497 Main Road
Glenorchy
Tasmania 7010 Australia
Phone: 61 3 62497868 (am)
Phone: 61 3 62713000 (pm)
Fax: 61 3 62730010
www.tececo.com

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Keeping you informed about the Eco-Cement project.   Issue 28                            July 2003

A Note from John Harrison

I recently received the following touching email from a student (deliberately unnamed but from North America, with corrections to grammar)

"I watched the discovery channel and the documentary on your Eco-Cement and I was very very impressed. I see your Eco-Cement replacing the calcium based cement used today. I'm running late for work right now but I was wondering if you can give me all the information on what you want me to take in school (university) to start up an Eco-Cement company here in North America. I currently have an associates degree in science, and am going to school (university) for a degree in operations management which will be done in 2 years. I realise that Eco-Cement is still in the making, but I want to be a part of the success which I know will happen one day. So if you could please send me all the information you think I would need. I do have lots of chemistry experience so I understand very clearly what you're doing. I'm working on my business skills to help me so that I can hopefully become CEO anywhere here in North America. So any help or guidance from you would mean a lot to me. Thank you for your time and I hope to hear from you soon!"

TecEco seem to be doing brilliantly except for one thing - the raising of the substantial amounts of capital that we need to get on with changing the world. I had no idea it would be so hard. How I just love the enthusiasm of young people with the same idea in mind!

Carbon Trading a Reality in Europe and Other News

The following press releases from Reuters are of considerable importance to TecEco.

E.U. Lawmakers Agree to Emissions Trading Scheme

26 June 2003
By Robin Pomeroy, Reuters


BRUSSELS, Belgium — European Union lawmakers agreed to a major law to fight against climate change to be put before the EU on Wednesday: The result if passed would be a cap on industry's greenhouse gas emissions and the creation of the world's first international emissions trading market.

If, as widely expected, the bill is endorsed by the European Parliament in a vote next Wednesday and then rubber-stamped by E.U. ministers, many firms will from January 2005 need special permits to emit carbon dioxide, or CO2, said E.U. parliament members.

"With this measure the E.U. can demonstrate to the world that it is not simply talking about the problem of global warming but taking practical action to address the issue," said British Liberal Democrat parliament member Chris Davies.

The legislation was finalized in talks between parliament's lead member on the issue, Portuguese center-right Euro MP Jorge Moreira da Silva, and the Greek presidency of the E.U.

Moreira da Silva said he was confident parliament would pass the law. "There is no uncertainty. All the political groups support this agreement," he said.

The emissions trading directive is the centerpiece of the E.U.'s efforts to reach its target under the United Nations Kyoto Protocol on climate change to reduce greenhouse gas emissions by 8 percent of 1990 levels by between 2008 and 2012.

The scheme is supposed to allow market forces to determine the price of reducing CO2, the main gas blamed for trapping heat in the atmosphere, the greenhouse effect, which many scientists say could cause disastrous changes to the world's climate.

The industries affected — including oil refineries, steel, cement, ceramics, glass, and paper — will feel the pinch next March when E.U. governments must say how they will allocate the CO2 allowances firms will need to operate from 2005. Governments will give out at least 95 percent of them free of charge but could choose to auction the rest.

New Market

The allowances will have a monetary value because companies that reduce their emissions will be able to sell excess credits to other firms that cannot reach their CO2 caps.

The European Commission said CO2 credits could change hands for around 15 euros a ton. Companies that fail to reach their targets or buy enough credits to make up the shortfall will be fined 40 euros per ton, rising to 100 euros after 2008.

The sectors affected produce 46 percent of E.U. CO2 emissions.

Although the emissions trading market will initially be restricted to E.U. industries, firms may later be able to buy CO2 credits from outside the bloc from other Kyoto Protocol states.

Under the final version of the law, factories might be allowed to opt out of the scheme if they can show they are making the equivalent effort to reduce greenhouse gases. This opt-out is likely to be used by Britain, which already has a national emissions trading scheme in place, and by Germany, where industry has long-running voluntary agreements with the government to reduce greenhouse gases.
--------------------------------------------------

EU parliament launches climate emissions trading

3 July 2003
By Robin Pomeroy, Reuters

Brussels

The European Parliament fired the starting gun on the world's first international emissions trading market by voting on Wednesday to cap European industry's carbon dioxide output and let firms trade the right to pollute.

The bill passed by the European Union's assembly will mean that from January 2005 many plants in the oil refining, smelting, steel, cement, ceramics, glass and paper sectors will need special permits to emit carbon dioxide (CO2).

"It means that the largest emissions trading scheme in the world to date will be a reality from 2005, and that the architecture foreseen under the Kyoto Protocol is coming to life," Environment Commissioner Margot Wallstrom said in a statement released after the vote.

The law is the centerpiece of the EU's efforts to meet its commitment under the Kyoto Protocol to reduce the emissions many scientists say are causing global warming. The United States withdrew from Kyoto in 2000, saying it would hurt its economy.

Market analysts have predicted trades in the right to emit CO2 among the 10,000 plants affected -- they produce 46 percent of EU emissions -- could be worth up to eight billion euros a year by 2007, creating a brand new financial market place.

Under the Kyoto, 1997 United Nations pact, the EU has to reduce its greenhouse gas emissions by eight percent of 1990 levels by between 2008 and 2012.

Business Certainty

Despite the new cap on emissions which are an inevitable result of burning fossil fuels like oil and gas, EU industry welcomed parliament's decision.

"This provides European business with the certainty it needs to begin planning for emissions trading which starts in January 2005," said Philippe de Buck, secretary general of the EU employers confederation UNICE.

The electricity sector, which accounts for some 60 percent of the emissions covered, said it welcomed CO2 trading as a way for industry to cut emissions where it costs the least.

"Eurelectric (the EU industry body) recognises that society will face a carbon-constrained future, and thus it is vital that all policies and measures in this domain be introduced at lowest cost for society and industry," it said.

But companies are concerned that EU policies to combat climate change emissions could put them at a competitive disadvantage.

The United States, which is the biggest emitter, has no intention of returning to Kyoto and the treaty does not constrain emissions from rapidly industrialising countries like India and China.

"This is a good solution at the European level, but a major issue, having Europe's partners on board remains to be settled," said a UNICE spokeswoman.

Business both in the EU and in countries like Canada and Russia want the EU to open up to some form of global emissions trading.

The European Commission will issue in the coming weeks a proposal on allowing EU firms to gain credits by helping reduce emissions in other countries, credits which they might then be able to sell on the EU market.

March Deadline

Rob Bradley, an environmental campaigner at Climate Action Network, welcomed the vote, and said now it was up to national governments, in the 15 existing EU states and the 10 new ones that will join next May, to rapidly put the scheme in place.

Governments must decide on how to allocate CO2 credits by next March. They will give out at least 95 percent of them free of charge but could choose to auction the rest.

"This is the starting pistol for getting national allocation plans and target setting. This is an incredibly short time scale member states should already be on that road," Bradley said.

Under the final version of the law, which now has only to be rubber stamped by member states, factories might be allowed to opt out of the scheme if they can show they are making the equivalent effort to reduce greenhouse gases.

This opt-out is likely to be used by Britain, which already has a national emissions trading scheme in place, and by Germany, where industry has long-running voluntary agreements with the government to reduce greenhouse gases.

--------------------------------------------------
http://www.planetark.org/dailynewsstory.cfm/newsid/21371/story.htm

World Coal Forms CO2 Sequestration Group

The Electricity Daily, 2 July 2003 - Led by the United States, many of the
largest coal burning countries in the world have signed an international charter
in support of joint carbon dioxide sequestration research and development.

--------------------------------------------------
http://www.wbcsd.org/includes/getTarget.asp?type=DocDet&id=1676

Bats

The European Directive on integrated pollution prevention and control is currently being implemented in the UK and other EU countries and requires large industrial installations to use the "best available
techniques" to control pollution. BAT's not only cover abatement technology, but new, cleaner process technologies. BAT's underpin the whole regime and the European Commission has set up an European Integrated Pollution Prevention and Control Bureau (European IPPC Bureau) in Seville, Spain to define exactly what BAT is for each industrial sector. Their findings are published in BAT Reference documents called "BREFs". The existing BREF for the cement sector is currently being reviewed and the IPPC Bureau is keen to hear about new technologies that it should consider.

TecEco will contact the Bureau and inform them of our work.

--------------------------------------------------
http://eippcb.jrc.es/.

Indian Interest

India is very high on our list of target countries because much of the concrete plant is antiquated and there is a low utilisation rate of fly ash.

Since the last newsletter we have had a number of visitors from that country checking out our technologies starting with Ashcock and Bonny Malik followed by Ajay Singh.

Ashcock and Bonny are business folk. Ajah is a chemical engineer and block machine maker from Delhi and he stayed with us for a few days. We have learned a lot from each other and Ajay will be going back home to Delhi to build Tececo's first block machine for testing purposes.

I also enjoyed the cultural excursion and hope to get to India myself in the not too distant future.

Emissions Reduction and other Advantages of TecEco Cements

Summary

Around 98% of the world’s energy is derived from fossil fuels that when burnt to produce energy release vast amounts of CO2. The production of Portland cement clinker, lime and magnesia all require energy and, in addition, result in the release of chemically bound CO2. The net result is a significant addition to global CO2 levels.

The TecEco technology offers a solution to this problem.

TecEco cements comprise a range of binders within a system whereby reactive magnesia is blended with Portland cement and usually a pozzolan to remove lime:

Two main formulation groups have so far been defined:

In both formulation groups the reactive magnesia firstly hydrates to brucite (magnesium hydroxide) and in Eco-Cements the reactive magnesia further carbonates to form magnesite and hydromagnesite.

It is the process of carbonation that is the key to TecEco’s abatement of carbon dioxide (CO2) from the earth’s atmosphere.

Underlying sustainability, emissions, pollution and other environmental issues are the material flows through our society that are largely driven by economic factors.

The built environment is, in effect, our footprint on the Earth, it is the accumulation of these material flows and accounts for some 30% of the raw materials we use, 42% of the energy, 25% of water used, 12% of land use, 40% of atmospheric emissions, 20% of water effluents, 25% of solid waste, and 13% of other releases [1] , [2] . Include infrastructure and the figures quoted would probably double.

The importance factors in relation to the sustainability of the built environment are the embodied energies of the materials used and the lifetime energies as a result of their properties and the way they are put together. Also important in relation to the wider environment is the composition of these materials which determines the effects of extraction, how they can be reused and their effects on earth systems on wastage.

To reduce the impact of our take-make-break economic system on the environment, it is fundamental that we think about the materials we use and the molecules they are made of.

Environmental and other Advantages of Including Reactive Magnesia in Hydraulic Cements such as Portland Cement.

The economic, technical and environmental advantages of TecEco cements are related and considered below under those headings.

Economic Advantages

In the take-make-waste linear system, which underpins the majority of the world’s economies, utility is added until final point of sale and from then on utility generally declines until wastage is complete. If utility can be maintained by greater durability or reuse then the system must produce less waste, slow down and consume less.

Achieving this should be the prerogative of governments around the world. New materials are required that are more durable and that exit the linear system forming return loops eliminating wastes, reducing output and thus input (the take) from natural ecosystems. Materials with a lower embodied energy and that can use waste of themselves be recycled or reused have substantial economic advantages and TecEco cements have been designed with these desirable characteristics in mind.

Energy

Energy is the largest cost factor in the production of mineral binders.

Whether more or less energy is required for the manufacture of reactive magnesia compared to Portland cement or lime depends on the stage in the utility adding process.

Table 1. Calcining energy compared on a mass basis on page 4 shows that given a take-make-waste system, on a mass for mass of natural materials consumed basis, less energy is required. TecEco argue however that the most valid point of comparison is when the utility is greatest and in the case of TecEco modified Portland cement this is when Portland cement and reactive magnesia have hydrated becoming a binders in concrete. In the case of Eco-Cements further utility is added when brucite carbonates completing a thermodynamic cycle and become magnesite again.

The mass comparisons in Table 1 are however also deficient in that the built environment has most utility when 3D space is created not mass. After all do we purchase 20 tonnes of bricks, timber, nails and tin for a home? The utility argument can therefore be carried further and a better basis of comparison is on a volume of binder material produced basis as in Table 2 , and in this case the hydrated product, brucite, has a lower embodied energy.

Cost

In terms of 3D space, the use of magnesia results in less embodied energy per hydrated cubic metre of building material [3] and hence potentially lower costs in terms of money spent for built environment constructed.

Given volume production and the development of TecEco cement and associated technologies even less process energy than in tables 1 and 2 should be required for the production of reactive magnesia because:


Table 1. Calcining energy compared on a mass basis.

Relative to Raw Material Used to make Cement

From Manufacturing Process Energy Release 100% Efficient (Mj.tonne-1)

From Manufacturing Process Energy Release with Inefficiencies (Mj.tonne-1)

Relative Product Used in Cement

From Manufacturing Process Energy Release 100% Efficient (Mj.tonne-1)

From Manufacturing Process Energy Release with Inefficiencies (Mj.tonne-1)

Relative to Mineral Resulting in Cement

From Manufacturing Process Energy Release 100% Efficient (Mj.tonne-1)

From Manufacturing Process Energy Release with Inefficiencies (Mj.tonne-1)

CaCO3 + Clay

1545.73

2828.69

Portland Cement

1807

3306.81

Hydrated OPC

1264.90

2314.77

CaCO3

1786.09

2679.14

     

Ca(OH)2

2413.20

3619.80

MgCO3

1402.75

1753.44

MgO

2934.26

3667.82

Mg(OH)2

2028.47

2535.59

Table 2. Calcining energy compared on a volume basis.

Relative to Raw Material Used to make Cement

From Manufacturing Process Energy Release 100% Efficient (Mj.metre-3)

From Manufacturing Process Energy Release with Inefficiencies (Mj.metre-3)

Relative Product Used in Cement

From Manufacturing Process Energy Release 100% Efficient (Mj.metre-3)

From Manufacturing Process Energy Release with Inefficiencies (Mj.metre-3)

Relative to Mineral Resulting in Cement

From Manufacturing Process Energy Release 100% Efficient (Mj.metre-3)

From Manufacturing Process Energy Release with Inefficiencies (Mj.metre-3)

CaCO3 + Clay

4188.93

7665.75

Portland Cement

5692.05

10416.45

Hydrated OPC

3389.93

6203.58

CaCO3

6286.62

8429.93

     

Ca(OH)2

5381.44

8072.16

MgCO3

4278.39

5347.99

MgO

9389.63

11734.04

Mg(OH)2

4838.32

6085.41


Carbon Credits

There will potentially also be a financial bonus attached to the use of reactive magnesia in TecEco cements in the form of carbon credits:

TecEco cement concretes can also contain a large amount of waste materials such as fly ash further reducing the embodied energy per unit volume of building material. Lower embodied energy means results in reduced emissions.

The possibilities for widespread abatement and solving global climate change issues are enormous and these are discussed in detail under the heading Environmental Advantages on page 6 .

Other Cost Factors

There are other more technical factors that will contribute to the economic advantages of blending reactive magnesia with Portland cement. These include strength, durability and the ability to blend large amounts of waste materials such of fly ash, and they will be discussed below in terms of technical advantages.

Existing plant and equipment can also be used for the production of TecEco cement reducing costs of entry.

Technical Advantages

Portlandite or as it is sometimes called, lime, has always been the weakness of Portland cement. It is more soluble than brucite, more mobile and more reactive with for example common salts in ground and seawaters. The reason is that the Ca++ ion is much larger at 114 picometres than the Mg++ ion at 86 picometres and the latter fits better in an atomic lattice with hydroxide anions and is therefore more stable. The essential feature of TecEco technology is replacing lime in Portland cement with brucite. Although it could of course be added directly as brucite, far more strength is gained through the process of the formation of the mineral from highly reactive magnesia in a manner that densifies Portland strength. Provided there is no delayed hydration this makes sense and technical advantages result.

Noticeable during the mixing and placing stages are a much better rheology and a marked tendency not to bleed. TecEco modified Portland cement concretes tend to resemble margarine more than traditional concretes with a low slump yet excellent workability. As the hydration of magnesia appears to take up water that would with Portland cement concretes tend to bleed, the evidence so far indicates less or no shrinkage in some formulations.

Other properties become more apparent on setting such as a usually higher strength than would be expected from the amount of Portland cement added and this is probably due to reduced water cement ratios and less cracking due to reduced shrinkage.

Over time noticeable will be the lack of crazy cracking due to carbonation and less corrosion, iron stains etc. as TecEco cements are much more durable.

It also takes some time for problems due to alkali aggregate reaction to emerge and with TecEco cements they will most likely never emerge.

There are many other technical advantages of TecEco cements. For example magnesite is more resistant to mild acids at low temperatures than calcite meaning Eco-Cement blocks will last longer than limestone or Portland cement blocks.

TecEco cements are also fire retardants as brucite breaks down releasing water vapour and magnesite breaks down releasing CO2 at a relatively low temperatures cooling or putting out fires.

No doubt in time more technological improvements will emerge as the properties of the new TecEco cements are determined. What is more noticeable is the lack of problems provided appropriate grades of reactive magnesia are used. The specification sheets from vendors do not convey the full story and people interested in using reactive magnesia should talk to TecEco.

Environmental Advantages

Apart from being much more durable, depending on the formulation and use, Eco-Cements used to make permeable materials such as bricks, blocks, pavers, mortars and pavement re-absorb CO2, are to some extent recyclable and are usually made including a high proportion of fly ash and other recycled usually pozzolanic industrial waste materials.

Around 98% of the world’s energy is derived from fossil fuels that when burnt to produce energy releases vast amounts of CO2. In terms of the volume of built environment and infrastructure that results, less energy goes into making TecEco Cements for the reasons given under the heading Energy on page 2 . Materials that have a lower embodied energy are more sustainable.

Lifetime energies are the energies required to heat and cool buildings over time. Building materials that have thermal capacity reduce lifetime energies and are therefore also more sustainable. TecEco cements, being mineral based, have a high thermal capacity and good insulating properties, especially with added waste organic matter such as saw dust and hence result in lower lifetime energies.

Industrial wastes are a major global problem, TecEco cements can accommodate a high proportion of many wastes reducing their impact on eco-systems.

If materials have closed loops and can substantially be recycled then their impact when they are no longer required is much less. If they can be made of materials more naturally assimilated back into the earth then nature can very quickly convert them back to its own uses. TecEco cements can be substantially recycled not only into more building materials but for other purposes as well. If wasted, they do not affect natural ecosystems as much as Portland cement because they have a lower pH.

If materials can be made that last much longer and require replacing less often, they are said to be more durable. More durable materials are therefore more sustainable. The durability of TecEco cements, therefore, also results in greater sustainability.

Perhaps the most publicised formulations of TecEco cements are Eco-Cements which contain a much greater proportion of materials such as reactive magnesia (and thus brucite) in the cement component that carbonate to completion in permeable materials, absorbing much more CO2. A typical Eco-Cement formulation for masonry products for example would contain 50 - 85% readily carbonated material in the cement component compared to 20-25% in the cement component of concrete masonry units (CMUs) containing Portland cement only. There is therefore approximately 50 - 85 % more carbonation in an Eco-Cement block compared to an ordinary concrete block.

TecEco Modified Portland cements

TecEco modified Portland cements are much more durable because brucite is so much less soluble, mobile or reactive than Portlandite. TecEco modified Portland cements are not attacked by salts, they maintain the passivity of steel and can be used with a wider range of aggregates. As a result concrete structures built using modified Portland cement containing a small proportion of reactive magnesia as well as fly ash should last a lot longer and need replacing less often using less energy to remove them, less energy to waste them (a high proportion of urban waste is discarded building materials) and less energy to reconstruct them. Because energy is directly related to CO2 emissions, net emissions are lower.

TecEco Eco-Cements

TecEco Eco-Cements differ in that they produce less net emissions because they re-absorb much more CO2 than does Ordinary Portland Cement (OPC).

The easiest way to understand them is to think about a 1:1:7, opc, lime and sand mortar in which there is a little less Portland cement and in which the lime is replaced with a bit more reactive magnesia which first hydrates and then carbonates. Toss in a bit of fly ash for good measure, and the nuisance waste consumes the lime. Magnesite is a strong often fibrous and acicular mineral and definitely worth encouraging in a binder. What follows is a bit more scientific explanation about carbon dioxide CO2 releases.

Energy Related Emissions

Process emissions for cement manufacture are the emissions from the energy used in mining, transport, mixing, homogenising, grinding, preheating, calcining, finish inter grinding, packaging, transport and warehousing etc. Process energies from the production of reactive magnesia, lime and Portland cement were considered under the heading “Energy ” on page 2 and are less for reactive magnesia when measured relative to the materials that are incorporated in a cement once set. On a per mole basis the production of magnesia is also more efficient. 98% of the worlds energy is derived from the use of fossil fuel. Assuming natural gas is used and an average emissions factor of .0640 Kg.Mj-1 [4] it is possible to calculate process emissions as in Table 3 and Table 4 on page 9 .

Chemical Release of CO2

A mole of both magnesite and limestone will, on calcination, chemically release a mole of carbon dioxide and a mole of the respective oxides and hydroxides will reabsorb a mole of the gas. Table 3 and Table 4 demonstrate that more CO2 is chemically released on a CO2/tonne product basis for both the calcination of magnesite and limestone than the production of Portland cement clinker and this is because the share of lime in Portland cement is only 65.5%. It is also true that on a mass basis, more CO2 is also chemically released by the calcination of magnesite than limestone, and this is because of the lower molecular weight of magnesium.

Portland cement as it hydrates produces around 24 mass% lime (referred to in the cement industry as Portlandite Ca(OH)2). In Eco-Cements relatively large proportions of reactive magnesia are blended with Portland cement and pozzolans and the magnesia hydrates first to become brucite (Mg(OH)2) and in permeable materials like bricks, blocks, pavers, mortars and possibly even highway and footpath pavement (for which it is suggested Eco-Cements should be used [5] ), virtually all of the brucite and lime (unless the latter is consumed by a pozzolan) will reabsorb CO2 out of the atmosphere and eventually reconvert to their respective carbonates completing what are thermodynamic cycles. As a result net emissions are less.

The proportion of materials, and in particular reactive magnesia in Eco-Cements that will carbonate in Eco-Cements is much higher, so much more CO2 is reabsorbed.


Table 3.  CO2 Emissions from energy calcining compared on a mass basis.

Relative to Raw Material Used to make Cement

From Manufacturing Process Energy Release 100% Efficient (Tonne CO2.tonne-1)

From Manufacturing Process Energy Release with Inefficiencies (Tonne CO2.tonne-1)

Relative Product Used in Cement

From Manufacturing Process Energy Release 100% Efficient (Tonne CO2.tonne-1)

From Manufacturing Process Energy Release with Inefficiencies (Tonne CO2.tonne-1)

Relative to Mineral Resulting in Cement

From Manufacturing Process Energy Release 100% Efficient (Tonne CO2.tonne-1)

From Manufacturing Process Energy Release with Inefficiencies (Tonne CO2.tonne-1)

CaCO3 + Clay

.10

.18

Portland Cement

.12

.21

Hydrated OPC

.08

.15

CaCO3

.11

.17

     

Ca(OH)2

.15

.23

MgCO3

.09

.11

MgO

.19

.23

Mg(OH)2

.13

.16

Table 4.  CO2 Emissions from energy calcining compared on a volume basis.

Relative to Raw Material Used to make Cement

From Manufacturing Process Energy Release 100% Efficient (Tonne.metre-3)

From Manufacturing Process Energy Release with Inefficiencies (Tonne.metre-3)

Relative Product Used in Cement

From Manufacturing Process Energy Release 100% Efficient (Tonne.metre-3)

From Manufacturing Process Energy Release with Inefficiencies (Tonne.metre-3)

Relative to Mineral Resulting in Cement

From Manufacturing Process Energy Release 100% Efficient (Tonne.metre-3)

From Manufacturing Process Energy Release with Inefficiencies (Tonne.metre-3)

CaCO3 + Clay

.27

.49

Portland Cement

.38

.67

Hydrated OPC

.22

.40

CaCO3

.27

.41

     

Ca(OH)2

.34

.52

MgCO3

.27

.34

MgO

.60

.75

Mg(OH)2

.31

.39

Table 5.  Total emissions summary.

CO2 EMISSIONS SUMMARY

 

Calcination Energy CO2 Release 100% Efficient

Calcination Energy CO2 Release with Inefficiencies

Chemical CO2 Release

Total CO2 Release 100% Efficient

   

Total CO2 Release with Inefficiencies

   
       

Raw Material

Product in Cement

Hydrated Cement

Raw Material

Product in Cement

Hydrated Cement

Total CO2 Released (tonnes/tonne)

                 

Relative to:

                 

Limestone and Clay

0.10

0.18

0.51

0.61

   

0.70

   

Portland Cement

0.12

0.21

0.51

 

0.63

   

0.73

 

Hydrated Portland Cement

0.08

0.15

0.36

   

0.44

   

0.51

CaCO3

0.11

0.17

0.44

0.55

   

0.61

   

Ca(OH)2

0.15

0.23

0.59

   

0.75

   

0.83

MgCO3

0.09

0.11

0.52

0.61

   

0.63

   

MgO

0.19

0.23

1.09

 

1.28

   

1.33

 

Mg(OH)2

0.13

0.16

0.75

   

0.88

   

0.92

                   

CO2 Released (tonnes/cubic metre)

                 

Relative to:

                 

Limestone and Clay

0.27

0.49

1.39

1.66

   

1.88

   

Portland Cement

0.36

0.67

1.62

 

1.98

   

2.29

 

Hydrated Portland Cement

0.22

0.40

0.96

   

1.18

   

1.36

CaCO3

0.27

0.41

1.19

1.47

   

1.60

   

CaOH

0.34

0.52

1.32

   

1.67

   

1.84

MgCO3

0.27

0.34

1.59

1.87

   

1.93

   

MgO

0.60

0.75

3.49

 

4.09

   

4.24

 

Mg(OH)2

0.31

0.39

1.81

   

2.12

   

2.20

                   

CO2 Released (cubic metres/cubic metre)

                 

Relative to:

                 

Limestone and Clay

136.94

250.60

711.54

848.48

   

962.14

   

Portland Cement

186.08

340.52

827.07

 

1013.14

   

1167.59

 

Hydrated Portland Cement

110.82

202.80

492.56

   

603.38

   

695.36

CaCO3

140.13

210.20

608.66

748.79

   

818.86

   

CaOH

175.92

263.88

676.71

   

852.63

   

940.59

MgCO3

139.86

174.83

813.14

953.00

   

987.97

   

MgO

306.95

383.69

1784.57

 

2091.52

   

2168.26

 

Mg(OH)2

159.15

198.94

925.26

   

1084.41

   

1124.20


Emissions Abatement and "Closed Loop" Materials Flow: A Recipe for Increased Sustainability.

What is important is that the sequestration by carbonation in the thermodynamic cycle magnesite=>magnesia=>brucite=>magnesite is potentially substantial and therefore represents a very useful way to create more sustainable building materials, particularly if the CO2 produced during calcining could be captured during the manufacturing process as TecEco propose to do with their new kiln [6] .

Given the huge size of the materials flow required to create and maintain the built environment the substitution of pure Portland cements by Eco-Cements on a widespread scale could result in massive abatement, particularly with capture of CO2 during manufacture.

To understand the huge scale of possible abatement and sequestration consider a typical concrete made with 15 mass% Portland cement compared to a concrete made with 15 mass% TecEco Eco-Cement that could be used for permeable masonry products such bricks, blocks, pavers and mortars as well as possibly highway and footpath pavement5 and hence carbonate. Of the TecEco eco- cement 25 mass % is Portland cement, 75 mass % is reactive magnesia as shown in Figure 1. Assume the Portland cement on hydration produces 24 mass % Portlandite.

Figure 1.  Emissions with and without capture CO2 from Eco-cement compared to Portland cement.  The determination of the figures is complex and has been done on the basis all factors being the same for the production of magnesia as for the production of Portland cement other than the calcination energies [7] .

The figure for the CO2 emissions from the production of Portland cement blocks used in calculating the numbers shown in Figure 1 of .896 tonnes CO2 to the tonne of cement is in broad agreement with the figures of Hendriks C.A. et. al. in an IEA paper [8] . The lime produced as Portland cement used in permeable materials sets is assumed to totally carbonate and results in net emissions of .78 tonnes CO2 to the tonne of cement.

Given the above, the 15% Portland cement concrete in the above example has net emissions of .299 tonnes to the tonne. The Eco-Cement formulation, on the other hand, has lower net emissions of .241 tonnes to the tonne. With the capture of CO2 during the manufacturing process which is relatively easy for the production of reactive magnesia, the figure for net emissions drops to a low .140 tonnes CO2 to the tonne of cement.

A new and 25% more efficient TecEco magnesia kiln is currently being designed (patents pending) in which CO2 is captured during calcining and grinding. The use of this kiln will become economically feasible in the long run due to the fact that the molecular weight proportion of CO2 in MgCO3 is so high with correspondingly high carbon credits and the fact that it will be practical to decommission existing cement plants and replace them with new plant as such plants become obsolete. If sustainable energy is used to power the new kiln that does not release CO2 such as from wind power then Eco-Cements could even become a net carbon sink.

The use of fly and bottom ash, in which the energy costs are already accounted for in the power industry, would also reduce net emissions because of dilution and because some process energies such as for mining would not be included.

The potential for greater sustainability by changing the materials flows involved in the construction of our built environment, which represents our footprint on earth, is enormous. Buildings and even roads could be built using Eco-Cements of similar composition to the above example.

Consider the abatement, if the above formulation of 15 mass% Eco-Cement was generally adopted for 80 % of construction purposes (With no fly or bottom ash as there would not be enough!). Using similar math the abatement that would result is shown in the following table.

Table 6.  Abatement from substitution of Portland Cement by Eco-cement.

 

Without  CO2 Capture during manufacture (billion tonnes)

With CO2 Capture during manufacture (billion tonnes)

Total Portland Cement Produced Globally

1.80

1.80

Global mass of Concrete (assuming a proportion of 15 mass% cement)

12.00

12.00

Global CO2 Emissions from Portland Cement

3.60

3.60

Mass of Eco-Cement assuming an 80% Substitution in global concrete use

9.60

9.60

Resulting Abatement of Portland Cement CO2 Emissions

2.88

2.88

CO2 Emissions released by Eco-Cement

2.59

1.34

Resulting Abatement of CO2 emissions by Substituting Eco-Cement

0.29

1.53

Abatement without capture of CO2 during manufacture is .289 billion tonnes and with capture 1.532 billion tonnes. If fly and bottom ash were used the abatement figures would be higher due to dilution as emissions from their production are accounted for in relation to the energy produced by burning coal.

Driving the Growth of the Global Cement Industry Through the TecEco Technology: An Opportunity to be Taken, not a Threat to be Ignored

Realistically there would also be considerable substitution of TecEco Eco-Cements replacing clay bricks, steel and aluminium used in construction. Driving this would be the fact that TecEco Eco-Cement concretes would be the first building materials devised of high thermal mass and low embodied energy. The cement industry should therefore see the production of Eco-Cements as an opportunity, not a threat [9] . Table 7 sets out TecEco's estimates of global markets for construction products, the realistic percentage substitution by TecEco Eco-Cements (assuming a mass for mass basis) and a total CO2 abatement worked out using a similar analysis that using in Table 6 . (The estimates ignore timber as it is a relatively short term carbon sink).


Table 7.  Abatement from substitution (MtCO2 t-1,millions of tonnes).

Building Material to be substituted

Realistic % Subst-itution by TecEco technology

Size of World Market (million tonnes

Substituted Mass (million tonnes)

CO2 Factors [10]

Emission From Material Before Substitution

Emission/Sequestration from Substituted Eco-Cement (Tonne for Tonne Substitution Assumed)

Net Abatement

           

Emissions - No Capture

Emissions - CO2 Capture

Abatement - No Capture

Abatement  CO2 Capture

Bricks

85%

250 [11]

212.5

0.28

59.5

57.2

29.7

2.3

29.8

Steel

25%

840 [12]

210

2.38

499.8

56.6

29.4

443.2

470.4

Aluminium

20%

20.5 [13]

4.1

18.0 [14]

73.8

1.1

0.6

72.7

73.2

TOTAL

   

426.6

20.7

633.1

114.9

59.7

518.2

573.4


These calculations indicate that if the TecEco technology can succeed in replacing non-cement based building materials, a further 518.21 or 573.42 billion tonnes would be sequestered on top of the figures from table 2 depending on whether CO2 is captured at source or not. Total sequestration if Eco-Cements were adopted for 80% of the current uses of Portland cement could therefore be as high as 2.105 billion tonnes.

Further sequestration would result from the inclusion of waste carbon based matter such as sawdust, waste timber shavings and chippings, plastics, rubbers etc, many of which are currently burnt adding to the global atmospheric CO2 level. Many of these materials also have the advantage of not only adding insulating capacity but strength to Eco-Cement products as they have innate tensile strength. Wood for example is in the order of 250 MPa whilst some waste plastics are closer to 1000 MPa. The figure is impossible to calculate because of the variation that may be expected, but is likely to be in the order of more than 0.5 billion tonne.

With the inclusion of materials containing carbon the total abatement from the widespread adoption of TecEco Eco-Cement technology could therefore be more than 2.5 billion tonnes. As the annual atmospheric increase in CO2 is around 12.7 billion tonnes [15] this would be over 15% of the annual increase.

Conclusion

The case for including reactive magnesia with Portland Cements in concretes is overwhelming and results in potential solutions to many of the problems of the material including greater sustainability.

As Fred Pearce reported in New Scientist [16] Magazine, “There is a way to make our city streets as green as the Amazon rainforest. Almost every aspect of the built environment, from bridges to factories to tower blocks, and from roads to sea walls, could be turned into structures that soak up carbon dioxide- the main greenhouse gas behind global warming. All we need to do is change the way we make cement”

The TecEco cement technologies therefore merit serious attention by industry and governments.



[1] Australian Federal Department of Industry (1999), Science and Tourism, Environmental and Economic Life Cycle Costs of Construction, Detailed Discussion Paper, Section 2, p8.

[2] The reference given by Industry Science and Tourism was David Malin Roodman and Nicholas Lenssen Worldwatch paper 124 How Ecology and Health Concerns Are Transforming Construction.

[3] There is a good argument for using volume comparisons as the build environment is composed of 3D space, not mass.

[4] This is an average figure from the Australian greenhouse office.

[5] There is considerable merit to the argument that road and footpath pavement should be. See newsletter 29 on the TecEco web site.

[6] Patents pending.

[7] Complex spreadsheets are available.

[8] Hendriks C.A. et. al. in an IEA paper, C.A. Hendriks, E. Worrell, L. Price, N. Martin, D. de Jager, K. Blok, and P. Riemer, Emission Reduction of Greenhouse Gases from the Cement Industry. International Energy Agency Conference Paper Retrieved from www.ieagreen.org.uk 01/07/02.

[9] This is very basic economics. The merit of diversification into Eco-Cement should be considered.

[10] Dr Selwyn Tucker, CSIRO dbce. Pers. com.

[11] This figure was derived from known figures in some countries.

[12] International Iron and Steel Institute figure Retrieved 08/08/03 from http://www.worldsteel.org/article/iisi20020118.

[13] International Aluminium Institute Retrieved 08/08/03 from http://www.world-aluminium.org/iai/stats/index.html.

[14] Alan Pears, RMIT, Melbourne, Australia

[15] Retrieved 08/08/03 from http://www.whrc.org/science/carbon/carbon.htm.

[16] Fred Pearce, Green Foundations, New Scientist, vol 175 issue 2351, 19 July 2002, page 39.