Life cycle assessment of hydrogen fuel cell and gasoline vehicles

A life cycle assessment of hydrogen and gasoline vehicles, including fuel production and utilization in vehicles powered by fuel cells and internal combustion engines, is conducted to evaluate and compare their efficiencies and environmental impacts. Fossil fuel and renewable technologies are investigated, and the assessment is divided into various stages.     

Life cycle analysis and cost of a molten carbonate fuel cell prototype

The LCA is a method enabling the performance of a complete study on the environmental impacts of the product, taking into consideration all its life cycle (“from the cradle to the tomb” or, better “from the cradle to the cradle” when also the maximum recycling/reusing of the materials is provided. There are many procedures to perform an LCA of the consumers’ products. In particular, the SUMMA method (Sustainability Multi-criteria Multi-scale Assessment) allows obtaining a number of indices of efficiency and environmental sustainability which make the LCA assessment much more complete and significant. LCA method often represents the basis for an additional assessment of industrial products and processes, the LCC (Life Cycle Costing) which, allowing the association of economic variables to any phase of the life cycle, represents a useful tool for financial planning and management. The case study analysed in the present work concerns an LCA analysis, using the SUMMA method and the LCC of one small size molten carbonate fuel cell, 2.5 kW, assembled in the Fuel Cells Laboratory within the Educational Pole of Terni at the Università degli Studi di Perugia. For sake of completeness of the results, the methods Ecoindicator99 and Impact2002 + were used in the analysis, as implemented in the used calculation software, the SimaPro 7.1 by PRè Consultants. From the registered results, it emerges that the environmental energy sustainability of the analysed element enables its widespread and in-depth employment in the phase subsequent to the optimisation of the connected economic frame; the scenarios opened by the present work envisage great margins of improvements of said aspects in the future experiments.     

Environmental life cycle feasibility assessment of hydrogen as an automotive fuel in Western Australia

A life cycle assessment has been undertaken in order to determine the environmental feasibility of hydrogen as an automotive fuel in Western Australia. The criterion for environmental feasibility has been defined as having life cycle impacts equal to or lower than those of petrol. Two hydrogen production methods have been analysed. The first is steam methane reforming (SMR), which uses natural gas (methane) as a feedstock. The second method analysed is alkaline electrolysis (AE), a mature technology that uses water as a feedstock. The life cycle emissions and impacts were assessed per kilometre of vehicle travel.     

Maximum equivalent power output and performance optimization analysis of an alkaline fuel cell/heat-driven cycle hybrid system

A generic model of the hybrid system consisting of an alkaline fuel cell (AFC) and a heat-driven cycle, which may work as either a refrigerator or a heat pump, is originally established. On the basis of the models of AFCs and three-heat-reservoir cycles, the equivalent power output and efficiency of the hybrid system are obtained. The performance characteristic curves of the hybrid system are represented through numerical calculation. The maximum equivalent power output and efficiency of the hybrid system are determined. Problems concerning the optimal operation of the hybrid system are discussed. The effects of the main irreversible losses on the performance of the hybrid system are investigated in detail. It is important to note that the waste heat produced in the AFC can be readily used in such a hybrid cycle.     

Life cycle assessment of refuse-derived fuel production from mixed municipal waste

The aim of this study is to identify and assess the potential environmental impacts caused by refuse-derived fuel (RDF) production from mixed municipal waste, in a mechanical–biological waste treatment plant in Krakow, Poland. The study is based on life cycle assessment methodology, employing EASETECH model. The system boundaries include only those operations which lead to the production of RDF. The adopted functional unit is 1 Mg of mixed municipal waste generated in Krakow, which enters the mechanical–biological waste treatment plant.     

Life cycle assessment of a micromorph photovoltaic system

In this paper the results from a in-depth life cycle analysis of production and use of a novel grid-connected photovoltaic micromorph system are presented and compared to other thin film and traditional crystalline silicon photovoltaic technologies. Among the new thin film technologies, the micromorph tandem junction appears to be one of the most promising devices from the industrial point of view. The analysis was based on actual production data given to the authors directly from the PRAMAC Swiss Company and it is consistent with the recommendations provided by the ISO norms and updates. The gross energy requirement, green house gas emissions and energy pay-back time have been calculated for the electric energy output virtually generated by the studied system in a lifetime period of 20 years. A comparative framework is also provided, wherein results obtained for the case study are compared with data from literature previously obtained for the best commercially available competing photovoltaic technologies. Results clearly show a significant decrease in gross energy requirement, in green house gas emissions and also a shorter energy pay-back time for the micromorph technology.     

Thermodynamic model for an alkaline fuel cell

Alkaline fuel cells are low temperature fuel cells for which stationary applications, e.g. cogeneration in buildings, are a promising market. In order to guarantee a long life, water and thermal management has to be done in a careful way. In order to better understand the water, alkali and thermal flows, a two-dimensional model for an Alkaline Fuel Cell is developed using a control volume approach. In each volume the electrochemical reactions together with the mass and energy balance are solved. The model is created in Aspen Custom Modeller, the development environment of Aspen Plus, where special attention is given to the physical flow of hydrogen, water and air in the system. In this way the developed component, the AFC-cell, can be built into stack configurations to understand its effect on the overall performance. The model is validated by experimental data from measured performance by VITO with their Cell Voltage Monitor at a test case, where the AFC-unit is used as a cogeneration unit.     

Life cycle assessment and environmental life cycle costing analysis of lignocellulosic bioethanol as an alternative transportation fuel

The objective of this paper is to conduct Life Cycle Assessment (LCA) and Environmental Life Cycle Costing (ELCC) studies for lignocellulosic bioethanol blends [E10 and E85 (10% and 85% by volume of bioethanol with gasoline, respectively)] and conventional gasoline (CG). To compare the environmental performance and economic advantage of the selected fuel blends, the impact potentials and the cost of fuel applications per kilometer by a middle size car was evaluated. According the LCA results, one kilometer driven by E10 and E85 fueled vehicles could reduce the greenhouse gas (GHG) emissions by 4.3% and 47% and ozone layer depletion emissions by 3% and 66%, respectively, relative to CG. However, shifting from gasoline to bioethanol increases the emissions that contribute to eutrophication and photochemical ozone depletion. In terms of acidification potential, E85 shows a more favorable result relative to E10 and CG. According to the ELCC analysis, E85 fuel use provides a 23% lower driving cost relative to CG based on a-1 km driving distance. The results showed that E85 seems to be the best alternative in terms of both GHG emission and fuel production cost reduction compare to CG.     

Energy and carbon payback times for solid oxide fuel cell based domestic CHP

Fuel cells already provide heat and power to people’s homes with lower direct CO₂ emissions and fuel consumption than traditional methods. However, their whole life cycle, including manufacture and disposal, must be considered to verify that these environmental impacts are actually reduced and not merely shifted elsewhere. The total carbon footprint and energy payback times have been widely reported for other emerging microgeneration technologies, but have not previously been calculated for fuel cell systems.     

Performance evaluation of an alkaline fuel cell/thermoelectric generator hybrid system

A hybrid system consisting of an AFC (Alkaline Fuel Cell), a TEG (Thermoelectric Generator) and a regenerator is put forward, where the AFC converts the chemical energy in the hydrogen into electrical energy and thermal energy, and the released thermal energy is subsequently converted into electrical energy through the bottoming TEG. The main irreversible losses in each element of the hybrid system are characterized, and numerical expressions for the efficiency and power output of the AFC, TEG and hybrid system are respectively derived. The fundamental relation between the operating current density of the AFC and the dimensionless current of the TEG is obtained, from which the region of the operating current density of the AFC that the TEG exerts its function is determined. By employing such a hybrid system, the equivalent maximum power density of the AFC can be increased by up to 23%. The effects of the operating current density, operating temperature, heat conductivity, and integrated parameter on the performance of the hybrid system are revealed. The results obtained in the present paper will provide some theoretical guidance for the performance improvement of the AFC.     

Water management in an alkaline fuel cell

Alkaline fuel cells are low temperature fuel cells for which stationary applications, like cogeneration in buildings, are a promising market. To guarantee a long life, water and thermal management has to be controlled in a careful way. To understand the water, alkali and thermal flows, a model for an alkaline fuel cell module is developed using a control volume approach. Special attention is given to the physical flow of hydrogen, water and air in the system and the diffusion laws are used to gain insight in the water management. The model is validated on the prediction of the electrical performance and thermal behaviour. The positive impact of temperature on fuel cell performance is shown. New in this model is the inclusion of the water management, for which an extra validation is performed. The model shows that a minimum temperature has to be reached to maintain the electrolyte concentration. Increasing temperature for better performance without reducing the electrolyte concentration is possible with humidified hot air.     

Dynamic simulation and lifecycle assessment of hydrogen fuel cell electric vehicles considering various hydrogen production methods

In this research study, a real model of a hydrogen fuel cell vehicle is simulated using Simcenter Amesim software. The software used for vehicle simulation enabled dynamic simulation, resulting in more precise simulation. Furthermore, considering that fuel cell degradation is one of the significant challenges confronting fuel cell vehicle manufacturers, we examined the impact of fuel cell degradation on the performance of hydrogen vehicles. According to the findings, a hydrogen vehicle with a degraded fuel cell consumes 14.3% more fuel than a fresh fuel cell hydrogen vehicle. A comprehensive life cycle assessment (LCA) is also performed for the designed hydrogen vehicle. The results of the hydrogen vehicle life cycle assessment are compared with a gasoline vehicle to fully understand the effect of hydrogen vehicles in reducing air emissions. The methods considered for hydrogen production included natural gas reforming, electrolysis, and thermochemical water splitting method. Furthermore, because the source of electricity used for electrolysis has a significant impact on the life cycle emission of a hydrogen vehicle, three different power sources were considered in this assessment. Finally, while a hydrogen vehicle with a degraded fuel cell emits lower carbon dioxide (CO₂) than a gasoline vehicle, the emitted CO₂ from this vehicle using hydrogen from electrolysis is approximately 25% higher than that of a new hydrogen vehicle.     

Cost targets for domestic fuel cell CHP

Fuel cells have the potential to reduce domestic energy bills by providing both heat and power at the point of use, generating high value electricity from a low cost fuel. However, the cost of installing the fuel cell must be sufficiently low to be recovered by the savings made over its lifetime. A computer simulation is used to estimate the savings and cost targets for fuel cell CHP systems.     

Life time test in direct borohydride fuel cell system

The electric performances of direct borohydride fuel cells (DBFCs) are evaluated in terms of power density and life time with respect to the NaBH₄ concentration. A DBFC constituted of an anionic membrane, a 0.6 mg_Pt cm⁻² anode and a commercial non-platinum based cathode led to performances as high as 200 mW cm⁻² at room temperature and with natural convection of air. Electrochemical life time test at 0.55 mA cm⁻² with a 5 M NaBH₄/1 M NaOH solution shows a voltage diminution of 1 mV h⁻¹ and a drastic drop of performances after 250 h. The life time is twice longer with 2 M NaBH₄/1 M NaOH solution (450 h) and the voltage decrease is 0.5 mV h⁻¹. Analyses of the components after life time tests indicate that voltage loss is mainly due to the degradation of the cathode performance. Crystallisation of carbonate and borate is observed at the cathode side, although the anionic membrane displays low permeability to borohydride.     

The influence of degradation effects in proton exchange membrane fuel cells on life cycle assessment modelling and environmental impact indicators

Although proton exchange membrane fuel cell (PEMFC) systems are expected to have lower environmental impacts in the operational phase, compared to conventional energy conversion systems, there are still certain economic, operational, and environmental setbacks. Durability under a wide range of operating conditions presents a challenge because degradation processes affect the PEMFC efficiency. Typically, life cycle assessment (LCA) of PEMFC systems do not include performance degradation. Thus, a novel semi-empirical PEMFC model is developed, which includes degradation effects caused by different operational regimes (dynamic and steady-state). The model is integrated into LCA through life cycle inventory (LCI) to achieve a more realistic and accurate evaluation of environmental impacts. Verification of the model clearly showed that the use of existing LCI models underestimates the environmental impacts. This is especially evident when green hydrogen is used in PEMFC operational phase, where manufacturing phase and maintenance (stack replacements) become more influential. Input parameters of the model can be modified to reflect technological improvements (e.g. platinum loading or durability) and evaluate the effects of future scenarios.     

Life cycle energy,environment and economic assessment of soybean-based biodiesel as an alternative automotive fuel in China

Life cycle energy, environment and economic assessment for conventional diesel (CD) and soybean-based biodiesel (SB) in China was carried out in this paper. The results of the assessment have shown that compared with CD, SB has similar source-to-tank (StT) total energy consumption, 76% lower StT fossil energy consumption, 79% higher source-to-wheel (StW) nitrogen oxides (NO_X) emissions, 31%, 44%, 36%, 29%, and 67% lower StW hydrocarbon (HC), carbon monoxide (CO), particulate matter (PM), sulfur oxides (SO_X), and carbon dioxide (CO₂) emissions, respectively. SB is thus considered to be much more renewable and cleaner than CD. However, the retail price of SB at gas stations would be about 86% higher than that of CD without government subsidy according to the cost assessment and China had to import large amount of soybean to meet the demand in recent years. Therefore, although SB is one of the most promising clean and alternative fuels, currently it is not a good choice for China. It is strategically important for China to diversify the feedstock for biodiesel and to consider other kinds of alternative fuels to substitute CD.     

Life cycle assessment of olive pomace gasification for an up-draft fixed bed gasifier system

Biomass gasification has been considered as an important renewable energy alternative to deal with the environmental problems originating from fossil fuels and climate change effects. Olive pomace as a by-product of the olive oil production process is a significant biomass source. Although gasification technology is accepted as an environmentally friendly power system, the studies to determine its environmental impact via Life Cycle Assessment (LCA) are very limited. LCA is a key tool to evaluate all environmental impacts from the beginning to the end of the process. The aim of this study is to assess the overall environmental impacts of the olive pomace gasification for electricity generation and evaluation of its solid by-products namely biochar and tar. Four scenarios were compared to estimate the environmental impacts of gasification by-products with a LCA approach, following to the cradle-to-grave approach. The production of olive, olive pomace generation during its processing for olive oil production, gasification of olive pomace, construction of the gasifier, gas cleaning system and syngas composition have been included in the evaluations. It is clear from the analysis results that the scenarios have very low impact values in the case of beneficial usage of biochar in different industries. In terms of ozone layer depletion potential (2.74 × 10 ⁻⁶ kg CFC11 eq) and global warming potential (36.99 GWP100a), the paramount scenario from an environmental viewpoint is the scenario having the biochar and tar usage as a resource in another industry.     

Life cycle assessment of hydrogen and diesel dual-fuel class 8 heavy duty trucks

Heavy-duty trucks, in particular class 8 tractor-trailer combinations for freight, are a major contributor to the total greenhouse gas (GHG) emissions in transportation systems worldwide. Diesel fuel vastly dominates this market due to its relatively low operating cost. However, both GHG and air pollutant emissions from diesel combustion are significant, which raises doubts about the long-term sustainability of this mode of transportation. A possible short-term opportunity to address this problem is to blend diesel with hydrogen by retrofitting existing fuel injection systems and fuel storage onboard the trucks. Thus, a life cycle assessment is conducted to evaluate the overall environmental and economic impacts of implementing hydrogen and diesel dual-fuel solutions in heavy-duty trucks. The results show a significant reduction in emissions, proportionally to the diesel displacement ratio. Importantly, the use of hydrogen fuel is also shown to provide potential cost savings in this highly cost-sensitive application for hydrogen pricing below C$4/kg. Hence, waste hydrogen available at low cost can facilitate immediate emission reduction and operational cost savings for existing truck fleets, and act as an economical bridge solution for sustainable heavy-duty freight.     

MEA for alkaline direct ethanol fuel cell with alkali doped PBI membrane and non-platinum electrodes

This paper reports on the fabrication of MEA for alkaline direct ethanol fuel cell (ADEFC). The MEA was fabricated using non-platinum electrocatalysts and a membrane of alkali doped polybenzimidazole (PBI). The employed oxygen reduction catalyst was prepared by pyrolysis of 5,10,15,20-tetrakis(4-methoxyphenyl)-21H,23H-porphine cobalt(II) supported on XC72 carbon. This catalyst is tolerant to ethanol. Electrocatalyst at the anode was RuV alloy supported on XC72 carbon. It was synthesized by reduction of respective salts at elevated temperature. Single cell power density of 100 mW cm⁻² at U = 0.4 V was achieved at 80 °C using air at ambient pressure and 3 M KOH + 2 M EtOH anode feed. The developed MEA is considered viable for use in emergency power supply units and in power sources for portable electronic equipment.     

Life cycle assessment of photovoltaic electricity generation

The paper presents the results of a life cycle assessment (LCA) of the electric generation by means of photovoltaic panels. It considers mass and energy flows over the whole production process starting from silica extraction to the final panel assembling, considering the most advanced and consolidate technologies for polycrystalline silicon panel production. Some considerations about the production cycle are reported; the most critical phases are the transformation of metallic silicon into solar silicon and the panel assembling. The former process is characterised by a great electricity consumption, even if the most efficient conversion technology is considered, the latter by the use of aluminium frame and glass roofing, which are very energy-intensive materials. Moreover, the energy pay back time (EPBT) and the potential for CO₂ mitigation have been evaluated, considering different geographic collocations of the photovoltaic plant with different values of solar radiation, latitude, altitude and national energetic mix for electricity production.