unconstrained technology, i.e. its capacity can be adjusted in response to a change in demand without being subjected to natural capacity constraints (e.g. the amount of water available in a specific region), political constraints (e.g. emission limits), etc. (Weidema et al. 1999).

The authors identified the renewable energy marginal technologies for the Sicilian electricity sector considering the following factors:

  1. 1.

    RES penetration in the Sicilian electricity mix in 2014;

  2. 2.

    the technical potentialFootnote 1 for the exploitation of RES in Sicily;

  3. 3.

    the European energy policies and the Sicilian energy strategies (Region of Sicily 2008, 2014, 2015).

As forecasts for 2030 were not available, the technical potential for RES exploitation in 2030 was assessed starting from the estimations of RES development in 2020, reported in national and regional studies (Benini et al. 2010; Alterach et al. 2011; Region of Sicily 2008, 2014, 2015).

In detail, considering that the RES exploitation in Sicily in 2016 (TERNA 2017) was still far from the forecasted potentials to be installed within 2020, the authors hypothesized that these potentials for 2020 will be installed in the medium—long period (from now to 2030).

The only exception was represented by the wind-based systems for which estimations for 2030 were available (ANEV—Associazione Nazionale Energia del Vento 2017).

In the following, the procedure for the identification of the renewable energy marginal technologies is described.

  • Hydropower

The main constraints of hydropower are low social acceptance, high initial investment costs and the need to consider other water-using sectors (e.g. irrigation in agriculture, domestic uses, other industrial uses, etc.) when planning the hydropower development (IEA 2011). In the Sicilian “Energy Master Plan” (Region of Sicily 2008), which is the official document describing the current energy sector and the future energy plans in Sicily, no significant hydropower use increase is taken into account as almost all the available potential is considered exploited and the potential of small hydro is very limited. Then, hydropower technologies cannot be considered marginal in the Sicilian energy system and the future increase of electricity generation from these plants, due to small hydro (Region of Sicily 2008; Cattini et al. 2011) can be assumed as negligible if compared to RS14.

  • Wind

Barriers to the diffusion of wind power generation include capital costs, uncertainty regarding policy support, impacts of its intermittent generation on the power systems, and low social acceptance due to the visual impact (IEA 2008).

An installed power equal to 2000 MW is forecasted for Sicily in 2030 (+14% compared to RS14) (ANEV—Associazione Nazionale Energia del Vento 2017). This estimation is done excluding the areas subject to environmental and technical constraints (e.g. protection of flora and soil orography). Then, considering this potential and the current installed power, wind plants can be considered as a marginal technology for the Sicilian energy system. Starting from the forecasted installable power (2000 MW) and considering an average wind plant productivity equal to 2000 MWh/MW (RSE 2017), a generation of 4000 GWh is estimated for 2030.

  • Solar

The penetration in the energy system of this technology mainly depends on its cost (and related incentives). Photovoltaics can be considered a marginal technology, as within the renewable technologies, solar power seems to be the most promising, considering the high solar irradiation in Sicily (Šúri et al. 2007; Huld et al. 2012) and the untapped potential (Region of Sicily 2008, 2014).

In detail, the overall installed solar power in Sicily was 1295 MW in RS14 while a PV installable capacity equal to 1812 MW is forecasted in 2020 (Region of Sicily 2014). Considering that the installed power in 2016 was equal to 1344 MW (+2.7% compared to 2015) (TERNA 2017), it is supposed that the estimated potential for 2020 could be installed by 2030. Starting from the forecasted installable power (1812 MW) and considering an average PV power plant productivity equal to 1500 MWh/MW (EC—JRC 2017), a generation of 2718 GWh is estimated for 2030.

  • Bioenergy

The potential electricity generation from thermal plants fuelled with bioenergy in Sicily in 2020 is estimated as 795 GWh (Benini et al. 2010), considering the limitations due to other potential uses of bioenergy, e.g. for agricultural applications. As in 2016, the electricity generation by bioenergy was 239.9 GWh (TERNA 2017), it is assumed that the estimated production of 795 GWh will be reached in a medium—long period (from now to 2030). Thus, thermal plants fuelled with bioenergy can be considered as a marginal technology for the Sicilian energy sector.

2.3 Electricity Generation Scenarios Definition

The definition of two possible scenarios for electricity demand in 2030 is based on the prediction of future electricity demand (TERNA 2015). The first scenario, named as “Base scenario” (BS30), estimates a decrease of −0.2%/year of the electricity demand for the Italian Islands (Sicily and Sardinia) (TERNA 2015), which results in a value of 21,512 GWh in 2030 (−3.2% if compared to RS14). The second one, named as “Development scenario” (DS30), estimates an increase of +0.6%/year of the electricity demand (TERNA 2015) which results in a demand of 24,443 GWh in 2030 (+10% if compared to RS14).

The exploitation of RES in both the forecasted scenarios is assumed to be equal to the technical potential discussed in Sect. 1.2.2. The main assumptions on the renewable marginal technologies of the BS30 and DS30 scenarios are summarized in Table 1.1.

Table 1.1 Main assumptions on the renewable marginal technologies in the forecasted scenarios
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The assessment of the electricity generation from thermoelectric plants fuelled with fossil fuels in the future scenarios is based on the difference between the renewable energy production and the forecasted energy demand in the same year. It is 14,062 GWh in BS30 and 16,993 GWh in the DS30 scenario. The percentage distribution of each technology in the thermoelectric sector is considered unchanged if compared to RS14. Both scenarios are in compliance with the European energy strategies as they reduce the fossil fuels dependence by increasing RES penetration.

Starting from the electricity mix in RS14 and in the two scenarios, the percentage composition of the generation of 1 kWh of electricity per type of plant and energy source was identified (Table 1.2).

Table 1.2 Percentage composition of the generation of 1 kWh of electricity per type of plant and of energy source in RS14, BS30 and DS30 scenario (%)
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3 Life Cycle Assessment

3.1 Goal and Scope Definition

An LCA approach has been applied to assess the potential energy and environmental benefits/impacts of the forecasted electricity mixes with respect to RS14. The assessment was carried out in compliance with ISO 14040 (ISO 2006a) and ISO 14044 (ISO 2006b). The production of 1 kWh of gross electricity was selected as a functional unit (FU). The system boundaries included the extraction and transport of raw materials and fuels, the plant construction and operation. For renewable energy systems also the end-of-life step was taken into account. For thermal power plants, the end-of-life was not considered due to a lack of reliable secondary data.

The Cumulative Energy Demand (CED) method was used to assess the primary energy consumption (Frischknecht et al. 2007a), while the impact assessment was performed by means of the ILCD 2011 Midpoint method (EC—JRC 2012).

3.2 Life Cycle Inventory

  • Data collection, data quality and assumptions

The data collection process and the assessment of the percentage composition of 1 kWh of electricity per type of plant and energy source are described in Sect. 2.2.

The eco-profiles of electricity generation by each power plant and energy source were taken from Ecoinvent (Frischknecht et al. 2007b) both for 2014 and 2030. The authors assessed the environmental impacts of the future scenarios by using the eco-profile referred to the current technology development for the following reasons:

  • The eco-profile changes of the electricity generated by thermoelectric plants (powered by both fossil fuels and bioenergy) occurring over the next decades were assumed negligible due to the use of mature technologies (Stamford and Azapagic 2014) and due to their lifetime (up to 50 years) (IEA 2014b);

  • The eco-profiles of wind and PV power plants are expected to improve with respect to the current ones thanks to the employment of more efficient materials and technologies. This will entail a higher electricity output per unit of input (IEA 2008) and, consequently, the reduced impact per kWh of electricity generated. However, due to the uncertainty on the technological development and on the life cycle data for future technologies (Stamford and Azapagic 2014), the authors, assuming a cautious scenario, considered negligible the future wind and PV plants eco-profile improvement.

3.3 Life Cycle Impact Assessment and Discussion of Results

No considerable variations are found in both the scenarios if compared with RS14.

In detail, CED per kWh of electricity produced is 8.9 MJprimary in the BS30 scenario and 9.1 MJprimary in the DS30 scenario. The percentage variations compared to RS14 are equal to −5.8% in BS30 and −3.3% in DS30 (Fig. 1.2). Such a decrease is essentially due to the reduced share of the electricity produced from non-renewable technologies in the future electricity generation mixes.

Fig. 1.2
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Non-renewable and renewable CED in reference and in forecasted scenarios

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The renewable primary energy consumption (CED renewable) increases in both the scenarios compared to the reference scenario. In detail, CED renewable is 1.7 MJprimary in BS30 and 1.5 MJprimary in the DS30 scenario, while it is equal to 1.0 MJprimary in the RS14 scenario. The environmental impacts are shown in Table 1.3. Both forecasted scenarios involve a reduction of the impacts in almost all the examined environmental categories, except for human toxicity—no cancer effect (HT—nce), ionizing radiation—human health (IR—hh), ionizing radiation—ecosystem (IR—e), particulate matter (PM) and mineral, fossil and renewable resource depletion (MFRRD).

Table 1.3 Environmental impact of 1 kWh of electricity in RS14, BS30 and DS30 scenarios
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For the HT—nce, IR—hh, IR—e and PM, the increase of the impact is mainly due to the higher penetration of CHP—biomass and PV plants in the forecasted 2030 energy systems. The increase ranges from +1.8% for HT—nce in DS30 to +39.6% for PM in BS30. In both scenarios, the high penetration of PV in the electricity mix is responsible for a relevant increase in MFRRD impact category (+47.9% in BS30 and +30.2% in DS30).

The reduced share of fossil fuels thermal power plants in the electricity mixes (−12.1% in BS30 and −7.8% in DS30 compared to RS14) involves a reduction of global warming potential (GWP) (−14.4% in BS30, −9.2% in DS30), human toxicity—cancer effects (HT—ce) (−7.6% in BS30, −4.9% in DS30) and photochemical ozone formation potential (POFP) (−12.0% in BS30, −7.3% in DS30), in both scenarios. In detail, the reduced impact in these categories is due to the lower production from power plants—natural gas and CHP other fuels, which are the two plants with the highest impact in these environmental categories.

The reduction of the ozone depletion potential (ODP) in both scenarios (−14.0% in BS30 and −9.0% in DS30) is mainly due to the lower generation from thermal power plants fuelled with natural gas. The reduced share of CHP other fuels and power plant—oil in the electricity mixes is mainly responsible for the decrease of terrestrial eutrophication (T-EU), freshwater eutrophication (F-EU), marine eutrophication (M-EU), acidification potential (AP) and freshwater ecotoxicity (F-E). The decrease ranges from −6.6% for T-EU in DS30 to −12.4% for F-EU in BS30.

The lower contribution of power plants powered with natural gas and oil products in both future electricity mix causes a reduction in the impact on land use (LU) (−13.1% in BS30 and −8.4% in DS30), while the reduced contribution from CHP other fuels generation is responsible for water resource depletion decrease (WRD) (−15.7% in BS30 and −10.1% in DS30).

3.4 Potential Contribution of Sicily in the Achievement of the 2030 European Climate Target

In order to assess the potential contribution of the Sicilian electricity sector in the achievement of the 2030 European climate target, starting from the impact of 1 kWh of electricity on the GWP impact category, the authors calculated the GHG emissions related to the total electricity demand in the forecasted scenarios (Table 1.4).

Table 1.4 GWP in the RS14 and in the forecasted scenarios
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The results of Table 1.4 show that the Sicilian electricity sector could contribute to the European climate policy for 2030, reducing GHG emissions of 2.2E−06 tonCO2eq (−17%) in the BS30 scenario, while in the DS30 the variations in the energy generation mix allow to maintain the same level of emissions, with a small decrease equal to −0.1%, even though the electricity demand has increased by 10% with respect to RS14.

4 Conclusions

The study presented an integration of the LCA approach and scenario analysis suitable for the evaluation of environmental strategies on a policy level.

In detail, the authors showed the potential contribution of two forecasted electricity scenarios in Sicily to the 2030 Europe climate and energy policy.

The analysis of a wide range of environmental aspects of sustainability through the multi-indicator approach of LCA was carried out. Both the assessed scenarios involve an overall reduction in almost all the environmental impact categories, in comparison with the reference scenario (RS14), confirming that the high penetration of RES could improve the electricity eco-profile significantly. However, with the current state of development of the electricity technologies generation, it is not possible to achieve improvements in the whole set of environmental impacts categories. Then, the integration of the LCA methodology with the scenario analysis could be a useful tool for identifying the potential negative impacts connected to the implemented strategies and could provide a useful support to policymakers in the identification of the more suitable strategies taking into account both the site-specific characteristics of the territory and the most pressing environmental issues.

With reference to the climate target, only the BS30 scenario, characterized by the reduction in the electricity demand and the increase of RES exploitation, could involve a reduction of the GWP. In the DS30 scenario, the benefits due to the increase of the RES are offset by the impacts caused by the electricity demand increase. In order to match the European climate goals strategies aimed at promoting RES, the focus on energy efficiency and on the final consumer’s behaviours is mandatory.