36 votes
Accepted

Why don't they make playgrounds generate electricity?

Because a playground equipped with generators would probably not be much fun. The merry-go-round would grind to a stop the moment it is no longer being pushed. The swings would not swing; they would ...
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  • 2,749
20 votes

How much power can a bicycle generator produce?

It depends on what power you can produce and the efficiency of the equipment you use to convert that mechanical power into electrical power. As a moderately fit 50+ cyclist, I can produce over 200 W ...
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  • 598
14 votes
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How many hours a day would you have to pedal to generate enough electricity for your apartment?

Summary: in the US about 150 hours a day, in Australia only about 90. Solar panels are better. Power Generated Most people who cycle regularly can produce between 150 and 250 watts for an hour. More ...
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  • 3,755
14 votes

Why don't they make playgrounds generate electricity?

A better target would be gym exercise machines Indoors, not exposed to elements, controlled environment so less chance of theft and vandalism. Customers stay on machines for a prolonged period ...
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  • 141
13 votes

Are fuel cell electricity generators a sustainable way of making electricity?

No. There is no readily available supply of net-positive-energy hydrogen on Earth, where most human power usage takes place. Hydrogen fuel cells may be a useful component of a total energy system ...
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11 votes

Getting power from an innovative new mechanism

No, you cannot get more energy out than you put in. No, you cannot invent a perpetual motion machine.
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  • 14.6k
11 votes

Why don't they make playgrounds generate electricity?

Playground equipment is very expensive and not typically something that local councils have large budgets for. Hooking it up to the electrical grid for minor amounts of electricity generation would ...
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10 votes

How much power can a bicycle generator produce?

BBC1's "Bang Goes the Theory" demonstrated a human-powered home in a TK programme. In this segment, 8.5 kW of power required 70 cyclists, of fairly typical fitness, or about 107W per cyclist. The ...
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9 votes

Is it possible to convert rain drops to energy?

It's possible, but the best way to do it was devised over a century ago: hydro power. Let the high land collect and channel lots of rain, and then put a turbine on the channel. The problem is that ...
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  • 14.6k
9 votes
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What method is best to gather energy?

Why did you rule out Solar? Solar is effective even in the state of Alaska. According to this article a 16 panel 2.5KW system in Fairbanks Alaska can provide you with around 500KWh/month of power ...
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  • 1,122
7 votes

Is oil actually a renewable and sustainable resource, but we just use much too much of it?

What does renewable mean? Wikipedia defines a renewable resource as (emphasis added): a natural resource which will replenish to replace the portion depleted by usage and consumption, either through ...
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  • 11.3k
6 votes
Accepted

Is the energy used to manufacture and install solar panels in proper balance with the energy output from them?

I asked my late father (an electrical engineer) this very question years ago and he said that essentially, the entire cost of a solar panel is the cost of the energy to make it. You dig dirt out of ...
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  • 1,807
6 votes

Anything similar to GravityLight that can be readily purchased?

The big advantage of GravityLight is that you can pull the weight once and then you have electricity for a relatively long period (I read somewhere it's 30 minutes). This is ideal when you need to ...
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  • 14.1k
6 votes

What is the wind wake effect and why is important for wind turbines?

The second slide of the presentation linked by you actually shows the issue with wake very clearly. You could also talk about turbulences instead of wake (my company actually does). Wake is simply the ...
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  • 587
6 votes
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Is wind power practically dead?

TL;DR: Wind is not dead, but a diverse set of economic, technical, and political factors have resulted in a leveling off of the rate of new construction. The cost to build new wind declined for years ...
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  • 11.3k
6 votes
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Why aren't all nuclear plants running at their full installed power to decrease emissions?

TL;dr -- it's most economical to operate nuclear plants at a fixed output level, so other fuels are used to adjust for variations in demand. Nuclear output at any given time is limited by outages, ...
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  • 11.3k
5 votes

Is 3 phase electrical generation more efficient to utilize than single phase?

I'm going to assume you'e in the USA since you're using Imperial units. 1) Is 3 phase power more efficient to generate/use? In bulk, yes. Three phase (or sometimes 6 phase/3 phase 220V in low-...
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  • 3,755
5 votes

What's the average efficiency of pumped hydroelectric energy storage facilities?

In this question about rooftop hydro I covered the efficiency question almost as an aside. I can't find an actual plant with efficiency over 80%, only claims that that might be possible. The average ...
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  • 3,755
5 votes

Is solar energy the best renewable source of energy?

The validity of your assumptions depend very much on your location and on the amount of energy you want to generate. Some small-scale solutions do not suffer from the same drawback as large-scale ...
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  • 14.1k
5 votes

Solar charging an e-bike's lithium battery while riding

Before you worry about charging, consider this: It takes about 85W to propel a 75kg cyclist at 20km/h under ideal conditions. Thin film (i.e. flexible) solar panels have an efficiency of ~9% and when ...
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  • 2,744
5 votes

Is wind power practically dead?

In 2018, global wind capacity increased from 515 GW to 564 GW - a 9.5% increase. 20 GW of that 49 GW increase was in China, 11 GW in Europe, 3 GW South America, 8 GW North America. A 9.5% year-on-...
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  • 14.6k
5 votes
Accepted

Will a warmer climate reduce energy demand and increase solar PV production?

tl;dr -- For the west coast of the U.S., a 20% decrease in heating demand and 18% increase in cooling demand results in a 5% reduction in carbon emissions from electricity and natural gas usage Here'...
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  • 11.3k
5 votes

Will a warmer climate reduce energy demand and increase solar PV production?

Wouldn't it therefore be better to have a small rise in global temperature? No. The radiative forcing by carbon dioxide does not increase solar radiation that can be captured by solar cells. The ...
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  • 3,025
5 votes

Why don't they make playgrounds generate electricity?

There are two main areas to consider here: Safety. Anything put near children has to be safe, and mains voltage and generators generally aren't. Damaged wires could electrocute somebody, a generator ...
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  • 51
5 votes
Accepted

Do solar panels generate more electricity in hot or cold climate?

If the amount of radiation stays the same, solar panels produce more energy when they are cooler. Heat causes efficiency to suffer. However, this is assuming the radiation amount is the same. Usually ...
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  • 3,025
4 votes

Is there an "energy returned on materials invested" index for energy sources?

Measuring impact I've yet to see a meaningful metric that relates directly to materials, other than the EROEI (Energy Returned On Energy Invested); and there's discussion about whether or not EROEI is ...
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  • 14.6k
4 votes
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Is an electric vehicle more sustainable just because it runs on batteries?

short answer: yes, it's better than driving a fossil-fuel car. Long answer: it may seem to make less sense if you only consider a very small range of impacts, where all of the costs are visible, but ...
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  • 14.6k
4 votes
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Does the price of polysilicon (for solar PV panels) depend on oil prices?

I did some digging and found data with a bit more resolution. First, polysilicon prices since 2010: Source: Fu, et al, Economic Measurements of Polysilicon for the Photovoltaic Industry: Market ...
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  • 11.3k
4 votes

Does the price of polysilicon (for solar PV panels) depend on oil prices?

No. As the graphs provided show, the prices both spike during the GFC, loosely speaking, but the oil price spikes later and declines faster, then continues a general slow rise while the price of ...
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  • 3,755
4 votes

Does the price of polysilicon (for solar PV panels) depend on oil prices?

Here's a quick answer; hopefully we'll see some more in depth answers too. Looking at the given charts closely, the price of polysilicon appears to decline from around $75 in early 2010 to $17 in ...
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