Hydrogen gas has the potential for use as a clean fuel in reaction with oxygen. The relevant reaction is 2 H2(g) + O2(g) → 2 H2O(l). Consider two possible ways of utilizing this reaction as an electrical energy source: (i) Hydrogen and oxygen gases are combusted and used to drive a generator, much as coal is currently used in the electric power industry; (ii) hydrogen and oxygen gases are used to generate electricity directly by using fuel cells that operate at 85 °C. Based on the analysis here, would it be more efficient to use the combustion method or the fuel-cell method to generate electrical energy from hydrogen?

Verified step by step guidance

1. Step 1: Understand the chemical reaction involved. The reaction 2 H2(g) + O2(g) → 2 H2O(l) is an exothermic reaction, meaning it releases energy. This energy can be harnessed in different ways to generate electricity.
2. Step 2: Consider the efficiency of energy conversion in combustion. In the combustion method, hydrogen and oxygen gases are burned to produce heat, which is then used to drive a generator. This process involves multiple energy conversion steps: chemical energy to thermal energy, thermal energy to mechanical energy, and finally mechanical energy to electrical energy. Each step has inherent energy losses, typically making this method less efficient.
3. Step 3: Analyze the fuel cell method. Fuel cells convert chemical energy directly into electrical energy through electrochemical reactions. This direct conversion typically results in higher efficiency because it bypasses the intermediate steps of converting energy into heat and then into mechanical energy.
4. Step 4: Consider the operating conditions. Fuel cells operating at 85 °C are designed to optimize the electrochemical reaction efficiency. The lower operating temperature compared to combustion processes reduces energy losses associated with heat transfer and increases overall efficiency.
5. Step 5: Compare the overall efficiencies. Generally, fuel cells are more efficient than combustion methods because they convert chemical energy directly into electrical energy with fewer energy losses. Therefore, using fuel cells to generate electricity from hydrogen is likely to be more efficient than using the combustion method.