Environmental aspects of fuel cells: A review

doi:10.1016/j.scitotenv.2020.141803

Science of The Total Environment

Volume 752, 15 January 2021, 141803

https://doi.org/10.1016/j.scitotenv.2020.141803 Get rights and content

Highlights

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Environmental impacts of conventional energy conversion devices were discussed.
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Common fuel cells were summarized and compared to each other.
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Environmental aspects of different types of FCs were summarized.
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Fuel source has a substantial effect on the environmental impacts of FCs.

Abstract

Fossil fuels represent the primary energy supply utilized worldwide. Despite this, fossil fuels are both limited resources and have severe environmental impacts that result in climate change and several health issues. Fuel cells (FCs) are efficient energy conversion devices, which can be used for energy conversion and storage. Although different types of FCs exhibit promising features for future usage, they also have some environmental aspects that ought to be addressed. This review summarizes the different types of FCs, including the advantages and disadvantages of each. The different environmental aspects of the common types of FCs are then comprehensively discussed. This review also compares FCs to conventional power generation systems to illustrate their relative environmental benefits.

Although FCs are considered more environmental-friendly compared to conventional energy conversion systems, there are still evident operational and environmental setbacks among different FC types. These setbacks, however, must be compared in context of the intended application, fuel type, and all other involved factors in order to have a clear and fair comparison. FCs are considered environmentally friendly and more efficient. However, this is usually only when considering the operational phase or the operational perspective. The main challenge facing FCs still remains fuel sourcing, like, for example, in the case of obtaining hydrogen for hydrogen FCs, where hydrogen production causes environmental impacts. The same applies for electrode materials, where, in many cases, either a noble metal such as platinum, or other precious metals, or costly material. With this consideration, a life cycle assessment (LCA) is a useful tool that considers all of the manufacturing, fuel sourcing, and operational phases. Although using FCs shows evident environmental improvements compared to conventional energy sources, the LCA of FCs compared to that of conventional power sources shows a similar performance. This is mainly due to the EIs associated with fuel sourcing and material acquisition, either for precious metals used for low-temperature FCs, or thermally and chemically stable materials used for medium- and high-temperature FCs. Both of these also contribute largely to the cost of FCs. Developments in both areas will undoubtedly help to make FCs both more environmental-friendly and cost-efficient.

Graphical abstract

Introduction

Rapid population growth and advancements in civilization have resulted in a rapidly growing demand for energy sources that are mainly dependent on fossil fuels. Fossil fuels pose many disadvantages. Not only are their prices unstable and erratically fluctuating, but they are also a limited resource with severe environmental impacts (EIs), which result in global warming and other more severe health issues (Asongu et al., 2020; Ike et al., 2020). Renewable energy sources, such as: solar energy (Wilberforce et al., 2019a), wind energy (Nazir et al., 2019), geothermal energy (Wilberforce et al., 2019a), tidal and wave energy (Soudan, 2019) and biomass energy (Inayat et al., 2019; Nassef et al., 2019b) are considered the best potential candidates to replace fossil fuels for energy supply in the near future.

Conventional energy conversion devices, such as internal combustion engines and thermodynamic cycles, are commonly used for the extraction and conversion of chemical energy contained in different fuels (Ge et al., 2016). During this process, huge amounts of greenhouse gases (GHGs) are produced, resulting in a detrimental effect on the environment (Elsaid et al., 2020a; Turconi et al., 2013). To limit the detrimental effects of these fossil fuel-based devices, renewable energy-based fuels, such as biodiesel and bioethanol, have been proposed to decrease these major EIs (Mofijur et al., 2016). Though the potential of these strategies minimizing EIs is undeniable, there is still a considerable amount of GHGs produced. Full reliance on renewable energy sources requires the development of efficient energy conversion and storage devices, to further reduce or eliminate EIs.

Fuel cells (FCs) are energy conversion devices that convert the chemical energy of different fuels (including those from various renewable energy sources) directly into electrical energy at a much higher efficiency, both theoretically and practically, as compared to conventional power generation sources (Sayed et al., 2019). These FCs are not only efficient devices, but are also: small in size, silent, and have much lower EIs compared to other conventional devices or technologies specifically during the operational phase (Abdelkareem et al., 2019a). For example, a proton exchange membrane FC (PEMFC) fueled by hydrogen produces water as a byproduct, with a small release of waste heat. This is very promising compared to the huge gaseous emissions, waste heat, and cooling demand in conventional power generation systems (Sayed et al., 2020). FCs have several other advantages. For example, they cover a wide range of applications ranging from a few watts to several gigawatts (Wang et al., 2011). Microbial fuel cells are another class of FC that utilize microbes, hence, more environmental-friendly and eco-sound with a wide range of applications, ranging from power generation to desalination. (Olabi et al., 2020; Sayed et al., 2020; Sayed and Abdelkareem, 2013).

Several reviews have been carried out to evaluate the performance of different types of FCs, the catalysts used, and the operational conditions (Tiwari et al., 2013). However, to the best of the authors' knowledge, no previous reports have summarized or compiled the environmental impacts of the different types of FCs in one report. Although some works have partially addressed some of the operational and environmental aspects of specific FCs, they did not address the collective aspects of FCs, or compared them to conventional systems.

This review summarizes the different environmental aspects of FCs. The review starts with an explanation for conventional power generation and its environmental impacts. This explanation also serves as an aid in the comparison of the performance of FCs compared to conventional power systems. The review then provides some background information on the different types of FCs, and their operational aspects. This necessary introduction helps better understand the environmental aspects discussed in detail afterward. The review then thoroughly discusses and analyzes the environmental impacts of different FC types, followed by an inter-comparison among these FCs, to show the relative impacts of each FC type in comparison to both the other FC types and conventional systems. The discussion adopts the life cycle assessment (LCA) as much as possible, as it is an effective tool in assessing both operational and manufacturing phases. The review also discusses environmental aspects, which include both environmental benefits and negative impacts. Benefits include lower GHG emissions and fuel consumption due to higher efficiency, with other advantages mentioned when compared to conventional systems. Negative impacts, such as higher GHG emissions, more utilized resources, and other significant impacts, are discussed and compared when discussing different FC types.

Section snippets

Environmental impacts of conventional power generation systems

A wide variety of energy resources are readily available on the planet and can be classified broadly into energy stored in fuels and energy associated with renewable actions. The chemical energy stored in fuel has been the primary source of energy since the early era of the industrial revolution. Fig. 1 below shows the primary energy supply by the energy source in million-ton oil equivalent (Mtoe) over the last three decades. The figure shows that the energy supply is currently dominated by

Fuel cells

A fuel cell (FC) is simply a device that transforms fuels' chemical energy into power directly, without any intermediate energy forms, via a reaction between fuel and oxygen O₂ (Abdelkareem et al., 2020b). In FCs, the fuel and oxygen react via an electrochemical reaction, producing electrical energy, CO₂, H₂O, and some waste heat, which is much less than that in conventional combustion (Schäfer et al., 2006). An FC is made up of two electrodes, anode and cathode. A fuel passes through the anode

Environmental aspects of fuel cells

As discussed in the previous sections, an FC is simply a device or a tool that can convert the chemical potential or energy directly into electrical potential or energy, i.e., electricity. In this section, the different environmental aspects, i.e., benefits and impacts of utilizing FC for power generation, are discussed. The advantages and disadvantages of using FCs as a power source to drive vehicles are also discussed, and both are compared to those of conventional power generation and

Conclusions

Fossil fuels are the primary sources for energy supply worldwide, representing about 80% of the current global energy supply. However, the dependence on fossil fuels has been declining over the years, with more attention given towards utilizing cleaner technologies, such as: hydropower, renewable energies, biomass, waste, and, more importantly, fuel cells. Fuel cells (FCs) are simple devices that directly convert chemical energy into electrical energy, which explains both their higher energy

CRediT authorship contribution statement

All authors have equal contribution.

Declaration of competing interest

The authors declare that there is no conflict of interest of the current work.

References (128)

A.M. Abdalla et al.
Nanomaterials for solid oxide fuel cells: a review
Renew. Sust. Energ. Rev.
(2018)
M.A. Abdelkareem et al.
Factors affecting methanol transport in a passive DMFC employing a porous carbon plate
J. Power Sources
(2007)
M.A. Abdelkareem et al.
Comparative analysis of liquid versus vapor-feed passive direct methanol fuel cells
Renew. Energy
(2019)
M.A. Abdelkareem et al.
On the technical challenges affecting the performance of direct internal reforming biogas solid oxide fuel cells
Renew. Sust. Energ. Rev.
(2019)
M.A. Abdelkareem et al.
Synthesis and testing of cobalt leaf-like nanomaterials as an active catalyst for ethanol oxidation
Int. J. Hydrog. Energy
(2020)
M.A. Abdelkareem et al.
Significance of diffusion layers on the performance of liquid and vapor feed passive direct methanol fuel cells
Energy
(2020)
P. Ahmadi et al.
Comparative life cycle assessment of hydrogen fuel cell passenger vehicles in different Canadian provinces
Int. J. Hydrog. Energy
(2015)
A.H. Alami et al.
Titanium dioxide-coated nickel foam photoelectrodes for direct urea fuel cell applications
Energy
(2020)
J. Ally et al.
Life-cycle assessment of diesel, natural gas and hydrogen fuel cell bus transportation systems
J. Power Sources
(2007)
M. Andersson et al.
SOFC modeling considering hydrogen and carbon monoxide as electrochemical reactants
J. Power Sources
(2013)

E. Antolini

The stability of molten carbonate fuel cell electrodes: a review of recent improvements

Appl. Energy

(2011)

S.A. Asongu et al.

The criticality of growth, urbanization, electricity and fossil fuel consumption to environment sustainability in Africa

Sci. Total Environ.

(2020)

T.M. Bachmann et al.

Life cycle assessment of domestic fuel cell micro combined heat and power generation: exploring influential factors

Int. J. Hydrog. Energy

(2019)

N.A.M. Barakat et al.

Pd-doped Co nanofibers immobilized on a chemically stable metallic bipolar plate as novel strategy for direct formic acid fuel cells

Int. J. Hydrog. Energy

(2013)

N.F. Barilo et al.

Overview of the DOE hydrogen safety, codes and standards program part 2: hydrogen and fuel cells: emphasizing safety to enable commercialization

Int. J. Hydrog. Energy

(2017)

A. Baroutaji et al.

Comprehensive investigation on hydrogen and fuel cell technology in the aviation and aerospace sectors

Renew. Sust. Energ. Rev.

(2019)

A. Bauen et al.

Assessment of the environmental benefits of transport and stationary fuel cells

J. Power Sources

(2000)

Y. Bicer et al.

Life cycle environmental impact comparison of solid oxide fuel cells fueled by natural gas, hydrogen, ammonia and methanol for combined heat and power generation

Int. J. Hydrog. Energy

(2020)

Y. Casas et al.

Integration of solid oxide fuel cell in a sugar-ethanol factory: analysis of the efficiency and the environmental profile of the products

J. Clean. Prod.

(2011)

U.M. Damo et al.

Solid oxide fuel cell hybrid system: a detailed review of an environmentally clean and efficient source of energy

Energy

(2019)

V. Das et al.

Recent advances and challenges of fuel cell based power system architectures and control – a review

Renew. Sust. Energ. Rev.

(2017)

R. Dones et al.

Int. J. Hydrog. Energy

(2020)

O. Ellabban et al.

Renewable energy resources: current status, future prospects and their enabling technology

Renew. Sust. Energ. Rev.

(2014)

Khaled Elsaid et al.

Environmental impact of desalination technologies: A review

Sci. Total Environ.

(2020)

K. Elsaid et al.

Environmental impact of emerging desalination technologies : a preliminary evaluation

J. Environ. Chem. Eng.

(2020)

K. Elsaid et al.

Environmental impact of desalination processes : mitigation and control strategies

Sci. Total Environ.

(2020)

S. Evangelisti et al.

Life cycle assessment of a polymer electrolyte membrane fuel cell system for passenger vehicles

J. Clean. Prod.

(2017)

D.M. Fadzillah et al.

Critical challenges in the system development of direct alcohol fuel cells as portable power supplies: an overview

Int. J. Hydrog. Energy

(2019)

C. Feng et al.

Carbon-CeO2 composite nanofibers as a promising support for a PtRu anode catalyst in a direct methanol fuel cell

J. Power Sources

(2013)

M. Granovskii et al.

Environmental and economic aspects of hydrogen production and utilization in fuel cell vehicles

J. Power Sources

(2006)

M. Granovskii et al.

Life cycle assessment of hydrogen fuel cell and gasoline vehicles

Int. J. Hydrog. Energy

(2006)

D. Hart et al.

Environmental benefits of transport and stationary fuel cells

J. Power Sources

(1998)

M.M. Hussain et al.

A preliminary life cycle assessment of PEM fuel cell powered automobiles

Appl. Therm. Eng.

(2007)

G.N. Ike et al.

Fiscal policy and CO2 emissions from heterogeneous fuel sources in Thailand: evidence from multiple structural breaks cointegration test

Sci. Total Environ.

(2020)

A. Inayat et al.

Fuzzy modeling and parameters optimization for the enhancement of biodiesel production from waste frying oil over montmorillonite clay K-30

Sci. Total Environ.

(2019)

H. Ito

Economic and environmental assessment of phosphoric acid fuel cell-based combined heat and power system for an apartment complex

Int. J. Hydrog. Energy

(2017)

Y. Ito et al.

Ultrahigh methanol electro-oxidation activity of PtRu nanoparticles prepared on TiO2-embedded carbon nanofiber support

J. Power Sources

(2013)

H. Jouhara et al.

Waste heat recovery technologies and applications

Therm. Sci. Eng. Prog.

(2018)

M. Kamil et al.

Comprehensive evaluation of the life cycle of liquid and solid fuels derived from recycled coffee waste

Resour. Conserv. Recycl.

(2019)

M. Kamil et al.

Economic, technical, and environmental viability of biodiesel blends derived from coffee waste

Renew. Energy

(2020)

S. Khanmohammadi et al.

Potential of thermoelectric waste heat recovery in a combined geothermal, fuel cell and organic Rankine flash cycle (thermodynamic and economic evaluation)

Int. J. Hydrog. Energy

(2020)

Y.D. Lee et al.

Environmental impact assessment of a solid-oxide fuel-cell-based combined-heat-and-power-generation system

Energy

(2015)

X. Li et al.

The energy-conservation and emission-reduction paths of industrial sectors: evidence from Chinas 35 industrial sectors

Energy Econ.

(2020)

J. Lin et al.

Life cycle assessment integrated with thermodynamic analysis of bio-fuel options for solid oxide fuel cells

Bioresour. Technol.

(2013)

S. Lion et al.

A review of emissions reduction technologies for low and medium speed marine diesel engines and their potential for waste heat recovery

Energy Convers. Manag.

(2020)

S. Longo et al.

Life cycle energy and environmental impacts of a solid oxide fuel cell micro-CHP system for residential application

Sci. Total Environ.

(2019)

P. Lunghi et al.

Life-cycle-assessment of fuel-cells-based landfill-gas energy conversion technologies

J. Power Sources

(2004)

J. Malinauskaite et al.

Energy efficiency in industry: EU and national policies in Italy and the UK

Energy

(2019)

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