Fuel Cells: Powering the Future

 

Introduction

Fuel cells, often lauded as the environmentally-conscious powerhouses of the future, have captured the world's attention due to their immense potential to transform energy production and storage. In this comprehensive exploration, we will journey into the heart of fuel cells, delving deep into their intricate mechanics, diverse applications, and the scientific principles underpinning their operation.

Understanding Fuel Cells

What is a Fuel Cell?

At its essence, a fuel cell is a remarkable electrochemical device that converts the stored chemical energy in fuels, typically hydrogen, into direct electrical energy. To grasp the full picture, let's embark on a journey through the core principles:

        In a typical fuel cell, fuel is fed continuously to the anode (negative electrode) and an oxidant (often oxygen from air) is fed continuously to the cathode (positive electrode). The electrochemical reactions take place at the electrodes to produce an electric current through the electrolyte, while driving a complementary electric current that performs work on the load.

Figure no .1

Image source and credit: FreudenbergGroup

 

·        Comparison with Batteries:

•       Although a fuel cell is similar to a typical battery in many ways, it differs in several respects. The battery is an energy storage device in which all the energy available is stored within the battery itself (at least the reductant).

•       The battery will cease to produce electrical energy when the chemical reactants are consumed (i.e., discharged). A fuel cell, on the other hand, is an energy conversion device to which fuel and oxidant are supplied continuously. In principle, the fuel cell produces power for as long as fuel is supplied. Fuel cells are classified according to the choice of electrolyte and fuel, which in turn determine the electrode reactions and the type of ions that carry the current across the electrolyte.

•       Appleby and Foulkes (1) have noted that, in theory, any substance capable of chemical oxidation that can be supplied continuously (as a fluid) can be burned galvanically as fuel at the anode of a fuel cell. Similarly, the oxidant can be any fluid that can be reduced at a sufficient rate.

•           Though the direct use of conventional fuels in fuel cells would be desirable, most fuel cells under development today use gaseous hydrogen, or a synthesis gas rich in hydrogen, as a fuel. Hydrogen has a high reactivity for anode reactions, and can be produced chemically from a wide range of fossil and renewable fuels, as well as via electrolysis.

 

Types of Fuel Cells:

Fuel cell	Abbreviation	Membrane	Worldwide use in %
Solid oxide fuel cells	SOFC	Yttria-stabilized zirconia	20
Direct methanol Fuel cell	DFMC	Solid polymer electrolyte (Nafion)	In research
phosphoric acid fuel cell	PAFC	Phosphoric Acid (H3PO4 )	In research
Polymer electrolyte fuel cell	PEMFC	Solid polymer electrolyte (Nafion)	70
Proton exchange membrane	PEMFC	Solid polymer electrolyte (Nafion)
alkaline fuel cell	APC	Aqueous solution Potassium Hydroxide (KOH)	10

 

Figure no 2 : Current World-wide use of fuel cell

 

How Do Fuel Cells Work?

Unveiling the inner workings of a fuel cell reveals a fascinating interplay of chemistry, physics, and engineering. The operation can be broken down into several key steps:

• Electrochemical Processes: Fuel cells involve electrochemical reactions, where hydrogen molecules (H2) at the anode split into protons (H+) and electrons (e-).
• Key Components: These electrochemical marvels consist of vital components like the anode, cathode, and an electrolyte, each playing a unique role in the energy conversion process.

Figure no .3 Chemical reaction of fuel cell  

 

The Science Behind Fuel Cells

Electrolysis and the Hydrogen Economy and current Results

Understanding the efficiency and sustainability of fuel cells involves diving into the science behind hydrogen production and utilization:

• Balancing Chemical Equations: Balancing the chemical equations is essential to assess the efficiency of hydrogen production methods.

The reaction occur are: -

Anode: H2 → 2H+ + 2e−

Cathode: 1 2 O2 + 2H+ + 2e− → H2O

                                                Table 1: - Reactions at different types of Fuel cells

Classification	Description	Reaction	Operating Temperature	Electrolyte type	Type
Proton exchange membrane fuel cell (PEMFC)	Uses hydrogen and oxygen as fuels, a polymer membrane as an electrolyte, and operates at ambient temperature.	Hydrogen (anode) + Oxygen (cathode) → Water + Electricity	80-100°C	Polymer membrane	Hydrogen
Alkaline fuel cell (AFC)	Uses hydrogen and oxygen as fuels, an alkaline solution as an electrolyte, and operates at ambient temperature.	Hydrogen (anode) + Oxygen (cathode) → Water + Electricity	80-100°C	Alkaline solution	Hydrogen
Molten carbonate fuel cell (MCFC)	Uses carbon monoxide and hydrogen as fuels, a molten carbonate as an electrolyte, and	Carbon monoxide (anode) + Hydrogen (cathode) →	600-700°C	Molten carbonate	Carbon monoxide, hydrogen
Solid oxide fuel cell (SOFC)	Uses hydrogen and oxygen as fuels, a solid oxide as an electrolyte, and operates at high temperature.	Hydrogen (anode) + Oxygen (cathode) → Water + Electricity	700-1000°C	Solid oxide	Hydrogen
Direct methanol fuel cell (DMFC)	Uses methanol as a fuel, a polymer membrane as an electrolyte, and operates at ambient temperature.	Methanol (anode) + Oxygen (cathode) → Carbon dioxide + Water + Electricity	60-100°C	Polymer membrane	Methanol
Phosphoric acid fuel cell (PAFC)	Uses hydrogen and oxygen as fuels, a phosphoric acid as an electrolyte, and operates at high temperature.	Hydrogen (anode) + Oxygen (cathode) → Water + Electricity	150-200°C	Phosphoric acid	Hydrogen

 

Figure no. 4 Efficiency of Different types of fuel cell

 

Voltage and Current: The Nernst Equation

To gauge the performance of fuel cells with precision, we turn to the Nernst equation:

• Understanding the Nernst Equation: This fundamental tool relates cell voltage to reactant activities, offering insights into efficiency and performance. At the heart of understanding and predicting fuel cell behavior lies the Nernst Equation. Formulated by the eminent German physical chemist Walther Nernst in the late 19th century, this equation allows us to calculate the voltage (or electromotive force, EMF) of a fuel cell based on the concentrations of reactants and products.
• Using the Nernst Equation: We'll explore practical applications of the Nernst equation in optimizing fuel cell systems.

E=Eo−nFRT​ln([C]c[D]d[A]a[B]b​)

E represents the cell voltage.

Eo is the standard cell voltage, a reference value.

R is the ideal gas constant.

T stands for temperature in Kelvin.

n is the number of electrons transferred in the reaction.

F is Faraday's constant.

The concentrations [A], [B],[C], and [D] correspond to the reactants and products of the electrochemical reaction.

 

 Recent Implementation of fuel cell

Case Study 1: Proton Exchange Membrane Fuel Cells (PEMFCs) in Automotive Applications

In a study of PEMFCs used in a fleet of hydrogen-powered buses, it was found that the system's overall energy efficiency (η) could be calculated using the following equation:
η = (Useful electrical energy output / Hydrogen energy input) * 100
Ballard Power Systems in collaboration with AC Transit and Sunline Transit Agency. In California, AC Transit and Sunline Transit Agency introduced a fleet of hydrogen fuel cell buses powered by PEMFCs.
The practical efficiency was measured at an impressive 60%, demonstrating the viability of PEMFCs in transportation.

Case Study 2: Solid Oxide Fuel Cells (SOFCs) in Combined Heat and Power (CHP) Systems.

In the Netherlands, Fuel Cell Energy Solutions deployed a 1.4 MW SOFC-based CHP system in a municipal district heating plant. The system simultaneously generated electricity and utilized waste heat for district heating, maximizing energy efficiency. Validation involved measuring electrical and thermal efficiency, as well as system reliability. The project showcased the effectiveness of SOFCs in providing sustainable, efficient, and reliable power and heat generation for urban areas.

  

               Figure no. 5 Annual global sales of FCEVs since 2017 and the projection until 2032

Fuel Cell Applications

Transportation

Fuel cell vehicles (FCVs) are heralded as a greener alternative to traditional combustion engine vehicles. We'll explore their advantages and conduct calculations to assess their efficiency and potential for reducing emissions.

Stationary Power Generation

Fuel cells extend beyond transportation and find applications in stationary power generation for residential, industrial, and remote settings. This section will evaluate the economic feasibility and environmental benefits of implementing fuel cell systems.

Space and Military Applications

Fuel cells have played pivotal roles in missions where reliability is paramount, such as space exploration and military operations. We'll delve into how fuel cells provide efficient and dependable power solutions in these mission-critical scenarios.

 

Challenges and Future Prospects

Overcoming Challenges

Hydrogen Production: One of the primary challenges in fuel cell technology is the production of hydrogen, a key fuel source. Currently, the majority of hydrogen is produced through a process called steam methane reforming (SMR), which relies on fossil fuels and emits greenhouse gases. However, there are innovative approaches to hydrogen production that show great potential:

• Electrolysis: Electrolysis, particularly using renewable energy sources like wind or solar power, has gained traction as a green method for hydrogen production. It involves splitting water into hydrogen and oxygen, producing a clean source of fuel.
• Biological Hydrogen Production: Researchers are exploring the use of microorganisms to produce hydrogen through biological processes, offering a sustainable and eco-friendly alternative.

Hydrogen Storage: Storing hydrogen efficiently and safely is another challenge. Hydrogen has a low energy density by volume, which necessitates effective storage solutions. Promising advancements include:

• Hydrogen Compression: Developing advanced compression techniques to increase the volumetric energy density of stored hydrogen.
• Hydrogen Solid-State Storage: Research into solid-state hydrogen storage materials, such as metal hydrides, for compact and safe hydrogen storage.

Cost Reduction: Reducing the cost of fuel cell systems is crucial for their widespread adoption. Innovative strategies include:

• Material Advancements: Exploring novel materials for fuel cells, such as non-precious metal catalysts, to reduce costs without sacrificing performance.
• Scale-Up: Scaling up production to achieve economies of scale, similar to what has been achieved with solar panels and batteries.

Challenges With Technology

• High initial costs: Fuel cells have been hindered by high initial costs, but costs are expected to decline as manufacturing capacity and capability increase and designs and integration improve.

• Supply management: High cost and limited supply of platinum, which is the most commonly used catalyst in PEMFCs 6. This has led to significant research and development efforts to minimize platinum usage while maximizing performance

• Safety concern: Hydrogen is a highly flammable gas that requires special handling and storage to ensure safety. The various aspects of hydrogen safety, such as hydrogen storage and handling, hydrogen leak detection, and hydrogen safety codes and standards need to be handled. 

• Operating Condition: Fuel cells must operate under a wide range of conditions, including temperature, pressure, and humidity. These conditions can affect the performance and durability of the fuel cell components, such as the membrane, electrodes, and catalysts. For example, high temperatures can cause thermal degradation of the membrane, while low humidity can cause membrane drying and cracking.

• Handling Impurities: The catalysts used in fuel cells must be stable and resistant to poisoning by impurities in the fuel or air. The materials used in the bipolar plates must be corrosion-resistant and electrically conductive. 

• Manufacturing: The manufacturing processes used to produce fuel cell components must be precise and consistent to ensure high quality and reliability. For example, the membrane electrode assembly (MEA) must be manufactured with precise thickness and uniformity to ensure optimal performance and durability.

• Thermal Management: Fuel cells generate heat during operation, which must be managed properly to prevent thermal degradation and ensure optimal performance and durability. For example, the cooling system must be designed to maintain the proper operating temperature range for the fuel cell components, if not done properly the Water flooding can cause. Fuel cells require a source of fuel, which must be processed and stored properly.

 

Fuel Cell Innovations

Fuel cell technology is experiencing a renaissance of innovation, offering a glimpse into a promising future of clean energy solutions:

Solid Oxide Fuel Cells (SOFCs): SOFCs have gained attention due to their high efficiency and ability to utilize a variety of fuels, including natural gas and biogas. Recent advancements in SOFC materials and manufacturing processes have made them more accessible for stationary power generation.

Proton Exchange Membrane Fuel Cells (PEMFCs): PEMFCs are finding applications beyond vehicles. They are becoming smaller and more efficient, making them suitable for portable power generation and backup power in remote locations.

Green Hydrogen: The production of green hydrogen using renewable energy sources is gaining momentum. Green hydrogen has the potential to be a game-changer in clean energy, with applications ranging from transportation to industrial processes.

Hybrid Systems: Combining fuel cells with other clean energy technologies, such as batteries and supercapacitors, is enhancing system efficiency and reliability. Hybrid systems can store excess energy and provide power during peak demand.

Commercialization: As fuel cell technology matures, more companies are entering the market, driving competition and innovation. This is leading to cost reductions and greater accessibility.

 

Conclusion

In summary, fuel cells are promising energy devices that convert fuels like hydrogen into electricity with numerous applications. They have potential environmental benefits but face challenges in hydrogen production, storage, and cost reduction. Recent innovations in solid oxide and proton exchange membrane fuel cells show promise. Collaboration among researchers, engineers, and policymakers is essential to harness the potential of fuel cells and move towards a cleaner and more sustainable energy future.

References

1.      Seventh Edition Fuel Cell Handbook. United States: N. p., 2004. Web. doi:10.2172/834188.

2.      Chakraborty, S.; Elangovan, D.; Palaniswamy, K.; Fly, A.; Ravi, D.; Seelan, D.A.S.; Rajagopal, T.K.R. A Review on the Numerical Studies on the Performance of Proton Exchange Membrane Fuel Cell (PEMFC) Flow Channel Designs for Automotive Applications. Energies 2022, 15, 9520.

3.      Sagaria, S.; Costa Neto, R.; Baptista, P. Assessing the Performance of Vehicles Powered by Battery, Fuel Cell and Ultra-Capacitor: Application to Light-Duty Vehicles and Buses. Energy Convers. Manag. 2021, 229, 113767

4.      ISO 22734:2019

5.      Modeling and control of fuel cell system and fuel processor, Jay Tawee Pukrushpan, University of Michigan

6.      Dutta, Sandip & Shimpalee, Sirivatch & Van Zee, J.. (2001). Numerical Prediction of Mass-Exchange between Cathode and Anode Channels in a PEM Fuel Cell. International Journal of Heat and Mass Transfer - INT J HEAT MASS TRANSFER. 44. 2029-2042. 10.1016/S0017-9310(00)00257-X.

7.      Sazali, N.; Wan Salleh, W.N.; Jamaludin, A.S.; Mhd Razali, M.N. New Perspectives on Fuel Cell Technology: Brief Review. Membranes 2020, 10, 99.

8.      Lixin Fan, Zhengkai Tu, Siew Hwa Chan,

9.      Recent development of hydrogen and fuel cell technologies: A review, Energy Reports, Volume 7,2021.

10.   Nancy L. Garland, Dimitrios C. Papa Georgopoulos, Joseph M. Stanford, Hydrogen and Fuel Cell Technology: Progress, Challenges, and Future Directions, Energy Procedia, Volume 28,2012.

11.   Manoharan, Yogesh & Hosseini, Seyed Ehsan & Butler, Brayden & Alzahrani, Hisham & Foua, Bi & Ashuri, Turaj & Krohn, John. (2019). Hydrogen Fuel Cell Vehicles; Current Status and Future Prospect. Applied Sciences. 9. 10.3390/app9112296.

Group 4 

Guided By :- Prof. (Dr). S .S Shinde

Presented By :-

Piyush Joshi

Swayam Jadhav

Akshata Kalbhor

Nidhi Hingankar

Vishwakarma Institute Of Technology, Pune.

....THANK YOU....