141–150 of 494 posts
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"We should put more resources into breeding faster horses now, internal combustion can wait." - someone in late 19 century.
Hah, well what was the rate of progress on breeding faster horses vs. internal combustion in the late 19th century? I don't imagine that the progress rate was very high for horses..
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It's neither, agreed. However, Sabine misconstrues things in the opposite direction and lies through omission to the audience. For example including startup energy and not ammortizing it over runtime, or not assuming that the energy consumption of the experiments is part of the required energy consumption of the fusion reactor, or trying to construe that once you have a fusion power reaction that is burning it is sti…
Where are you getting this impression? Her video pretty clearly focuses on the confusion between the Qs. Where does she get the napkin math wrong? She uses a published figure for total energy required during the operation of ITER when it’s up and running not a one time startup cost figure. Id she misrepresented that number, what would be a more honest total power consumption figure? As far as construing the output, s…
She doesn't even show her calculations on how she calculates some of her Q_total examples.
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Study this: https://www.lazard.com/perspective/levelized-cost-of-energy-... Ignoring storage: it makes no sense now to build anything but wind and solar. Only the marginal cost of gas is cheaper (meaning existing plants, not new ones). Including storage: conventional is still cheaper, but not by much (within a factor of 2): $81 for PV+storage vs. $44 for gas combined cycle. We should put more resources into storage n…
"We should put more resources into breeding faster horses now, internal combustion can wait." - someone in late 19 century.
"Why breed faster horses now when maybe my grandchildren will get to zoom around in cars?"
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"We should put more resources into breeding faster horses now, internal combustion can wait." - someone in late 19 century.
Well, if we'd have gone down that road, plus strong environmental awareness, maybe the Earth wouldn't be warming up so badly right now, and the oceans wouldn't have islands of plastic (= oil) waste. Now, sure, we wouldn't have enjoyed some of the benefits of car technology, but - public transport (esp. trains) makes up for a lot of that. OTOH, public transport pollutes too.
Meta-question about fusion energy -something I don't understand about the movement. I spent a few years as CTO of a company providing heat-to-electricity plants. We financed and built them off high-heat plants like natural gas turbines. The "fuel" was heat going up the stack - so it was essentially free. We still couldn't compete with conventional electricity plants, even with a $30/tonne price on carbon in Canada. G…
Natural gas is only inexpensive because of fracking. With fracking in the USA at least the people involved can set up an LLC that dissolves after the well runs out. They are not required to disclose the contents of the fracking wastewater fluid. It gets pumped back down underground where it could dissipate into the rest of the water system. These people claim that it's safe for decades when our computer models can't…
The models may or may not be accurate but they have nothing to do with predicting the weather. There isn't any weather underground... It's all slow diffusion and buoyancy.
A better starting place might be asking where the model inputs come from.
Meta-question about fusion energy -something I don't understand about the movement. I spent a few years as CTO of a company providing heat-to-electricity plants. We financed and built them off high-heat plants like natural gas turbines. The "fuel" was heat going up the stack - so it was essentially free. We still couldn't compete with conventional electricity plants, even with a $30/tonne price on carbon in Canada. G…
It's not but people don't seem to realize this or maybe just don't want to think about it. Spending $100B to produce 1GW of power (made up numbers) is not an economical source of power. So hydrogen being free (deuterium and tritium are essentially free; Helium isotopes are more complicated) is irrelevant until the capital cost of the plane is much, much lower.
And even then you still have to deal with these significant issues:
- Neutron embrittlement of the container;
- Energy loss from the chamber from neutrons; and
- Containment. The plasma is essentially an extremely high temperature turbulent fluid. Because of the turbulence and the super-high temperatures containment is likely to remain a significant issue.
I hope fusion becomes commercially viable and economical but I'm just not convinced (yet) that that will ever be the case. It certainly won't be ITER even with tens of billions spent on it.
People get caught up on the fact that stars do fusion without considering what's different. To summarize:
- Energy loss from neutrons is essentially a non-issue because of gravity and just the size of stars. To put this in context, it's estimated that photons created at the Sun's core take ~30,000 years to escape;
- Stars are relatively inefficient with their fuel. IIRC the Sun converts ~4.5M tons of matter into energy every second. It sounds like a lot but that's a tiny fraction of the Sun's mass (~10^30 kg). That's because hydrogen atoms are so unlikely to fuse and they go through several intermediate states before that happens. Fusion in the lab already produces many more fusion reactions per unit mass than stars do.
I firmly believe that space-based solar power collection is our most likely future.
EDIT: corrected "photons"
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Because to achieve 1MW of energy from fusion, you put 200MW of power into the lasers. And, you have to fire these lasers with unfathomable precision at a tiny piece of gold, in order to heat up an even tinier pellet of hydrogen, which then heats up enormously for a few milliseconds before fizzing out. ICF is a good way of studying what happens inside a hydrogen bomb, but it is in no way imaginable how you could use i…
What stops you from using the "even tinier piece pellet of hydrogen"[sic] from initiating fusion in a slightly less tiny pellet of hydrogen that it's sitting on top of, which initiates fusion in a slightly less tiny pellet of hydrogen, and so on? Aside from concern for your own survival, of course. Maybe if you can't fathom the precision required to irradiate the NIF hohlraum sufficiently isotropically to achieve ign…
The same thing that stops you from igniting the initial pellet with the hohlraum - you don't have anything creating the kind of confinement necessary to keep the plasma together.
The only thing allowing the plasma to get hot enough for fusion is the initial velocity of the inward-spreading shockwave from the initial explosion of the outer shell of the pellet. As the velocity of this shockwave inevitably decreases, confinement is inevitably lost and the plasma dissipates and cools down.
Probably in principle you could use the energy of the first pellet's plasma to cause similar shockwaves in a second, larger pellet and so on, but that requires an entirely different geometry, its not just a matter of putting the second pellet close to the first one.
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Would more cheap (in all ways) energy be a bad thing? I don't think so, people pay money for that sort of thing.
Heat pollution. Green house gasses are not the only way to cook ourselves. Though there are some people working on beaming heat into space, I suspect they haven’t fully accounted for heat absorption by atmospheric dust.
The sun deposits enormous amounts of energy onto earth every single day: Around 340 W/m² (averaged over the whole earth), or a total of 43 x 10^15 Watts. Essentially all of it is radiated back into space (mostly as infrared). We have a temperature equilibrium because energy intake is largely constant (surface/cloud albedo notwithstanding) while radiation back into space grows with fourth power of (surface/atmospheric) temperature.
Current global energy consumption is on the order of 2 x 10^12 Watts, over four orders of magnitude lower. If we somehow increase energy production by ~two orders of magnitude, to the point of ourselves emitting 1% of the solar energy intake on top, the surface temperature would need to rise by about 0.75 °C to maintain equilibrium. An order of magnitude more (i.e. three orders of magnitude above current consumption, roughly 10% of solar intake) would correspond to a 7.2 °C rise.
(Point of reference: Global power consumption has barely doubled in the past 40 years. No telling what "free" energy would cause though.)
Presumably we'd have geo-engineered a solution by that point, but it's surprisingly not too early to start thinking about the problem!
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Natural gas plants are cheap but they cause global warming, so soon we will not be able to use them. For example, the U.S. target is to have zero carbon emissions from electricity generation by 2035, and zero carbon emissions at all by 2050.
Their carbon emissions are still dramatically lower than those of coal and oil. There are bigger fish to fry than NG. NG is likely going to be a critical transitional fuel for the planet to depend on while we get to more abundant renewable options, grid batteries and nuclear/fusion/thorium.