37 votes
Accepted

Why does it take so long to restart a nuclear power plant?

When a reactor is shut down the core produces much less heat, but they do still produce heat through a mechanism known as decay heat. The fact that the core is producing less heat means that the ...
Chuck's user avatar
  • 3,565
13 votes

Why does it take so long to restart a nuclear power plant?

Xenon is a result of the nuclear reaction and a neutron poison. If you don't wait for the xenon to decay, it eats up too many neutrons and you can't go critical. They always say "there are not ...
user1683793's user avatar
  • 1,000
11 votes

Wind farms that wind up in the wind, and then unwind producing energy when the wind is still

The storage part of the RES systems is probably the biggest challenge today. There are several ways to store energy. By far the most used way today is Pumped storage hydroelecticity systems. ...
NMech's user avatar
  • 24.3k
7 votes

Why does it take so long to restart a nuclear power plant?

The answer really boils down to two factors: safety and testing. I'm going to give a generic summary of these two things below, but the real answer is quite complicated. The crux of nuclear plant ...
grfrazee's user avatar
  • 3,587
6 votes

Wind farms that wind up in the wind, and then unwind producing energy when the wind is still

You've described energy storage, or physical batteries. You wouldn't need half of each wind farm dedicated to this; you would simply store the excess, beyond what is used at a given time. It's not ...
RC_23's user avatar
  • 831
6 votes

Why aren't gravity batteries everywhere?

So, this battery costs US$70, weighs 406 grams, and holds around 200,000 Joules of energy. To get the same energy from that weight as a "gravity battery" you'd have to pick it up over 49 kilometers ...
TimWescott's user avatar
  • 2,522
6 votes

Wind farms that wind up in the wind, and then unwind producing energy when the wind is still

I suppose what you had in mind with your question was something like, every single turbine winches up a heavy weight to its tower while surplus energy is available, then lowers it again to recuperate ...
leftaroundabout's user avatar
5 votes
Accepted

Why are both conductors in a High Voltage Direct Curent powerline isolated from ground?

Because they're both live Just because you see multiple wires doesn't mean they are carrying different things. They are frequently paralleled for more ampacity. It's perfectly common in HVDC lines to ...
Harper - Reinstate Monica's user avatar
5 votes

Why are both conductors in a High Voltage Direct Curent powerline isolated from ground?

There are a few possible reasons. Elimination of electrolysis problems with ground connections. Elimination of variations in ground resistance. Grounding one of the conductors on the HVDC line might ...
Transistor's user avatar
  • 10.6k
5 votes

Why aren't gravity batteries everywhere?

Consider 1 kWh = 1000 W * 3600 seconds = 3,600,000 J. 1 kg lifted 1 m = ~10J. Let's use 1 metric tonne. 1000Kg. So we get 10,000 J per meter of elevation. 3,600,000 / 10,000 = 360 meters. Around ...
Sherwood Botsford's user avatar
5 votes

Wind farms that wind up in the wind, and then unwind producing energy when the wind is still

You're describing a Gravity Battery. While the other answers have pointed out that water is the most common lifted weight, EnergyVault is a Swiss company that's basically lifting concrete blocks. The ...
user121330's user avatar
4 votes
Accepted

Why shouldn't we put high voltage cables physically underground?

Your four drawbacks are very good reasons for not laying cables on the ground and just covering them with soil or "stuff". Erosion will be a major issue. Exposed cables would be a safety hazard to ...
Fred's user avatar
  • 9,667
4 votes

Wind farms that wind up in the wind, and then unwind producing energy when the wind is still

As other answers have pointed out, the key to a system that utilizes renewable energy sources with an energy storage backup envisioned by the question is the ability to store large amounts of energy ...
njuffa's user avatar
  • 141
4 votes
Accepted

What, roughly, are the characteristics of nuclear power in grid management?

In the US, Nuclear is used to base load the grid. As implemented in the USA, Nuclear energy has very high fixed costs and relatively low variable cost. So it is in the utility's interest to run their ...
Tiger Guy's user avatar
  • 6,793
3 votes

Expected power increase when replacing old (>20 years) wind turbines

Wind turbune efficiency is limited to 59% by Betz law Modern turbines are close to this limit, about 75% of optimum. Older turbines, that are also of the same type, will have almost the same ...
Surprised Seagull's user avatar
3 votes

Why aren't gravity batteries everywhere?

Are there some shortcomings that I am missing here? Yes there are a couple of things you have missed. Firstly I will deviate slightly from your question but I believe this is relevant. The need for ...
Brad's user avatar
  • 318
3 votes

What's the history of the 345 kV voltage level in power transmission?

With the high voltage AC power lines, there are trade offs between losses due to resistance in the wires, where the higher voltages are better and losses due to capacitance to the air, etc. where ...
user1683793's user avatar
  • 1,000
2 votes

Power consumption of mining rig?

Since I lack the reputation to write comments: The electricity cost of mining is way higher than the earnings. Small scale mining is not profitable anymore for a long time already, mining farms have ...
OpticalResonator's user avatar
2 votes

Why shouldn't we put high voltage cables physically underground?

I do not know the laws in your country, but the key is "risk assessment". And the risk we are talking about is the risk of killing someone, not the risk of the cable being damaged. Irrespective of ...
ericnutsch's user avatar
  • 8,136
2 votes
Accepted

What is the specific issue with frequency fluctuation in the grid?

A 1% shift in grid frequency will shift the running speed of every AC induction motor connected to it by 1%. Factory machinery and AC-powered clocks would all slow down, with potentially disastrous ...
niels nielsen's user avatar
2 votes

natural gas-fired power plants

The answer to the energy content of natural gas is a matter of chemistry. Natural gas (methane) is $\mathrm{CH}_4$, and Carbon-Hydrogen bonds contain a good deal of energy per bond, which are broken ...
RC_23's user avatar
  • 831
2 votes

What does "shuffling" mean in the context of electrical grid power distribution?

Where the houses are on single-phase supplies, they are wired so that one third of the houses are on each phase. That evens out the load. If all the houses get a 3-phase supply, there is always a ...
Simon B's user avatar
  • 214
1 vote

Lead Cladding on Telephony (landline) copper cables. Any other early industrializers with this problem?

Since you mention the Model T Ford in regards to vulcanized rubber, I'm using the 1920s as a reference period. Various newspaper articles give the price of lead in London from 1913 to 1925 and for ...
Fred's user avatar
  • 9,667
1 vote

Can the power of a diesel electric generator, installed in a factory, escape into the national grid?

For me, it appears that even if the generator is adjusted to deliver exactly the same power as needed by the loads in its factory, nothing stops those loads to draw energy from the grid and nothing ...
Transistor's user avatar
  • 10.6k
1 vote

Can the power of a diesel electric generator, installed in a factory, escape into the national grid?

There should be a connection "box" between the generator and the grid side to prevent "backfeeding" the grid. All the inverters for the many PV panels connected to the grid will ...
Solar Mike's user avatar
  • 15.6k
1 vote

Expected power increase when replacing old (>20 years) wind turbines

Larger turbines have to be spaced further apart. See Sustainable Energy Without the Hot Air by David MacKay. He gives a figure of 2 W/m2 although this may have improved a bit since his book was ...
Transistor's user avatar
  • 10.6k
1 vote

What fraction of energy is typically lost in transmission over power lines?

Losses are due to skin effect. Direct current flows through the full cross-sectional area (CSA) of the, typically aluminum, conductor, while alternating current flows on the outer surface of the ...
StainlessSteelRat's user avatar
1 vote

What, roughly, are the characteristics of nuclear power in grid management?

Re: load following, from Wikipedia Modern nuclear plants with light water reactors are designed to have maneuvering capabilities in the 30-100% range with 5%/minute slope. Nuclear power plants in ...
Pete W's user avatar
  • 1,526
1 vote

Simple clarification about EV charging

The listing in the provided link is a summary of generally accepted sources of power for EV charging systems. Your question appears to be what is allowed by those sources, which really is not related ...
fred_dot_u's user avatar
  • 7,055
1 vote

Simple clarification about EV charging

On a 230 V system 16 A would be the circuit breaker rating for one circuit with a couple of sockets on it. A typical cooker would be 35 A. In Ireland the traditional connection is single-phase 63 A. A ...
Transistor's user avatar
  • 10.6k

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