_______ is one of the chemical used to produce Ocean Thermal Energy.
NH3
Understanding Chemicals in Ocean Thermal Energy Conversion (OTEC)
Ocean Thermal Energy Conversion (OTEC) is a renewable energy technology that harnesses the temperature difference between warm surface ocean water and cold deep ocean water to generate electricity.
The process typically involves a working fluid that has a low boiling point. This fluid is vaporized by the warm surface water, and the resulting vapor drives a turbine connected to a generator. The vapor is then condensed back into liquid using the cold deep water, and the cycle repeats.
Identifying the Ideal Working Fluid for OTEC
A suitable working fluid for OTEC must:
- Have a low boiling point at typical ocean surface temperatures.
- Be able to efficiently absorb and release heat.
- Be relatively non-toxic and environmentally friendly (though this can vary).
- Be cost-effective.
Analyzing the Options
Let's look at the properties of the given options:
- \(\text{HCl}\) (Hydrogen Chloride): This is a strong acid. It is corrosive and has a boiling point of around \(-85 \, ^\circ\text{C}\) at standard atmospheric pressure. While it has a low boiling point, its corrosive nature makes it unsuitable for use in large-scale power systems like OTEC.
- \(\text{N}_2\) (Nitrogen): Nitrogen is an inert gas with a very low boiling point of around \(-196 \, ^\circ\text{C}\). Its extremely low boiling point means it would require very cold temperatures to condense effectively, which is not ideal for the temperatures available from deep ocean water. It's also a gas at OTEC operating temperatures, making the cycle less efficient.
- \(\text{H}_2\) (Hydrogen): Hydrogen is a highly flammable gas with an extremely low boiling point of around \(-253 \, ^\circ\text{C}\). Its flammability and very low boiling point make it impractical and dangerous for use as a working fluid in OTEC.
- \(\text{NH}_3\) (Ammonia): Ammonia is a commonly used working fluid in OTEC systems, particularly in the "closed-cycle" OTEC design. It has a relatively low boiling point (around \(-33 \, ^\circ\text{C}\) at standard atmospheric pressure), which is suitable for vaporization by warm surface water (around \(25 \, ^\circ\text{C}\)). It also has favorable thermodynamic properties for heat transfer. While ammonia is toxic, OTEC systems using it are designed to minimize leakage.
Based on the requirements for an OTEC working fluid and the properties of the options, ammonia (\(\text{NH}_3\)) is a commonly used and effective chemical for this application.
Conclusion
Among the given options, ammonia (\(\text{NH}_3\)) is a chemical widely used as a working fluid to produce Ocean Thermal Energy due to its low boiling point and thermodynamic properties suitable for harnessing the temperature difference in ocean water.
Revision Table: Properties of Potential Working Fluids
| Chemical | Formula | Approximate Boiling Point (at 1 atm) | Suitability for OTEC |
|---|---|---|---|
| Hydrogen Chloride | \(\text{HCl}\) | \(-85 \, ^\circ\text{C}\) | Corrosive, not practical |
| Nitrogen | \(\text{N}_2\) | \(-196 \, ^\circ\text{C}\) | Extremely low boiling point, inefficient cycle |
| Hydrogen | \(\text{H}_2\) | \(-253 \, ^\circ\text{C}\) | Highly flammable, extremely low boiling point |
| Ammonia | \(\text{NH}_3\) | \(-33 \, ^\circ\text{C}\) | Low boiling point, good thermodynamic properties, commonly used |
Additional Information on OTEC Working Fluids
Besides ammonia, other working fluids can be considered for OTEC, depending on the specific cycle design (e.g., closed-cycle, open-cycle, hybrid). Examples include hydrofluorocarbons (HFCs) and chlorofluorocarbons (CFCs), although their environmental impact is a concern. Some designs also use water vapor itself as the working fluid in open-cycle systems.
The choice of working fluid significantly impacts the efficiency and cost-effectiveness of an OTEC plant. Ammonia remains a popular choice due to its balance of properties, despite its toxicity requiring careful handling and system design.
Important Questions from Work Power and Energy
Which of the following is an example of potential energy?
Energy in natural systems is transferred by _______.
Choose the best option from the following.
A body of mass 2kg is thrown up vertically with a kinetic energy of 500J. If the acceleration due to gravity is 10 m/s2, the height at which the kinetic energy of the body becomes half of the original values is _____
Arjun has a mass of 50 kg, he eats banana of 1000 calories. If this energy is used up to lift him from the ground, the height to which he can climb is _______. Take g = 10 m/s2 and 1 calories = 4.2 Joule.
When a body of mass 'm' attains a velocity 'v' from rest in time 't', then kinetic energy of translation is:
