Using nuclear cooling water to heat buildings

Steve Garson_2

This is a little bit off topic, but read on:

Nuclear power plants use water for cooling. The water then goes to holding ponds to release some heat and then it goes into the ocean. Would it make sense to pipe that water to nearby buildings for heat? Once the heat is transferred, it could be piped back to the plant. This would save water and reduce the environmental impact of the heat on the oceans.

Is this crazy? Would too much heat be lost in the pipes?

Maine Doug_52

It may work in the

winter but the plants would still need a summer heat rejection mechanism.

Brad White

I don't think

Steve meant to use the neighboring 250,000 homes to heat in order to save a parabolic cooling tower..

Rather I think the suggestion is one of a way to use it in a positive way when you can.

The concept of using condenser water for low temperature heating is sound. Probably a nice bone to throw at the locals for the privilege of living near a plant. Perry knows best of all for nuclear plants, but the temperatures of condenser water in an AC system at least are in the 90-95 degree range. Makes for good reheat!

Perry_3

Great theory.... but you missed a few things...

You are absolutely correct that power plants in general (not just nuclear plants) release a lot of "warm" water somewhere.

I believe that you misunderstand a few things though....

My first catagorization will be on cooling techique for the condenser.

Most power plants either use a direct - once through - cooling (i.e: pump water from a lake or a river - and returned the warmed "circulating water" back to the lake or river); or a cooling tower (let the warm water "rain" down a tower where direct air and evaporitive cooling takes place). There are an extreem minority (a few) plants that use air cooled condensers and a fair number that use a "spray pond" which is halfway between the direct and the cooling tower.

So lets focus first on the direct cooling. Typically the power plant will return the circulating water back to the lake or river 10 - 15 deg F warmer than it was taken out. This has an effective maximum limit as returned circulating water above about 90 F starts effecting the efficiency and power capability of the power plant. The reason for this is that the point of condensation (or boiling) of water at a vacuum of 30" mercury is 92 F. Given a simple once through condenser (the most common kind) you need water that is colder than 92 F at the outlet to be able to maintain anything close to a 30" vacuum. As the water temperature goes up - so does the condenser pressure. Not a good thing - trust me on that.

In the summer that river might be fairly warm - 70 or 80 F, and you then get 80 - 95 F return water. Only problem is... how many people need heating in the summer?

In the winter - heating season that river or lake may well be in the 30's (our Lake Michagan intake is currently running about 34 F). Now we recirc some circulating water back in to raise that to over 40 F; but even still the circulating outlet water is in the range of 50 F. Not much to warm a house on.

The case of a cooling tower is a better scenerio. They can usually maintain their inlet circulating water in the winter in the mid 70's to 80's even in the coldest weather, and might see 10 F higher condenser outlet temperatures. In the summer the maximum water temperature is typically about 10 F above the ambient air temperature.

I believe Brad White proposed extracting from the condensate stream. That is not practical - or efficient for several reasons. The biggest being that power plants wish to protect their condensate flow at all cost, both in quantity and in anything that could introduce contaminations.

A much more pratical problem is how do you recover and pipe that heat to a large collection of houses or businesses for heat. Power plants (and especially nuclear power plants) tend to be somewhat remote from population centers. I do note that some power plants do sell medium pressure steam - as it is more economical to to pipe steam long distances than warm water.

Nuclear plants have a few other issues: If you have a pressurized reactor then you do not have to worry much about potentially radiation contamination of the circulating water. The reactor is cooled by a primary loop of water that goes through a "steam generator." Reactor water only gets to the condenser steam side if their is a steam generator tube leak. While that does occur from time to time - it is usually a very small amount; and any radiation is still contained in the steam/condensate system. It would take an additional condenser tube leak at the same time to leak any radiation to the circulating system.

In a boiling water plant the steam and condensate is radioctive. All it takes is a condenser tube leak and you cold leak radioactivity into the circlating systems.

I will note that in either case the level of radioactivity is very small. The worst stuff is contained in the fuel rods - and should never enter the water streams in either plant (but fuel leaks do occur from time to time).

Given even the "remote" chance of transmitting radiation to the general public - I don't think any nuclear plant would be willing to enter into a commercial deal to let you use their warmed water.

I note that some of this is technically rediculous... All nuclear plants dump a very small amount of radiation into the circulating water streams. These levels are below the levels that can affect people and wildlife - but we do it.

Radiation is used a lot for medical purposes. Many people get some form of radiation trace compound for certain procedures. They excrete it via normal biological processes into the sewer system - and all sewage treatment plants are full of it... However, since they are not a nuclear facility - and since the levels are below what the medical and science community consider harmfull the sewage treatment plants do not have to track it or do anything about it.

A nuclear power plant faces all kinds of regulations on what they can release. Out plant "reseaded" our plants sewage treatment facility with bacterially ripe sludge from the nearby town last year. We immediately alarmed for excessive radiation release via our sewage treatment plant. The plant may well have paid hundred of thousands of dollars of fines. The source of the radiation was traced back to that drum of "sewage seed" - and the radioactive isotopes were common medical isotopes and not power plant isotopes.

Oh, I should also mention that for some of the heat exchangers I deal with.... The lake silt that settles out in them - is so naturally radioactive that we have to treat them as nuclear waste in our power plant (you would not believe how minor this level of radiation is). That is how restricive nuclear plants are regulated. So next time you hear about all of the "low level" nuclear waste a nuclear plant generates. Think of the existing local lake mud and lake silt as radioactive waste just due to natural background radiation.

I should mention that we have to report in anytime we personally undergo a medical treatment that involves radionucleids. We may be prevented from working in certain parts of the plant until they clear themselves out to a certain level as their is no way to pass our exit portal monitors with that level of radiation in our bodies.

I do suppose that should a large industrial user need a large quantity of warmed water - then his locating by a power plant might make sense in certain climates.

I should also point out that a backup heating supply would have to be planned on. Power plants do trip, shutdown, and are often down for a month at a time for maintenance.

Hope this helped,

Perry

brucewo1b

I hope you guys aren't

thinking about getting rid of all my good fishing spots;-)

Perry_3

Fishy subject

Nope - once we dump the warm circ water (even if it has some slight extra radioactive stuff) it is considered OK.

Power plant outlets and cooling ponds are great places for the fish.

An interesting side note: When our plant was proposed - back in the 1960's. A use of the warmed water was proposed in our initial site description.

4 nuclear units - and one fish farm to help stock fish in Lake Michagan.

2 units were built (i.e.; there are two independent reactor - steam generator - electrical generator sets at Point Beach), and the pipe stubbed in from the circulating outlet to run to the "planned" fish farm.

The fish farm has not yet been built. However, we are now discussing the possibility of putting the other two nuclear units up in the future.... and that fish farm has come up in discussions again as something we could do to "help" the image of the plant.

Now would that be a fishing spot or what....

Perry

brucewo1b

Perry I was more relating to cooling the water

even more by reuse of the discharge waters, as you know already warm water discharge outlets make great areas for fish.

Unknown

snow melt

Perry,

I believe that in Sweden they use the heated water to run through a few intersections in the downtown area to keep them from snow and ice. Constant circ, maintaining a constant temp on the surface of the street and then allowing cooled water to dump back into the river/pond..

90F water would be perfect! Now all we have to do is get it there

Perry_3

I wouldn't worry about that.

I cannot immagine another industry that could fully use a power plant's circulating water output. Perhaps a very tiny stream - but nothing more.

Off the top of my head I cannot remember if our plant (each power unit) is circulating 200,000 GPM or 400,000 GPM of circulating water. That is for a 535 MW power plant (a mid sized unit); and we have two units.

There are many plants out there in the 750 - 1200 MW range. The water use is beyond most people's level of comprehension.

What other industry could use more than a tiny fraction of that? Even our fish farm concept would only uses a small slip stream of the circulating outlet water.

Perry

[Deleted User]

A hybrid systems would work EXCELLENT...

Pipe the relatively low temp cooling water down the street past homes, business etc. Have water source heat pumps in the homes to take advantage of the low grade heat. The C.O.P. of a water source heat pump could be raised to a minimum of 5:1 using this technology. This would substantially increase the cradle to grave efficiency of the whole electrical train, thereby increasing demand capacity and reducing electrical consumption and carbon footprinting.

But, as friend Perry pointed out, the potential loss of power and shut down of physical plant could severely affect the operations...

Something to think about tho... Even if the boilers tripped off line, the cooling pumps could still run, thereby providing a good heat source to the WSHP's down line.

Unfortunately, this whole scheme would require a LOT of forward thinking and planning, and lawyers would get involved, and the whole thing would be abandoned...

I like your line of thinking tho, and it is that kind of out of the box thinking that will bubble to the fore front once we get a concensus together on the environmental damage we are currently inflicting upon Mother Nature. And once that (acknowledgement and reaction) occurs, people like you and me will be standing there, with the proper solution (pun intended) in hand, ready to apply these hydronic technologies, and people will be flocking to your door...

There are some places over in Europe whereby excess power plant capacity is used in district heating systems for everything from space heating to snow melting, but then again, they've already acknowledged the crisis...

ME

Brad White

Low Temperature Heating on the Air Side

This thread reminds me of a system I designed (from another engineer's concept) over 15 years ago. Using run-around heat recovery of a 100% OA system at a pharmacy college here in Boston.

Glycol would circulate from exhaust air to outside air. The fluid would leave the OA coil at about 48-52 degrees having heated that supply air to about 50 degrees using counter-flow. This would then go to the exhaust airstream (75 degree air) and cool the exhaust air down to the 40's. The fluid would be raised to the 62 degree range and head to the OA airstream again. If the supply discharge temperature dropped below setpoint, a heat exchanger would boost the incoming fluid to the OA coil by a few degrees as needed.

None of the fluids involved ever got above 70 degrees nor went below 45 degrees. Naturally the extremes of OA temperature gave is the delta-T to make this happen. But it proves you do not need hot water to get useful heat in a practical way.

Perry_3

Small cogeneration plants

are more commonly used for this type of application. Plant size is usually less than 100 MW of electrical generation and they can be sited in or near a city (and multiple cases of several smaller units exist combined into one plant exist).

It is very unusual to have the modern larger central station power plants anywhere near a city - in any country of the world. Constucting the necessary pipelines and pumping stations to route water 20 to 100 miles (or more), and the pumping cost are what makes this impractical.

The smaller plants typically do not have either the thermal efficiency or the cost efficiency of the large central stations; but, in some cases they still make sense. It makes the most sense if it can be paired with some kind of industrial process that requires a heat source.

Perry

Perry_3

How to cover plant trips or shutdowns

Quote:

"But, as friend Perry pointed out, the potential loss of power and shut down of physical plant could severely affect the operations...

Something to think about tho... Even if the boilers tripped off line, the cooling pumps could still run, thereby providing a good heat source to the WSHP's down line."

Mark: It's not that easy. The heat is coming from condensing the steam exhaust from the turbines that are used to turn the electrical generators.

If the plant trips, or is shut down, there is no more steam flow through the turbins - and no steam to condense (OK a nuke plant may have some steam to condense in certain situations where they dump steam directly to the condenser bypassing the turbines - which is a short term stratagy not a long term shutdown one).

With no steam the circulating water does not warm up.... Brrrr....

Thus, for this type of system to operate you would need backup boilers - or other power units that are in operation.

The best applications of such systems are with small cogeneration plants where they normally have several small power units operating. If one trips or shutdowns the other units supply the auxiliary heat load. Even then - They will commonly have a backup boiler somewhere that can be brought on line in an hour or so if needed.

However, the genearl idea of use of the low grade heat dump from power plant is not a new discussion.

Approximately 2/3 of the energy in the fuel (regardless of the type of fuel) is dumped as low grade heat sources. The quantity is incredibly vaste... Unfortunately, many people have tried to come up with economical ways to harness it before - and have rarely been successfull as most power plants are located well away from where such energy could be used.

I too studied central heating districts... Its a very good way to go (why do houses have boilers and furnaces - why not a district heating / cooling plant and each house gets a hot water, and a chilled water line for all heating and cooling applications. Heat exchangers are then used. Overall much cheaper and efficient than individual boilers / furnaces and air conditioners in each house.

Perry

Maine Doug_52

We have a

cogen plant down the street that powers the paper mill and provides process steam. IIRC it is 174 MW. They have excess steam. When conditions are right, they shutdown part of the mill, sell the NG and use fuel oil and sell the excess power. So a very cold winter day can be good income.
There is enough excess steam to snowmelt the entire main street but it is used to heat the river.

Maine Doug_52

Cooling water use

Perry, I used to live not far from a power plant in Florida. It had two canals to carry cooling water from and to the St. Johns river. I was always amazed at the vastness and flow rate of the water when viewed close up. You are right on about comprehending such flow numbers and that this is pumped water. Eleventy billion Taco 007's?. One could probably float a semi and make it an amusement park ride out to the river.

Perry_3

How much would it cost to...

Paper mills are perfect cogen oportunities. Lots of paper mills have attached power plants just for that reason.

Considering the waste heat that is dumpled...

How much would it cost to build and maintain a system to snow melt the main street?

Or how much would it cost to build and maintain a system to extract heat energy from the "warmed" river water and heat buildings?

Start putting some numbers together and I believe you will see why it is not done very often - anywhere in the world.

At this point, there are often cheaper ways of doing these other things. Now if energy prices double or tripple - perhaps some of these other things may make more sense.

Unfortunaely, one of the disadvantages of relatively cheap energy in the USA is that it often does not make purely econimic sense to recover and use waste heat. Same is true of a lot of other industrial plant processes. Want another great example: Look at the large steel mills - or any good sized foundry. Lots of waste heat tossed away their as well - and metal production facilities are typically located near population centers.

Perry

[Deleted User]

Water source heat pumps EWT can go below freezing...

and still produce net positive results. So if and when the plant trips, so long as flow of river water is mantained, the WSHP's would still be capable of producing heat, just not as efficiently as they would if the heat were there.

Most WSHP manufacturers would probably prefer that we not allow much higher than 70 degree F entering water temperatures anyway just to avoid blowing the gaskets off the compressors. This would require a mix down strategy to insure this, which can be done with off shelf technology.

Funny that you should mention the location of the power plant in relation to the load potentials. Here in Denver, I can think of at least 3 (4 if you include the Coors power plant which is already running at 80% thermal efficiency due to heat recovery and utilization) rather sizeable power plants whose rejection heat could be utilized.

I understand the distance thing as well. THe remote power plants would preclude obvious use, however, why not locate large industrial thermally intensive manufacturing facilities near those remote plants?

Speaking of which, there is a hydroponic tomato growing facility north of Denver that has done just that. The greenhouses are heated by the heat recovered from the heat rejection process of a near by generation plant. As I said before, it has to be planned for early in the development stages, as it was in this particular case. More info at http://sec.edgar-online.com/1998/08/20/17/0000927356-98-001429/Section12.asp

Off hand Perry, what would you say the typical thermal efficiency of a combustion type power plant would be, on average, and best and worst case scenarios?

I've heard numbers, but not from what I would consider an authority.

ME

[Deleted User]

Low temperatue heating on the SNOWMELT side...

I just finished a series of articles for Contractor Magazine on alternative energy sources for SM systems, and found some examples in Japan where they were using EWT's of around 40 degrees F to maintain snow free surfaces for 80% of the snow time... And of the balance of non snow free times, less thant 3/4" ever accumulated, but it never did freeze. And as Martha would say, "That's a GOOD thing..."

We're just too used to driving tacks with sledge hammers :-)

ME

Perry_3

You cannot assume that the water flow will continue

Mark:

You are making an assumption that the circulating water can be maintained. That is not true unless you have multiple power units in a configuration that does not require the inlet and outlet flows to be stopped periodically.

If you are looking at a single unit power plant. The circulating pumps must be turned off for maintenance to them, circulating piping, and the circulating side of the condenser.

In addition - perhaps what caused the plant to trip was a failure or problem with these components. Our last unit trip was cased by the failure of one of the circulating water pumps (we have two "half capacity" pumps). The unit was down for about a week before we got restarted with only one pump (full repairs of the failed pump took several months).

In another case several years ago - we had a very large fish intrusion event that knocked 1 unit off line and we were barely able (and very lucky) to maintain the other unit online (at 25% power). It was at least a week before we had the one unit back to full power, and my memory is that it took several weeks to where we could restart the other unit.

As far as using heat pumps.... If they are so good at any temperature - why don't people just pump local river water through them to recover heat. I know the answer - do you?

As far as cogeneration - or co-use. You are right about the advanced planning required - or the availability of space. It is very easy to find space near remote power plants. I applaude the people who sought one out to build their facility next to so they could use the waste heat. Most city based plants do not have a lot of free area arround them that an energy using industry could locate into - and it is too costly to pump these energy stream very far.

Concerning the efficiency of power plants. All plants that produce power by the burning of fuel to heat a process stream that extracts power (and this includes nuclear plants) is limited by the same efficiency law. The efficiency of the plant is one (1) minus the ratio of the heat sink temperature divided by how hot the fuel is burned; with temperatures expressed as absolute temperatures from absolute zero (If I recall correctly 0 F = 463 R; where R stands for the Rankine temperature scale).

Since the heat sink temperature is typically the atmospeher or a local river or lake, the only way to improve efficiency is to raise the temperature of combustion. The temperature of combustion has limts imposed by the materials that contain the heat source and in recent times by the limitations on the formation of NOx (low NOx burners are low temperatur burners).

While the numbers can be moved a few % depending on local conditions - or certain technologies... Most steam cycle based power plants typically have a thermal efficiency in the range of 34%. Combustion turbine cycle plants - with exhaust gas recovery steam cycle systems can be in the range of 50% thermal efficiency. The combustion turbine cycle plants are typically fired with natural gas or refined oil - and is often very pricy power (even at 50% cycle efficiency). Steam cycle plants are usually fired with coal, nuclear, largly unrefined oil, other waste streams (wood, garbage, tires, etc). The later with the other waste streams are typically smaller units (on the order of 20 to 50 MW).

Each power plant will be designed to operate at the most economical efficiency in a ballance to construction, operating, and maintenance cost. Lower efficiency units are cheaper to build and easier to operate and maintain. Very large plants are usually where you see advaced steam cycles (supercritical) and other technolofgies to get a few more % efficiency as the cost of the advanced technology can be paid for based on the size of the unit and they can support a larger technical staff to operate and maintain those systems and features.

Hope that helps,

Perry

[Deleted User]

And THAT would pose a serious problem...

No flow, no go.

As for using river water directly, my guess would be bio fouling of the heat exchanger surfaces. Moss, algae and other little critters blocking the heat flow paths.

I did work on a heat recovery system one time in a large commercial laundry that pulled waste water directly out of the trench drain, lint, soap scum and all and pumped it theourgh the shell side of a tube and shell heat exchanger. THey had an arrangement with a 4 way valve that would reverse the direction of flow everytime the heat exchanger was used. Seemed to be pretty effective.

I also worked on another similar system that diverted the washing machine discharge into a large non pressurized poly propylene storage tank, and then pumped that hot water into the next washing machine for whats known in the industry as the "break" cycle, and the inside of that tank was COMPLETELY clogged with lint within 2 years. No easy solutions for that tank...

I believe that the issue of bio fouling could probably be overcome with the same reverse flow technology incorporated on the T&S system. Most fouling "material" has a tendency to lay into a flow path in a certain trailing manner. When you reverse the flow, the trailing matter acts like a hook or sail and gets broken off by the reversing flow.

Or, is there another reason (environmental concerns) that would preclude the use of river or lake water for natural heating and cooling.

Here in Colorado, we are allowed to use lakes, rivers streams and ponds as heat source/dumps with the Department of Environmental Water Quailites permission, and as long as you are not posing any kind of risk to the water quality, they are pretty free with their permits.

In my research for an article I am doing on alternatives to conventionally powered snowmelt systems, I came across a patented device from Germany that is a concrete sewer pipe with PEX tightly wound into the poured concrete to act as a heat recovery heat exchanger. Looks to hold some pretty significant possibilities to me...

Gotta think outside the box :-)

ME

ME

Unknown

heat recovery

ME,

I too have used lake and ocean water for ground source heat pumps. Pretty simple plan.

wheels

Christian Egli_2

Priorities set straight, just say no to opportunities

There really isn’t such a thing as waste heat that electric power plant operators just decide to throw out, just because it’s fun billing the customers for it... heat is heat, you can either make juice out of it or sell it as good heat, and in the end, it all gets dumped into the atmosphere in search of the coldest possible atmospheric temperatures. Both homes and cooling towers compete to one another‘s exclusion in this task.

A power plant burns fuel at sky high temperatures, then squeezes everything it can until it dumps empty carcasses at cold atmospheric temperatures - there is no way at all to go any colder here on earth, maximum thermal efficiencies are set in stone.

A home heating plant squeezes heat from fire temperatures down to room temperatures, regardless of how efficient the label says your boiler is, this whole scheme will never match what a modern power plant can do. The sophistication just does not compare, even our most modern residential boilers cannot be outdone by generations-old power plants. No way, unless of course, we rewrite the book on thermodynamics; cold source room temperatures are by default higher than atmospheric temperatures, it’s nice and warm inside... not outside.

That said, a nuclear plant may want to distribute heat to its good neighbors in a civic minded purpose to generate public goodwill, which they deserve.

There are several nuclear plants I know of that do feed heat to their neighbors. Goesgen delivers about 1% of its uranium heat to a neighboring paper pulp factory: a load of steam is tapped off the appropriate steam header and heats a tertiary steam circuit a few miles long to the cardboard factory - it’s not waste heat. This is a single reactor plant, the place has it’s own regular boiler house, and when things are not glowing on their own, there is a back up boiler that burns... cough cough... electricity. This plant also restitutes river water upstream of a hydroelectric plant - water which it pumped from downstream. Nice clean filtered water - talk about nice neighbors.

I include a brochure on this power plant: Goesgen

http://www.kkg.ch/pdf/061025_Technische_Brosch_re_E.pdf

Beznau, another nuclear plant, is also part of a district heat network where it supplies live heat to several distinct communities, one of about 200 homes just 7 miles away, a next one of about 300 homes on a 9 mile branch, and yet another 600 homes a further 16 miles away. Here, there are two reactors backing each other up, so everything is cool. But again, this is not waste heat we’re talking about - it’s special heat that was bled off the nuclear cycle and the operators had to decide whether to make either a full complement of electricity, or a bit less power along with a little bit of heat. You can’t do both without reducing the theoretical maximum amount of electricity. These power plants struggle about these wrenching decisions and the Beznau district heat does not either only come of atomic origin.

It’s one thing for plants dedicated to first producing heat, to then go on and discover they can also scrape some electric power along the process and another altogether to build and design a maximum efficiency electric plant but yet leave a few crumbs of tempting heat for the neighbors. Maximum electric efficiency schemes suck everything out of the coal fire or the radioactive glow and leave nothing for the birds, nothing at all (within the confines of thermodynamic efficiency, which apply equally to homes and power plants).

Considering the modern operating costs politically imposed on nuclear plants, it makes no sense to forgo electric generation revenue for less profitable heat only sales. I’m not talking about skimping on imposed safety costs (hugely self imposed) but the whole overhead costs of halted nuclear construction. For instance, the Perry plant, consists of two reactors both fully built, but the second unit has never been authorized for production, to the thrill of environmentalists who love to see all this waste. Perry has to make double mortgage payments, and only generates half revenues - how do you think this all affects the cost to the end user? - how do you think it puts the squeeze on the plant operators? Closer to us here in Dayton, we were forced into stupid investments such as building the Zimmer plant into near full completion, then at the last minute, it was decommissioned. How expensive is that? It feels like we bought a new Cadillac just to go drive it off the cliff. After struggling to maximize revenue in order to make ends meet, it’s just not conceivable to build these extraordinarily expensive electric plants to just turn them into banal heating boilers.

How does selling power compare to selling heat for half the amount? A pickup truck and an armored car serve the same purpose, you could easily handle valuable cash in the pickup, but you wouldn’t haul dirt in the secured cab - you don’t need the full security squad for that, it plainly is an efficiency mismatch.

Both Beznau and Goesgen are beautifully visible from the plane on the approach to Zurich. For local tourism, if you sit port side on a flight from Dayton to New York, you get to enjoy the thrill of flying over Cleveland. Perry is there, it's a mere tiny speck along with its brand new never used abandoned cooling tower. Wouldn’t it have been nice to see it smoke during the big black out?

Perry, whack me if I botch some numbers, but here is a thing that bugs me. It seems along this thread that we are faulting good old power plants for only converting 1/3 the fuel into electricity, while the rest gets flushed to the fish. That’s two thirds waste, it seems, one third work... well, what exactly do home heating systems produce? It is ultimately all leaked to the birds (birds, fish, your choice) but it is 100% waste and zero work output (with the tiny exception of self motive steam heat) It even gets much worse with forced air heat which may suck up much extra power to get the heat moving - home heating, compared to a power plant turns out way more than 100% inefficiency waste. Power plants do not come with yellow energy guide labels that stink that bad.

Appearances are deceiving though, and the cooling water on a massive power plant does represent an incomprehensible sea of heat, it is heat, real heat... but it is low grade heat that is diluted to homeopathic concentration. It’s value is worth very little compared to the cost of harnessing it. A similar flood of heat pours out our homes, first through flue losses in a small way, secondly, through windows, walls and air infiltration losses. We loose everything to the environment and this second stream is the giant one, yet it flows through our fingers escaping our reach. This heat loss flow is the same than the one gushing out a cooling tower - it’s not for us to reach anymore beyond tight economical factors.

In regards to grasping at low grade heat, I probably think better investments can be made in solar applications - but it all depends. The sun pours the heat on us in such massive amounts that a slight seasonal blip in earth inclination changes everything from summer to winter. Try heating up the whole outdoors with a boiler - we couldn’t even design something big enough.

This low grade heat that is frustratingly far out of reach and that cannot be collected efficiently generates the exact same problem linked to botched hot water radiant setups. How useful is it to have a maximum efficiency boiler producing maximum amounts of very low grade water that an inappropriately designed radiant system wouldn’t harness? Here, in spite of the promising AFUE labels, you’ll still be stuck with enormous fuel bills and... out of touch heat. It’s not always easy doing everything right.

There is nothing wrong with our power plants, there is much wrong with our home heating systems, and when talking about smarter ways of doing things (which there always is) it’s not a case for crucifying the nuclear and coal plants for not being even more sophisticated, but a case for piling on the homeowner self impressed with the yellow label on the burner. Busting government granted monopolies and red tape regulation would probably open up huge opportunities for energy exchanges between neighbors. Cogeneration, just like we see in so many old books on how it used to be done a hundred years ago, heat, steam, power altogether.

Before my words start getting a radioactive glow, I think I’ll stop. Thanks for harnessing something of value in all my outputs.

Uni R_2

Greenhouse Operations

I was under the impression that some reactor(s) supplied low grade heat to greenhouse operations thereby melding hydronics, hydroponics, steam, nukes and some solar through good old fashioned photosynthesis. It is easier to move the greenhouse operations than the low grade heat.

Christian Egli_2

Swinging the tomatoes

The abstract Mark E provided comes with incredible detail. Note how, just like the fish culture that was contemplated at Perry’s plant, a greenhouse next to a nuclear plant sucking on the low grade heat does not improve the efficiency of the nuclear plant, it’s the opposite, it’s the greenhouse that may operate at better efficiency given a suitable source of heat.

Here, we should be faulting current non-cogenerating hothouses, not the maximum efficiency electric power plants we already have.

Back to greenhouses, as noted in the article, three big concerns, nail biting concerns appear to the hydroponic farmer.

1) in order to prevent serial killing frost on a cold night, you need enormous power - this is by no means provided with low grade heat (the plant Mark zeroed in on is connected to some factory which might not be using power and heat at night, a perfect match for the two neighbors. Again, it is not just low grade heat we’re talking about)

2) green plants live on CO2, starve them and they die. A farmer is obviously concerned about this. Within only minutes of shutting air supply to a hot house you start asphyxiating your cute tomatoes on an oxygen diet. Much artificial CO2 has to then be pumped in. It’s source? why, the boiler smokestack. (Plants change CO2 levels way more than us humans do, and often the heating boilers do not even produce enough to feed the green monsters)

3) after all this heating and all this breathing, preventing the murderous mid day warmth from decimating the whole colony is the next task. In the sun, the heat is not welcome at all anymore - so, you couldn’t just go with continuous low grade heat circulation for flywheeling through the night. No, you need massive live heat swings.

On all three points, the nuclear exhaust would be defective. Low grade heat is just that, a low grade value.

Now,

Read all this the other way, and it becomes obvious how much we need to install cogeneration capabilities or even shift sharing of a boiler house to make for efficient greenhouse production. Sadly, much of this is highly restricted by public utilities commissions and other state agencies as the amount of legalese in Mark’s document demonstrates. We don’t have a technology problem, we have bureaucratic problems... and no cure.