[zirkon]

This seems to be a much over looked topic.

First the characteristics of porland cement:
-Cement is the essential ingrediant for concrete
-To create the special abilities of portland cement we need temperatures of up to ~1480°C.
-The average amount of energy needed to create 1 gramm of portland cement is at least 1700 Joule.
-The world production of cement in 2002 was 1,800 million metric tons.
A quick calculation to find out how much energy was needed to create that much cement would be nice:

1,800,000,000,000,000 Gramm cement
times
1700 Joule
equals
3.06 Million Terra Joule = 3.06*10x18 Joule
I guess ...
1 Joule is the same as one Watt of thermic energy
so we are talking about 3.06 Billion Giga Watt of thermic energy...

How much is that in U-235?
24.78966346 MWh(t) is the poweramount of 1 g u-235
this translates into 89242.788MW that could be given off in one second.
times 1000 for 1kg of u-235
89242788MW or 89.243 TerraW of thermic energy...
3.06 Billion Giga Watt is the same as
3.06 million Terra Watt
Therefore 3.060000 divided by 89.243 equals
ca. 34288 kg u-235
now to make this a normal reactor load with 5% enrichment
34288 kg times 20 equals ca. 685 tonns ...
wow that is still a lot of uranium...
but less than I imagined....

hm maybe I made an error somewhere?

Anyway the heat needed seems to be a rather large amount of Watt. Although it should be noted that this is just heat energy so any heat source will do as long as it hot enough.

So far the only carbon free solution I can come up with is the use of high temperature nuclear reactor process heat (round about 800°C so far) in conjunction with somekind of a heat compressor to boost the provided heat up to 1500°C. A heat compressor is basicly a refridgerator in reverse...
But since this has to be a really large installation wow... not that easy to build...
Maybe electrical heating would be a better alternative than a compressor?

But I wonder how you can achieve the desired results with any technology - it is just plain difficult without something that burnes nice and hot.

Here is the source I got the numbers from...
http://en.wikipedia.org/wiki/Portland_cement

Zirkon

(oh and correct me if I am wrong!)

[Leanan]

You might find this story at The Oil Drum of interest.

The raw materials we will need for alternative energy - concrete, steel, copper, silicon, aluminum, etc., - are in short supply, or will be if we start building tons of nuclear power plants, solar panels, etc. And they will be a lot harder to mine, refine, and manufacture when cheap oil is gone.

[aahala]

This seems to be a much over looked topic.

First the characteristics of porland cement:
-Cement is the essential ingrediant for concrete
-To create the special abilities of portland cement we need temperatures of up to ~1480°C.
-The average amount of energy needed to create 1 gramm of portland cement is at least 1700 Joule.
-The world production of cement in 2002 was 1,800 million metric tons.
A quick calculation to find out how much energy was needed to create that much cement would be nice:

1,800,000,000,000,000 Gramm cement
times
1700 Joule
equals
3.06 Million Terra Joule = 3.06*10x18 Joule
I guess ...
1 Joule is the same as one Watt of thermic energy
so we are talking about 3.06 Billion Giga Watt of thermic energy...

Perhaps I'm the one confused, but the number you came up with seems
to be almost a 1,000 times greater than the energy put out by the US
electrical grid in a year.

As I understand it, to convert joules to watthours, you must divide by 3,600. Since we are talking about energy rather than power, the "hour" part is assumed.

[hotsacks]

Every construction product I can think of has rocketed up in price over the last year.Every one except for portland cement.
Anyone know why?

[zirkon]

thanks for the replie aahala
Actually you must multiply it because you are expending the power in one second power that you would otherwise spend over the time of one hour.
I basicly changed everything to the timeframe of 1 second.
But of course I could be wrong...

(I think thats why those lasers in this fusion experiment could put out as much power as all the powerplants in the world - the amount of time was MUCH smaller than one second (national ignition facility I think it was))

Zirkon

[strider3700]

Every construction product I can think of has rocketed up in price over the last year.Every one except for portland cement.
Anyone know why?

cement was already way up before last year, it just didn't climb much more. 3 years ago I could pour a retaining wall at about $75/cubic yard. last summer it was $150.

[Leanan]

Portland cement has rocketed up.

In the '70s, we were forced to add asphalt and fuel adjustment factors to our contracts. The prices rose so fast that holding the contractor to them meant they'd go bankrupt, which didn't help anyone. So now there's an automatic adjustment if the market price increases.

Last year, we were forced to do the same thing with steel and Portland Cement Concrete.

[Etalon]

Where did you get 1700J/Gram from? sounds very high to me. Not saying its wrong, but im surprised.

*edit*,

Sorry!, you did say

[grabby]

you have to devide your joules by 3,600,000 to get kilowatt hours.
or by 3,600 to get watt hours.

This may help you a bit:
pound of Uranium-235 = 3,700,000,000,000 joules
1 pound of uranium = 1157 TONS of coal.
1 kilowatt hour = 3,611,060 joules
1,024,629 kilowatt hours for a pound of uranium.

1 million barrels of oil is 73 gigawatts.

When you get it figured out, post it, I'd like to know what it is.
I do know one thing, not many things take more power than the USA.

the usa power consumption per year equals the whole world tidal forces for one YEAR!

The sun burns the amount of hydrogen oin one second that the USA burns in one day. (Course the reaction is different, but hey, hydrogen is used up either way.


so the sun outperforms the USA in energy wastage.

[Etalon]

sun wasting energy eh grabby? Be mighty cold here if it didnt

[zirkon]

Thank you Grabby!
So
back to the Joules I guess

This time I will change the amount of heat needed into kW/h.
Okay

3,06*10x18
divided by 3600 to get 1 watt hour = 8,5*10x14
divided by 1000 to get to 1 kilo Watt hour = 850.000.000.000 kW/h

Hm now that looks much better.
divided by 1000 to get to 1 Mega Watt hour = 850.000.000 MW/h

Now about the needed uranium:
1,024,629 kW/h per pound that means we need

850,000,000,000 divided by 1,024,629 =829568.556 pound of uranium or how many tonns of Uranium?
divided by to to get kilos = 414784.278 kg/U
= 414.784 t/U U-235

Hm thats better.
now times twenty to simulate the usual load...
8295.68 tonns of U-238 95% and U-235 5%

yupp that seems to be plausible...

Okay now about the barrels of oil...

Is it Watt/s or Watt/h Grabby=

does not matter will compute them both:

Lets see:
1 million barrels of oil is 73 gigawatt per second
that means the following
3.6*10x18 divided by 73 Gigawatt
equals 41,917,808 times 1 million barrels - no not probable...

1 million barrels of oil is 73 gigawatt per hour
850 terrawatt per hour divided by 73 Gigawatt per hour equals 11,643,356,200 barrel oil ?! eleven billion barrel??

That would mean something like over 582 billion Dollars at 50$ per barrel that would have to be paid for the nessary oil...

Now what happens when I divide it with the amount of produced portland cement?
582 billion Dollars divided by 1,800 million metric tons mean something
like 323,33 dollars per ton of portland cement...

hm my hypothesis is that it is actually 73 giga kW/h
that would mean something like 11 million barrel of oil...
and the oil cost per ton of portland cement drops to 32,3 Cents per ton of portland cement.

So you tell me what is more likely?

now for the Uranium:

38,25$/lb that means
829568.556 times 38,25 equals 31.730.997,27 USD

Hm maybe that is not the price for the whole element?

I know that somewhere in this forum there is a post about the real cost of a fuel rod...
because only when I take 20 times the Price I get up to something like
634,619,199.45 USD for the whole reactor load which would be comparable to the oil costs...
Lets see...
OK 0,352 USD per ton portland cement....

Okay a little bit more than the oil price unless I am wrong somewhere...

You tell me ...


Zirkon

[parainwater]

3.06 x 10^18 joules = 3.06 x 10^18 newton-meters. There are
4.45 newtons per poundforce and 3.28 feet per meter. So we have
2.26 x 10^18 ft-lb using three significant figures. There are 778 ft-lbs per
BTU. Therefore we have 2.90 x 10 ^15 BTU or 2.90 QUADS. A gallon of
gasoline contains about 124,000 BTU thermal energy per US gallon.
So 2.90 x 10^15 BTU is the same energy content of 2.34 x 10^10 US gallons. If we divide this by 365 days per year we get 64 million gallons
of gasoline equivalent energy per day. Or to look at it another way 3.06 x 10^18 joules divided by 365 days per year divided by 24 hours a day divided by 3600 seconds per hour gives us 97 gigawatts of power consumption.

[Tanada]

Every construction product I can think of has rocketed up in price over the last year.Every one except for portland cement.
Anyone know why?

Partly cause it rocketed up first and everything else is just catching up, and partly because the cement production plants around here have converted to using scrap automotive tires as their primary fuel source, something they get free or cheap from people who need to dispose of them, like high volume tire retailers.

[hotsacks]

Partly cause it rocketed up first and everything else is just catching up, and partly because the cement production plants around here have converted to using scrap automotive tires as their primary fuel source, something they get free or cheap from people who need to dispose of them, like high volume tire retailers.

I talked with my ready mix supplier about this today.He confirmed what Tanada,Strider and Leanan have said about rapid price increases occurring in the past.But he said that the biggest reason for price stability today was because of huge increases in plant efficiency,something in the order of 30% over what it was a few years ago.He pointed out the kilns are coal fired.The fluctuating points are in transportation costs.Also,fly ash has replaced gypsum in the batching mills and is far cheaper.

[aflatoxin]

The portland cement palnt I visited in 1995 used 4 tons of coal per kiln per hour. Each kiln made 40,000 pounds of cement. There was no energy recovery at this plant. There have been changes made to the facility since then, part of an effort to reduce dioxin emissions.

For those of you who are unaware of this, portland cement kilns crank out a enormous amount of dioxin. The environment in the kiln is at a perfect temperature for the chlorine in the ore to combine with the carbon in the fire to produce dioxin. This stuff is one of the deadliest chemicals known to man.

Back on topic here. The coal is only part of the story. The plant had five 2000 horsepower ball mills, and about 100 25-50 horsepower fans. Plus the crusher (At least 1000 horsepower). There was also any number of beltlines, screw auger conveyors, and miscellaneous stuff. All of that equipment was electric.

The coal had to come from somewhere. Trucked in. The cement had to go somewhere. Trucked out.

There was a limestone quarry at the plant. The coal was hauled in by rail from Utah.

I dont have the time to add all of this up, but I'm sure someone could derive a pretty good idea of total energy useage from this real-world example.

[gg3]

I have also read that portland cement plants are using scrap tires as a fuel source for heating the kilns.

Hotsacks, you say "fly ash has replaced gypsum in the batching mills..." Can you clarify? "Batching" normally refers to "batch plants," i.e. the plants that weigh out ingredients for concrete and load them into the transit mixers. "Mills" normally connotes "portland cement mills." In some languages, the words for a central-mixing plant (which weighs ingredients into a large stationary concrete mixer, and then loads the concrete into a transit mixer that serves as an "agitator" to keep the concrete fresh on the way to the job site) translate to English as "mill." Which type of plant are you talking about?

Fly ash, and agricultural byproducts such as rice hull ash, can be used as "pozzolanic admixtures" in concrete: compounds that have cement-like properties or that disperse the particles of cement more efficiently. (Normally, cement particles tend to clump together on a borderlline-microscopic level; this is an inefficient use of the cement. Dispersing the particles is more efficient, allowing a reduction of the cement content of the concrete for a given degree of compressive strength.)

In these cases, the fly ash or rice hull ash etc. are added at the batch plant, and can replace up to 50% of portland cement (by weight) in the concrete. This produces a significant reduction of embodied energy content and thereby reduces costs.

However, the resulting concrete has a few tradeoffs: a) It is harder to work on the jobsite; concrete finishers (the guys with the trowels) report that trying to finish it (float and trowel to a smooth surface) is like trying to get a smooth surface on sticky oatmeal. b) Apparently it loses imperveiousness to some degree, i.e. moisture can penetrate the mass more readily than with conventional concrete. This makes it more susceptible to damage from freeze/thaw cycles, i.e. less durable in temperate climates. c) It may also break down more readily over time than conventional concrete. For these reasons, fly ash concrete may not be suitable for certain types of civil engineering projects, e.g. you wouldn't want to use it in bridge piers though it could be OK for grade-beam house foundations.

---

Another agricultural byproduct I've read is being used is "hemp hurds," a byproduct of industrial hemp production. Apparently the hemp plant concentrates minerals from the soil in the hurds, so they have a high mineral content and bind well with other ingredients to produce a concrete-like material. In France hemp hurds are mixed with lime and sometimes with gypsum, and sand is added to produce mortar and stucco for masonry construction. There has also been mention of using hemp hurd concrete for pouring walls.

Hemp hurd concrete appears to me to vaguely resemble the "natural cement" concrete of the early 20th century: so called because natural cement was produced from naturally occurring mineral formations and kilned at comparatively low heat. Natural cement was largely superseded by portland cement due to the latter having a higher compressive strength and better uniformity in concrete. However the replacement occurred during the period of time immediately before Abrahms' water/cement ratio law was discovered, so it's possible that over time, natural cement concrete could have been standardized to the point where it would have been a reliable building material for certain types of work.

I tend to believe that the compressive strength of concrete is a direct reflection of embodied energy in total, i.e. thermodynamically speaking, energy in, energy out, in this case the "energy" to resist gravity via compressive strength. So the best one can do is to use the cement as efficiently as possible by maintaining the lowest w/c ratio for the type of work involved, using plasticizing admixtures (water-reducers) where possible, and following best practices in terms of batching, mixing, placing, finishing, and curing. (Curing in particular is a good way to get "free energy" in the sense that a moist cure will bring out much more of the latent strength of the concrete than a "dry" cure, allowing less portland cement to be used in the concrete and less concrete in the job.)

The interesting thing about hemp hurds is that they are halfway between a cementitious product and an aggregate. They are woody and fibrous so they tend to be used in a manner that has a large particle size, like an aggregate. Yet their mineral content apparently has a synergistic effect when used in combination with lime and gypsum. So what I think we have here is something roughly analogous to a natural cement (in that the mineral ratios are naturally-occuring, and the resulting material does not require high temperature kiln production), which could be called a "natural cementitious aggregate." There are probably other types of agricultural byproducts with similar useful properties, and this needs to be a research topic. (Prediction: at some point the Portland Cement Association will change its name to the Cementitious Materials Association:-)

---

If we assume that fly ash, rice hull ash, natural cements, and "natural cementitious aggregates" will make greater inroads into construction practices, for example housing, what we get here is an interesting synergy:

First, to get comparable results to conventional concrete, we might need to use a greater overall quantity of these "unconventional" concretes in a job. For house construction with poured walls (including ICF construction, using "insulated concrete forms" that remain part of the structure) (or in certain types of block construction), this means thicker walls. Thicker walls could of course get us back to where we started, having the equivalent embodied energy content of thinner walls with conventional concrete. But clever engineering here will seek out the "sweet spot" where a wall is thick enough to do the job without being so thick as to lose the advantage of the lower embodied energy material.

Second, thicker walls have more thermal mass (in effect similar to insulating properties) than thinner walls, so they tend to improve the energy efficiency of a structure over its lifetime.

Regardless of what types of cementitious materials are used, it still seems to me that the most energy-efficient construction is construction that is designed for the longest reasonable lifespan. Some years ago a concrete industry trade group issued a compilation of findings that demonstrate that, in the long run, a well-designed concrete structure has the lowest embodied energy content per year of its lifespan, compared to wood and steel frame construction. If you build for permanence, you only use the embodied energy "once" for all time. Ancient Rome was blessed with mineral deposits that made for an ideal natural cement. Roman concrete masonry and roads of > 2,000 years ago are still reasonably sound (though not sufficiently so to meet modern standards for usability). 2,000 years is a darn good track record.

---

If we assume modern standards for usability, we might reasonably get 250 to 500 years' worth of viable service from a well-engineered and well-built structure. This is not unreasonable considering the fact that masonry buildings of that age range are still in full use in the UK and Europe.

So it seems to me that with a greater emphasis on building for permanence (rather than for short-term gain; look around at all the truly crappy concrete you see, e.g. concrete buildings with more rock pockets than a rock concert), we may find that even under post-peak conditions, concrete is still a fully viable material for building a sustainable future.

[hotsacks]

Great information gg3.
I was referring to batch plants where I take it independent operators design a mix to individual specifications.e,g, 3000 or 5000 psi.
Your remarks about the true value of embodied energy in concrete construction opens a new way of thinking about it for me.I am always looking for better sustainable building practise.In that light,concrete always appeared the'enemy'.
I'd be interested in hearing your thoughts on ferrocement,if any.It seems a reasonable substitute in place of a solid pour in many instances.Thin shell construction offers the same durability and the strength at a lower embodied energy cost.Engineering schools,however,seem reluctant to take the material seriously. Comments?

[lonewolf]

redacted

[zirkon]

Ah now that makes more sense!
Now lets go back to the money again shall we?

so 517,000,000 barrels per year that makes 50 USD per Barrel means
25.85 billion USD

Now to the yellow cake
Per kg of yellow cake you have to pay ca. 84 USD on the spot market...
The usable energy contend lies in the 0.7 percent of U-235...

So where do we get from here...
I had calculated that I would need 414,784.278 kg/U-235
now to get the amount of yellow cake:
100/0.7=142.8571429
Therefore if I want to buy yellow cake with the same Energy contend as 414 tons of u-235 I need 142.8 times as much...
So lets see...
Okay I get 59,254,896.87 kg of yellow cake x 84 USD
Okay now I get 4.977 billion USD...

Now about the deficiencies of this calculation:

Concerning the oil

1 you need lots of barrels of oil to transport those barrels of oil
How much? That is an important question I think...
2 you normaly do not burn crude oil in your plant...

Edit:
Well it occured to me that i could simply check out the heating oil price in germany so per barrel of oil transported to my house I would have to pay
131.57 Euros - this includes all taxes.
So that equals USD 156.34 per barrel of 159 liters...
So now I would have to pay 80.828 billion USD to get the nessesary amount of heating oil transported to my doorsteps... and thats the all included retail price!

Hm lets compare that with natural gas shall we?
0.821414786072E+11 = 82.14 billion m³ of natural gas...
Actually you have to pay per kwh heat energy - dont ask me why
however the cheapest price was 3.75 Euro Cents per kw/h...
So I would have to pay for the same amount of heating power 31.875 billion Euros... how many USD? 37.877 billion USD!

But there are big differences in the local markets... the price I took was the absolute cheapest... In Berlin you have to pay 5,34 cents and the price range goes up to 12,13 cents per kw/h...
hmm I wonder why that is the case...

The unverfied price for coal seems to be 310 Euros per ton. This is including taxes and shipping...
So the retail price tag for coal would be 36.7 billion Euros or 43.61 billion USD.
It should be mentioned that the price of coal is subsidised in germany ...

And since its so much fun lets see how much I would have to pay for
electrical heating :
Price per kw/h 15.53 Eurocents in Berlin germany...
So for all the electrical heating I would have to pay 132.005 billion Euros
or 156. 86 billion USD...
and thats before taxes I believe...




Concerning the uranium:
The yellow cake HAS to be refined to get to your reactor load -
The enrichment process is not perfect - that means you cannot concentrate the U-235 as much as you may like so you need more uranium than the amount I calculated so far... Numbers anyone?
That means unless we have the numbers for the fuelrod prduction and the enrichment process we do not have the whole price picture. Does somebody got some numbers somewhere?

But the very raw numbers say that uranium is still very cheap compared to oil...
Judging from those very preliminary numbers "crude" uranium is five times cheaper than crude oil for the same energy contend....

As I said we stll need the numbers the uranium refinement process (try to put yellow cake into your standart reactor!).


Oh and thank you lonewolf for that informative Website!



Zirkon

[zirkon]

Preliminary conclusions:

For the world production of portland cement you need 850 billion kw/h
of energy.

the simple comparison of raw materials and their energy contend shows us that we need

59254.897 tons of yellow cake
or
517,000,000 barrels of crude oil

Now about the prices:

Lets say we have a doorstep policy
that means its all included transport, taxes and so on for Germany Berlin

coal costs me (unverified and not Berlin)
43.61 billion USD

Oil costs me
80.828 billion USD

natural gas costs me in berlin retail
53.94 billion USD (+16%taxes?)

the electricity in berlin would cost me
156. 86 billion USD (+16%Taxes?)


This still leaves the question open how much I would have to pay for the uranium equivalent...
Known facts:
1:I do know that the enrichment process is not perfect therefore I would need more yellow cake in reality - how much more?
2:The actual processing into the fuelrod for the reactor load cost also a certain amount of money - how much does it cost?

So the question would be how would a doorstep (generic) fuelrod pricetag look like?


Somebody got some info about that?

Zirkon