Ch 3 - Fuel Cells, Faradays Laws Flashcards
fuel cell design
Reactants (fuel (hydrogen) & oxidant (oxygen)) are continuously supplied from an external source.
Electrodes are porous to allow gases to diffuse and react.
Catalysts (e.g., platinum, nickel) speed up reactions.
The electrolyte carries ions between electrodes.
how fuel cell works
oxidation of fuel (hydrogen) at the anode. releases electrons. creates potential difference between cells.
fuel ions (Hplus ions) go throuhg porous carbon anode -> electrolyte solution -> cathode.
while this is happening, oxidant (oxygen) enters cathode compartment. get reduced. forms water and heat which is released through bottom inlet (outlet)
advantages of fuel cells
- lower emission of harmful sulfur and nitrogen containing compounds (compared with direct combustion of fuels)
- low maintenance and running costs
- quiet
- no direct co2 emissions from Hydrogen fuel cells
- Much greater efficiency than direct combustion, particularly if thermal
energy produced is harnessed for car/
home heating
disadvantages of fuel cells
- storage and safety issues (high explosive hydrogen fuel )
- expensive to manufacture
- requires new refill stations for hydrogen fuel
- hydrogen fuel made from electrolysis of water - how eco-friendly it is depends on where the electricity used for this process came from
- Potentially still not as efficient or
convenient as batteries
first law
The amount of electric charge (Q, in C) carried in a galvanic cell is directly proportional to the mass (m, in g) lost from the anode or gained at the cathode.
reaction that occurs at the anode
H2 + 2OH- -> 2H2O +2e-
reaction that occurs at the cathode
O2 + 2H2O + 4e- -> 4OH-
advantages of using porous electrodes
Increased surface area → Faster reactions
Better reactant access → Ideal for fuel cells
Improved current flow → Higher efficiency
Enhanced catalytic activity → Boosts reaction speed
Efficient mass transport → Reduces buildup of byproducts
disadvantages of using porous electrodes
Risk of blockage → Pores can clog over time
Fragility → More delicate than solid electrodes
High cost → Expensive to manufacture
Potential side reactions → Unwanted reactions may occur
Limited durability → Degradation reduces effectiveness
purpose of electrolyte in fuel cells
completes the circuit - allows flow of ions through the cell.
How can the risk of hydrogen explosions be minimized?
Control ignition sources
use well-maintained high-pressure containers
install hydrogen leak detectors
follow hazardous materials guidelines.
advantages of using hydrogen gas as opposed to petrol
Eco-Friendly – Hydrogen combustion produces only water vapor, reducing greenhouse gas emissions.
High Energy Efficiency – Fuel cells convert hydrogen into electricity more efficiently than petrol engines.
Abundant Resource – Hydrogen is the most abundant element and can be produced from water.
Quiet Operation – Hydrogen fuel cells run more quietly than internal combustion engines.
Reduced Dependence on
Fossil Fuels – Hydrogen can be produced renewably, reducing reliance on oil.
disadvantages of using hydrogen gas as opposed to petrol
Storage Challenges – Hydrogen requires high-pressure tanks
High Production Costs – Electrolysis and other production methods are expensive and energy-intensive.
Infrastructure Limitations – Hydrogen refueling stations are scarce compared to petrol stations.
Flammability Risk – Hydrogen is highly flammable and requires strict safety measures.
Lower Energy Density by
Volume – Hydrogen gas takes up more space compared to liquid fuels like petrol.
