Life Cycle Assessment of a high temperature molten salt concentrated solar power plant

Realizing and installing renewable energy plants have an environmental “footprint” that has to be evaluated to quantify the real impact of renewable technologies on the environment. Nowadays, the most important tool to evaluate this impact of a product is the Life Cycle Assessment (LCA).The aim of this work is to present a Life Cycle Assessment of an innovative solar technology, the molten salt concentrating solar power (CSP) plant combined with a biomass Back-Up Burner, developed by Italian Research Centre ENEA and able to produce clean electricity by using solar energy. The Life Cycle Assessment was carried out by means of the SimaPro7 software, one of the most used LCA software in the world.In the second part of the study the environmental performance of the CSP plant was compared with these of conventional oil and gas power plants.     

Life Cycle Assessment of Substitute Natural Gas production from biomass and electrolytic hydrogen

The synthesis of a Substitute Natural Gas (SNG) that is compatible with the gas grid composition requirements by using surplus electricity from renewable energy sources looks a favourable solution to store large quantities of electricity and to decarbonise the gas grid network while maintaining the same infrastructure. The most promising layouts for SNG production and the conditions under which SNG synthesis reduces the environmental impacts if compared to its fossil alternative is still largely untapped. In this work, six different layouts for the production of SNG and electricity from biomass and fluctuating electricity are compared from the environmental point of view by means of Life Cycle Assessment (LCA) methodology. Global Warming Potential (GWP), Cumulative Energy Demand (CED) and Acidification Potential (AP) are selected as impact indicators for this analysis. The influence of key LCA methodological aspects on the conclusions is also explored. In particular, two different functional units are chosen: 1 kg of SNG produced and 1 MJ of output energy (SNG and electricity). Furthermore, different approaches dealing with co-production of electricity are also applied. The results show that the layout based on hydrogasification has the lowest impacts on all the considered cases apart from the GWP and the CED with SNG mass as the functional unit and the avoided burden approach. Finally, the selection of the multifunctionality approach is found to have a significant influence on technology ranking.     

Operational energy in the life cycle of residential dwellings: The experience of Spain and Colombia

Life Cycle Assessment (LCA) has been applied within the residential building sector of two buildings, one in each a developed (Spain) and a developing (Colombia) country. The main goal of this paper involves the environmental loads and also brings together the operational energy for activities during the operation phase such as HVAC, domestic hot water, electrical appliances, cooking and illumination. The present research compares two real scenarios: Situation 1, where 100% of the dwelling’s energy is supplied with electricity only and Situation 2, where dwellings can be operated with natural gas plus electricity.     

Environmental aspects of electricity generation from a nanocrystalline dye sensitized solar cell system

A Life Cycle Assessment, LCA, of a nanocrystalline dye sensitized solar cell (ncDSC) system has been performed, according to the ISO14040 standard. In brief, LCA is a tool to analyse the total environmental impact of a product or system from cradle to grave. Six different weighing methods were used to rank and select the significant environmental aspects to study further. The most significant environmental aspects according to the weighing methods are emission of sulphur dioxide and carbon dioxide. Carbon dioxide emission was selected as the environmental indicator depending on the growing attention on the global warming effect. In an environmental comparison of electricity generation from a ncDSC system and a natural gas/combined cycle power plant, the gas power plant would result in 450 g CO₂/kWh and the ncDSC system in between 19–47 g CO₂/kWh. The latter can be compared with 42 g CO₂/kWh, according to van Brummelen et al. “Life Cycle Assessment of Roof Integrated Solar Cell Systems, (Report: Department of Science, Technology and Society, Utrecht University, The Netherlands, 1994)” for another thin film solar cell system made of amorphous silicon. The most significant activity/component contributing to environmental impact over the life cycle of the ncDSC system is the process energy for producing the solar cell module. Secondly comes the components; glass substrate, frame and junction box. The main improvement from an environmental point of view of the current technology would be an increase in the conversion efficiency from solar radiation to electricity generation and still use low energy demanding production technologies. Also the amount of material in the solar cell system should be minimised and designed to maximise recycling.     

Evaluation of a solar driven trigeneration system with conventional and new criteria

Solar-driven trigeneration systems are able to cover all the building energy needs in heating, cooling and electricity using only the solar energy. The objective of this paper is to evaluate a solar trigeneration system under different criteria in order to make clear that there are numerous factors which have to be taken into consideration in the trigeneration system design. The examined system consists of parabolic trough solar collectors, a storage tank, an organic Rankine cycle and an absorption heat pump. The system is evaluated using different evaluation criteria which are associated with the energy, the exergy and the financial performance of the system. Moreover, a new criterion which takes into account the building energy needs is introduced and is investigated in different scenarios. The final results of this work clearly indicate that the optimisation of the solar driven trigeneration systems is depended on the desired design conditions and goals.

Abbreviations: COP, Coefficient of performance; ECO, Economizer; EES, Engineering Equation Solver; EVAP, Evaporator; ORC, Organic Rankine Cycle; PTC, Parabolic trough collector; SC, Scenario     

Is life cycle assessment (LCA) a suitable method for quantitative CO2 saving estimations? the impact of field input on the LCA results for a pure vegetable oil chain

The environmental and social sustainability of biofuel production and use is today the most critical issue for the development of support policies in this sector.The Life Cycle Assessment (LCA) methodology is commonly agreed as the main tool for the estimation of the impact of biofuel chains, even in quantitative terms. This is also reflected in the recently issued EU Directive (Renewable Energy Directive, RED) on the promotion of the use of energy from renewable sources. However, the results of Life Cycle Assessment works largely depend on the quality of the information given as input to the study, as also very recent research works started to investigate: in addition, the comparison of a large number of very different (technically, geographically, agronomically) biofuel chains, as some Life Cycle Assessments and reviews tried to do, is a very difficult task due to the extremely large number of variable conditions and parameters. This paper, by considering a very specific biofuel chain (production and use of Pure/Straight Sunflower Oil in North-Central Italy), discuss some limits and constraints of the application of the LCA method. The work investigated within which boundaries Life Cycle Assessment could be implemented to perform quantitative assessments, as requested by the current supporting policies in the biofuel area. Results showed very large variations in the calculation of the CO₂ equivalent emissions, thus illustrating how achievable results depends on the local agricultural practices and performances, even for such a small and well defined biofuel chain. The adoption of the present standardized Life Cycle Assessment approach for generalized evaluations in the bioenergy sector and, in particular, for quantitative assessments should therefore be reconsidered. Concluding, LCA studies, even while addressing very specific and well defined chains, should always provide the bias of the calculations, as this range of variation of Life Cycle Assessment results could be significantly greater than the initially set quantitative targets and therefore the whole investigation would be at risks of inconsistency. Proposals are finally given for small scale projects, with the aim of developing sound but realistic processes to assess biofuel sustainability.     

Life cycle assessment (LCA) of waste management strategies: Landfilling,sorting plant and incineration

This paper focuses on a Life Cycle Assessment (LCA) of four waste management strategies: landfill without biogas utilization; landfill with biogas combustion to generate electricity; sorting plant which splits the inorganic waste fraction (used to produce electricity via Refuse Derived Fuels, RDF) from the organic waste fraction (used to produce biogas via anaerobic digestion); direct incineration of waste. These scenarios are applied to the waste amount and composition of the Municipality of Roma (Italy) and are evaluated under different points of view: global and local emissions, total material demands, total energy requirements and ecological footprints. Results, reliable for most of the European big cities, show landfill systems as the worst waste management options and significant environmental savings at global scale are achieved from undertaking energy recycling. Furthermore, waste treatments finalized to energy recovery provide an energy output that, in the best case, is able to meet the 15% of Roma electricity consumption.     

Assessment of system variations for hydrogen transport by liquid organic hydrogen carriers

One option to transport hydrogen over longer distances in the future is via Liquid Organic Hydrogen Carriers (LOHC). They can store 6.2 wt% hydrogen by hydrogenation. The most promising LOHCs are toluene and dibenzyltoluene. However, for the dehydrogenation of the LOHCs – to release the hydrogen again – temperatures above 300 °C are needed, leading to a high energy demand. Therefore, a Life Cycle Assessment (LCA) and Life Cycle Costing are conducted. Both assessments concentrate on the whole life cycle rather than just direct emissions and investments. In total five different systems are analysed with the major comparison between conventional transport of hydrogen in a liquefied state of matter and LOHCs. Variations include electricity supply for liquefaction, heat supply for dehydrogenation and the actual LOHC compound. The results show that from an economic point of view transport via LOHCs is favourable while from an environmental point of view transport of liquid hydrogen is favourable.     

Life cycle assessment of biodiesel production using alkali, soluble and immobilized enzyme catalyst processes

This study deals with the Life Cycle Assessment (LCA) of three different catalytic processes for biodiesel production. In the LCA study, a “cradle to gate” approach was adopted to estimate the environmental impact of different catalytic processes such as immobilized, soluble biocatalyst and alkali catalyst. The results revealed that, biodiesel production using immobilized biocatalyst has less environmental impact compared to alkali and soluble biocatalyst. The environmental impact of the immobilized biocatalyst depends on the reusability factor.     

LCA sensitivity analysis of a multi-megawatt wind turbine

During recent years renewables have been acquiring gradually a significant importance in the world market (especially in the Spanish energetic market) and in society; this fact makes clear the need to increase and improve knowledge of these power sources. Starting from the results of a Life Cycle Assessment (LCA) of a multi-megawatt wind turbine, this work is aimed to assess the relevance of different choices that have been made during its development. Looking always to cover the largest possible spectrum of options, four scenarios have been analysed, focused on four main phases of lifecycle: maintenance, manufacturing, dismantling, and recycling. These scenarios facilitate to assess the degree of uncertainty of the developed LCA due to choices made, excluding from the assessment the uncertainty due to the inaccuracy and the simplification of the environmental models used or spatial and temporal variability in different parameters. The work has been developed at all times using the of Eco-indicator99 LCA method.     

Survey on the P.V. Generator of Castellina in Chianti (Italy)

The aim of this study was the definition of low-cost solutions to optimise and maintain a satisfactory cost balance in the medium-long term between the different sub-systems and components of P.V. power generators.

In particular, the long-term objective is to keep the cost of support structures below about 20% of the total system cost.

A unit of about 200 modules was investigated in the Chianti Region of Castellina and in this paper results will be presented on the following topics

-the feasibility study of the most appropriate solution of a low-cost, simple, light-weight (0.3 kg/Wp), flexible and continuous array support structure (made of timber and steel wires).

-The study of the soil and of the site including site preparation by simple machines.

-The design of the solution retained valid after the imposed limitations for the plant approval.

-The construction and assembling of the entire P.V. plant.

-The measurements' campaigns carried out on the main structural components and the discussion of these results compared with design assumptions.

-The extrapolation of the real costs to larger P.V. units.

-The conclusive remarks on the experience acquired during the implementation of the project, its realization, its testing and operation over more than 18 months of life-time.     

Hydrophilic and hydrophobic materials and their applications

Wettability of a material’s surface plays a significant role in how fluids interact with such surfaces. Wetting behavior is universal but can vary depending on the chemical nature of the solid and liquid phases. Plants and animals adapt to their environment by having evolved special properties. These properties are such as hydrophilic and hydrophobic. Hydrophilic surface has a strong affinity to water and spreading of water on such surface is preferred. The degree of hydrophilicity of the substance can be measured by measuring the contact angle between the liquid and solid phases. Hydrophobic materials are known as non-polar materials with a low affinity to water, which makes them water repelling. A contact angle of less than 90° indicates hydrophilic interaction where as an angle greater than 90° indicates a hydrophobic interaction. More recently, superwetting such as superhydrophilicity has been receiving an increased focus in the literature due to its potential significance. Superhydrophilic surface has a contact angle of less than 5°.

The fabrication of hydrophilic materials can be carried out in two main ways: depositing molecules on surfaces or modification of surface chemistry. Both methods have been successful historically in achieving their intended purposes. Hydrophobic and superhydrophobic materials can be produced with many fabrication methods such as layer-by-layer assembly, laser process, the solution-immersion method, sol-gen techniques, chemical etching, and Hummer’s method.

The applications of such an important property are significant. For example, hydrophilic surfaces can be used in anti-fogging applications, biomedical, filtration, heat pipes, and many others. Hydrophobic and superhydrophobic materials have been successfully applied in many sectors, such as: (I) the removal of petroleum from aqueous solutions, (II) applied to plastic, ceramics, and mesh to contribute to the oil removal from aqueous solutions, (III) hydrophobic layers have a strong self-cleaning effect on plastics, heat pipes, metals, textiles, glass, paints, and electronics, (IV) hydrophobic layers improve the anti-freezing behavior of heat pipes which prevents unwanted build-up and (V) they function as a water and dust protecting coat on electronics.

The presence of this property is historic but there is still a huge potential for development for its applications in many sectors such as water treatment, heat transfer applications, biomedical devices, and many more.     

Life cycle assessment of electricity generation in Mexico

This paper presents for the first time a Life Cycle Assessment (LCA) study of electricity generation in Mexico. The electricity mix in Mexico is dominated by fossil fuels, which contribute around 79% to the total primary energy; renewable energies contribute 16.5% (hydropower 13.5%, geothermal 3% and wind 0.02%) and the remaining 4.8% is from nuclear power. The LCA results show that 225 TWh of electricity generate about 129 million tonnes of CO₂ eq. per year, of which the majority (87%) is due to the combustion of fossil fuels. The renewables and nuclear contribute only 1.1% to the total CO₂ eq. Most of the other LCA impacts are also attributed to the fossil fuel options. The results have been compared with values reported for other countries with similar electricity mix, including Italy, Portugal and the UK, showing good agreement.     

Two-dimensional numerical modeling of combustion of Jordanian oil shale

A two-dimensional (2-D) modeling of the burning process of Jordanian oil shale in a circulating fluidized bed (CFB) burner was done in this study. The governing equations of continuity, momentum, energy, mass diffusion, and chemical combustion reactions kinetics were solved numerically using the finite volume method. The numerical solution was carried out using a high-resolution 2-D mesh to account for the solid and gaseous phases, k-ε turbulence, non-premixed combustion, and reacting CFD model with the same dimensions and materials of the experimental combustion burner used in this work. The temperature distribution and evolution of species were also computed.

Proximate and ultimate analyses were also performed to evaluate the air–fuel ratio and ash content. The required thermophysical properties, such as heating value, density, and porosity were obtained experimentally, while the activation energy was obtained from published literature.

It was found that the temperature contours of the combustion process showed that the adiabatic flame temperature was 1080 K in a vertical burner, while the obtained experimental results of maximum temperature at various locations of the burner in actual, non-adiabatic, non-stoichiometric combustion reached 950 K, showing good agreement with the model.     

Prediction of asphaltene deposition parameters in porous media using experimental data during miscible gas injection

The study of asphaltene deposition under actual field conditions is impossible. Therefore, many models have been derived based on experimental data. All models have some matching parameters, which are estimated along with numerical solving or simulation to match experimental and simulation data, so it is possible that these were estimated as required (tuning factor).

In this study, two miscible CO₂ injection dynamic tests in porous media were performed. In these tests, CO₂ and live oil were injected into the core simultaneously. The CO₂ concentration was more than the onset concentration for asphaltene precipitation.

The main objective of this work was to determine the deposition coefficients from the experimental data, so these were predicted by using basic equations using the material balance. Also, by mathematical methods, the relation between these parameters was determined.

Results from this work imply that the deposition parameters can be estimated from the experimental data and these parameters are not constant during modeling and simulation.     

Life cycle assessment of H2 generation with high temperature electrolysis

Water electrolysis is a well-established process for hydrogen production but requires efficiency improvements to reduce costs. High temperature electrolysis (HTE) as a means to higher efficiency was advanced in the EU project RelHY. Through Life Cycle Assessment (LCA), also the environmental performance of five HTE-based hydrogen production systems was evaluated: operation with power and steam from a nuclear plant, continuous and intermittent operation with wind power and water, intermittent operation with natural gas or biogas reforming as back-up. Large scale natural gas reforming (NGR) was used as a reference. The LCA aims to identifying environmental hotspots of HTE plants and comparing their operation. The results show that stack manufacturing has the strongest impact during construction of the HTE plant while the impacts during H₂ production are largely due to power supply. All HTE variants studied lead to less life cycle CO₂-equivalent emissions than NGR. However, only the wind powered HTE variants without back-up use less energy than NGR. The other impacts and flows show different patterns. The results and limitations of the study are discussed.     

Environmental assessment of electricity generation from an Italian anaerobic digestion plant

A standard ISO Life Cycle Assessment study was carried out to evaluate the environmental sustainability of electricity production from an anaerobic digestion (AD) plant using a mixture of dedicated energy crops, agricultural residues and livestock effluents as input materials. The functional unit was 1 MJ of electricity. System boundaries were from cradle to grave and covered all the phases from energy crops cultivation to the production of biogas and its use in a Combined Heat and Power plant to produce electricity. Liquid and solid digestate storage and spreading on agricultural land were included. Primary data were collected from the AD plant for all the above phases. Since heat produced is used only internally, no allocation was applied in the study. As regards digestate management, CH₄ emissions were calculated from literature, whereas four literature methods were applied for calculation of nitrogen emissions with the goal to perform a sensitivity analysis on LCA results. ILCD Handbook impact assessment methodologies were used. Results show that the main hotspots are energy crops cultivation and the management of digestate, mainly because of both nitrogen and methane emissions, affecting Global Warming, Acidification, Marine and Freshwater Eutrophication. Finally, a detailed Monte Carlo analysis, was carried out to evaluate the results uncertainty. The study represents the state of the art about the environmental performance of the AD plant with the use of sensitivity and uncertainty analysis, which both improve the reliability of results, and allows drawing general conclusions on how to mitigate the environmental impacts of AD process.     

MCFC matrix: A comparison between the traditional tape casting process and the upgraded plastic extrusion technology set up by FN

Since 1990 FN S.p.A (a 98.65% ENEA participated Company), in collaboration with ENEA and AFCo-Ansaldo Fuel Cells Company, has been involved in research and development activities in the field of high temperature fuel cell porous components and in their traditional manufacturing processes (tape casting and sintering).In alternative to the traditional tape casting technology, FN has developed an innovative process based on the moulding plastic technology for the production of MCFC ceramic matrixes. With the new technology the environmental impact is reduced as it has been shown by LCA (Life Cycle Assessment) preliminary studies. These results are not the only advantages: the new process allows the realization of various and/or complex component shapes, a higher productivity level, cost reducing and the complete re-workability of rejects.In this paper a comparison between the traditional tape casting process and the new route process is shown.     

How can life cycle assessment foster environmentally sound fuel cell production and use?

Successful market penetration of Fuel Cell (FC) technologies requires increased research and technological efforts towards improved efficiency, durability, costs and environmental performance according to accepted standards. Life Cycle Assessment (LCA) can help understand to what extent FCs are environmentally sound, to what extent they can be improved and what steps and components require attention. A guidance manual for LCA application to FC technologies, processes and systems, compliant with the International Reference Life Cycle Data System (ILCD), was developed within the European Union-funded Fuel Cell-Hydrogen Guide (FC-Hy Guide) Consortium. The purpose was to provide entrepreneurs, consultants and experts with a specific guidance tool for use in policy context and decision-making. This paper presents the application of the FC-Hy Guide scheme to Molten Carbonate Fuel Cells (MCFC), with focus on the following aspects: (1) data quality; (2) information needed; (3) background and foreground data; (4) FC stack and balance of system; (5) improvement potential; (6) sensitivity of results and data uncertainty.     

Energy efficiency in transport and mobility from an eco-efficiency viewpoint

European Union countries’ current energy policies for the transport sector promote, amongst other initiatives; urban mobility plans, the renewal of fleets of cars and industrial vehicles and the introduction of biofuel. From the point of view of eco-efficiency and Life Cycle Assessment (LCA), energy policies must go further. The objective of this paper is to analyse the current transport model and the policies on energy efficiency being promoted in the EU from a LCA point of view. Special attention has been paid to private vehicles, in assessing the environmental impact of the various stages of manufacture, their use and disposal, and the consequences of plans to renew fleets. How old should a vehicle ideally be so that when it is changed, the embodied energy in the materials of the vehicle is less than the gain in energy efficiency due to changing the model for example? In addition the paper analyses the different means of transport in the energy consumption-time ratio from a LCA viewpoint. The fact that reducing transport times leads to greater energy consumption gives rise to the question: how long does nature take to repair the environmental damage caused?