NUCLEAR POWER PLANTS and water vapour.

[ajanta]

18Aug 2012. Revolutionary new technology that produces “petrol from air” is being produced by a British firm, it emerged tonight.

A small company in the north of England has developed the “air capture” technology to create synthetic petrol using only air and electricity.

Experts tonight hailed the astonishing breakthrough as a potential “game-changer” in the battle against climate change and a saviour for the world’s energy crisis.

The technology, presented to a London engineering conference this week, removes carbon dioxide from the atmosphere.

The “petrol from air” technology involves taking sodium hydroxide and mixing it with carbon dioxide before "electrolysing" the sodium carbonate that it produces to form pure carbon dioxide.

Hydrogen is then produced by electrolysing WATER VAPOUR captured with a dehumidifier.

The company, Air Fuel Synthesis, then uses the carbon dioxide and hydrogen to produce methanol which in turn is passed through a gasoline fuel reactor, creating petrol.

EVERY DAY water vapour comes out from Nuclear power plants. I knew that water vapour is responsible for global warming too. SO can we turn it into fuel again ?

 

[exchemist]

18Aug 2012. Revolutionary new technology that produces “petrol from air” is being produced by a British firm, it emerged tonight.

A small company in the north of England has developed the “air capture” technology to create synthetic petrol using only air and electricity.

Experts tonight hailed the astonishing breakthrough as a potential “game-changer” in the battle against climate change and a saviour for the world’s energy crisis.

The technology, presented to a London engineering conference this week, removes carbon dioxide from the atmosphere.

The “petrol from air” technology involves taking sodium hydroxide and mixing it with carbon dioxide before "electrolysing" the sodium carbonate that it produces to form pure carbon dioxide.

Hydrogen is then produced by electrolysing WATER VAPOUR captured with a dehumidifier.

The company, Air Fuel Synthesis, then uses the carbon dioxide and hydrogen to produce methanol which in turn is passed through a gasoline fuel reactor, creating petrol.

EVERY DAY water vapour comes out from Nuclear power plants. I knew that water vapour is responsible for global warming too. SO can we turn it into fuel again ?

1) Nuclear power plants do not produce water vapour.

2) The process is similar to photosynthesis: CO2 + water + energy -> fuel molecule + oxygen. All it is doing is driving a combustion reaction backwards by putting energy in.

3) That energy has to come from somewhere. If it is not from the sun, or from nuclear fission, then the process does not solve any problems.

4) This story is 3 years old.

 

[ajanta]

1) Nuclear power plants do not produce water vapour.

2) The process is similar to photosynthesis: CO2 + water + energy -> fuel molecule + oxygen. All it is doing is driving a combustion reaction backwards by putting energy in.

3) That energy has to come from somewhere. If it is not from the sun, or from nuclear fission, then the process does not solve any problems.

4) This story is 3 years old.

1), 2), 4), Its ok ? But I didn't understand about 3). Thanks.

 

[cosmictraveler]

1) Nuclear power plants do not produce water vapour.

Water in a nuclear reactor is heated by the fission process which boils the water turning the turbines with the steam that is created. That's how nuclear power plants make electricity. Steam is then vented up and away through the cooling towers that you see. The excess water goes out into cooling canals.

 

[Janus58]

Water in a nuclear reactor is heated by the fission process which boils the water turning the turbines with the steam that is created. That's how nuclear power plants make electricity. Steam is then vented up and away through the cooling towers that you see. The excess water goes out into cooling canals.

The steam coming out of the cooling tower is not the steam that runs the turbines nor used for directly cooling the reactor. It is from a separate water system used for cooling the water that is used to cool the reactor.

 

[exchemist]

Water in a nuclear reactor is heated by the fission process which boils the water turning the turbines with the steam that is created. That's how nuclear power plants make electricity. Steam is then vented up and away through the cooling towers that you see. The excess water goes out into cooling canals.

The steam circuit in all steam power plants is CLOSED. The low pressure steam at the exhaust side of the low pressure turbine is condensed and reused. It is never vented. Same goes for steam ships (e.g. nuclear submarines, LNG carriers).

There is a separate water circuit used to cool the condensers, and in some designs this is itself cooled for reuse by being sprayed from the top of cooling towers and collected once more at the bottom. A bit of this evaporates, creating the diffuse clouds of condensation you see from cooling towers. In other designs water is taken from a river for cooling and returning to the river a few degrees warmer than when it left, in which case there are no cooling towers and no clouds of condensation. But in neither case is actual steam vented to atmosphere. That is only done on steam locomotives, because in that application there is insufficient space to mount a condensing circuit.

 

[cosmictraveler]

The steam circuit in all steam power plants is CLOSED. The low pressure steam at the exhaust side of the low pressure turbine is condensed and reused. It is never vented. Same goes for steam ships (e.g. nuclear submarines, LNG carriers).

There is a separate water circuit used to cool the condensers, and in some designs this is itself cooled for reuse by being sprayed from the top of cooling towers and collected once more at the bottom. A bit of this evaporates, creating the diffuse clouds of condensation you see from cooling towers. In other designs water is taken from a river for cooling and returning to the river a few degrees warmer than when it left, in which case there are no cooling towers and no clouds of condensation. But in neither case is actual steam vented to atmosphere. That is only done on steam locomotives, because in that application there is insufficient space to mount a condensing circuit.

Thank you for that information.

 

[Russ_Watters]

1) Nuclear power plants do not produce water vapour.

That's wrong: [most] nuclear plants produce enormous amounts of water vapor.

Cosmictraveler's misunderstanding about the one vs two steam loops (it's actually three, counting the one we're discussing) and open vs closed cycles in the reactor or plant or pieces of cycles is neither here nor there. Clearly, the OP was referring to the cooling tower water loss, which is, in fact, an open steam cycle and does produce an enormous quantity of water vapor. How much?

The circulation rate of cooling water in a typical 700 MW coal-fired power plantwith a cooling tower amounts to about 71,600 cubic metres an hour (315,000 US gallons per minute)[11] and the circulating water requires a supply water make-up rate of perhaps 5 percent (i.e., 3,600 cubic metres an hour).

https://en.wikipedia.org/wiki/Cooling_tower

The thermodynamics are the same and the average nuclear reactor is 1000 MW, so that's 22.500 gallons per minute of water loss to vapor.

In any case, the answer to the OP's question is yes. Yes, you can unburn combustion products. But why would you want to? It will always use more energy than you get back when you burn them again.

 

[ajanta]

That's wrong: [most] nuclear plants produce enormous amounts of water vapor.

Cosmictraveler's misunderstanding about the one vs two steam loops (it's actually three, counting the one we're discussing) and open vs closed cycles in the reactor or plant or pieces of cycles is neither here nor there. Clearly, the OP was referring to the cooling tower water loss, which is, in fact, an open steam cycle and does produce an enormous quantity of water vapor. How much?

https://en.wikipedia.org/wiki/Cooling_tower

The thermodynamics are the same and the average nuclear reactor is 1000 MW, so that's 22.500 gallons per minute of water loss to vapor.

In any case, the answer to the OP's question is yes. Yes, you can unburn combustion products. But why would you want to? It will always use more energy than you get back when you burn them again.

Thanks for your important information. I will reply later about to unburn the water vapour.

 

[ajanta]

Now I'm understanding about 3) of exchemist. Its most important. Now a days hydrogen fuel is producing by some renewable energy sorce like wind mill, solar panel, ocean wave. So it is ecofriendly. When they wanna produce hydrogen fuel, they have to unburn water. Hydrogen is using to produce liquid hydrocarbon fuel and it will be ecofriendly when another gas(CO2) is collected from atmosphere to produce the hydrocarbon fuel. This fuel can be use as jet fuel car fuel etc. When the fuel will burn it will produce CO2 that will not increase CO2 emission. But water vapour can be produce artificially. So it produces water vapour and nuclear power plant too. But if we unburn the water vapour of nuclear power plant by any renewable energy sorce then the hydrogen fuel will be renewable fuel. But there is a problem that if the renewable energy sorce is so far from the nuclear power plant so power transmission loss is important and may be high voltage power transmission line can solve the problem. Thanks.

 

[exchemist]

That's wrong: [most] nuclear plants produce enormous amounts of water vapor.

Cosmictraveler's misunderstanding about the one vs two steam loops (it's actually three, counting the one we're discussing) and open vs closed cycles in the reactor or plant or pieces of cycles is neither here nor there. Clearly, the OP was referring to the cooling tower water loss, which is, in fact, an open steam cycle and does produce an enormous quantity of water vapor. How much?

https://en.wikipedia.org/wiki/Cooling_tower

The thermodynamics are the same and the average nuclear reactor is 1000 MW, so that's 22.500 gallons per minute of water loss to vapor.

In any case, the answer to the OP's question is yes. Yes, you can unburn combustion products. But why would you want to? It will always use more energy than you get back when you burn them again.

Fair enough about the 5% evaporation loss from cooling systems. I admit I was thinking of plants that use rivers or the sea instead of cooling towers - most if not all of the UK nuclear plants are like this (e.g. Sizewell, Dounreay, Hinckley Point). And so, if I'm not mistaken, are the Japanese. No cooling towers and no evaporation loss.

 

[exchemist]

Now I'm understanding about 3) of exchemist. Its most important. Now a days hydrogen fuel is producing by some renewable energy sorce like wind mill, solar panel, ocean wave. So it is ecofriendly. When they wanna produce hydrogen fuel, they have to unburn water. Hydrogen is using to produce liquid hydrocarbon fuel and it will be ecofriendly when another gas(CO2) is collected from atmosphere to produce the hydrocarbon fuel. This fuel can be use as jet fuel car fuel etc. When the fuel will burn it will produce CO2 that will not increase CO2 emission. But water vapour can be produce artificially. So it produces water vapour and nuclear power plant too. But if we unburn the water vapour of nuclear power plant by any renewable energy sorce then the hydrogen fuel will be renewable fuel. But there is a problem that if the renewable energy sorce is so far from the nuclear power plant so power transmission loss is important and may be high voltage power transmission line can solve the problem. Thanks.

Yes the big problem we have to solve for a fossil-free - and hence a stable CO2 - future is transport fuels. These require high energy density, i.e. a lot of stored energy in return for only a small weight and volume to accommodate on a vehicle. The chemical energy in fossil fuels, combining with oxygen taken from the air, is ideal and hard to match. A process like this, which is similar to photosynthesis in that it drives an energy-releasing oxidation reaction backwards via input of energy from another source, offers the prospect of fuels for transport very like those we use today. This can be very useful, so long as the energy source is not fossil-fuel derived. But it is important to realise it needs this energy input: some of the more breathless media reports suggest it is "free" energy, from thin air, which is of course nonsense.

 

[Billy T]

Yes the big problem we have to solve for a fossil-free - and hence a stable CO2 - future is transport fuels. These require high energy density, i.e. a lot of stored energy in return for only a small weight and volume to accommodate on a vehicle. The chemical energy in fossil fuels, combining with oxygen taken from the air, is ideal and hard to match. A process like this, which is similar to photosynthesis in that it drives an energy-releasing oxidation reaction backwards via input of energy from another source, offers the prospect of fuels for transport very like those we use today. This can be very useful, so long as the energy source is not fossil-fuel derived. But it is important to realise it needs this energy input: some of the more breathless media reports suggest it is "free" energy, from thin air, which is of course nonsense.

Correct. That other energy source is the sun. Not "similar to photosynthesis" but photosynthesis in sugar cane - tested for 30+ years in Brazil and shown to be a more economical car fuel than gasoline* with slightly more HP in same IC engine and most importantly both renewable and slightly net negative CO2 release.

Plus sugar cane alcohol also is converted (by Brazil's Brasken, especially) into hundreds of tons of three different plastic each year (PVC, polyethylene & polyethylene) with profit. CO2 removed from the air while making money with the process.

SUMMARY: Don't re-invent the wheel with complex expensive (and capital intensive) technology. Thousands of unemployed in Africa, could have jobs as cane planters & cutters. They would then become buyers of first world's high value added products. - A "win/win" for all but Big Oil that is screwing you.

* Perhaps not true currently with the oil price depressed by over supply but was true for 30 years, and will be again as oil is finite / not renewable as well as one of the world's major sources of man-made global warming.

I would ask: "How dumb can people be?" but it is not their stupidity; they have been mislead by Big Oil's lies:
(Switching to alcohol car fuel will destroy the rain forests., etc) And Big Oil's money that has gotten US Congress to make importation of sugar cane alcohol, illegal.

 

[Russ_Watters]

Fair enough about the 5% evaporation loss from cooling systems. I admit I was thinking of plants that use rivers or the sea instead of cooling towers - most if not all of the UK nuclear plants are like this (e.g. Sizewell, Dounreay, Hinckley Point). And so, if I'm not mistaken, are the Japanese. No cooling towers and no evaporation loss.

I did a little research and found that things are very different for the UK vs the US, though a lot more use once-through cooling in the US than I realized (I thought for environmental reasons it was forbidden):

According to a 2006 Department of Energy (DOE) report discussed in the Appendix, in the USA 43% of thermal electric generating capacity uses once-through cooling, 42% wet recirculating cooling, 14% cooling ponds and 1% dry cooling (this being gas combined cycle only). The spreads for coal and for nuclear are similar. For 104 US nuclear plants: 60 use once-through cooling, 35 use wet cooling towers, and 9 use dual systems, switching according to environmental conditions. This distribution is probably similar for continental Europe and Russia, though UK nuclear power plants use only once-through cooling by seawater, as do all Swedish, Finnish, Canadian (Great Lakes water), South African, Japanese, Korean and Chinese plants. IAEA figures show 45% of nuclear plants use the sea for once-through cooling, 15% use lakes, 14% rivers, and 26% use cooling towers.

http://www.world-nuclear.org/info/Current-and-Future-Generation/Cooling-Power-Plants/
So, near equal amounts of cooling tower and once-through/water-only cooling in the US, but once-through only in the UK and several other countries. I guess if you have access to the ocean, you can do once-through cooling with a lower delta-T and thus less of an environmental impact.

And like you, I know mostly what I'm near: I live near the Limerick plant in southeastern PA. There are 5 plants in PA, all situated on rivers at least 60 miles from the ocean, and all using cooling towers to cool them, using the river only to make-up the evaporation loss:
http://www.eia.gov/nuclear/state/2008/pennsylvania/pa.html

Now, when you heat the river/ocean water you will still get increased evaporation, but probably a lot less than a cooling tower. Thermodynamically, the processes are the same; a cooling tower is just more effective at it (more of the heat loss is latent heat of evaporation).

There was something else in the OP I found somewhat dubious:

I knew that water vapour is responsible for global warming too...

This implies you are suggesting that water vapor from cooling towers contributes to global warming. I don't think that's true. Clearly, it can have a local weather impact - nuclear plant cooling towers sometimes produce persistent clouds. But the atmospheric steam cycle is fast, with a very high circulation rate: hours for a pop-up thunderstorm to days for a major weather system. I don't think we have the ability to substantially affect the long-term humidity of the atmosphere (unlike CFCs, which are persistent for decades and CO2, which is persistent for centuries).

...and if we did, there are other ways that are much worse: several large rivers in the Western US no longer flow to the ocean (they simply become dry) because all of their water is diverted to drinking and farming. Most of the irrigation water from farming is evaporated into the atmosphere (though they are getting better about making an effort to reduce that). So if it were an issue, that would be a much bigger issue than power plants.

 

[ajanta]

I did a little research and found that things are very different for the UK vs the US, though a lot more use once-through cooling in the US than I realized (I thought for environmental reasons it was forbidden):

http://www.world-nuclear.org/info/Current-and-Future-Generation/Cooling-Power-Plants/
So, near equal amounts of cooling tower and once-through/water-only cooling in the US, but once-through only in the UK and several other countries. I guess if you have access to the ocean, you can do once-through cooling with a lower delta-T and thus less of an environmental impact.

And like you, I know mostly what I'm near: I live near the Limerick plant in southeastern PA. There are 5 plants in PA, all situated on rivers at least 60 miles from the ocean, and all using cooling towers to cool them, using the river only to make-up the evaporation loss:
http://www.eia.gov/nuclear/state/2008/pennsylvania/pa.html

Now, when you heat the river/ocean water you will still get increased evaporation, but probably a lot less than a cooling tower. Thermodynamically, the processes are the same; a cooling tower is just more effective at it (more of the heat loss is latent heat of evaporation).

There was something else in the OP I found somewhat dubious:

This implies you are suggesting that water vapor from cooling towers contributes to global warming. I don't think that's true. Clearly, it can have a local weather impact - nuclear plant cooling towers sometimes produce persistent clouds. But the atmospheric steam cycle is fast, with a very high circulation rate: hours for a pop-up thunderstorm to days for a major weather system. I don't think we have the ability to substantially affect the long-term humidity of the atmosphere (unlike CFCs, which are persistent for decades and CO2, which is persistent for centuries).

...and if we did, there are other ways that are much worse: several large rivers in the Western US no longer flow to the ocean (they simply become dry) because all of their water is diverted to drinking and farming. Most of the irrigation water from farming is evaporated into the atmosphere (though they are getting better about making an effort to reduce that). So if it were an issue, that would be a much bigger issue than power plants.

Yes, water vapour is responsible but not from the cooling towers.

 

[ajanta]

'Irrigation water from farming is evaporated into the atmosphere (though they are getting better about making an effort to reduce that). So if it were an issue, that would be a much bigger issue than power plants'....... I think if it would vertical farming irrigation !

 

[trevor borocz johnson]

Hydrogen is then produced by electrolysing WATER VAPOUR captured with a dehumidifier

does steam in some way speed up the process of electrolysis?

 

[Russ_Watters]

does steam in some way speed up the process of electrolysis?

Yes, the heat of vaporization is part of the energy required for electrolysis, so if you already have steam, you can skip it. Problem: electrolysis doesn't work on steam. But you can use pressurized, high temperature water for some of the benefit:

High temperature electrolysis is more efficient economically than traditional room-temperature electrolysis because some of the energy is supplied as heat, which is cheaper than electricity, and also because the electrolysis reaction is more efficient at higher temperatures. In fact, at 2500 °C, electrical input is unnecessary because water breaks down to hydrogen and oxygen through thermolysis. Such temperatures are impractical; proposed HTE systems operate between 100 °C and 850 °C.[1][2][3]

The efficiency improvement of high-temperature electrolysis is best appreciated by assuming that the electricity used comes from a heat engine, and then considering the amount of heat energy necessary to produce one kg hydrogen (141.86 megajoules), both in the HTE process itself and also in producing the electricity used. At 100 °C, 350 megajoules of thermal energy are required (41% efficient). At 850 °C, 225 megajoules are required (64% efficient).

https://en.wikipedia.org/wiki/High-temperature_electrolysis

 

[billvon]

does steam in some way speed up the process of electrolysis?

No. However, you can perform high temperature dissociation of water with a high temperature heat source. You could get such a heat source from a pebble bed modular reactor (PBMR) or similar gas-phase reactor.

I don't think hydrogen will ever be a valid fuel source until we have high temperature dissociation. Electrolysis simply makes no sense; if you use clean energy to make hydrogen, and then have to generate electricity somewhere else with a coal power plant, you have done much more damage than you would have done by simply using the clean energy to begin with. However, dissociation provides fuel from a lower quality energy source (i.e. heat) - and the waste heat from _that_ process can still be used to generate electricity.

 

[Waiter_2001]

Where does this water COME from??