Questions tagged [renewable-energy]

Energy sources that do not rely on the consumption of an exhaustible fuel. Tidal, geothermal, and the direct and indirect solar energies (direct: photovoltaics, CSP, solar thermal; indirect: wind, wave, biomass) are renewable energy.

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39 views

Tesla patented a device he believes gathered energy from light. (US 685,957 - Apparatus for the Utilization of Radiant Energy): [duplicate]

The invention is a sheet metal (top) place high above the ground. The sheet of metal is connected to a capacitor (the ⊔⊓ shapes) connected to the Earth. (The other stuff on the right of the image is a ...
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38 views

Creating a Bouyancy Force Generator

How much energy is needed to maintain boiling water? (I'm assuming $1400~\rm W$). With that said, when air is added to an object to decrease its density, does the strength of its buoyant force ...
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45 views

Why does pumped hydro require reservoirs for efficient energy storage?

The problems with using pumped hydro as a long term battery are: Hard to find locations physically suited for an extreme height gradient for two massive reservoirs (main issue). Water evaporates, so ...
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Is there a fundamental limit on the efficiency of discharging a battery, similar to the efficiency limit on operating a fuel cell?

I am wanting to compare the efficiency limits of storing electrical energy with a battery to storing electrical energy with hydrogen using water electrolysis and a fuel cell. The electrolyzer/fuel ...
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2answers
105 views

To grow one $\rm m^2$ of crop plants, how many $\rm m^2$ of solar panels do you need?

In vertical farms you need to use LEDs to make plants grow, which in turn have to be powered e.g. by solar panels. If solar panels had the same efficiency as plants, then you would need the same ...
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34 views

Producing Pressurized Hydrogen Underwater Then Using it To Do Work

This is a bit of a weird one but I didn't know where else to ask this. I was recently talking to my brother and he told me about an idea he had talked with his boss about how to create compressed ...
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Does the second law of thermodynamics imply that renewable energy also leads to global warming/climate change?

So I have this (possibly dumb) question about the implications of the second law of thermodynamics to the use of renewable energy for the world, so please bear with me. Here goes: Apart from the ...
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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 ...
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Can a positive ion generator ionizing water create electricity with a net gain of electricity?

Traditional ion generators work by sending electricity through air to ionize air with a negative charge. This is said to benefit human health. But, it should be possible to extract ions from atoms and ...
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Why is the Weibull distribution used to describe wind speeds?

Frequently, it is stated that the distribution of wind speed at a certain location can be described by the so-called Weibull distribution: $$ W(x;\lambda,k):=\frac{k}{\lambda}\left(\frac{x}{\lambda}\...
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What is and how do you calculate design wind speed, on wind turbines?

I am finding hard to get a consense on the definition of design wind speed, on eolic turbine matter. I thought it was he velocity that correspondes to the maximum power output, but I have already ...
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Why aren't gravity batteries everywhere? [closed]

The problem of energy storage, especially with regard to renewables, remains unsolved. Or at least there do not seem to be any popular solutions. Why not gravity batteries? I love the idea, and ...
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58 views

Why/when is an indirect AC - DC - AC frequency converter superior to a direct AC-AC frequency converter? [closed]

I am currently studying wind power and the power electronics used for it. In wind power a generator is driven by wind, thus the resulting power is of widely varying frequency and amplitude. The power ...
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118 views

Water tower power generation

I understand that one of the concerns with generating power from a water tower, allowing the falling water to turn a generator, is that if the water wasn't coming from a natural source, thus having to ...
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Power grid stability in an only inverter grid

I think i there is little misconception in my head regarding the cause and effect of changing grid frequency and therefore I am confused about the transition from fossil fuels to regeneragtive energy ...
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Textbook recommendation renewable energy

I am supposed to teach a lecture on the broad field of renewable energy for the first time. I wanted to check how other people cover the field, but there is a plethora of books on the subject and even ...
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Why can't a low solidity wind turbine be used in high torque applications through gearing? [closed]

From my understanding, low solidity wind turbines (such as the three blade type) are more efficient due to a higher tip speed ratio, giving a higher coefficient of performance. However, they are not ...
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Why are solar panels kept tilted?

I have noticed that, in my country India, most of the solar panels are tilted southward at an angle of ${45}^{\circ} .$ Even on buildings with inverted V-shaped roofs, solar panels are still oriented ...
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Theoretical physics for better batteries?

It is Earth day, so I started thinking about the theoretical physics problems that could help reduce greenhouse-gas emissions and fight climate change. We actually have a reasonable range of ways to ...
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Can we use the power of ice to float to make free electricity?

ice and water have a volume to weight ratio of 12/11 so 11 tons of ice will support 1 ton of weight 1 ton of ice takes 1000 watts or 12000 b.t.u. of energy to be produced question is, at what depth ...
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Where does the energy from tidal power plants come from? [duplicate]

Tidal power plants taps into the energy in the motion of the oceans due to the gravitational interaction between the earth and the moon, so much is clear to me. This question is about where would this ...
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Can Bhaskara's Wheel increase the efficiency of wind mills?

Bhaskara's wheel is an ancient attempt at perpetual motion. The idea is that gravity will pull the water toward the center for the bottles at the top and toward the ends for the bottles falling to ...
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Potential effect of another “year without a summer” on solar-powered society? [closed]

In the "year without a summer", a volcanic eruptions caused enough sunlight to be blocked for average global temperatures to drop by 0.4–0.7 °C. What would be the effect of this sort of event on a ...
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382 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 follwoing (power,rotor speed) diagram for different wind speeds at some wind speed(6m/s for example)how could a turbine running ...
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Is nuclear power desireable in the long term, given the fact that it's an unnatural heat input to our planet? [closed]

I've been reflecting on whether we want nuclear at all in the long term (compared to renewables like wind, solar, and hydro). There's a certain amount of heat (energy) entering our planet and leaving ...
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On what planet within the Asteroid Belt would solar panels work the best?

I was researching for a project and came across this question. Maybe this is a bit too broad? How might solar energy work on Mars? Would it be sufficient to sustain a colony?
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104 views

Hydrogen as energy storage

How viable is hydrogen as an energy storage medium? It would be extremely easy to split water into hydrogen and oxygen . It also has high energy content so relatively a large amount of energy can be ...
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35 views

Is there common ground between wind and solar technologies/methods for harnessing energy? And how does this compare to nonrenewable methods?

To clarify: not asking similarities between solar and wind energy as a whole but only its technologies/methods of harnessing energy [example: ?turbine blades? in solar towers and wind turbines] Is ...
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1answer
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Can solar panels cool the atmosphere? [duplicate]

I am just curious if solar panels, because they absorb radiation, cool the atmosphere. If there were enough of them, would the temperature be different? I'm not a physicist or student.
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104 views

Effect of wind power on the global climate by decreasing kinetic energy of air

Assume the hypothetical situation that all global energy is produced by wind power and instead of fossil fuel power etc. Since every wind turbine decreases the kinetic energy of the air a bit, I am ...
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1answer
176 views

Could it be practical to harvest energy from sinking objects into deep water? [closed]

I'm imagining a canister for storing compressed gas connected to a fully inflated balloon. This is sea-level. The valve is open so air can move freely between the bag and the tank. Some heavy objects,...
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Why are spin coated polymer solar cells more efficient?

Reading papers on polymer solar cells (PSC from now on), it is seen that many different coating techniques are used in order to coat polymer films on substrates. It is also seen that spin coated ...
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Can water differential be used to store renewable energy?

Excuse me if the question is poorly worded or there already is a similar question, I searched but as a physics layman I do not know the proper terminology. I was watching a Nova story just now and ...
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156 views

Losses occurring in solar cells [closed]

If a solar cell is subjected to a light of intensity $1000$ $\text{W/m^2}$, the output at the cell is much less than ideal case scenario. What are all the factors causing energy losses in a solar cell?...
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43 views

Why is Alternative energy most commonly stored in metal acid batteries? [closed]

Why is alternative energy most commonly stored in relatively expensive metal acid batteries, which have a short life, rather than hydrogen gas accumulated through electrolysis? Hydrogen is a ...
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3answers
2k views

Can aurorae/northern lights be used as an energy source?

Their temperature is high, they have high velocity. Can they be used as an source of energy? If not why? If yes how?
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How do solar panels and wind turbines prove the law of conservation of energy?

The law of conservation of energy makes sense to me in certain systems but in others I can't seem to comprehend it. For example, a car moves because the stored chemical energy within its fuel is ...
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385 views

Water turbine power generation for large and small turbines

If you have a small water turbine and a larger water turbine in a river, would the larger turbine produce more power or would they produce the same because of the equal speed of the river?
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474 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 ...
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166 views

Solar power with parabolic mirrors/lenses + peltier elements?

Peltier elements are used to use electricity create temperature gradients for example for the purpose of cooling electronics (and then in a secondary step remove the heat from the hot side). However ...
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I think I may have found a renewable energy source [closed]

Hello guys so I have this idea of mine which I can't get my head around and I need someone to tell me why it won't work, so let's say you have a fully pressurised tank of air and you blow that ...
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438 views

Is there a temperature drop at the rotor plane of a wind turbine?

A wind turbine rotor produces power from the torque generated by the rotor blades. This torque arises from forces on blade elements which in turn are the consequence of pressure differences on each ...
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113 views

Wind turbine design question [closed]

I am planning to design a wind turbine that is has rotor blade radius of 0.915m and is connected to a generator. The generators specifications are, it is an ac generator with 5000 coil turnings and a ...
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1answer
489 views

Measurements of the pressure drop across wind turbines?

Mathematical analyses of wind turbines show that a discontinuous pressure drop happens at the rotor plane. I am looking for measurements of this effect, but I could not find any. Do you know any (...
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Solar energy in a specific location

How to find the amount of solar power in a specific location on Earth per month? By solar power I mean the energy received from the sun in a squared meter.
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121 views

How to calculate power necessary generated from wind turbine to run a motor

I was making a small/cheap wind turbine, and I am stuck on how to calculate the power needed (speed of wind) to run a brushed motor (since I figured that would be the easiest to run with rotor blades ...
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3answers
4k views

Could sound be considered a kind of renewable energy? [closed]

Is sound energy useful as a source for generating electricity? If so, could it be a renewable resource?
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185 views

which is efficient on solar electricity by photo voltaic or thermal

As we know solar energy used to generate electricity in two major ways: photovoltaic and thermal energy. The most small applications or personal use are mostly using solar cells. But when it comes to ...
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8answers
499 views

Why not use our own light production to produce new energy instead of wasting it?

Why don't we use our own light production at night (I mean home, buildings, streets,..., lighting) to charge photovoltaic panels instead of wasting it?
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is it viable to pump water with wind before turning it into electricity? [closed]

If one was to place many [short] turbines along a windy bridge, a levee or a windy road could one remedy the losses from many small generators, low voltage and large distances by pumping water in ...