CCEA A-Level Environmental Technology 3930
Fossil Fuels
Global Action on Energy Conservation and Climate Change
Macrogeneration
Microgeneration
Energy From Wind
Energy From the Sun
Energy From Biomass
Energy Storage
Plastics for the Future
Renewable Energy Investigations
Sustainable Development
Waste Management
Waste to Energy Technologies
Land Contamination and Remediation
Hydrogen Fuel Cells
Transport System Challenges
Energy Performance of Buildings
Emerging Technologies
Sustainable Urban and Rural Communities
The Code for Sustainable Homes
Hydrogen Fuel Cells
Fuel cell applications and the challenges of hydrogen
- 3 things to know
- A2 1
Overview
Backup, remote and telecommunications power, fuel cell cars, buses in Belfast, trains, boats and portable generators, backup efficiency, round-trip efficiency and car emissions calculations, and the cost, transport and storage of hydrogen.
What you need to know
Answer each one before you reveal it.
Electricity makes hydrogen at 70% efficiency, and a fuel cell turns the hydrogen back into electricity at 50% efficiency. What is the overall efficiency?
Why are hydrogen fuel cells used for stationary backup power?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Why are hydrogen fuel cells used for stationary backup power?
Model answer
A fuel cell starts quickly when the mains supply fails and runs for as long as hydrogen is available. Hospitals and data centres use fuel cells to keep essential equipment running.
- 2
Why do fuel cells suit power generation in remote locations?
Model answer
A fuel cell needs no grid connection and has few moving parts, so it needs little maintenance. Hydrogen can be delivered occasionally or made on site from renewable electricity.
- 3
Why are fuel cells used as stand-alone power supplies for telecommunications installations?
Model answer
Mobile phone masts need an uninterrupted supply, often at remote sites. A fuel cell gives longer backup than batteries and is quieter and cleaner than a diesel generator.
- 4
A 1.0 kW backup fuel cell runs for 10 hours and uses 0.60 kg of hydrogen, which contains 120 MJ/kg. What is its efficiency?
Model answer
The fuel cell is 50% efficient. The electrical output is 1.0 kW × 10 h = 10 kWh, or 36 MJ. The hydrogen supplied 0.60 × 120 = 72 MJ, and 36 ÷ 72 × 100 = 50%.
- 5
How does a fuel cell electric car work?
Model answer
A fuel cell stack turns hydrogen from a high-pressure tank into electricity, which drives an electric motor. A small battery stores energy recovered during braking and helps with acceleration.
- 6
Why are fuel cells well suited to buses?
Model answer
Buses run fixed routes and return to one depot, so a single refuelling station can serve a whole fleet. Hydrogen buses refuel in minutes and have a long range.
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