Questions tagged [energy]

The ability a physical system has to do work on other physical systems.

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23
votes
7answers
7k views

Are there technologies that provide unlimited free energy?

Many different sources claim to be able to produce "unlimited free energy". For example: UNLIMITED FREE ENERGY IDENTIFIED Company claims to have developed new technology that provides unlimited free ...
173
votes
4answers
25k views

Does a webpage with a black background save energy?

Blackle is a search engine that claims to save energy because it uses a black background. Is there any evidence to back up their claim that a website using a black background will save energy, and if ...
42
votes
3answers
8k views

Did wind power supply less than half a percent of global energy in 2014?

From The Spectator: Wind turbines are neither clean nor green and they provide zero global energy: Here’s a quiz; no conferring. To the nearest whole number, what percentage of the world’s energy ...
8
votes
2answers
2k views

How long does it take for renewable technology to recoup its energy cost?

There are a number of technologies which are aimed at producing energy from non-fossil sources, among which very popular are wind power and solar power technologies. However, I have encountered a ...
29
votes
5answers
4k views

Are there fewer accidental deaths at nuclear power plants than others?

I have seen the stats on this website saying that the number of death caused by nuclear accidents was way smaller then those caused by any other energy production factory. Do you have any information, ...
23
votes
2answers
2k views

Does the amount of land needed to get the USA to zero-carbon electricity correspond to a small area of Texas?

After watching Elon Musk's presentation regarding the Tesla Powerwall, I had a question. On his diagram of the USA, he claims that a "tiny blue square" on the top of Texas that consists of solar ...
44
votes
1answer
12k views

Did/does the US government keep secret papers by Nikola Tesla?

A popular conspiracy theory holds that Tesla invented a free energy device, but that the powers that be prevented him from publishing it, because it would hurt their investments. Of course, free ...
65
votes
0answers
8k views

Does one transaction on Bitcoin require 215 kWh? [closed]

This seems unbelievable: This averages out to a shocking 215 kilowatt-hours (KWh) [sic] of juice used by miners for each Bitcoin transaction (there are currently about 300,000 transactions per ...
11
votes
2answers
22k views

Can permanent magnets be exploited to create energy?

There are many videos on youtube in which permanent magnets are used to make a motor. Although it might be possible in an ideal environment (e.g. no friction). As these devices are rotating ...
11
votes
2answers
780 views

Is flying the worst choice of travelling, considering the greenhouse effect and carbon-dioxide emission? [closed]

The communities I live in in Germany keep telling everybody that flying should be avoided by all circumstances, because it has a far bigger ecological footprint than any other mode of transportation. ...
21
votes
3answers
3k views

Does the digestion of some foods burn more calories than it supplies?

Calories in food is a measurement of the amount of energy it will provide to the body. I've heard that eating some foods actually make you USE more calories than you consume. Do any foods actually ...
14
votes
2answers
480 views

Are CFLs always more ecologic than incandescent light bulbs?

Incandescent light bulbs are now being phased out in many countries. In practice, the replacements are mostly compact fluorescent lamps (CFL). In many cases, the energy savings created by CFLs justify ...
14
votes
3answers
1k views

Are electric cars beneficial to the environment compared to low consumption modern cars?

Imagine an electric car in a country where most energy come from coal (which i believe is the dirtiest). Add this to the pollution that disposing the batteries will create, or the carbon footprint ...
13
votes
1answer
484 views

Can drilling for geothermal energy trigger a major earthquake?

I remember reading about this geothermal project being cancelled due to concerns over (relatively) small seismic events caused by the drilling. Have there been any instances of, or reasonable ...
6
votes
1answer
1k views

Do photovoltaic solar panels need replacement after 20 years?

Many manufacturers of photovoltaic solar panels offer some sort of warranty that is valid for 15 to 25 years. Many people suggest that after that period of time, a replacement of the panels is ...
5
votes
1answer
3k views

Does the Theradome Laser Helmet deliver around 7 J/cm2 to the head?

The Theradome Laser Helmet is claimed by its manufacturers to promote healthy hair growth. In this infographic, they claim it delivers energy to the skull at a concentration of 6.959 j/cm2 - ...
5
votes
3answers
558 views

Is the production of nuclear power very expensive? [duplicate]

Reuters recently published the following piece: Nuclear energy too slow, too expensive to save climate: report Inside, it says: The cost of generating solar power ranges from $36 to $44 per ...