Which is correct about fuel cells? (a) Cell continuously run as long as fuels are supplied. (b) These are more efficient and free from pollution. (c) These are used to provide power and drinking water to astronauts in space programme. (d) All of these

Fuel cells are remarkable devices that convert chemical energy directly into electrical energy, offering a high level of efficiency. At the heart of a fuel cell is the electrochemical reaction that takes place between a fuel, usually hydrogen, and an oxidant, which is often oxygen. This reaction occurs in two separate electrodes, the anode and the cathode, which are divided by an electrolyte.

The key to this process is the catalyst, typically made of platinum, which facilitates the separation of hydrogen into protons and electrons at the anode. The protons then pass through the electrolyte to the cathode, while the electrons travel through an external circuit, creating electric current. Upon reaching the cathode, electrons reunite with protons and oxygen to produce water as a by-product. The beauty of this energy conversion lies in its cleanliness – the only emissions are water vapor and heat.

The efficiency of a fuel cell is a measure of how well it converts the energy in the fuel into electrical energy. In terms of electrical efficiency, fuel cells can outperform traditional combustion engines, which are often subject to energy losses through heat and noise. A fuel cell's efficiency can range from about 40-60%, and can even exceed this range in some applications when waste heat is also utilized in a combined heat and power (CHP) system.

Factors like the type of fuel cell, the quality of the components, and the operating temperature all play a vital role in determining the overall efficiency. For comparison, internal combustion engines generally have an efficiency of about 25-30%. The high efficiency of fuel cells makes them an attractive option for various applications where energy conservation and reducing emissions are crucial.

Fuel cells have a venerable history in space exploration and their role in space programs is critical. They provided the electrical power for NASA's Apollo missions to the moon. Moreover, the water produced as a by-product of the power generation process served a dual purpose as drinking water for astronauts. Since space missions require reliable and efficient sources of power, fuel cells are a natural fit due to their high energy density and efficiency.

Space Shuttle

The Space Shuttle program utilized fuel cells to produce power for onboard systems during missions.

Current and Future Missions

Today, fuel cells are also being considered for long-term space missions, like those to Mars, where resupplying is not feasible. Their reliability, coupled with the ability to also produce necessary water, makes them a pivotal technology for the future of space exploration.