Nuclear fusion reaction releases almost twice the energy put in

throwaway389430@lemmy.cafe to News@lemmy.world – 629 points –
Nuclear fusion reaction releases almost twice the energy put in
newscientist.com
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Firstly, the energy output falls far short of what would be needed for a commercial reactor, barely creating enough to heat a bath. Worse than that, the ratio is calculated using the lasers’ output, but to create that 2.1 megajoules of energy, the lasers draw 500 trillion watts, which is more power than the output of the entire US national grid. So these experiments break even in a very narrow sense of the term.

It's so refreshing to see an article at least mention the way these tests are measured are based on the energy just in the laser itself and not the total energy used.

I agree it's good that the article is not hyping up the idea that the world will now definitely be saved by fusion and so we can all therefore go on consuming all the energy we want.

There are still some sloppy things about the article that disappoint me though...

  1. They seem to be implying that 500 TW is obviously much larger than 2.1 MJ... but without knowing how long the 500 TW is required for, this comparison is meaningless.

  2. They imply that using more power than available from the grid is infeasible, but it evidently isn't as they've done it multiple times - presumably by charging up local energy storage and releasing it quickly. Scaling this up is obviously a challenge though.

  3. The weird mix of metric prefixes (mega) and standard numbers (trillions) in a single sentence is a bit triggering - that might just be me though.

Electricity stuff is funny because it combines metric and imperial units sometimes to make bastard measurements

Huh? Whatchu talkin bout Willis?

Watt is a Joule per second

Volts, Amps, kWh, MJ... These are all metric.

Sssch don't tell the Americans or they will try to wrangle in BTU in nuclear power plants

WE INVENTED IT AND BUH GAWD, WE WILL MEASURE IT IN MURICA UNITS!

Ignore how nonsensical BTUs are: Gonna shove energy and weight into a single measurement and it changes based on the initial temperature of the water.

Or HVAC uses tons of ice needed to cool something. Euroguys probably don't have air conditioners, just that tilt window technology.

I do like the obscure AWG scale especially 0000

Y'all do know what BTU stands for, right?

British Thermal Units. It’s the energy needed to heat 1 lb of water 1 degree F.

The bad part is that no one bothered to set the starting temp of the water so there’s 5 separate standards for what the hell a BTU actually is, which makes it a really bad standard.

Yeah electricity is weird because Americans use metric for it. And it’s that way because metric predates it

Fun fact: While metric predates our full understanding of electricity, our understanding of electricity played a key role in the definition of the SI units.

As I understand it, the reason the SI unit for mass is kg not g - making it an outlier to my mind - is so that electical engineers could keep volts and amperes as convenient numbers.

Long read: https://arxiv.org/abs/1512.07306

In a number of instances where there is not a standard in place already it is not uncommon to see metric measurements mixed with imperial or US customary measurements.

I’m not in any way shape or form claiming that ALL of it is mixed.

However what does actually happen is the a unit of measure might be mixed with a customary one and then that becomes the defacto measurement, you may see wire resistance shown as a mix of Ohms/1000ft.

I am not getting into an argument about the merits of metric, I’m on board, I am with you. That doesn’t mean there aren’t some silly oddballs.

Is their an imperial equivalent to ohm?

It might be the case that imperial resistance is ohm the same as metric. Metric uses ohm as it's constituent with base units of metric, but imperial doesn't abide by rules like that.

If you had to make a imperial equivalent to resistance, it would be a fraction of the resistance of the monarchs finger.

Until we actually electrocute a king there probably won’t be

There's no non metric electrical units except ohms/1000 ft or cross section dimensions, and AWG (and MCM kilo circular mils kcmils) versus mm^2

Why US uses awg with reverse scale instead of diameter is insane

formula: D(AWG) = 0.005·92^((36-AWG)/39) inch

Still, from an acorn grows a massive tree.

Exactly. These tests aren’t meant to create a practical solution, but to provide knowledge and insight that a) it is possible and b) exactly what is necessary to make it happen, at a physical level. Before this, it (more out than in) was all theory, but now we’re got some hard data to work with.

That’s a big step we’ve been chasing for a long, long time.

Yeah, and a good sign is that the countries with money to invest in the race all seem to be convinced we've got the science right and that the engineering challenges are solvable. There have been so many records broken recently we're getting towards the end of the mile stones, hopefully soon we'll start hearing about self sustaining experiments with records for how long they ran