Hydroelectricity - salt vs fresh water

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In summary, the speaker is seeking help with a science project testing the hydroelectric voltage of salt water vs. fresh water. They expected salt water to produce more due to its weight but got opposite results. They built a mini hydroelectric plant and measured the output with a voltage meter. The results were in the mid 40s for fresh water and low 40s, some 30s for salt water. The speaker wonders if there could be other factors affecting the results, such as velocity of water and dynamic viscosity. They confirm that the temperature and flow were consistent for both waters.
  • #1
mariothingy
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I am doing doing a science project for school and I didnt get the results i was expecting so I was wondering if somebody would help me :)
I wanted to test whether salt water or fresh water would produce more hydroelectric voltage. I expected the salt water to produce more because it is heavier. It was the opposite - can somebody help me understand why that is? Thx!
 
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  • #2
mariothingy said:
I am doing doing a science project for school and I didnt get the results i was expecting so I was wondering if somebody would help me :)
I wanted to test whether salt water or fresh water would produce more hydroelectric voltage. I expected the salt water to produce more because it is heavier. It was the opposite - can somebody help me understand why that is? Thx!

This is pretty vague. How was the comparison made? What kind of test was done?
 
  • #3
We built a mini hydroelectric plant. A stream of water flows to a wheel that spins which is attached to a DC motor. A voltage meter is attached to the motor so we can measure the output. We made sure the water always hits the wheel at the same place by gluing the container in place. We got results in the mid 40s for the fresh water and low 40s, some 30s for the salt water.
 

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  • #4
mariothingy said:
We built a mini hydroelectric plant. A stream of water flows to a wheel that spins which is attached to a DC motor. A voltage meter is attached to the motor so we can measure the output. We made sure the water always hits the wheel at the same place by gluing the container in place. We got results in the mid 40s for the fresh water and low 40s, some 30s for the salt water.

Nifty. Was there any attempt to make sure that the temperature of the water(s) was the same for each run? How about the starting level for the water in the reservoir?

It's possible I suppose that some other property of the water is affecting the results. Some things to consider:

1. Velocity of water existing the reservoir port. What affects it? (Look up Bernoulli equation)
2. Dynamic Viscosity of seawater versus fresh water (probably a 7% difference!)
 
  • #5
Yes, the water was at room temperature for both, and we measured the flow at a certain point on the jar. Thanks for the response :)
 

Related to Hydroelectricity - salt vs fresh water

1. How does hydroelectricity work using saltwater?

Hydroelectricity using saltwater involves the use of a dam or barrier to trap seawater and create a difference in water levels. This difference in water levels creates potential energy, which is then converted into kinetic energy as the water flows through turbines. The turbines are connected to generators that produce electricity.

2. What are the advantages of using saltwater for hydroelectricity?

One advantage of using saltwater for hydroelectricity is that there is an abundant supply of saltwater available in oceans and seas around the world. Additionally, saltwater is denser than freshwater, which means it can generate more energy when flowing through turbines. Saltwater hydroelectricity also does not require the construction of large reservoirs, reducing the impact on the environment.

3. How does hydroelectricity using fresh water differ from saltwater?

The main difference between hydroelectricity using fresh water and saltwater is the source of water. Freshwater hydroelectricity typically involves the use of rivers and lakes, while saltwater hydroelectricity uses the ocean or sea. Freshwater hydroelectricity may also require the construction of large reservoirs and dams to control the flow of water.

4. What are the potential environmental impacts of using saltwater for hydroelectricity?

One potential environmental impact of saltwater hydroelectricity is the disruption of marine ecosystems and habitats. The construction of barriers and turbines can also affect the migration patterns of marine animals. Additionally, the use of saltwater for hydroelectricity may have a negative impact on water quality and marine life.

5. Is saltwater hydroelectricity a sustainable source of energy?

Saltwater hydroelectricity is considered a renewable and sustainable source of energy because it relies on the natural water cycle and does not emit greenhouse gases. However, the construction and maintenance of infrastructure for saltwater hydroelectricity may have negative impacts on the environment. It is important to carefully consider these impacts and implement sustainable practices in the development and operation of saltwater hydroelectricity projects.

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