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 ...
- 2,849
15
votes
Accepted
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 ...
- 3,875
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 ...
- 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 ...
- 1,603
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.
- 14.7k
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 ...
- 211
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 ...
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 ...
- 14.7k
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 ...
- 11.8k
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 ...
- 14.5k
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 ...
- 587
6
votes
Accepted
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 ...
- 11.8k
6
votes
Accepted
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, ...
- 11.8k
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 ...
- 14.5k
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-...
- 3,875
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 ...
- 3,875
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 ...
- 2,804
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-...
- 14.7k
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'...
- 11.8k
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 ...
- 4,786
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 ...
- 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 ...
- 4,786
4
votes
Accepted
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 ...
- 11.8k
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 ...
- 3,875
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 ...
- 8,755
4
votes
Accepted
What has been the greenhouse gas impact of shutting down Japanese nuclear power plants post-Fukushima?
Change in capacity
From 2004 to 2014, nuclear capacity did not change substantially:
Change in generation
However, the generation mix did change quite a bit (2014 nuclear data not available, so ...
- 11.8k
4
votes
Will negative power pricing counteract the growth in solar PV capacity?
No. Negative pricing does not pose any obstacle to renewables on the grid.
Low prices open the door for storage-focused companies — using technologies like pumped-hydro and chemical batteries — to ...
- 2,804
3
votes
Is solar energy the best renewable source of energy?
Renewables shouldn't be thought of as an either / or proposition. If we're thinking about an entire economy you want a variety of sources at a variety of scales, with a variety of storage systems.
...
- 31
3
votes
Is solar energy the best renewable source of energy?
My interest here is in biomass. I say for my region of the country or world biomass is about as renewable as u can get! I am mowing my 1 acre of grass and compressing the dry clippings into pellets ...
3
votes
Are RECs (Renewable Energy Certificates) an effective method to "green" industry?
As greening measures go RECs tend to be one of the better options since they guarantee that for each certificate a given amount of renewable electricity is generated, so if that's what you want they ...
- 3,875
Only top scored, non community-wiki answers of a minimum length are eligible