All Questions
Tagged with renewable-energy fluid-dynamics
16
questions
1
vote
1
answer
156
views
Unusual temperature shape in gravel heat storage
I’m currently doing undergrad research on using a gravel (basalt 2-5mm grain size) bed as an heat storage. In order to heat up the gravel inside, hot (~100°C) and dry (RF<4%) air with a pressure of ...
- 11
0
votes
0
answers
53
views
Wind turbines or tidal power stations incorporating elements of origami or reconfigurable materials: is innovation possible from physics?
If I refer well (I'm not a physicist) one of the oldest uses/applications of renewable energy is to try to exploit the wind and tides by means of designs of machines: windmills and water wheels. Today ...
1
vote
3
answers
897
views
How could more rotor speed mean less energy in wind turbine?
there's a question that has been annoying me for a while, consider the following (power,rotor speed) diagram for different wind speeds
at some wind speed (6m/s for example) how could a turbine ...
- 23
0
votes
2
answers
595
views
Changing number of wind turbine blades
I have read (and to some degree understood) that if one were to increase the number of blades for a wind turbine, it would be reasonable to reduce its rotational speed. In my mind I'd associate this ...
- 487
1
vote
0
answers
86
views
How big is the power loss of a downwind wind turbine due to turbulence created by an upwind turbine?
When a horizontal axis wind turbine is placed downwind of another horizontal axis wind turbine (distance between the two is minimal), then the downwind wind turbine has a lower power output because of
...
- 833
0
votes
2
answers
72
views
Is the amount of hydro-electricity harvested, proportional to the number of turbines? [closed]
I've looked on this site and people have said that it wouldn't make more energy that it would cost to have water turbines on a water tower. But if it only takes say three pumps (I don't know what it ...
- 1
2
votes
2
answers
5k
views
Do wind turbines convert the kinetic energy of air?
It is often said that wind turbines convert the kinetic energy of the wind into electricity. But in respect to horizontal wind turbines with airfoil shaped blades this is imho not the case.
Wind ...
- 833
5
votes
2
answers
234
views
Potential energy of Hydroelectric plant before the dam was built
So the energy potential of a Hydroelectric dam is the difference between the head and base. Before the dam was built where does all that energy go? I can understand that for a long valley that is ...
- 153
8
votes
3
answers
3k
views
Why is there no upper-bound on power-efficiency of Hydro-turbines?
We have Betz's law, an upper bound on power efficiency, for wind-turbines. But there is no theoretical upper limit on hydro-turbines, Why this is so?
Is it mainly due to the incompressibility of ...
- 543
13
votes
2
answers
931
views
Energy from man-made tornadoes
Peter Thiel just paid $300,000 to Canadian inventor Louis Michaud who is working to construct useful "man-made tornadoes" or "atmospheric vortex engines" which could be components of future power ...
- 180k
5
votes
1
answer
1k
views
Does water need to pumped up from deep ocean?
OTEC (Ocean Thermal Energy Conversion) utilizes the temperature gradient between cold deep ocean water, and warmer water to do work. I understand the pressure in the depths may be as high as a couple ...
- 4,723
4
votes
1
answer
1k
views
Wind Turbine Impact
OK, I'm not sure this is not a silly question, but here goes.
I've often wondered what the impact is of wind turbines on the weather. My question is, since wind turbines transform wind energy into ...
- 5,497
12
votes
3
answers
523
views
What does the quantification of causes and effect look like, for clouds in offshore wind turbine wakes?
At Horns Rev windfarm off the coast of Denmark, sometimes in winter, clouds appears in the wake of the turbines. I've only seen photos of the phenomenon when the wind direction is exactly aligned with ...
- 4,154
8
votes
6
answers
2k
views
Why do blades of windturbine propellers as comp. to propellers of ships cover very different areas?
This is a thought I asked myself often, but never did real efforts
to get an answer. Barsmonsters question about number of fans of a
wind turbine made me think of it again
Why do blades of aircraft ...
- 6,914
46
votes
2
answers
5k
views
Wind generators - why so few blades?
Why commercial wind generators usually have just 2-3 blades?
Having more blades would allow to increase power OR decrease diameter.
Decreased diameter would also reduce stress due to different wind ...
- 2,409