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
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
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
Should we leave all fossil fuels in the ground and not use them?
Yes, we should leave the larger part of all known fossil fuel reserves in the ground. Scientists have calculated that if we want to keep global temperature rise under 2 degrees C (which was agreed ...
- 14.5k
10
votes
Accepted
Is electricity used at night more likely to be renewable?
In Ireland, electricity is equally likely to be from renewable sources during the day as during the night
ENTSO-E, the European Network of Transmission System Operators for Electricity, provides a ...
- 11.8k
8
votes
Hydro-electric generation from roof-collected rainwater
If it's a very simple motor then it may be possible just to run it backwards to generate electricity. If it's got electronic controls, probably not.
But is it worth it? Do a quick calculation of the ...
- 14.7k
7
votes
Is pellet fuel a sustainable energy source in the way it's used now?
It depends.
It is possible to farm wood sustainably, or unsustainably. Both ways happen now.
It is possible to use wood pellets for energy while trapping particulate matter and other non-GHG ...
- 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
Are trees more productive than wind turbines?
Wind turbines do not turn the ground between them into desert. There is still farming and growth of various plants (even trees) possible. It should not be excluded in those comparisons and ...
- 929
5
votes
Accepted
Is "renewable" a proper term for both solar and hydro power?
There are lots of ways to subcategorise renewables, for example:
Indirect + direct solar (wind, wave, hydro, biomass, biogas, PV, CSP, solar thermal, - and what's used up here in all cases is ...
- 14.7k
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
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
Accepted
Cost benefit analysis of a PV array with racking to set optimal angle, vs a larger array
According to the New Zealand Ministry of Business, Innovation, and Employment (pdf), the average home in New Zealand uses 7,046 kWh per year, and pays a rate of $0.2879/kWh (NZD).
I used this as a ...
- 11.8k
5
votes
Are trees more productive than wind turbines?
A tree farm of that size in a temperate climate would only produce ~1.7GWh/y (net). You are overestimating the productive value of trees by a factor of ~15.
A 5MW wind turbine can produce a maximum ...
- 2,814
5
votes
Why do some people say that biofuels are renewable energy source if producing biofuels requires nitrogen fertilizers?
They're called renewable because it's possible to do them in a renewable manner. Specifically, the energy in them comes from the sun, in a fairly short time span (i.e. years, rather than millennia or ...
- 14.7k
5
votes
How much land needed to dispose of blades from wind turbines?
This wont answer your question, but will attempt to show, why the question is based on wrong assumptions.
That headline you're concerned about is missing a "yet". True, currently recycling ...
- 587
5
votes
grid-based gravity assist power generaiton
I think you have exactly the right term already. The Institute of Electrical Engineers use "gravity energy storage" and wikipedia has a Gravity Battery page.
The main issue is that pumping ...
- 3,875
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 ...
- 4,871
4
votes
Does a PV panel take more energy to build than it generates in its lifetime?
Yes, PV is viable.
That's why somewhere around a billion solar panels have been connected to the grid - about 200 GW of capacity, with another 50 GW or so coming online in 2016.
I'm afraid that the ...
- 14.7k
4
votes
Solar Panel short section of string due to obstacle
You must open circuit the panels you're not using, do not short circuit them. Open circuit is fine, the panel just sits there and no current flows. You'll see quite a high voltage on the terminals (it'...
- 3,875
4
votes
Why the world is using non renewable resources?
To add to @Fred 's answer, there are a few things that can easily be overlooked.
In order to generate clean green energy you need to invest into these power production facilities. Obviously we know ...
- 191
4
votes
Is "renewable" a proper term for both solar and hydro power?
However, in the cases of wind, solar, and geothermal, this isn't so
obvious -- nothing is being used up (at least not in a measurable
quantity) which would need to be renewed.
Furthermore, ...
- 3,690
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 ...
- 2,814
4
votes
Shading percentage to cause hot spots
Yes, partial shading is very likely to cause hotspots. Those hotspots may be up to 19º C warmer than nearby panels, according to Efficiency analysis of PV power plants shaded by MV overhead lines.
It'...
- 2,849
4
votes
Why create green hydrogen using renewable energy? Why not directly use electricity from Renewable sources?
It's a matter of energy density. Compared to lithium-ion batteries, compressed hydrogen gas stores about 150 times as much energy per kilogram, or twice as much energy per liter.
If you're using the ...
- 608
4
votes
Accepted
What are the most viable options for long-duration storage of large amounts of energy?
With renewables being in large part weather-dependent, the issue of energy storage is slowly moving to the center stage of the incipient net-zero economy.
I agree.
Lithium ion batteries are kinda ...
- 4,871
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 ...
Only top scored, non community-wiki answers of a minimum length are eligible