Read the following passage given below and answer the question.

Production of electricity by thermal plants is not very efficient method. It is now possible to make cells in which reactants are fed continuously to the electrodes and products are also removed continuously. One of the most successful fuel cells is hydrogen fuel cell.

Which is not true for fuel cell?

Not cost effective

The correct answer is option 2. Not cost effective.

Fuel cells are electrochemical devices that convert chemical energy from a fuel into electricity through a reaction with oxygen or another oxidizing agent. Let's break down the options to understand why **option 2** ("Not cost effective") is not true and the others are correct:

1. Efficient (True)

Fuel cells are highly efficient in converting energy. Unlike combustion-based power generation, which can have significant energy losses, fuel cells convert the chemical energy directly into electrical energy with minimal heat loss. The efficiency of fuel cells can reach 60% to 70% in some applications, and if the waste heat is captured and used (combined heat and power systems), the efficiency can approach 85%.

2. Not cost effective (False)

Fuel cells are currently not widely cost-effective for many commercial applications due to the high cost of the materials used (e.g., platinum catalysts) and the infrastructure needed to produce and supply hydrogen fuel. While the costs are coming down as technology advances, they are still higher than traditional power sources like fossil fuels. Therefore, this statement is true, making this the false option in the context of the question. Cost reduction remains a major hurdle to widespread fuel cell adoption.

3. Pollution free (True)

Fuel cells produce electricity with minimal environmental impact. The primary by-product when hydrogen is used as the fuel is water vapor, making it a pollution-free process. There are no greenhouse gas emissions or air pollutants such as nitrogen oxides (NOx) and sulfur oxides (SOx) typically associated with combustion engines or power plants.

However, it is important to note that the production of hydrogen fuel itself may involve environmental costs if not sourced from renewable methods. But the operation of the fuel cell is inherently clean.

4. Can be used by astronauts (True)

Fuel cells have been used in space missions, such as on the Apollo and Space Shuttle programs, to provide electricity and water to astronauts. Since fuel cells generate water as a by-product, they are particularly advantageous in space, where both electricity and water are needed. Their ability to work efficiently and without polluting makes them an ideal choice for astronauts in space.

Conclusion:

Fuel cells are efficient, pollution-free, and have been successfully used by astronauts, but they are still not widely cost-effective for large-scale commercial use at this time. Thus, option 2 (Not cost effective) is the correct answer as the statement is false in the context of the question.