Climate Change

[xilman]

Originally Posted by VictordeHolland

Indeed, filthy stuff it is. Better to use it for the BBQ : .
But I don't think nuclear is the solution in densely populated area's. Better to build more windturbines and solar. Or import energy from Germany when they are selling it on sunny days at negative prices, yes they paid to use their electricity. And yes that really happened a couple of times last year.

I would very happily have a 20kW pebble-bed reactor buried under my back garden.

Intrinsically sub-critical and fail-safe. Plenty of ground-water here to take away heat which wasn't otherwise used to warm my home 9 months of the year and allow me to grow tender plants (including food) in my garden.

[kladner]

Originally Posted by VictordeHolland

Indeed, filthy stuff it is. Better to use it for the BBQ : .
But I don't think nuclear is the solution in densely populated area's. Better to build more windturbines and solar. Or import energy from Germany when they are selling it on sunny days at negative prices, yes they paid to use their electricity. And yes that really happened a couple of times last year.

+1!

[only_human]

One problem in moving nuclear plants away from dense population areas is that all the water cooling opportunities are in the same places that populations accumulate.

Small and medium reactors might have smaller cooling problems (har har) but multiplying installations increases the number of sites to secure. They might have more opportunities to use supercritical CO₂ instead of steam - and that is interesting but I still want to see better spent fuel infrastructure. I follow an interest group called Thorium Now and it's nice to dream about modernizing and innovating the power plants.

There is a guy talking about mixing molten salt with supercritical CO₂ to make power on demand with a really small turbine. Of course solar concentrators can also keep a bunch of molten salt on hand.

[only_human]

Senior House Republican Says Earth Is Cooling

Scientists Trace Heat Wave To Massive Star At Center Of Solar System

[kladner]

Originally Posted by only_human

Senior House Republican Says Earth Is Cooling

Scientists Trace Heat Wave To Massive Star At Center Of Solar System

Finally! A bit of sense from scientists!

[LaurV]

Originally Posted by only_human

Senior House Republican Says Earth Is Cooling

Well, what that article says between the rows of text, is that both "global war[m/n]ing" and "clima[te/x] change" are rhetorics invented in America.... (by liberals or anti-liberals, who cares?...)

[kladner]

I expect some dispute with the conclusions presented in this article. To me, the connections are obvious.
http://www.progressive.org/news/2016...global-warming

Supporters of nuclear power like to argue that nukes are the key to combating climate change. Here’s why they are dead wrong.
Every nuclear generating station spews about two-thirds of the energy it burns inside its reactor core into the environment. Only one-third is converted into electricity. Another tenth of that is lost in transmission.

Every day, large reactors like the two at Diablo Canyon, California, individually dump about 1.25 billion gallons of water into the ocean at temperatures up to 20 degrees Fahrenheit warmer than the natural environment.
Diablo’s “once-through cooling system” takes water out of the ocean and dumps it back superheated, irradiated and laden with toxic chemicals. Many U.S. reactors use cooling towers which emit huge quantities of steam and water vapor that also directly warm the atmosphere.

[CRGreathouse]

Of course 100% of the heat is eventually added to the environment, it's just a question of how much we can use along the way. Would someone who cares more than I do compare the heat generated by a MW/hr from fossil fuels (100% of the heat, plus the marginal warming effect of the CO₂) vs a MW/hr from nuclear (100% of the heat)? Probably someone has computed this information, somewhere on the Internet, but I haven't seen it.

Maybe coal is very efficient in turning its heat into electricity, enough so to offset its carbon. Maybe the conversion efficiencies are similar but carbon dioxide warming is very significant. Of course this (intentionally) leaves out other factors like fly ash, mercury, SO₂/NOx, low- and high-level reactor waste, and Fukushima-type incidents.

[xilman]

Originally Posted by CRGreathouse

Of course 100% of the heat is eventually added to the environment, it's just a question of how much we can use along the way. Would someone who cares more than I do compare the heat generated by a MW/hr from fossil fuels (100% of the heat, plus the marginal warming effect of the CO₂) vs a MW/hr from nuclear (100% of the heat)? Probably someone has computed this information, somewhere on the Internet, but I haven't seen it.

Maybe coal is very efficient in turning its heat into electricity, enough so to offset its carbon. Maybe the conversion efficiencies are similar but carbon dioxide warming is very significant. Of course this (intentionally) leaves out other factors like fly ash, mercury, SO₂/NOx, low- and high-level reactor waste, and Fukushima-type incidents.

The words "Carnot cycle" spring to mind.

[CRGreathouse]

Originally Posted by xilman

The words "Carnot cycle" spring to mind.

Right. Fundamentally, I would expect both to have a similar efficiency because they should both be Carnot engines, which don't care how the heat was generated. But I'm game to learn how the real world interacts here. If anything I'd expect the nuclear reactor to operate at higher efficiency because of the larger thermal gradient.

[xilman]

Originally Posted by CRGreathouse

Right. Fundamentally, I would expect both to have a similar efficiency because they should both be Carnot engines, which don't care how the heat was generated. But I'm game to learn how the real world interacts here. If anything I'd expect the nuclear reactor to operate at higher efficiency because of the larger thermal gradient.

The thermal gradient is largely set by the materials of which the turbine is made. It's not obvious to me why one of the two power sources should be able to use a turbine which the other cannot.