Energy and the Water Supply Footprint

*Basically water is just consumed in thermal power and not converted. So ther is no question of water scarcity for power plants since the condensate is recycled.

* rain water storage, scientific distribution, supply and utilization of water resources could be another strategy on the context.

*Basically water is just consumed in thermal power and not converted. So ther is no question of water scarcity for power plants since the condensate is recycled.

Are you saying that conventional power stations do not use water? Dry cooling stations use substantially less than the old evaporative cooling tower stations, but you still need water.

To give an idea, the South African supplier, Eskom used 1,32 l/kWhr in 2006 down from around 3 l/kWhr in the '80s.

The prof,

Nice of meeting you in CR4. Water is required, but is recoverable or reusable. The major real burden is the demineralization process costs, regeneration and TDS head aches of feed water treatment process.

Yes, the condensate is recycled, but the cooling water is evaporated in cooling towers for heat rejection, and the vapor lost to the atmosphere is said to be "consumed." How to reduce the water consumption in conventional wet cooling is an important problem.

Air is the simple abundant heat exchanger fluid, which can be suitably substituted against water. Of course design improvisations are must.

Air cooliing, even with blowers, can't compete with cooling methods using change of state, where much higher W/cm^2 (heat flux) is possible using pool boiling or (best of all) forced convection boiling. The problem with air cooling is that there are not very many molecules at the heated surface. The computer industry is already reaching the limit of what air cooling can do. Since you are interested in design improvisations, I will take the liberty of bringing these to your attention: For a review of the state of the art, and an alternative, see this pending patent application for a Vapor Vortex Heat Sink For an improved exhaust steam condensing system using the thermal separation of a vortex tube, but in a dynamic apparatus, see this other pending patent application for a Radial Counterflow Steam Stripper

Hi WILLMOT,

Nice of meeting you in CR4. Thank you so much for the patent searches and additional information on condenser systems, very worthwhile informations of course.

To make it more simple, like thin film evaporation works on vacuum and hot metal surface area counter current flow principle, I think the reverse could be possible like release of used out steam at maximum possible height forcing it against multiple heat conduction plates to fall by gravity, the other side of plates being open air cooled, a protected walled structure of good heights etc,. etc. The up going steam can also lose its velocity against gravity, leading to auto condensation and so on. Just a common sense idea.

Leaving aside all, to me all heat and burning based energy utilities as primary energy source is the coolest blunder humanity is still doing with

What do you mean - patent searches? His name is on the patents - this is only advertising.

It would think that better use of the money and time would to be to move the water from places of excess to the place of need. Many of us have seen the reports of floods and of drought in the media. While one area of a continent maybe facing a drought another maybe be flooding. Better management of this would help alleviate this problem and others. Instead of just rationing and limiting what uses there are for the resource. We have built major pipe lines to move Natural Gas and Fuels around why not water. Some would argue the cost. Pay for it now or pay a lot more for it later. All rationing is going to do it increase the cost of every good depending upon it. That is just about everything! Why not put the money toward infrastructure for the future instead of the ever increasing cost of living.

Ozzh,

G.A to you. I agree with your point on need for rationale supply of water to remote areas. Irrespective of the cost involved, if water is distributed on a uniform manner, we can even counter global warming as well solve most of the social problems. Ancient civilizations relied on natural flow based water flow streams, should we also continue the same trend?

The water footprint problem is already disturbing, and carbon dioxide capture by amine scrubbing will double water consumption at power plants. Evaporated cooling water going into the atmosphere is wasted. Air cooling can't substitute because of low heat flux without change of state. An improved method for heat rejection at thermal power plants is needed. Here is one alternative: expand turbine exhaust steam between opposed coaxial counter-rotating radial turbines. The wet steam does work rotating the radial turbines. High enthalpy steam and condensate go radially outward, and low enthalpy steam (the slow molecules in the Maxwellian speed distribution) are stripped out radially inward in area-preserving fractal vortex network in the shear layer between the turbines and axially extracted to the condenser. The condenser has an easier job of heat rejection because the condensate and high speed molecules are elsewhere, and only the low enthalpy steam needs to be condensed. Essentially, you split the steam into two streams and only condense the low enthalpy stream in the condenser.

Isn't that horse dead yet?

though I doubt that would stop you from flogging it some more

Spam Spam Spam

I don't understand your comment. It appears to have no relation to the technical merits of the suggestion I made, other than to fault me for suggesting it because I have claimed priority for the idea. Spam under your definition would comprise everything anyone writes and subsequently refers to. Do you have anything useful to contribute to the discussion?

Spam is generally considered worthless postings I believe. Anyone can make whatever assumptions they wish.

I would never suggest such a thing though!

Large steam turbines already have isentropic efficiencies around 90%+.

Your suggestion still won't circumvent the laws of thermodynamics which have an isentropic efficiency of 100% as the best you can get.

The requirement to reject a large amount of heat will be unaltered by your method (unless you can manage to rewrite the laws of thermodynamics).

The main point is not to improve efficiency, but to reduce water consumption, which is a growing concern because power plants are second only to agriculture. A smaller job of heat rejection means less water vapor lost to the atmosphere. Power harvesting from waste heat is another benefit, which increases plant efficiency. By splitting turbine exhaust steam into a hot stream and a cool stream (as in a vortex tube) and condensing only the cool stream (the low speed molecules in the Maxwellian speed distribution), the job of heat rejection becomes easier. Organizing turbulence by intelligent geometry is not in violation of the Second Law, although the operation of the vortex tube (and the Ranque effect) is still a mystery. Seems like Maxwell's Demon is at work, so I see your concern.

1. Improved efficiency will reduce cooling water requirements (less heat rejected, therefore less cooling water needed). This should be part of all new power plants anyway.

2. As far as possible, locate plants near the sea or pipe sea water in and use for cooling.

This increases the capital cost of the plant, but enables the use of almost free sea water instead of paying for fresh water.

Evaporation from cooling towers improves local rainfall by increasing local humidity. This effect is only significant for very high output power plants and even then is quite localized.

Disposal of the highly salt enriched cooling tower blow down could be a problem or could be used as a source of minerals which could be sold to the chemical industry and as fertilizer.

Scarcity of potable water will probably force increased use of sea water cooling anyway.

Use of fresh water for cooling is a waste of a precious resource, although there may be locations where it will is necessary.

Calcium carbonate and other scale-forming compounds are abundant in seawater. Demineralizing the boiler make-up water for use as a working fluid is already a major problem, and adding demineralization of the cooling water as well would not be practical, so that leaves once-through cooling using seawater, where the cooling water is not evaporated and recycled but just passes through the plant bearing off the thermal load. In the US recently, once-through cooling using seawater has been prohibited at nuclear power plants due to concerns over thermal pollution and fish deaths.

That article on Reuters is beyond silly!

The distance they are required to go from shore for discharge of the warmer and the number of discharge points might be questioned but the rejection mentioned I consider more or less idiotic - true green!

By accepting a higher condenser temp (and hence reduced efficiency), it should be possible to use waste heat to distill either poor quality ground water or sea water.

The resultant high quality potable water can then be sold and the power station become a net producer of potable water rather than a consumer.

The saline waste water (if not too saline) can be used to grow the appropriate algae, which can be processed and sold as stock food. Addition of CO2 from the flue gases will dramatically increase output while reducing CO2 entering the atmosphere. The potential income from stock food could easily exceed the value of the power generated.

Fly ash can be made into cement by adding lime to the powdered coal entering the boiler. This will simultaneously remove sulfur and nitrogen oxides while turning the fly ash into an hydraulic cement. The down side is probably increased problems with slagging of tubes and need to modify the boiler because combustion characteristics will be altered.

Utility companies should cease looking on themselves as pure power producers and start thinking as integrated manufacturers of a variety of products.

(When I suggested some of this to a senior manager of NSW Electricity Commission many years ago the response was "We are in the power production business, not manufacturers". Fly ash disposal was, and still is, a significant problem for the industry).

If the integration makes sense commercially and engineering wise it is done. See the Great Plains Gasification project (Antelope Valley Elec Coop) or whatever the name is today.

The lignite gasification to make CH4 is the smallest part of the project. They make everything from CH4 to sulfate fertilizers, amines, N2, argon, neon, krypton and I don't remember what else. CO2 is sent by pipeline to Alberta for injection into old oil wells to enhance production.

The CO2 and saline water are not presently needed for algae growing - that is still a green dream. Fly ash to cement - only have to add lime, the basic component?

You talk about, they only have to modify boilers etc, modifying the entire plant on an unproven basis. The manager you talked to was correct. It is not their business to do R&D but to produce power.

When they way is shown they will follow.

I agree that utility companies should look on themselves as more than power producers. With just a little more intelligence and a modest investment in upgrading their facilities, they could find new revenue streams by using their "waste" products.

Fly ash containment ponds are one example. The slurry could be dewatered and shear-thickened to make bricks. See this new patent for such a device. Fly ash bricks need only pressure to cohere, unlike conventional bricks, which must be fired at considerable energy expense (and pollution). They have the desirable property of adsorbing Hg from the ambient air. One thing is certain: the old approach of just dumping the mess can't continue, lest more ash spills blight the landscape.

Heat distillation has the problem of scale, but the waste heat could be used directly to drive an organic Rankine cycle for power harvesting to improve plant efficiency.

Water is becoming a critical limiting factor on power generation, especially in drought-afflicted regions such as Australia. A lot of water is produced in combustion, and just goes out the stack. How about recovering water from flue gas? Stripping water and N2 out of flue gas would reduce the volume of the gaseous emission stream by 80%, which is tantamount to carbon capture.

The most exciting possibility of all, to me, is cracking CO2 to get elemental carbon in the form of anode-grade coke and nanotubes by a new process, radial counterflow shear electrolysis. The energy for the cracking should be supplied by wind, solar, and the spinning reserve, in a hybrid power system. This would also recycle O2 for oxyfuel combustion or oxygen-blown gasification, saving the cost of the air separation unit.

I fail to understand how or why the utilities are to become R&D centers when they have experience at operating but generally zero at design. That is what GE & others do - when it makes sense.

@ Wilmot - good job of flogging useless patents - all your own I see.

Going to 'crack' CO2 to make carbon? One of the most stable molecules you are intending to disassociate? Sure it is possible but energy wise it makes zero sense. The part about saving the cost of a O2 separation unit is laughable as that is far cheaper than what you are proposing.

Regards,

Russ

russ123, maybe you would be so kind as to comment in detail on why you find my contributions "useless." I was under the impression that the CR4 forum was in the spirit of cooperative problem solving, but you have been around here much longer than I have. Maybe you would also like to share some of your ideas for improvements. If so, I promise to read them carefully with an open mind.

I fail to understand your comment: "Sure it is possible but energy wise it makes zero sense. The part about saving the cost of a O2 separation unit is laughable as that is far cheaper than what you are proposing." Please explain.

The bond dissociation energy for going from CO2 to CO is 5.5 eV, and of course you are right that it makes no sense to burn more coal to crack the CO2 from coal emissions. That would create more CO2 than is cracked. Therefore wind and solar and the spinning reserve would have to be the energy source. This would provide a way for wind and solar energy to be used and widely deployed despite the intermittency and other problems with substituting them for baseload power. CO2 cracking would give them a job they can do and gradually integrate them in the grid.

I understand why utilities are very cautious about changes, since so many people depend on them to provide reliable power. But some entrepreneur might undertake to dispose of the waste and give the utilities a share in the profits.

The outcome of the GE Challenge competition (all funding went to measuring and software, for the "smart grid") indicates that improvements in power generation are not currently of interest to GE, at least those that were not invented at GE. In what appears to be a deliberate insult, GE did not send any comments, thanks or acknowledgment to the contestants (other than the prize winners), so it appears that ideas outside of the smart grid were not even read or considered, and went straight into the round file. Perhaps that's where they belonged, but generation ideas were solicited, and most of the 3800+ ideas submitted in the GE Challenge were in that category.

@ wilmot - Nothing to do with the spirit of cooperation at all. If I feel something has merit I am happy to say so but hho, electrolysis, cracking of CO2 are not things I consider even a slight bit serious.

Air separation plants are usually one of the cheaper components of any industrial complex. Today they are more or less a commodity. They stand alone with only a remote operator and remote plus common maintenance staff.

Any process to break the CO2 bonds would no doubt be continuous - wind and solar do not fit. When wind and solar can be available as baseline power by using some type of storage they will replace coal fired plants - not be used for H2O or CO2 cracking.

Walk in to a steel melt shop and start talking about tweaking the melt schedule or modifying equipment and see what happens. They are, as utilities are, production units. The CEO that starts playing around will soon be looking for a new position.

The typical utility staff does not have the necessary mindset, knowledge or capabilities to play R&D. That would be true at least 99,9% of the time. The staff would never agree but as they have never done that type of engineering they have no idea.

I doubt that GE intended any insult by not providing a gold star to all participants. If anyone went into the competition with that in mind, then what to say. I expect the round file is where most belonged - I expect that most of Edison's ideas ended up there as well - he just kept going to sort out the occasional good one..

They were entering a contest - not a 1st grade play.I doubt that GE expected anything more than a PR show anyway. GE has very smart people on their staff that have been considering many things from all angles for many years. They also have works in progress that no outsider has any idea of.