Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

MIT-designed project achieves major advance toward fusion energy

news.mit.edu

Post reply on HN
Print view View original

291–300 of 438 posts

Re: MIT-designed project achieves major advance toward fusion energy

#291

Post by chriswarbo »

veltas wrote: post #284
codethief wrote: post #281

Earlier quoted context omitted.

> Fusion is in theory something that could give us true energy abundance. Well, at least for a few hundred years but then: > if you plot the U.S. energy consumption in all forms from 1650 until now, you see a phenomenally faithful exponential at about 3% per year over that whole span. The situation for the whole world is similar. […] the Earth has only one mechanism for releasing heat to space, and that’s via (infrar…

How do we know that global temp rise isn't just due to energy usage? I mean "does that calculation fit at all?", not "carbon dioxide is fake".

It's the difference between a hand-warmer and a coat. The hand-warmer adds extra heat to the system (like the heat from burning fossil fuels). A coat doesn't add any extra heat, it just traps some of the heat that would otherwise be lost (like greenhouse gasses).

Hand-warmers can keep part of the body warm for a few hours. Coats can keep the whole body warm for years.

Re: MIT-designed project achieves major advance toward fusion energy

#292

Post by filleokus »

codethief wrote: post #281
mchusma wrote: post #112

Earlier quoted context omitted.

You are right, people who flippantly dismiss fusion just don't understand it. -Fusion has made consistent improvement, roughly in line with expectations for the level of investment (20 years away predictions were considering if we invested massively, which we did not). - Fusion is in theory something that could give us true energy abundance. Want to just desalinate water like crazy? Want to extract gigatons of carbon…

> Fusion is in theory something that could give us true energy abundance. Well, at least for a few hundred years but then: > if you plot the U.S. energy consumption in all forms from 1650 until now, you see a phenomenally faithful exponential at about 3% per year over that whole span. The situation for the whole world is similar. […] the Earth has only one mechanism for releasing heat to space, and that’s via (infrar…

Huh, that's interesting!

I wonder, in a strictly thermodynamic way (ignoring CO2 etc), how big of an impact it would have to remove all internal combustion engines in land-based transportation and power generation (coal plants).

ICE's have like a 30-40% efficiency? Compared to electric engines 80-90%. But on the other hand, you probably consume quite a bit of energy producing the batteries...

Re: MIT-designed project achieves major advance toward fusion energy

#293

Post by codethief »

roenxi wrote: post #282
codethief wrote: post #281

Earlier quoted context omitted.

> Fusion is in theory something that could give us true energy abundance. Well, at least for a few hundred years but then: > if you plot the U.S. energy consumption in all forms from 1650 until now, you see a phenomenally faithful exponential at about 3% per year over that whole span. The situation for the whole world is similar. […] the Earth has only one mechanism for releasing heat to space, and that’s via (infrar…

If there is enough ambient energy to literally boil the seas then we're probably going to find it easy enough to leave the earth and go somewhere cooler.

I don't think it'll be easy.

We would have the same (if not higher) energy consumption per capita on any other planet. And unless that planet is humongously large (which would also increase its surface-level gravity, thus rendering it uninhabitable), the relation between surface temperature and energy consumption will be similar[0]. Now there's only a finite number of planets in our solar system and leaving our solar system, say in the direction of Proxima Centauri (the star nearest to the Sun), amounts to traveling ~4.2 light-years. At a velocity of 0.1c (which is a lot – especially if you're trying to move an entire species[1]) that means a travel time of 42 years (as seen from our current frame of reference). Any velocity lower than that and we're getting into hundreds-of-years territory, so we'll be needing space ships across we can live for generations.

Also, a space ship is not that different from a planet, in that it also has to obey thermodynamics. So the surface temperature issue there is just the same. (In fact it's worse, since our space ship will likely be smaller and we also need to factor in additional waste energy of the space ship's propulsion engine or whatever we're using.)

[0]: https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law

[1]: Or, say, half the species (or whatever amount necessary to make the total energy consumption on the planets we already inhabit drop to levels such that the planets' surfaces don't start to boil).

Re: MIT-designed project achieves major advance toward fusion energy

#294

Post by thow-58d4e8b »

veltas wrote: post #284
codethief wrote: post #281

Earlier quoted context omitted.

> Fusion is in theory something that could give us true energy abundance. Well, at least for a few hundred years but then: > if you plot the U.S. energy consumption in all forms from 1650 until now, you see a phenomenally faithful exponential at about 3% per year over that whole span. The situation for the whole world is similar. […] the Earth has only one mechanism for releasing heat to space, and that’s via (infrar…

How do we know that global temp rise isn't just due to energy usage? I mean "does that calculation fit at all?", not "carbon dioxide is fake".

Not even close.

Global energy use is around 170,000 TWh/year (1). This includes electricity generation, as well as fuel for transport, burning wood for heat, etc.

Heat flow from mantle is 403,000 TWh/year (2)

Solar irradiance is ~1200W/m2, which adds up to massive 5B TWh/year.

Extra radiative forcing from greenhouse gases in IPCC scenarios is ~3W/m2, or around 12.5M TWh/year.

The radiative forcing is two orders of magnitude larger than our energy use.

(1) https://en.wikipedia.org/wiki/World_energy_supply_and_consum...

(2) https://www.nature.com/articles/ngeo.2007.44

Re: MIT-designed project achieves major advance toward fusion energy

#295

Post by phreeza »

mchusma wrote: post #112
dfdx wrote: post #34

Plenty of skepticism in these comments. I've been following CFS for a while and can present a point of view for why this time might be different. Fusion energy was actually making rapid progress in the latter half of the twentieth century, going from almost no power output in the fifties and sixties to a power output equal to 67% of input power with the JET reactor in 1997. By the eighties there was plenty of experim…

You are right, people who flippantly dismiss fusion just don't understand it. -Fusion has made consistent improvement, roughly in line with expectations for the level of investment (20 years away predictions were considering if we invested massively, which we did not). - Fusion is in theory something that could give us true energy abundance. Want to just desalinate water like crazy? Want to extract gigatons of carbon…

> I like to think of solar, batteries, fission, and wind as compelling ways to go mostly carbon free and lower energy costs about 2x over the next 20 years or so.

> Fusion is what reduces energy cost potentially another 10x, which really changes the game for lots of things. Exciting stuff. Kudos to this team.

Citation needed... If the fusion reactors end up needing tape of room temperature superconductors to keep their confinement going, and they degrade rapidly due to neutron radiation, I could easily see solar being cheaper in the long run. I'm not saying this is exactly what will happen, but I have never seen compelling proof that fusion will really be so cheap in terms of capex or opex per Watt.

Re: MIT-designed project achieves major advance toward fusion energy

#296

Post by ajdegol »

tsimionescu wrote: post #277
mchusma wrote: post #112

Earlier quoted context omitted.

You are right, people who flippantly dismiss fusion just don't understand it. -Fusion has made consistent improvement, roughly in line with expectations for the level of investment (20 years away predictions were considering if we invested massively, which we did not). - Fusion is in theory something that could give us true energy abundance. Want to just desalinate water like crazy? Want to extract gigatons of carbon…

> Fusion is in theory something that could give us true energy abundance. The biggest problem is the 'in theory' part. With current plausible designs, the vast majority of the fusion reaction's energy is carried away by high-powered neutrons, which are entirely waste products.

The neutrons are what we will extract energy from, the alpha particles continue heating the plasma.

Re: MIT-designed project achieves major advance toward fusion energy

#297

Post by codethief »

ifdefdebug wrote: post #289
codethief wrote: post #281

Earlier quoted context omitted.

> Fusion is in theory something that could give us true energy abundance. Well, at least for a few hundred years but then: > if you plot the U.S. energy consumption in all forms from 1650 until now, you see a phenomenally faithful exponential at about 3% per year over that whole span. The situation for the whole world is similar. […] the Earth has only one mechanism for releasing heat to space, and that’s via (infrar…

Well if we transform solar into electric then into motion or bound carbon, that should actually help reduce the heat balance?

> into motion

Kinetic energy will end up getting converted to waste heat nonetheless.

> or bound carbon

This seems hard to imagine. We're dealing with waste energy here, so a very high-entropy type of energy. Bound carbon is low-entropy, so the conversion is impossible[0] unless we put that entropy elsewhere.

As an analogy, consider a fridge: It brings your food from a high-entropy (high-temperature) to a low-entropy (low-temperature) state but in order to do that it also has to produce waste heat (entropy) on the outside.

[0]: https://en.wikipedia.org/wiki/Second_law_of_thermodynamics

Re: MIT-designed project achieves major advance toward fusion energy

#298

Post by veltas »

thow-58d4e8b wrote: post #294
veltas wrote: post #284

Earlier quoted context omitted.

How do we know that global temp rise isn't just due to energy usage? I mean "does that calculation fit at all?", not "carbon dioxide is fake".

Not even close. Global energy use is around 170,000 TWh/year (1). This includes electricity generation, as well as fuel for transport, burning wood for heat, etc. Heat flow from mantle is 403,000 TWh/year (2) Solar irradiance is ~1200W/m2, which adds up to massive 5B TWh/year. Extra radiative forcing from greenhouse gases in IPCC scenarios is ~3W/m2, or around 12.5M TWh/year. The radiative forcing is two orders of ma…

Thanks, this is the calculation I was looking for.

Re: MIT-designed project achieves major advance toward fusion energy

#299

Post by roenxi »

codethief wrote: post #293
roenxi wrote: post #282

Earlier quoted context omitted.

If there is enough ambient energy to literally boil the seas then we're probably going to find it easy enough to leave the earth and go somewhere cooler.

I don't think it'll be easy . We would have the same (if not higher) energy consumption per capita on any other planet. And unless that planet is humongously large (which would also increase its surface-level gravity, thus rendering it uninhabitable), the relation between surface temperature and energy consumption will be similar[0]. Now there's only a finite number of planets in our solar system and leaving our sola…

We're talking a world where humanity has enough energy on tap that not only could it have feasibly evaporated the Pacific Ocean, but that it basically has evaporated the Pacific Ocean, as a side effect of doing something else.

We can barely speculate about such a world, but interstellar travel would not be much of a challenge with that sort of energy abundance. We'll find a way.

Re: MIT-designed project achieves major advance toward fusion energy

#300

Post by liamwire »

ncmncm wrote: post #204
IntrepidWorm wrote: post #197

Earlier quoted context omitted.

Don't attribute to conspiracy what can be adiquately explained by beurocracy.

Millions of large buildings, and tens of thousands of huge ships, dams, and bridges are built on time and on budget. The alternative would be that management cannot be judged on its results. Some bridges, invariably urban, go massively over budget and schedule. Urban tunnels, routinely. Military procurement, routinely. Are people who manage those systematically dumber than the rest? Or do they have different measures…

Or, Occam’s razor. A sufficiently complex engineering task can exist such that it fully taxes even international, multi-nation state-backed parallel capacity for engineering, and science.

This is already demonstrated by your own examples provided, just at a smaller scale.

If there were ever such a project to push against the capacity of our ability to do truly enormous, complex engineering, I’d say a massive, cutting-edge fusion reactor is as good a candidate as one could propose.

Moreover, the economic and educational stimulus these projects provide cannot be ignored when accounting for the indirect, long-tail returns this project, and those similar, provide.

Put another way: ostensibly, achieving net energy gain from fusion is the end of our near-term (energy) needs, conveniently breezing over the evolution and refinements of any system, as well as delivery and storage, but these are paths that are comparatively well mapped out. It then follows that, short of catastrophic losses prior to succeeding (which while not a given per se, seems more a function of time than of ability outright), any reasonable cost is worthwhile. Reasonable, in this context, meaning one that doesn’t bankrupt, or otherwise severely impact the participants in a negative fashion. Given the scale of these budgets vs. that of social welfare programs, military spending, etc. I don’t see that as an issue worth being concerned over. One can know the budget has been exceeded, without that also bringing down the house.

Ultimately, to an extent you’re asserting a false dichotomy. It can be true that there’s continued, substantial progress towards the stated goals of these projects, even if the budgets, horizons, and timelines aren’t to your taste. It can also be true that there’s waste, inefficiencies, and even (both legalised and otherwise) corruption. One does not preclude the other.

Post reply on HN