Global Materials Resources-China's Journal of Materials Science and Technology and Acta Metallurgica Sinica plus comments on Superalloy Melting

I am pleased to bring to the (further?) attention of the Materials Science and Engineering community, these two titles from China's Materials Science and Technology community,
1. The Journal of Materials Science and Technology
2. Acta Metallurgica Sinica.

Don't be put-off with either the slow download time not one or two broken links...

Cheers for their effort,

NB. I trust I may eventually receive a response from the author to my original enquiry which brought me to their site in the first place:

"Desulphurization during VIM Refining Ni-base Superalloy using CaO Crucible" in China's JMST.

Link to My Record of Comment

Comment reproduced:

"I am surprised that my earlier work is not referenced in such work: J. ALEXANDER: "Optimizing deoxidation and desulphurization during vacuum induction melting of alloy 718", & MATER. SCI. TECHNOL. 1985, 1(2), 167-70. Some online references may be found via my pages: http://materialsscienceengineeringdefined.blogspot.com/ Either search VIM or direct link: J. ALEXANDER: "Optimizing deoxidation and desulphurization during vacuum induction melting of alloy 718", & MATER. SCI. TECHNOL. 1985, 1(2), 167-70

Nice to know that others have become interested in such themes [after all this time]. "
Comment by the author of MATER. SCI. TECHNOL. 1985, 1(2), 167-70 and author of these weblog pages.

PS. There is still (understandably) much discretion by manufacturers on how to achieve "Clean, very low oxygen, dissolved(gas) and total oxygen, (the latter includes oxide particles) together with very low sulphur (mostly oxysulfides) not to mention the very low harmful trace elements obtained in today's large size VIM melting facilities despite low surface to volume ratio limiting mass transfer and chemical exchange withe the vacuum atmosphere.

Yet all the above melt specification, so important for superalloy manufacturing, can be achieved.

cf. Past Boiling Point, Materials World 1 June 2009 by Gaylord Smith, Brian Baker, Lewis Shoemaker of Special Metals Corporation, R & D, Huntingdon, West Virginia, USA who describe the developments of INCONEL alloy 740, suitable for use in the high temperature environments of supercritical boilers for energy generation.

Full article currently available only to IOM3 members, open to all with 2 month delay, I believe.

PS if the reader decides to joins IOM3 after reading my pages please mention your source and drop me a line.

Light up-date meets Coal-fired power generation, the Mercury Connection: Mercury Emissions, Removal, Products, Processes

Most of us in the northern hemisphere will remember, mercury, that marvelous room-temperature liquid metal which was used for high-school science class demonstration purposes, carefully confined to the high-school science lab fume cupboard and even earlier as the thing in the thermometer stuck in our mouth and at the time of no concern as a hazardous materials recycling issue, I guess.

Currently the push towards lower energy lighting in particular has drawn both regulators and concerned citizens attention to the situation concerning the use of mercury (Hg) in theses products and in particular the increasing tendency to use cfl-compact fluorescent light bulbs.

One natural question comes to mind. How does the light source and it's compulsory recycling compare with other products and process emissions of Hg? cf. fig. Hg in products from USA's EPA. (Environmental Protection Agency).



Which Processes emit Hg and to what extent? cf. TABLE and FIG. for USA from EPA below.














The Following Fig. taken from Wikipedia shows a partial life cycle assessment approach a comparing potential Hg emissions in two current light-bulb products.










The global distribution of Hg emissions are mapped as follows, due to The Encyclopedia of Earth.

Current and future Trends reported by USA and The European Union (EU) are as follows:
USA EU.

This short introductory graphic series would not be complete without a few pointers to the substantial work in progress aimed at eliminating Hg both from CFL's light cycle and the Coal-fired power generation cycle.

Sources and references:

1. EPA's Road-map and the Executive Summary.
The Road-map focuses on six key areas:
1.mercury releases to the environment;
2.mercury uses in products and industrial processes;
3.managing commodity-grade mercury supplies;
4.communicating risks to the public;
5.international mercury sources; and
6.conducting mercury research and monitoring.

2. The Encyclopedia of Earth .

Hg removal Coal powered flue gases

3. CONTROL OF MERCURY EMISSIONS FROM COAL-FIRED ELECTRIC UTILITY BOILERS _pdf format Air Pollution Prevention and Control Division National Risk Management Research Laboratory Office of Research and Development U.S. Environmental Protection Agency Research Triangle Park, NC


4. Control of Mercury Emissions from Coal-Fired Power Plants:
A Preliminary Cost Assessment _pdf format , Thomas Brown, William O’Dowd, Robert Reuther, and Dennis Smith U.S. Department of Energy Federal Energy Technology Center

LEDs - Light up The World Foundation.

In my previous post, I felt that I had not done full justice to LED lighting and to the people behind The Light up The World Foundation (Lutw).

The Light Up The World Foundation (Lutw) aims to bring efficient, durable and near permanent White Light Emitting Diodes (WLED) lighting solutions powered by renewable energy to the world's poor in ecologically sensitive and remote rural areas. Lutw support their engagement by quoting Lawrence Berkeley National Laboratories (LBNL) as saying that, "the primary source of greenhouse gas emissions in the developing world comes from dirty, hazardous and expensive fuel-based sources such as kerosene for lighting.

LBNL states explicitly that the only real way to meet the increasing lighting energy demands is to replace fuel based lighting with solid state lighting systems."

History of the foundation from their website:
Scots born, Dr. David Irvine-Halliday, a Professor of Electrical Engineering at the University of Calgary, had in 1997 the vision to use LED lighting to bring practical, economical, and environmentally safe lighting to the developing world.

Dave, who had been working with LEDs for more than two decades, spent most of 1997 and 1998 trying to make an acceptable white light from various combinations of colored indicator LEDs. He made white light but it was simply not bright enough to be of any practical use in the developing world. Around the end of 1998 Dave discovered that Nichia, a Japanese company, had invented the White LED a few years earlier and he immediately requested that they send him samples. When he and his technician, John Shelley, lit their very first White LED it was most definitely the “Eureka” moment – “Good God John, a child could read by the light of a single diode”.

(cf. my own home experience in the previous post whereby I can read comfortably with an 18 diode,spot of 1W. "a wee Eureka" but I did not say that I bought my second packet 2 spots at half price because this product was not selling well. A pity that I did not have more of the suitable sockets, great for directional bedside reading!)

My own first encounter with "Light Up The World" dates back roughly to 2005 when creating my first personal pages drawn-up to document my personal experience, publications and writings. The latter link many be given only upon request.

More history...

Short summary -" What are LEDs". (quoted from Lutw.org)
- LEDs are made from layers of different semi-conductor material formed on a sapphire substrate, one on top of the other using a process called Epitaxial crystal growth
- About 13,000 LEDs can be formed on the substrate which can be about .25 x.25 units in size
- Tiny gold contacts are applied to each chip site
- Each individual chip is packaged to form a lighting device

Much of the current research appearing recently in science break-through alerts aims to further reduce the materials and manufacturing cost of WLEDs

More on technology from Lutw...

Strategic Alliances and Project Management Lessons_case study.

Arcadis Greystone
Canadian Hydro Developers
Carmanah Technologies Corporation
Kyocera Solar
Philips Lumileds
Luxeon Star LEDs
Nemalux LED Lighting
SunEnergy Power International
University of Calgary

"LUTW has grown from a single idea to a global humanitarian organization that is the leader in its field. Each step, and each increase in capacity, has been the result of collaborative effort.

It is an excellent example of the mutually beneficial results and opportunities created through partnerships. These include major industrial partners, NGO's, local communities and academia. LUTW is able to create strong relationships with various groups in many capacities, through its ingenuity and commitment to making positive changes in the world. LUTW will continue to build strong partnerships to deliver high quality projects and reach more people in need."


A wealth of further information is available on Lutw's media section.

Light emitting diode-LED lighting up-date almost thwarted by Nature. Choose the proper bulb.

A Nature News Alert, 20 May09, Lighting technology: Time to change the bulb, I felt, was a particularly well written “up-date”, for the wider public seeking an overview on light bulbs to choose, from an increasing variety, hence this post, at this particular time. Nature's article relates the evolution in domestic and commercial light sources (bulbs) from the standard incandescent (being phased out) to the innovative, not yet fully commercial, electromagnetic induction types, through the low energy compact fluorescent (CFL) and the now most awaited source, white-light emitting diodes, white LEDS.

A funny thing though, I got a quick read at the article online, referenced it to read again, but the online reader will either have to take my word for it or better ferret out the paper edition or subscribe to the journal, since it is no longer freely available online. Nevertheless the above link will give the reader many thoughtful comments with links for the scientists among us to delve into.

Like many in this part of the world, I have a sample of all sorts of light sources including my recent change of 4 halogen spots 50W each for 4 LED spots (18 diodes each, power consumption per “spot”= 1W ) almost for the fun I tell my sceptical or vested interest friends.

Compound this with my recent encounter with D. MacKay’s powerfully simple well documented approach to energy (production - consumption balance) which includes a chapter on light sources. In fact I had intended to use without restraint MacKay’s work, as invited, in order to clarify any further study of lighting issues. Even after reading the comments some from true experts in lighting sources and design, I still feel that all could benefit from the Mackay’s book, his approach and clear thinking thinking.

Cable-up and bare with “us”.

MacKay's power standard unit is the kilowatt-hour per day (kWh/d).
ref. D MacKay Ch.2, The balance sheet, § Energy and power P.24 in the free online edition of his book "without" full title “Sustainable Energy — without the hot air” cf. Link2 below.

One of the most common, if not the most commonly encountered domestic unit of energy is the Watt due to the many domestic electrically powered appliances from cooking, cleaning, communication-phone, PC and leisure TV and audio (especially electric but not only, since any energy form can be converted to equivalent electric energy units)

Power is the rate at which we use or produce energy,

From energy to power:
The watt (40W = about 1 kWh/d) and the kilowatt (1 kW = 1000W = 24 kWh/d)
"What Watt"?
Use what is commonly known as dimensional analysis to work that thru'
(40W x 24h)/d = 960 Wh/d nearly 1000 Wh/d or 1 KWh/d.

[Error of 4% cf. Bank account return Rates?
MacKay, who may have played rugby, kicks such considerations into touch and as in the same keeps the playing field clear and allows the suffocating players breathing space.]

To quote MacKay again "The kilowatt-hour per day is a nice human-sized unit: most personal energy-guzzling activities guzzle at a rate of a small number of kilowatt-hours per day. For example, one 40W light bulb, kept switched on all the time, uses one kilowatt-hour per day.

(In his book ref.2 below, he uses the common analogy with fluids (water)
-volume or quantity is in litres,
-flow is litres/minutes.
Spending some time to allow the widest public reading of his book and approach)

Light cf. MacKay, Ch 9, Lighting home and work “The brightest domestic light bulbs use 250W, and bedside lamps use 40W.
In an old-fashioned incandescent bulb, most of this power gets turned into heat, rather than light.

A fluorescent tube can produce an equal amount of light using one quarter of the power of an incandescent bulb. "

How much power does a moderately affluent person use for lighting?
My [MacKay’s] rough estimate, based on table 9.2, above, is that a typical two-person home with a mix of low-energy and high-energy bulbs uses about 5.5 kWh per day, or 2.7 kWh per day per person. I assume that each person also has a workplace where they share similar illumination with their colleagues; guessing that the workplace uses 1.3 kWh/d per person, we get a round
figure of 4 kWh/d per person.”

Street-lights in fact use about 0.1 kWh per day per person, and traffic lights only 0.005kWh/d per person – both negligible, compared with our home and workplace lighting.
What about other forms of public lighting – illuminated signs and bollards, for example?

There are fewer of them than street-lights; and street-lights already came in well under our radar, so we don’t need to modify our overall estimate of 4 kWh/d per person."

Car lights
In some countries, drivers must switch their lights on whenever their car is moving. How does the extra power required by that policy compare with the power already being used to trundle the car around? Let’s say the car has four incandescent lights totalling 100W. The electricity for
those bulbs is supplied by a 25%-efficient engine powering a 55%-efficient generator, so the power required is 730W. For comparison, a typical car going at an average speed of 50 km/h and consuming one litre per 12 km has an average power consumption of 42 000W. So having the lights on while driving requires 2% extra power.

What about the future’s electric cars? The power consumption of a
typical electric car is about 5000W. So popping on an extra 100W would
increase its consumption by 2%. Power consumption would be smaller
if we switched all car lights to light-emitting diodes, but if we pay any
more attention to this topic, we will be coming down with a severe case of
every-little-helps-ism.”

The economics of low-energy bulbs (MacKay word for word)

“Generally I (MacKay) avoid discussing economics, but I’d like to make an exception
for light-bulbs. Osram’s 20W low-energy bulb claims the same light output as a 100W incandescent bulb. Moreover, its lifetime is said to be 15 000 hours (or “12 years,” at 3 hours per day). In contrast a typical incandescent bulb might last 1000 hours. So during a 12-year period, you have this choice (figure 9.3): buy 15 incandescent bulbs and 1500 kWh of electricity (which costs roughly £150); or buy one low-energy bulb and 300 kWh of electricity (which costs roughly £30).

Should I wait until the old bulb dies before replacing it?
It feels like a waste, doesn't it? Someone put resources into making the
old incandescent light bulb; shouldn't we cash in that original investment
by using the bulb until it’s worn out? But the economic answer is clear:
continuing to use an old light-bulb is throwing good money after bad.

If you can find a satisfactory (affordable) low-energy replacement, replace the old bulb now."

NB. From MacKay ref. Mythconceptions Ch. 9, p59:
Here MacKay answers one argument made by a comment contributor to Nature’s article which opened my post (above) hence my early recommendation to consider comment not only in themselves but to weigh them against “the MacKay” criteria:

To the often made argument in favour of light bulbs as a source of domestic heating;
“There is no point in my switching off lights, TVs, and phone chargers during the winter. The ‘wasted’ energy they put out heats my home, so it’s not wasted.”
MacKay replies; "This myth is True for a few people, but only during the winter; but False for most.

If your house is being heated by electricity through ordinary bar fires or blower heaters then, yes, it’s much the same as heating the house with any electricity-wasting appliances. But if you are in this situation, you should change the way you heat your house. Electricity is high-grade
energy, and heat is low-grade energy. It’s a waste to turn electricity into heat. To be precise, if you make only one unit of heat from a unit of electricity, that’s a waste. Heaters called air-source heat pumps or ground-source heat pumps can do much better, delivering 3 or 4 units of heat for every unit of electricity consumed. They work like back-to-front refrigerators, pumping heat into your house from the outside air (see Chapter 21, MacKay's book Link 2 below).

For the rest, whose homes are heated by fossil fuels or bio-fuels, it’s a good idea to avoid using electrical gadgets as a heat source for your home – at least for as long as our increases in electricity-demand are served from fossil fuels. It’s better to burn the fossil fuel at home. The point is, if you use electricity from an ordinary fossil power station, more than half of the energy from the fossil fuel goes sadly up the cooling tower. Of the energy that gets turned into electricity, about 8% is lost in the transmission system. If you burn the fossil fuel in your home, more of the energy goes directly into making hot air for you.

Mercury in CFL's.
What about the mercury in compact fluorescent lights? Are LED bulbs better than fluorescents?
Researchers say that LED (light-emitting diode) bulbs will soon be even more energy-efficient than compact fluorescent lights.

The efficiency of a light is measured in lumen's per watt. I checked the numbers on my latest
purchases: the Philips Genie 11W compact fluorescent bulb (figure 9.4) has a brightness of 600 lumens, which is an efficiency of 55 lumens per watt; regular incandescent bulbs deliver 10 lumens per watt; the Omicron 1.3W lamp, which has 20 white LEDs hiding inside it, has a brightness of 46 lumens, which is an efficiency of 35 lumens per watt. So this LED bulb is almost as efficient as the fluorescent bulb. The LED industry still has a little catching up to do. In its favour, the LED bulb has a life of 50 000 hours, eight times the life of the fluorescent bulb. As I write, I see that CREE is selling LEDs with a power of 100lumens per watt. It’s projected that in the future, white LEDs will have an efficiency of over 150 lumens per watt [Model by Azevado in pdf].

I expect that within another couple of years, the best advice, from the point of view of both energy efficiency and avoiding mercury pollution, will be to use LED bulbs.
cf. graph on page 58 of his book ref.2 below.

MY LOW ENERGY CFL and LED INITIATIVES:

What about transition from 4 small halogen 50W spots to LEDS. This was a simple thing to do since the light sockets were of the same type, "nail head form". Efficiency? Three are in the kitchen and if fairly weak (how many lumens? - I was told on buying them that here, 1W was roughly 10 watts standard incandescent say 30W...) They give off a rather attractive bluish-white light in three different directions according to how they are positioned, and are certainly sufficient to make a tea-pot of late night infusion, wash-up dishes etc. The other LED is in the toilet where the socket is suitable and is largely sufficient for late night contemplation of say the paper version of David Mackay's book or an Ian Rankin detective story. Most of my remaining light sources are I back-up kitchen neon (if needed) and 6 CFL's 11 to 20W. I must admit I feel a bit abused since mostly unaware of the mercury issue I went for the energy economy. When the full picture struck home I checked the recycle bin in my favourite "do-it-yourself store". I must admit that I have strong doubts concerning the procedures used in practice to recycle CFL's and neons. The proportion of bulb breakage in any handling and transport will be, in all probability, important!

Relative contributions to mercury pollution may be found in ref.3 below.

Of course my efforts as a low to average car user will largely out-weigh my efforts of "enlightenment." cf Mackay again ref2.

Further reading
1. “Lighting technology: Time to change the bulb”
2. online book "Without Hot Air"
3. More on Mercury, Hg
a. Hg Fluorescent Light Bulbs.
b. Consumer products containing mercury
processes which release Hg.
c. Released to the atmosphere in process esp. Coal fired Power Gen.

4. CREE LED light source.

Other:
5. http://www.eup4light.net/
My first favourite site on LED-lighting.
6 LED light Directionality_Light-up the World

Notes:


Add my early strong intuition, from my readings, that LED lighting was the future’s pack leader or LEDER putting links on my first personal pages which unfortunately for me gave any publicity revenue to my Internet provider at the time, Orange which was making me see LED- Red with anger and LED-Green with envy - notice in passing that these two colours were the first wavelengths-colour to be obtained from LEDS. My admiration for semi-conductor materials stems from an all too-short spell in that industry almost 20 years earlier. The careful, finely tuned precision and pluri-disciplinarity of the semiconductor materials field of applied solid state physics and chemistry was to my mind, extremely intellectually satisfying. Here small was beautiful. Here was the setting for today’s nano-age. If this is not sufficient some years ago I found some comfort for my own intuition in the choice of research themes made by Prof. Colin Humphries, Cambridge Univ, a past President of The Institute of Materials, Minerals and Mining (IOM3) to work on gallium nitride (GaN) based LEDS not only for Lighting but also for the medical applications of the technology.

PS. Due to comments a Definition of Luminaires is given :
Luminaires is a complete lighting unit that consist of a lamp or lamps. Luminaires also refer to the parts that help position, protect and connect the lamps. link_html .

Concrete Up-dates

This post follows naturally from my two previous posts on CO2 reduction in Concrete manufacturing and use throughout it's life-span. The figure opposite sums-up much of what has be written previously and is taken from a full well presented article in the NYT of 11 April 2009 entitled Concrete Is Remixed With Environment in Mind.

As often quoted in my pages (Napoleon) "A good drawing is worth more than a long discourse" the reader is cordially invited to consult the figure-click to enlarge.

The article is an excellent paper for public understanding of cement and concrete. All sort of careful chemistry is going on: Some add silica fume industrial waste which improves impermeability and gives reinforced steel bars corrosion protection from road salts. Some add titanium oxide to accelerate oxidation which breaks down organic airborne pollutants so producing a permanently attractive white surface.

NYT reporter Henry Fountain, goes much further than the scientists reported in my earlier post and introduces NYT readers to the much more heartening and ambitious aim of "reversing the manufacturing CO2 emissions equation" to achieve a negative carbon emissions, or overall absorption during the "concrete life-cycle", by both reducing the emissions during production and absorption of CO2 during it's useful life.

"Some researchers want to eventually eliminate Portland cement entirely and replace it with other cements to produce zero-carbon, or even carbon-negative, concrete."

Dr. Brent R. Constantz, company founder, of Calera does not describe Calera as a cement company:

“We’re primarily driven by the need to capture large amounts of CO2 and sequester it,”

NB. The high standard fall-out from Dr. Constantz, background in cements, having made specialty products for use in orthopedic surgery. But he

Back-ground from from NYT- cement manufacture basic process:

"Portland cement is at the heart of concrete’s environmental problems. About a ton of CO2 is emitted for every ton of cement produced. The basic manufacturing process involves burning limestone and other minerals at about 2,700 degrees Fahrenheit(about 1480°C) to create an intermediate product called clinker.

“Essentially, we’re trying to make the same minerals that they did in 1825,” said Mr. Stehly, who is head of a committee addressing sustainability issues at the American Concrete Institute.

The cement industry, particularly in the United States and Europe, has reduced CO2 emissions through the use of more efficient kilns and processes, and is now allowed to add some ground unburned limestone to the clinker, reducing the actual cement in the mix. But about half of the CO2 from cement cannot be eliminated — it is produced in the reaction, called calcination, that occurs as the limestone (which consists of calcium carbonate) is being burned."



NYT points to two innovative companies, strongly engaged in this adventure:

1. Calera Corporation, is developing a process to bubble gas-fired electric power plant flue gases through seawater or other brackish water, using the CO2 in the gases to precipitate carbonate minerals for use as cement or aggregates in concrete. The process mimics, to some extent, what corals and other calcifying marine organisms do.

2. Carbon Science associated with Novacem, a British start-up, is developing a cement that does not use carbonates and can make concrete that absorbs carbon dioxide.

1. Calera Corporation,

At a site adjacent to a gas-fired electricity generation plant in Moss Landing, Calif., the Calera Corporation is developing a process to bubble power plant flue gases through seawater or other brackish water, using the CO2 in the gases to precipitate carbonate minerals for use as cement or aggregates in concrete. The process mimics, to some extent, what corals and other calcifying marine organisms do.

Calera calculates that producing a ton of these minerals consumes half a ton of CO2, so the resulting concrete could potentially be carbon negative — sequestering carbon dioxide permanently.

Brent R. Constantz, the company’s founder, has a background in cements, having made specialty products for use in orthopedic surgery. But he does not describe Calera as a cement company. “We’re primarily driven by the need to capture large amounts of CO2 and sequester it,” he said.

The company probably will begin by making aggregate, because the barriers to making a commercially acceptable product are lower than with cement. Even with aggregate, any new product must meet standards and must be accepted by the concrete industry, which can be conservative. “Any time you introduce anything new,” Dr. Constantz said, “it’s a challenge.”

More about Calera in Scientific American[pdf].

2. Carbon Science associated with Novacem, a British start-up, is developing a cement that does not use carbonates and can make concrete that absorbs carbon dioxide.


"To reduce concrete’s carbon footprint to near zero or less, different approaches are needed. Novacem, a British start-up, is developing a cement that does not use carbonates and can make concrete that absorbs carbon dioxide. Carbon Sense Solutions, in Halifax, Nova Scotia, wants to bubble CO2 through wet cement, sequestering the gas through carbonation (a process that occurs naturally, though very slowly, under normal conditions)."

My professional house journal, Materials World, almost a year earlier (7 months ago) in their news report entitled Concrete carbonation,MW 01 Oct. 2008 described the above second highly innovative company(2) in a balance way.

The pros (a) and cons(b)
a)The pros:

Combustion flue gases will be redirected to the curing process. The resulting effluent is scrubbed of CO2 in under an hour. The gas is stored in the concrete as calcite with no further reactions occurring.

‘Calcite, otherwise known as limestone, is the process feedstock for cement. We are simply reverting it back to its natural and most stable state. You can call this cradle-to-cradle engineering,’ says Robert President of Carbon Sense Solutions. The material is said to store up to half the weight of cement as CO2.

Niven is guarded about revealing more about the process, but says, compared to previous efforts at concrete carbonation, this work involves ‘a new reactor design that achieves complete carbonation, faster processing and improved material properties [faster early strength development, lower permeability, reduced shrinkage cracking and efflorescence resistance]’.

b) The cons:

However, concrete and cement science expert Dr Charles Fentiman of Fentiman Consulting in Southwater, UK, is sceptical about the ability to achieve complete carbonation during curing. He reserves judgement until the work is taken out of the laboratory and shown to overcome the practical problems that have impeded academics and industry for decades.

He says, ‘This seems to be an idea of making concrete elements and giving a warm cure in CO2. [But] in my experience, as soon as cement hydration starts, the CO2 coats everything and blocks further hydration. It does accelerate hardening, but then ongoing strength development is low and the concrete remains porous because hydration is blocked’.

Fentiman explains that academics have previously tried to overcome this through super-critical carbonation after the concrete has cured and the cement hydrated. However, ‘this would greatly slow the manufacturing process and the extra cost would need to be covered by the end user’.

Prepare for the worst but hope for the Best.

Link: Innovation_Two Commented Videos not to be Overlooked_Your Company (profit and loss) and even Country (Survival) bottom lines in Greatest Danger!

Link
Conversations-on-Innovations: Innovation_Two Commented Videos not to be Overlooked_Your Company (profit and loss) and even Country (Survival) bottom lines in Greatest Danger

Concrete Thinkers_Putting CO2 emissions into perspective_but how sucessful are they in this?

In my previous post, I recommended, from my scant readings of non-metallic materials, The Portland Cement Association ,Concrete Thinkers _ page and mentioned in my post, what I saw as short comings in several science news releases from the scientific community.

Specifically, I felt that the scientific teams mentioned lacked commitment and resolve in setting their sights and hence their objectives to the highest levels, ie. choosing near zero-carbon emissions and not categorically "zero-carbon emissions". [Either the scientists in question appeared to lack commitment and resolve in setting their objectives or having seen how difficult getting results from the lab. to full scale in industrial ( socio-economic) practice preferred to remain modest and prudent, I did not know. But we shall see in posts to follow that more ambitious approaches seek not only to achieve zero-emissions but carbon negative standards ie. CO2 absorption rather than emissions.]

Back to Concrete Thinkers site,while it does give a good summary of the state of the art, progress and approaches which now lead to 2% or less CO2 emissions with referenced white papers, the paragraph which caught my eye for future reference was as in the title of my current post title "Putting CO2 emissions into perspective". Upon a second reading with intent to blog I found the paragraph guilty of many of the faults over and above the use of non- International standard Organisation (ISO) units. The paragraph leads the reader to believe that one will gain a much more balance view of activities leading to specific and CO2 emissions based on units and comparable chores (daily,annual etc.) Meaningless comparisons, activities are not comparable between one another, no comparable standard activity is taken when common energy units are an obvious choice and these could be related to some common daily "global" activity cf. Prof David J.C. MacKay's approach referenced below:

Read Concret Thinkers page with some specific critical comments as follows:

"The manufacture of cement produces about 0.9 pounds of CO2 for every pound of cement. Since cement is only a fraction of the constituents in concrete, manufacturing a cubic yard of concrete (about 3900 lbs) is responsible for emitting about 400 lbs of CO2.[1] The release of 400 lbs of CO2 is about equivalent to[2]" [refs.1,2 refer to papers on their site]:

* The CO2 associated with using 16 gallons of gas in a vehicle (what sort of vehicle!!!)
(16x3.79 litres = 60.64 litres and if your Limousine gives you 100 kms per 5 litres then, => 60.64 /5)x100 = 1212.8kms and say at a speed of 100km/h Then you get 12.12h driving pleasure!)

* The CO2 associated with using a home computer for a year (24h a day connected?)
* The CO2 associated with using a microwave oven in a home for a year (a few minutes or 1 h, lets say per day?)
* The CO2 saved each year by replacing 9 light bulbs (N° of W (Watts and KWh?) in an average house with compact fluorescent light bulbs (Units please?)

Other sources responsible for CO2 emissions include: [I have given the conversion factors below to play with but....

* 28,400 lbs for an average U.S. house in a year
* 26,500 lbs for two family vehicles in the U.S. in a year
* 880,000 lbs for a 747 passenger jet traveling from New York to London

The reason concrete is responsible for 1.5 to 2% of the U.S. anthropogenic CO2 (that is, due to humans) is due to the vast quantities of concrete used in the world around us.

Metrics - Conversion
lbs, US: 1 pounds (lbs) (avoirdupois) is equal to 0.45 kilograms

Yards cu: 1 cubic yards is equal to 0.76 cubic meters
1 cu yd concrete 3900lbs ( kg) => 400lbs CO2 )

gallons US: 1 gallon (US) is equal to 3.79 liters
gallons GB: 1 gallon (British) is equal to 4.55 liters

miles 1 miles (statute) is equal to 1.61 kilometers.

Concrete
400lbs/3900lbs roughly, 1/10 =10% CO2
Therefore, For every unit weight of concrete produced the weight of CO2 emissions is 1/10 or 10% of the weight of concrete produced
Cement
For every unit weight of cement produced approximately the same weight of CO2 is emitted. (or 1 unit of cement produced roughly 0.9 or 90% of CO2 emissions is also produced)

Does anyone know of a better account?

Sources and References:

1. The Portland Cement Association ,Concrete Thinkers _ page

2. A much better approach is that of Cambridge,UK, Prof. David J.C. MacKay, in his freely available ebook Without Hot Air!

What a coincidence (serendipity) I came across David MacKay's Video on light bulbs!

3. CO2 and other greenhouse gases GHG's
Global Warming Potentials (GWP) and Atmospheric Lifetimes (Years)
LINK to US Environment Protection Agency (EPA).

NB. To be fair here are a couple of graphs from references on the Thinkers Site that are more informative than the written paragraph presented by the Thinkers. All and more are referenced on the Thinker site cf. in particular the Stewardship pages