Questions related to energy produced by renewable systems such as solar, wind, water and geothermal.
Questions tagged [renewable-energy]
78 questions
25
votes
5 answers
Why don't hydroelectric plants use cascades of turbines instead of single turbines?
In a gas turbine engine there're multiple sets of blades - one set after another and combustion products pass all the sets and each set of blades gets some of the power. This increases utilization of power from burning gas.
Meanwhile hydroelectric…
sharptooth
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13
votes
7 answers
What are the disadvantages of concentrated solar thermal power?
Concentrated solar power looks on the surface to be an excellent source of grid power. It's sustainable, has no obvious waste products to deal with either during construction or operation, and with thermal storage it can generate power at night or…
Stephen Collings
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13
votes
7 answers
Wind farms that wind up in the wind, and then unwind producing energy when the wind is still
Given the difficulty of producing energy for a region when the wind isn't blowing, why is it not possible to have half of each wind farm producing energy directly, and the other half working to lift a weight, that then descends and produces energy…
apg
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13
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3 answers
How to correctly size the blades for a small educational wind turbine?
I want to design a small wind turbine that can be easily carried out of the classroom into the sports field in relatively low-wind conditions (5-15km/h) that can power a small ultra-bright 5V LED - just enough to show that it works.
How do I…
jhabbott
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9
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3 answers
Why don't we just build a giant wind turbine?
The power generated by a wind turbine is given by:
$$\mathrm{Power} = \frac{1}{2}C\rho AV^3$$
Where:
$\rho = \text{Air density}$
$C = \text{Coefficient of performance}$
$A = \text{Frontal area}$
$V = \text{Velocity of the wind}$
In other words,…
Chong Lip Phang
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8
votes
1 answer
To what degree are wind and water turbines exchangeable?
Assuming maximum efficiency is not the primary concern (but net positive efficiency is), to what extent could a wind turbine operate in water and vice versa?
How do the different turbine types fare in this respect? I.e., HAWT / VAWT (Savonius,…
Zubo
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7
votes
7 answers
Why is hydro-electric power still scarce in some places?
70% of the Earth's surface is covered in water, why can't a hydroelectric power plant be set up on each and every river? Is it that its too expensive?
Why is electricity still a problem in countries that have abundant number of rivers? Why can't…
Sristy
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6
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1 answer
Do regulations in the United States limit the size of aerial wind turbines?
What with all the work done by the FAA recently on regulating drone usage, I thought it would be nice to turn my eyes to the sky for another, less-known type of aerial denizen: the aerial wind turbine.
Wikipedia has all the relevant information, so…
HDE 226868
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5
votes
3 answers
Relationship between wind velocity, turbine rotor diameter, and power output
I'm trying to understand and identify the equations to use in defining the relationship between wind velocity, turbine rotor diameter, and power output for a wind turbine.
To simplify my question, let's use the following assumptions:
Average wind…
Dwiparna Datta
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5
votes
2 answers
Is the fill factor of a photo-voltaic cell constant?
An important factor in specifying the efficiency of photo-voltaic (PV) cells is called the fill factor (FF). It is defined as the ratio of the maximum power of the cell to the product of the open-circuit voltage $V_{oc}$ to the short-circuit current…
Moody
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4
votes
2 answers
Could future fusion energy exist without the input of any petroleum or natural gas products?
Given a successful deuterium-tritium fusion reactor such as that conceived by ITER, could the world's energy needs theoretically be met without the input of any petroleum or natural gas products?
Deuterium is currently typically produced by the…
Steve M
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4
votes
2 answers
Advantages of hydrogen gas turbine over fuel cell
In the setting of large-scale electricity generation, I was wondering why one would want to burn hydrogen in a gas turbine instead of using it to power a fuel cell. Aren't fuel cells more efficient because they're not bound by the Carnot limit? Two…
Damian Birchler
- 143
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3
votes
0 answers
Parameter effects on kinetics of esterification for bio-diesel production
I want to discuss the effect of parameters on the kinetics of esterification for bio-diesel production. In esterification process, temperature effect and molar ration are two important parameters. During conversion of oliec acid with methanol to…
user30377
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3
votes
1 answer
What is the power and max flow rate required to rotate a 300 W wind turbine?
I have purchased a wind turbine with a power of 300 W, the start up wind speed is 2.5 m/s, rated wind speed is 11 m/s, and the survival wind speed is 45 m/s, and what I'm going to do is to make an educational modeling for how to generate electrical…
Mohamed AbdelAlim
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3
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1 answer
What mathematical operation should I do in order to translate from TWyr/y to TWyr_30 in this article?
In this article
https://www.sciencedirect.com/science/article/pii/S266711312200002X
the authors show a result of prediction on energy reserves (in particular solar ones) as known in 2015 (Figure 1) and as known in 2022 (Figure 2).
In the first one…
Mathieu Krisztian
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