Would nuclear fusion solve global warming?

[Matdoya]

Dear all,

 

it is said that once nuclear fusion is invented, all of our energy problems would disappear, but will it solve global warming?

 

The problem with global warming upto this date has two sides:

-> We produce heat

-> We produce carbon dioxide

 

If only heat would cause global warming then for sure nuclear fusion wouldn't solve the problem.

 

The fact is that when burning fossil energy sources we reintroduce heat (and carbon dioxide) that once already _was_ present on the planet.

 

If we would consume as much energy from nuclear fusion as we do today from fossil energy sources we introduce heat into the atmosphere _that_ _didn't_ _ever_ was present on the planet in all of it's history. And heat, being the most entropic form of energy, will not simply go away, it will heat up the planet even more than it ever was (apart from the very beginning when there wasn't fluent water and stuff).

 

The only problem with my theory is that I don't know the physics of the effect of carbon dioxide on global warming. If we should be able to use nuclear fusion in stead of fossil and if we, for instance, pump the overhead of carbon dioxide into lower layers of the earths crust, maybe the heat wouldn't cause that much problems.

 

Or would it ?

 

Seeing forward to your comments,

 

S.

[Mokele]

The heat output of humans has minimal effect on global warming. It's all greenhouse gasses, because they retain heat from a much more powerful source, the sun. Given that fusion wouldn't produce any greenhouse gasses (beyond those emitted by trucks and such used to build the reactor), it would help a lot.

[CaptainPanic]

In 2005,

total worldwide energy consumption was 500 EJ/year (= 5 x 10^20 J/year)...

The total energy from the sun that reaches earth is: 174 PW, or 5480000 EJ (which is about 11000 times as much as we consume).

 

The earth actually absorbs a bit less: 3,850,000 EJ, but that is still 7700 times as much as our total energy consumption.

 

Therefore, even if we double our energy consumption, you aren't very likely to see any change.

 

Greenhouse gases on the other hand trap a percentage of this massive amount of solar energy. And that is actually significant.

[scalbers]

Sounds using the sigma T^4 relationship that we would be OK for now, though just an order of magnitude or two from having an issue.

 

Sources like wind, solar, and tidal would be better since they would just dissipate as heat anyway.

Edited February 16, 2009 by scalbers

[dirtyamerica]

I'm a proponent of coal energy (considering I work at a coal plant) as it's a very reliable source of energy. The technology for capturing greenhouse gases is continually improving. It's just a matter of retrofitting existing plants, building new, state of the art plants and motivating poorer contries to go greener with their fleets of energy centers.

 

Just as well, I'm for nuke energy. I wouldn't want nuclear waste stored in my backyard but here's how I justify it: So many tons of nuke waste, buried in a secure, underground location, IMO, is far less damaging than the output of all those unwanted gases that we breathe and wreak havoc on our climate. I don't know the statistics of waste output between a coal plant vs. a nuke plant....I'm just sayin'..

 

In either case, you still have the release of heat from processes and equipment, just not the gases from a nuke plant. To this day, it still cracks me up when I see a clip on tv about pollution and they show the cooling towers of a nuke (or coal) plant...so water vapor is a pollutant? hehe

[iNow]

Well, yes. Water vapor does lead to further heating. I would not, myself, go so far as to call it a pollutant, because that's silly. However, water vapor is one of the most dominant contributors to increased climatic temperatures. One key difference between water vapor and carbon dioxide, however, is that water generally only stays in the atmosphere for 7-10 days. After that, it comes together, forms clouds, and condenses into rain... ergo, is no longer in the atmosphere for concern (at least until it evaporates again).

 

Carbon dioxide, however, stays in the atmosphere for centuries, and takes an incredibly long amount of time to stop having an effect on climate and temperature. For example, even if we stopped emitting ALL carbon dioxide emissions today... we just drop it down to zero (which we cannot do, but let's just say we pulled it off), the planet would continue warming for a century or two just from all of our past contributions of carbon dioxide to the atmosphere that we've already made up to this point.

 

I can appreciate that there are technologies to help make coal cleaner, but I struggle to think that there are not better ways altogether to make energy which don't have the same short and long term costs as coal. You mentioned nuclear, which is one, but there are other sources such as solar and wind which are several orders of magnitude cleaner than nuclear, and even more so than coal. We simply need to achieve better storage/battery technologies and have a smarter grid for distribution. Even without a smarter grid, however, solar and wind can be used for local energy needs (by putting them in your own yard or on your own roof), and they don't require long distance transmission (and hence loss on the lines) like those other sources you mentioned. Yet another benefit. All coal has going for it is that we're used to it, we have an existing infrastructure, and it's energy dense and easy. The costs, however, FAR outweigh those particlur benefits, IMO.

 

Either way, I agree it's silly when we see cooling towers emitting water vapor as a way to raise peoples attention to global warming, however, that water vapor does, in fact, have a pretty significant impact and it would be silly of us to ignore that truth.

Edited February 17, 2009 by iNow

[npts2020]

I'm a proponent of coal energy (considering I work at a coal plant) as it's a very reliable source of energy. The technology for capturing greenhouse gases is continually improving. It's just a matter of retrofitting existing plants, building new, state of the art plants and motivating poorer contries to go greener with their fleets of energy centers.

 

Just as well, I'm for nuke energy. I wouldn't want nuclear waste stored in my backyard but here's how I justify it: So many tons of nuke waste, buried in a secure, underground location, IMO, is far less damaging than the output of all those unwanted gases that we breathe and wreak havoc on our climate. I don't know the statistics of waste output between a coal plant vs. a nuke plant....I'm just sayin'..

 

In either case, you still have the release of heat from processes and equipment, just not the gases from a nuke plant. To this day, it still cracks me up when I see a clip on tv about pollution and they show the cooling towers of a nuke (or coal) plant...so water vapor is a pollutant? hehe

 

I would agree with you if there were no other options. However, we have a lot of options which will be more beneficial to the majority of us. In the first place, nuclear power has consistently cost more than claimed so as to become one of the most expensive methods of generating electricity and would not even be considered economically feasible if not for generous government subsidies. Coal is cheap but very environmentally damaging. After mining, even if you capture and dispose of every carbon atom emitted, there is a buildup of toxic sludge that is not easy to dispose of (save failure of your retention system and dumping it into the local watershed) as a few communities have found out recently. Wind, passive and active solar, tidal, and geothermal among others are all better options for the long term, if we desire ever to lessen environmental impact of power generation.

 

(aside; all of the nuclear power plant cooling towers in the world do not significantly increase water vapor in the air)

[iNow]

(aside; all of the nuclear power plant cooling towers in the world do not significantly increase water vapor in the air)

 

I tend to agree, but I was mostly suggesting that this could rapidly change if we start building them en masse.

[Airbrush]

Diversified sources of energy is the solution. The US and China will be tempted to keep using coal, since both countries have a large cheap coal supply. Homes, cars, and industries could be made much more energy efficient. Water should be heated by pipes on the roofs of houses, better insulation, and solar cells on roofs, stuff like that.

 

I would like to see more designs for tidal and ocean wave generation of power.

 

Someone above said that nuclear FISSION is an expensive energy source, I would think nuclear FUSSION would be way more expensive, but cleaner. I'm waiting for the price to come down so everyone can have their own nuclear FUSSION reactor in their back yard.

Edited February 17, 2009 by Airbrush

[scalbers]

I wonder how much water vapor even today's cars emit, compared to nuclear plants? At any rate, I'd imagine that most of the water vapor would quickly condense as clouds and rain and be less than the amount that naturally evaporates off the oceans. One exception I think is in Alaska for example in the winter where car emissions aren't well ventilated and can help create a local fog?

 

Yes, fusion power continues to be intriguing.

[deepak.rajimr]

yes i think that nuclear fusion can save the world

[coreview2]

Well, yes. Water vapor does lead to further heating. I would not, myself, go so far as to call it a pollutant, because that's silly. However, water vapor is one of the most dominant contributors to increased climatic temperatures. One key difference between water vapor and carbon dioxide, however, is that water generally only stays in the atmosphere for 7-10 days. After that, it comes together, forms clouds, and condenses into rain... ergo, is no longer in the atmosphere for concern (at least until it evaporates again).

 

The problem I have with this presumption is that water to water vapor to clouds to rain is a continuous cycle. It's not like evaporating molecules have to stand in line and wait for cycle part 5 of another molecule to finish before evaporation starts. That a given H2O molecule is said to stay in the atmosphere an average of 7 days says nothing of significance about overall and constant presence of water vapor. It is the constant effect of overall humidity that matters not a day or week in the life an individual H2O molecule.

 

I've wondered on a real world experience on trips to the desert in New Mexico in contrast to times in Florida about how quickly that very dry arid air gets so cold at night. Certainly CO2 doesn't vanish at night, but it would be interesting to know how much of the day's heat it keeps in relative to Florida with its very frequent days and nights of 90 - 98% relative humidity.

[bascule]

"Global warming" is caused by what's known as a radiative imbalance. The earth absorbs more solar radiation than it reflects back out into space. This is what has lead to an increasing trend in global mean surface temperatures.

 

Anthropogenic heat sources are no match for solar radiation.

[foodchain]

I think the problem with any energy production really is consumption. If you have an ever increasing base of consumption that will always require more energy production or what not to keep up any desired standard of living for the mass.

 

Beyond that I know that nuclear energy would be great if it were people safe, but you have to think of everything that can go wrong along with waste products and so on, it just takes one bad accident to affect the entire globe.

 

I do think nuclear will eventually be part of the solution, I just don't see how its really safe to do that currently.

 

A better fix would be population not constantly increasing really, amongst and ocean of other concerns.

[insane_alien]

foodchain, an accident with a fusion reactor just means you have to resurface the inside of the reaction chamber. it very localised.

 

even with fission reactors, they require poor design, insufficient contaiment infrastructure and the operators to disable all safety mechanisms before you get a disaster with global effects(chernobyl).

 

and the radioactive waste from a fusion reactor tends to be shortlived, not very much of it and you only get it when you replace parts of the reactor exposed to high neutron flux.

[Green Xenon]

foodchain, an accident with a fusion reactor just means you have to resurface the inside of the reaction chamber. it very localised.

 

even with fission reactors, they require poor design, insufficient contaiment infrastructure and the operators to disable all safety mechanisms before you get a disaster with global effects(chernobyl).

 

and the radioactive waste from a fusion reactor tends to be shortlived, not very much of it and you only get it when you replace parts of the reactor exposed to high neutron flux.

 

Approximately how long will it take until we have aneutronic fusion to generate electricity? 50 years?

[insane_alien]

well, there are a few proposed neutron emissionless fusion reactions proposed but we have to overcome a lot of technical challenges before we can choose a specific fusion reaction to generate power from. current favourites are deuterium-tritium fusion as it can be done at lower temperatures than the rest.

[foodchain]

Approximately how long will it take until we have aneutronic fusion to generate electricity? 50 years?

 

They can do fusion, it just simply cant be sustained, and you have to think that 1 gram of material releases just a giant amount of energy basically in a pop I think which is highly destructive or cannot be controlled yet is the real technical problem, no ability to harness that nuclear "explosion" really. I know that a few projects are up and running, but in many cases again all you have is a pop with no way to funnel anything out or harness the energy released. I know it does not have many of the same problems with older technology such as waste, and if mastered we can just live pollution free off of the oceans, but it also might just be a pipe dream. The idea has been around for a long time, its nothing new as its discovery to my understanding goes back to the hydrogen bomb.

 

My points are simply what would that look like if it became a main fuel source for humanity?

[SH3RL0CK]

Well, theres always the PACER proposal for power generation by nuclear fusion: http://en.wikipedia.org/wiki/PACER_(fusion)

 

From the article,

The PACER project, carried out at Los Alamos National Laboratory in the mid-1970s, explored the possibility of a fusion power system that would involve exploding small hydrogen bombs (fusion bombs)—or, as stated in a later proposal, fission bombs—inside an underground cavity.

 

The proposed system would absorb the energy of the explosion in a molten salt, which would then be used in a heat exchanger to heat water for use in a steam turbine.

 

This can be done today (and could have been built using technology from the 1970's). But it was determined then (and probably still is today) to be impractical. Again from the article:

As an energy source, the system is the only one that could be demonstrated to work using existing technology. However it would also require a large, continuous supply of nuclear bombs, making the economics of such a system rather questionable. The production of thermonuclear, or even just nuclear, bombs requires high immediate capital expenses, and also has long-term environmental costs. Additionally, the political effects of beginning a large-scale production of nuclear bombs could potentially be large, and with increasing bomb numbers, increased security measures would be necessary. The entire system—fissile material production, bomb fabrication, and power generation—could be carried out in a single well-guarded site, but only for great development costs that would likely never be recovered by generating energy.

 

See also Project Gnome which was a real test of this concept in 1961: http://en.wikipedia.org/wiki/Project_GNOME

Edited September 14, 2009 by SH3RL0CK

[insane_alien]

and far more practical tests are being performed by JET and (eventually) ITER.

 

we can break even(just) already. ITER should allow us to make a surplus but it primarily for control and materials testing.

 

the major problem with fusion reactors is that they don't miniturize well. bigger is better. unfortunately nobody is willing to shell out the funds for something like that.

[dr.syntax]

I think the problem with any energy production really is consumption. If you have an ever increasing base of consumption that will always require more energy production or what not to keep up any desired standard of living for the mass.

 

Beyond that I know that nuclear energy would be great if it were people safe, but you have to think of everything that can go wrong along with waste products and so on, it just takes one bad accident to affect the entire globe.

 

I do think nuclear will eventually be part of the solution, I just don't see how its really safe to do that currently.

 

A better fix would be population not constantly increasing really, amongst and ocean of other concerns.

 

the World`s population can be brought under control, I don`t see how any of the problems facing us can be resolved. ...DS

[scalbers]

There is a proposed DEMO plant to come on the heels of ITER. Also here is a powerpoint on a "fast track" to fusion power.

 

http://www.journalday.org/activity/branches/South_West/Events/page_8460.html

 

Here is the Wikipedia page on DEMO:

 

http://en.wikipedia.org/wiki/DEMO

Edited September 19, 2009 by scalbers

[coreview2]

Fusion would be a wonderful thing, especially for space craft.

 

The one concept that is commonly overlooked is Earth's own heat. 99% of our planet is above 1000C and a very large part of that heat is within contemporary drilling range.

 

http://earthquake.usgs.gov/research/structure/crust/crust.php

 

There are vast areas of Earth's crust that are less than 10KM thick. The energy there is pure high grade heat (via a binary system often used in geothermal plants). In this case, it produces no emissions, no pollution, and no waste.

[D H]

Fusion would be a wonderful thing, especially for space craft.

Only if the fusion engine infrastructure can be made sufficiently small. Otherwise you'll have a fusion-powered equivalent of SMART-1, which took 13 1/2 months to spiral out to the Earth-Moon L1 point and another 2 1/2 months to spiral in to its target lunar orbit.

 

And only if you want to explore the solar system.

 

There are vast areas of Earth's crust that are less than 10KM thick.

Yeah, but those spots are all a mile or more underwater.

[coreview2]

Yeah, but those spots are all a mile or more underwater.

 

A lot are, but quite a number intersect with land too, like Iceland. It's also not too hard to drill through water.

 

A few years back a rather underfunded academic group drilled down to magma to explore the academic nature of the geology. While a very large percentage of the crust is within drilling range, a significant amount is within easy drilling range.

 

The 99% of Earth that is above 1000C is a source of energy that dwarfs nuclear, solar, hydro, wave, fossil fuels and wind power. Well, at least until "Mr. Fusion" from BACK TO THE FUTURE becomes reality.