Which statement about energy conversion efficiency is true?

Which statement about energy conversion efficiency is true?

• A. Hydrogen fuel cells can convert up to 60% of the energy from hydrogen into electricity, while traditional fossil fuel engines convert less than 30%.
• B. Hydrogen fuel cells can convert about 80% of the energy, and traditional engines about 60%.
• C. Hydrogen fuel cells achieve around 40% efficiency, and engines around 60%.
• D. Both hydrogen fuel cells and traditional engines convert roughly 50%.

Answer: (A)

The main idea is how efficiently a device turns chemical energy into usable energy form: electricity for a fuel cell versus mechanical work for an engine. Hydrogen fuel cells convert chemical energy directly into electricity, and their electrical efficiency is typically around 60% under favorable conditions. Internal combustion engines, like those in traditional fossil-fuel vehicles, are less efficient because a large portion of the energy is lost as heat and through friction, giving braking efficiencies around 25–30% in practice. So the statement that hydrogen fuel cells can convert up to about 60% of the energy in hydrogen into electricity, while traditional fossil fuel engines convert less than 30%, matches these well-known performance ranges. The other options propose figures that are too high or inverted for these technologies, which is why they don’t fit real-world performance.

The main idea is how efficiently a device turns chemical energy into usable energy form: electricity for a fuel cell versus mechanical work for an engine. Hydrogen fuel cells convert chemical energy directly into electricity, and their electrical efficiency is typically around 60% under favorable conditions. Internal combustion engines, like those in traditional fossil-fuel vehicles, are less efficient because a large portion of the energy is lost as heat and through friction, giving braking efficiencies around 25–30% in practice. So the statement that hydrogen fuel cells can convert up to about 60% of the energy in hydrogen into electricity, while traditional fossil fuel engines convert less than 30%, matches these well-known performance ranges. The other options propose figures that are too high or inverted for these technologies, which is why they don’t fit real-world performance.