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Phosphoric acid fuel cell

Phosphoric acid fuel cell is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Phosphoric acid fuel cell rather than just read about it. In short: Phosphoric acid fuel cells (PAFC) are a type of fuel cell that uses liquid phosphoric acid as an electrolyte. They were the first fuel cells to be commercialized.

Phosphoric acid fuel cell — main illustration
Phosphoric acid fuel cell — illustration

Key takeaways

  • Phosphoric acid fuel cell belongs to biology; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Phosphoric acid fuel cell to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Phosphoric acid fuel cell from memory before moving on to harder problems.

Reference excerpt

Phosphoric acid fuel cells (PAFC) are a type of fuel cell that uses liquid phosphoric acid as an electrolyte. They were the first fuel cells to be commercialized. Developed in the mid-1960s and field-tested since the 1970s, they have improved significantly in stability, performance, and cost. Such characteristics have made the PAFC a good candidate for early stationary applications.

Design Electrolyte is highly concentrated or pure liquid phosphoric acid (H3PO4) saturated in a silicon carbide (SiC) matrix. Operating range is about 150 to 210 °C. The electrodes are made of carbon paper coated with a finely dispersed platinum catalyst.

Electrode reactions Anode reaction: 2H2(g) → 4H+ + 4e

Cathode reaction: O2(g) + 4H+ + 4e‾ → 2H2O Overall cell reaction: 2 H2 + O2 → 2H2O

Advantages and disadvantages At an operating range of 150 to 200 °C, the expelled water can be converted to steam for air and water heating (combined heat and power). This potentially allows efficiency increases of up to 70%. PAFCs are CO2-tolerant and can tolerate a CO concentration of about 1.5%, which broadens the choice of fuels they can use. If gasoline is used, the sulfur must be removed. At lower temperatures phosphoric acid is a poor ionic conductor, and CO poisoning of the platinum electro-catalyst in the anode becomes severe. However, they are much less sensitive to CO than proton-exchange membrane fuel cells (PEMFC) and alkaline fuel cells (AFC). Disadvantages include rather low power density and chemically aggressive electrolyte.

Applications

PAFC have been used for stationary power generators with output in the 100 kW to 400 kW range and are also finding application in large vehicles such as buses. Major manufacturers of PAFC technology include Doosan Fuel Cell America Inc. (formerly ClearEdge Power & UTC Power) and Fuji Electric. India's DRDO has developed PAFC based air-independent propulsion for integration into their Kalvari-class submarines.

See also Glossary of fuel cell terms

References

External links National Pollutant Inventory - Phosphoric acid fact sheet UTC Power Official Site Photo Gallery of Fuel Cells Being Used Today Cox Communications Installs Fuel Cells in California Archived 2011-12-03 at the Wayback Machine D.O.E. -PAFC Fuel Cell Basics Alternative Energy Magazine Archived 2011-09-17 at the Wayback Machine Supermarket Benefits From 400kW Fuel Cell Stationary Fuel Cells at Retail and Grocery Sites

Illustrations

Phosphoric acid fuel cell: Diagram of a phosphoric acid fuel cell
Diagram of a phosphoric acid fuel cell
Phosphoric acid fuel cell: PureCell System 400 CEP
PureCell System 400 CEP

Worked examples

Example 1 — a first encounter with Phosphoric acid fuel cell

Start with the simplest possible case. Write down what Phosphoric acid fuel cell claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Phosphoric acid fuel cell before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Phosphoric acid fuel cell ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Phosphoric acid fuel cell

In research
Phosphoric acid fuel cell appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Phosphoric acid fuel cell in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Phosphoric acid fuel cell is common in secondary-school and first-year university syllabi. It links to neighbouring topics Fuel cells, so understanding it makes those chapters shorter.
In everyday life
Look for Phosphoric acid fuel cell outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Phosphoric acid fuel cell in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Phosphoric acid fuel cell means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Phosphoric acid fuel cell out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Phosphoric acid fuel cell in simple terms?

Phosphoric acid fuel cells (PAFC) are a type of fuel cell that uses liquid phosphoric acid as an electrolyte. They were the first fuel cells to be commercialized.

Why does Phosphoric acid fuel cell matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Phosphoric acid fuel cell?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Phosphoric acid fuel cell.

Tags

  • Fuel cells

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