This a totally ignorant question - can you add “something” to the plasma to achieve the “jello like” analogy to water?
Why is nuclear fusion so hard?
71–80 of 182 posts
Re: Why is nuclear fusion so hard?
#72Would zero gravity be helpful in order to make it easier to get fusion working?
The particles in a fusion reactor are moving at 10 km/s. They don't particularly care about gravity.
For components of the reactor, gravity tends to be helpful. It's much harder to cool superconductors or generate steam if your liquids aren't flowing along the bottom. Turbines don't work nearly as well if their inlets are sputtering like a coffeemaker.
Re: Why is nuclear fusion so hard?
#73Earlier quoted context omitted.
Base load power is not a useful feature. To follow the demand curve you generally what to turn massive amounts of production off at specific points in the day, base load is simply what you keep running during those periods. Nuclear power plants for example where known to be hard to throttle which was a significant design issue. Historically, the tradeoff is worth it as the cost per kWh was less, but again not a usefu…
I used to be a reactor operator and never saw any evidence they were hard to throttle. That's why they are used for warship propulsion: loads in battle are not predictable by their nature, what with changes in course, catapult launches, etc.
I know nothing about the subject, but my understanding was that iodine pits could be a problem for thermal spectrum reactors if they had to suddenly raise power output after dropping it.
Re: Why is nuclear fusion so hard?
#74This a totally ignorant question - can you add “something” to the plasma to achieve the “jello like” analogy to water?
That's actually a very reasonable question. The answer is: no, but explaining why is non-trivial. The short version is that at 10 million degrees, matter behaves so differently than it does at room temperature that none of your everyday intuitions apply.
Re: Why is nuclear fusion so hard?
#75Earlier quoted context omitted.
I used to be a reactor operator and never saw any evidence they were hard to throttle. That's why they are used for warship propulsion: loads in battle are not predictable by their nature, what with changes in course, catapult launches, etc.
You're both right- technically, nuclear reactors are on of the fastest-ramping sources available. A reactor in SCRAM can drop down to However, zero reactors are capable of doing so economically. The cost of a nuclear plant is in its construction, upkeep, and staff. Those costs are the same at 110% and 30% output, but revenue isnt. In order to turn a profit a nuclear plant needs to be running at 80%+, 24/7. Ultimately…
Nuclear plants have high capital costs and low marginal costs for each bit of energy they make. That doesn't mean they can't produce all the power: France is at 80% from nuclear.
Re: Why is nuclear fusion so hard?
#76> Some kinds of instability are slow enough that we can control them. For example bicycles are unstable, but many of us eventually learn to ride them.
Actually, bicycles are only unstable when they are moving slowly (or stopped), and most people never learn how to stabilize one in this unstable regime. It can be done, but it's very, very hard.
Re: Why is nuclear fusion so hard?
#77Earlier quoted context omitted.
That’s a function of how recently solar and wind became cheap. China has a 31x increase in wind power over the last 10 years. The next 10 will be very interesting assuming prices continue to fall. When having a 30% oversupply of wind / solar still costs less than any alternative and they are only gettting cheaper eventually noting else comes close.
It's also a function of not yet having really cheap, scalable storage that's not limited by geography. In any case, it's clear that nuclear can do the job if we're smart about it, because France did it.
Right now, France is running almost carbon-free: 83% nuclear, 14% wind and 10% hydro:
http://www.gridwatch.templar.co.uk/france/
But that works in part because they're also exporting 15% of their generation to the UK, Switzerland, Italy and Spain. The export is reducing the need for gas plants in these neighbours, which have higher marginal costs. If France was an isolated grid, or if the neighbours had a similar generation mix, it would be harder to do this without a lot of storage, or throttling the nuclear plants.
Re: Why is nuclear fusion so hard?
#78Earlier quoted context omitted.
I used to be a reactor operator and never saw any evidence they were hard to throttle. That's why they are used for warship propulsion: loads in battle are not predictable by their nature, what with changes in course, catapult launches, etc.
You're both right- technically, nuclear reactors are on of the fastest-ramping sources available. A reactor in SCRAM can drop down to However, zero reactors are capable of doing so economically. The cost of a nuclear plant is in its construction, upkeep, and staff. Those costs are the same at 110% and 30% output, but revenue isnt. In order to turn a profit a nuclear plant needs to be running at 80%+, 24/7. Ultimately…
> The cost of a nuclear plant is in its construction, upkeep, and staff. Those costs are the same at 110% and 30% output, but revenue isnt. In order to turn a profit a nuclear plant needs to be running at 80%+, 24/7.
The same can be said about wind and solar power.
Re: Why is nuclear fusion so hard?
#79Earlier quoted context omitted.
Yeah this is something people keep forgetting. The reason fossil fuels have such an impact is because the industry is happening at such a scale. Solar and wind are working at miniscule size ... and ... "no" impact (well, wind clearly has impact already, but ... let's forget that). Well actually, solar does have an impact. In Spain there's a couple large wind farms I visited and ... not that it should surprise anyone…
Your facts appear incorrect. Renewables consistently produce more than 60% of Portugal's energy needs, and have topped 100% on occasion. The figure for Spain is more than 35%, and more than 35% of electricity consumption in Germany. I'm not sure how you get from 60% to "no impact". It's really quite a puzzling statement. As is the suggestion that windfarms cause some kind of ecological blight to farmland. Not only is…
I'm very pro-renewable and new nuclear, but when you say "60% of Portugal's energy needs, and have topped 100% on occasion" do you mean the entire country's energy requirement, or just 'electricity'?. Because as rosy as that sounds, I doubt it takes into account oil-based travel infrastructure, which if the last pie-chart I recall seeing for an average country has any bearing, is a BIG slice.
Re: Why is nuclear fusion so hard?
#80This is somewhat tangential to the specific issue here, but I was surprised by this: At the center of the Sun, fusion power is estimated by models to be about 276.5 watts/m3. Despite its intense temperature, the peak power generating density of the core overall is similar to an active compost heap, and is lower than the power density produced by the metabolism of an adult human.[1] So practical fusion power requires…
Ah, one of my favorite astronomy-related trivia.
It also shows how a supernova can (briefly) shine as brightly as its whole host galaxy (i.e. some 10-11 orders of magnitude stronger than an average dwarf star - like you wrote, those basically "smoulder").