Life Cycle Assessment of Energy Systems and Sustainable Energy Technologies

Hindering global warming and achieving a more competitive, secure and sustainable energy sector are some of the most relevant goals of the 2030 Framework for climate and energy of the European Union. European countries have to identify and implement strategies for contributing to these ambitious goals. In this context, the authors carried out a scenario analysis on the Sicilian electricity mix in order to estimate the life cycle energy and environmental benefits of the increase of the use of renewable energy technologies for electricity production, and the potential contribution of Sicily in the achievement of the European energy and environmental targets. In detail, the authors identified two electricity generation scenarios for 2030 starting from the Sicilian electricity mix in 2014, performed assumptions on the forecasted electricity demand and assessed the potential of renewable energy sources exploitation and the technical, political, social, and environmental constraints. Then, they applied the Life Cycle Assessment methodology to assess the eco-profiles of the identified electricity generation mixes and compared them with the eco-profile of electricity produced in 2014. The results of the comparison showed a reduction of most of the 16 examined environmental impact categories, except for those related to human toxicity, particulate matter, ionizing radiation and resource depletion.

In the present study the main environmental impacts of different solutions for photovoltaic electricity production in the Italian context are discussed. For solution we mean the combination between the cell technology (CdTe, single or multi-crystalline silicon, etc.) and the installation option (roof, ground, etc.). Environmental impacts are analyzed by means of the Life Cycle Assessment approach according to ISO 14040 standard. The life cycle environmental impacts of the different solutions are, also, compared with the impacts of a natural gas combined cycle plant which is, in Italy, the main technology replaced by new photovoltaic installed power. Results show that there isn’t a photovoltaic solution which is the best for all the impact categories. All the solutions have several environmental advantages compared to fossil fuel technologies, even compared to natural gas combined cycle. The main negative effect is a relevant land use for ground installations, which represent in Italy almost the 40% of the photovoltaic installed power. Moreover criticalities for what concerns human toxicity impact categories have to be underlined. All the photovoltaic solutions, in the case of non-cancer effect, and five out of eleven, in the case of cancer effects show higher impacts than natural gas combined cycle plant.

Geothermal energy is a resource of natural and renewable energy and its exploitation in the Italian Tuscany Region contributes significantly to the regional share of electricity generation from renewable sources, with a value that has grown to about 35% in 2015. The energy produced by geothermal source, such as that produced by other energy sources, generates non-negligible impacts on the environment, closely related to the site-specificity of the source itself. This preliminary study analyzes the operational phase of seven geothermal plants located in the three main Tuscan geothermal areas, with a specific focus on the impacts generated by emissions into the atmosphere. The aim is the assessment of the geothermal power plants environmental performances in relation to the geomorphological characteristics of the sites and the technologies used to exploit the resource.

The application of LCA in the energy consumption management can address the sustainability of energy systems. The chapter first aims at summarizing general trends in addressing environmental implication of energy use. Second, LCA methodology is briefly introduced in order to clarify its potentialities and general use in the energy field area. In particular, LCA can contribute to select the best technological choices for an energy system. A challenge in the use of LCA is identified in the representation of a complex system in which the energy producers’ contribution changes on a temporal basis. Two approaches are proposed for the LCA use in the short-term perspective: attributional LCA and consequential LCA. The proposed approach examines the application of LCA in a short-term perspective. Both approaches can be used to analyze an efficient configuration of the system. However, the more the temporal and geographical area is restricted, the more specific issues have to be adopted to provide a reliable analysis. In particular, consequential and attributional approaches should be used under different hypotheses and with proper adaptation. The proposed approach examines the application of consequential LCA in a short-term perspective, defined as the time span in which the market system has not reacted to a change yet. Moreover, it could claim environmental impact savings in the presence of an accurate model that is able to predict the hourly marginal technology of the near future (one day to 1 week). The future application of the proposed approach would be a tool that manages to assess the best hourly consumption trajectory in order to minimize environmental impacts.

Electrical energy production from renewable sources has dramatically grown in the recent years in the developed countries, putting the hard problem to be solved of supply discontinuity. How to reach high efficiency and reliability of electrical energy storage system is thus now one of the most challenging goals to be reached: among all, one of the most simple and widespread to use is the electrochemical storage systems. This paper analyzes the sustainability of a small vanadium redox flow battery performed by an LCA approach. This electrical energy storage system was selected for its significant advantages in use, such as the almost infinite lifetime of the vanadium electrolytes, which represent a potentially significant advantage in terms of a sustainable future made of less fossil fuels and more renewable energy. In fact, the LCA analysis performed shows that the production of the battery has a moderate impact, including the effect toxicity while at the end of life, the material and the electrolyte are completely reusable with a small fraction that goes to landfill disposal.

Among the different alternatives to conventional fossil fuels, the production of renewable energy from biomass (i.e. bioenergy) is regarded as an interesting option since it involves the valorisation of waste streams, residues and non-food crop biomass. Although a standardised framework regulates the Life Cycle Assessment (LCA) methodology, its application in practice poses some methodological difficulties. This chapter reviews the main methodological issues that a LCA practitioner has to face when it comes to the environmental assessment of bioenergy systems. Despite its complexity, consequential LCA is considered an interesting approach for informing policy-makers and decision-makers about the indirect effect of a specific strategy. In this sense, indirect environmental burdens such as indirect land use change should be included in the study. Moreover, the selection of the system function and system boundaries are other methodological issues that directly affect the results obtained and, therefore, the comparability of LCA studies, intensified in particular in the case of bioenergy systems due to their complexity. In more detail, some bioenergy systems co-produce multiple products, increasing the variability of the functions provided by the system, as well as of the system boundaries chosen to overcome multifunctionality (subdivision, system expansion or allocation). The selection of the appropriate methodology and impact categories, as well as the gaps in characterisation factors, is other methodological drawbacks.

Over the years, the application of Life Cycle Assessment (LCA) to agricultural biogas energy source allowed to depict the environmental impact related to this renewable energy source as well as to highlight mitigation strategies oriented to improvement of Anaerobic Digestion sustainability. A review focused upon the recently published LCAs of agricultural biogas plants was carried out. The review highlighted a huge variability on environmental results due to the ways the feedstock mixtures are produced, managed and supplied; and the regions in which the plants are located. Differences were also related to the ways the energy produced were utilised, whether it was input to the national grid, and/or recycled within the system.

In the context of an increased bio-based economy characterized by both reduced dependence upon imported fossil fuels and reduced greenhouse gases emissions, bio-fuels and the other bio-based supply chains have reached a worldwide expansion. Taking into account the high environmental impact of the agricultural production and the potential conflicts among food, energy and environment, this review provides an overview of the opportunities and constraints specifically related to the environmental performance of different candidate lignocellulosic feedstock in the Italian context. Peer-reviewed Life Cycle Assessment (LCA) studies were analysed and compared on a mass basis. Several biomass-based supply chains from wood and herbaceous residues or dedicated crops on marginal and fertile lands (under different fertilization management) were considered. A cradle-to-farm gate attributional LCA approach was applied to assess the environmental profile and the linked major hotspots as useful information to evaluate the most promising feedstock for bio-energy or integrated biorefinery systems. The results have demonstrated that short rotation forestry and medium rotation forestry cultivation systems, characterized by restrained mineral fertilization, can have a better environmental performance than herbaceous crops under both standard and reduced fertilization management, offering substantial benefits for almost all investigated impact categories.

In recent years advanced biorefineries based on organic residues and waste have gained increased attention for their potential to obviate first-generation biorefineries environmental burdens. During the conceptual design phase of an advanced biorefinery the role of Life Cycle Assessment (LCA) is crucial for providing information on its environmental performances, better solutions, preferable process setup, more suitable feedstock, trade-off, and so on. This review focuses on advanced biorefineries LCAs in order to accomplish a synthesis of the state of the art from the methodological point of view. Some main methodological issues have been analyzed and discussed on 24 LCAs. Attention has been drawn to functional units, system boundaries, inventory data collection, allocation methods and multifunctionality management approach. Results show different approaches and solutions to the analyzed aspects but some clear addresses can be pointed out. It has been observed that LCA of biorefineries can be classified in three different types in base on focal aim, and then functional units are consequentially defined. A large variability has been observed regarding system boundaries even if “cradle-to-gate” appears the most common. Inventories are mainly based on secondary data due to the very innovative features of the analyzed technologies. No general consensus has been observed concerning allocation of environmental impact between co-products.

In recent years, there has been growing interest in third-generation biofuels, i.e., fuels from algal biomass. Considering microalgae, the production and transformation processes are currently under study by researchers across the world, as microalgae appear to be a promising alternative to meet our sustainability goals in the energy sector. Considering the Life Cycle Assessment (LCA) applied to biofuels from microalgae, a number of studies have been published to date, covering a wide geographical range and analyzing several process configurations. This chapter presents the microalgae-to-biofuel process and a review of the published LCA studies in the field. The findings show that the majority of these studies do not have access to primary data but only to secondary data sources. Most studies do not consider the whole process, but only some of the process stages, thus limiting the relevance of the results to the specific context to which they refer. Only about half of the studies reviewed consider the impacts of water and land use, and only two present a detailed analysis of the economic and social impacts. For this reason, further efforts are still necessary in order to obtain a comprehensive sustainability assessment of this potential solution to the energy problem.

Global policies for reducing fossil fuel dependency and CO₂ emissions have fostered the development of low carbon sustainable energy. Since first generation biofuels may generate environmental burdens related to agricultural production, second and third generation biofuels from lignocellulosic feedstock and algae-to-energy systems have been developed. In this study, the Life Cycle Assessment methodology is applied to compare quantitatively, utilizing primary data, the impacts of the first generation in respect to the third-generation biofuels. Results show that micro-algae are neither competitive yet with traditional oil crops nor with fossil fuel. The use of renewable technologies as photovoltaics and biogas self-production might increase the competitiveness of micro-algae oil. Further investigations are however necessary to optimize their production chain and to increase the added value of co-products.