Fuel cells depend on chemical energy generated by the reaction: 2 H2+O2–2 H2 O The automobile in

Fuel cells depend on chemical energy generated by the...

Fuel cells depend on chemical energy generated by the reaction: $$ 2 \mathrm{H}_{2}+\mathrm{O}_{2}--2 \mathrm{H}_{2} \mathrm{O} $$ The automobile industry plans for fuel cells to be powering millions of vehicles by $2020 .$ In terms of the stored energy per unit mass, $\mathrm{H}_{2}$ supplies $120 \mathrm{MJ} \mathrm{kg}^{-1} .$ This compares with about $45 \mathrm{MJ} \mathrm{kg}^{-1}$ for hydrocarbon-based petrol (gasoline). Write a brief summary of advantages and disadvantages of $\mathrm{H}_{2}$ and petrol as fuels for the motor vehicles, taking into account supply, demand, efficiency and environmental issues.

Fuel cells depend on chemical energy generated by the reaction:
$$
2 \mathrm{H}_{2}+\mathrm{O}_{2}--2 \mathrm{H}_{2} \mathrm{O}
$$
The automobile industry plans for fuel cells to be powering millions of vehicles by $2020 .$ In terms of the stored energy per unit mass, $\mathrm{H}_{2}$ supplies $120 \mathrm{MJ} \mathrm{kg}^{-1} .$ This compares with about $45 \mathrm{MJ} \mathrm{kg}^{-1}$
for hydrocarbon-based petrol (gasoline). Write a brief summary of advantages and disadvantages of $\mathrm{H}_{2}$ and petrol as fuels for the motor vehicles, taking into account supply, demand, efficiency and environmental issues.

Key Concepts

Market Demand and Economic Considerations

Market demand and economic aspects involve considerations of production scalability, cost, and consumer acceptance. Although hydrogen has attractive energy and environmental properties, its large-scale production and storage come with higher initial costs. In contrast, petrol’s established production systems and market infrastructure provide economic advantages, although these must be balanced against environmental and efficiency drawbacks.

Infrastructure and Supply Challenges

Infrastructure and supply are key considerations in the adoption of any fuel technology. While the widespread use of petrol is supported by an extensive global distribution network, hydrogen fueling infrastructure is still in development. The costs, technical challenges, and logistics involved in scaling a hydrogen supply chain—including storage, transportation, and refueling stations—pose significant hurdles that must be overcome for large-scale adoption.

Fuel Conversion Efficiency

Fuel conversion efficiency is a measure of how effectively a fuel’s chemical energy is converted into useful work. Fuel cells, which use hydrogen, often have higher theoretical efficiencies compared to internal combustion engines typically used for petrol. This means that even though hydrogen is stored at a high energy density, the efficiency of converting that energy into mechanical power becomes a critical determinant of overall performance.

Environmental Impact

The environmental impact of a fuel encompasses the emissions produced during fuel production, conversion, and combustion. Hydrogen fuel cells produce water as the main by-product, representing a cleaner alternative to petrol, which emits pollutants and greenhouse gases. However, the overall environmental benefits depend on the source of hydrogen, with renewable-based production methods offering the greatest environmental advantages.

Energy Density

Energy density refers to the amount of energy stored per unit mass of a fuel. This is a critical factor when comparing fuels for vehicle propulsion, as it influences the range and performance of the vehicle. Hydrogen, for instance, has a higher gravimetric energy density compared to hydrocarbon-based fuels, meaning it can potentially provide more energy per kilogram, although practical challenges such as storage efficiency must also be considered.

Transcript

00:01 Okay, so this question actually asks us to compare the hydrogen and patrol as a fuse.

00:11 We want to list the advantage and disadvantage of these two fuels.

00:17 So first, let's look at the advantage of the hydrogen.

00:24 So let's say the hydrogen, right? the first advantage is definitely it's very available because the hydrogen element, right, is very abundant in the earth.

00:41 So it's very available because, right, the hydrogen bond element is abundant in the earth.

00:50 And also it's very environmental friendly because the production, of the product of the combustion, right, is just water.

01:02 So it's actually very environmental friendly.

01:12 And also, if you look at the energy density, right, it has very high energy density.

01:25 So which means with the same mass, right, you can produce more energy.

01:31 So which means your cars, right, can actually go further with the same amount of mass.

01:38 Of the fuels.

01:42 And for its disadvantage, same.

01:44 It's also about availability.

01:52 The hydrogen element is very illivable on earth.

01:55 However, for fuels, you have to use hydrogen gas.

01:59 Hydrogen gas is not abundant on earth.