However to go from liquid water to water vapor you need to add even more energy [0]. The enthalpy of vaporization for water is 2257 kJ/kg, it takes much more energy to boil water at 100°C than it takes to get there from room temperature.
Warming by 75 degrees + boiling = 2570 kJ/kg -> enough to boil 23 liters of water
I'm guessing in reality the energy needed to operate the kettles would lie somewhere in between, as a small part of the water will be boiled and most of it kept around 100°C. For 2L kettles the value seems in the right ballpark.
This is missing the heat of vaporization[1] needed to actually boil the water though, i.e. to turn 100C liquid water to 100C steam. That's another 2250kJ/kg on top of the 313.8kJ/kg you've mentioned.
It's why steam is such a great carrier of energy for industrial applications.
I guess you could argue that you wouldn't evaporate all water in the kettle, but then you do want a rolling boil. It's probably a bit up for discussion at which point you'd stop heating the kettle.
One does not have to argue for that interpretation - raising the temperature to boiling point, not boiling it dry, is indisputably the accepted and intended meaning of the phrase wherever English is spoken... though it would fit with a certain stereotype of scientists if a bunch of plasma physicists did not know how to make a pot of tea!
Not exactly. In American English "bring a pot to a boil" is much more common. When I read "enough energy to boil 60 kettles of water" I thought "vaporize".
Disagree that this is a) a much more common phrasing or b) that your interpretation would be the common one. I've yet to run into a situation where somebody asked me to "boil some water" and intended for me to vaporize all the water in some vessel.
It's also an incredible waste of time to argue over definitions. They're always disputable because they always arise in response to two people using a word differently. Maybe they're wrong and you're right, or maybe others also use the word that way—it doesn't matter. Humility and aiming at mutual understanding is far more worthwhile.
Here, as soon as someone recognizes that the amount of energy cited is way higher or lower than would be implied by their own definition, they should 1) identify the difference ("Boil here means 'boil n kettles dry' rather than 'bring n kettles to boil'") and 2) in most cases, avoid the wasted debate by adopting the other person's language if further conversation using the concept is needed.
In the light of this, what is your objection to my comment? As far as I can tell, it is in conformance with your numbered principles.
I understand this just to validate design choices and it is a good step forward. However, it doesn't make nuclear fusion a reality in two decades unless further records are set using this design
> only enough to boil about 60 kettles' worth of water
Exactly, no one has 3l kettles, but it's the right ballpark. You could also run about 9k kettles for that 5 seconds but not boil them, and if you tried to run 60 kettles consuming all that power for 5 seconds you would have quite the fire...
I have! Duckduckgo it.
They already started construction on a larger one? What if it had invalidated design choices?
The government money was already allocated and even the government can't unring that bell!
So net power is -989MW, assuming both flywheels are at full pelt the whole time and no power is required before fusion is acheived.
Plasma heating in JET is done via NBI+ICRH and is about 59 MW.
When discussing fusion power, we can all debate how many kettles we can boil.
Kind of funny :)
> This is more than double what was achieved in similar tests back in 1997.
> It's not a massive energy output - only enough to boil about 60 kettles' worth of water. But the significance is that it validates design choices that have been made for an even bigger fusion reactor now being constructed in France.
I thought this was interesting as 59 megajoules of energy or 11 megawatts of power seems more than you would need to boil 60 kettles' of water. In fact, it takes 4,184 joules to raise the temperature of 1kg of water by 1 degree. Or 313800 joules to raise 1kg of water by 75 degrees. That means JET could have boiled about 188 kg of water.