I am making a very simple request. They can keep their process secret. Just be clear about what goes in and what comes out, and tell us from where they intend to get the inputs and where they intend to put the outputs. Give us enough information to evaluate the overall system mass and energy balances. This is the kind of information that has been freely provided by every other proposed carbon sequestration process.

What are they hiding? Why are they hiding it?

I think Calera is bluffing. I am calling their bluff. It is time for them to show their cards or fold.

O’Neil’s response shows that *Caldeira is correct.*  Calling him names doesn’t change any facts.

Calera’s process uses hydroxide.  Producing hydroxide (there are no significant natural deposits) releases CO2.  Calera’s claims of sequestration are based on ignoring this essential fact—the claims are fraud. 

At their Moss Landing pilot plant, there’s hydroxide on-site left over from previous magnesium manufacturing.  Its production released much more CO2 than Calera’s use of it will sequester.  They’re ignoring those emissions and pretending the on-site hydroxide was a naturally occuring resource to make their sequestration claim.

The company’s refusal to provide simple information about process input and outputs seems to confirm they’re a greenwash scam.

What then if there anywhere on the world exists an abundant and regularly feed supply of magnesium hydroxide which is itself recycled from MgCl2 otherwise not used and dumped into rivers?

That seawater is not the most appropriate magnesium source for cement production from the Calera type, this J agree. But there exist also other magnesium hydroxide-turned by product MgCl2 sources/outlays for which it is meaningful to use them say in cement production plus the MgCl2-recycling byproduct gypsum.

What is the quality of with magnesium hydroxide produced Calera cement, in comparison to Portland Cement. Anybody any information? This is for me the interesting question. J do not defend Magnesium-containing seawater as an ideal source for magnesium hydroxide based cement production. But what with magnesium hydroxide of the type described here. THIS magnesium hydroxide turned into cement of the Calera type should pass the carbon footprint test. Plus avoiding dumping MgCl2 into rivers. 

The idea with magnesium hydroxide is more a cry for another cement production. If they make at Calera cement production experiments with there over the last 40 years conventionally produced magnesium hydroxide it is okay. But future real Calera cement production needs another resource endowment than magnesium based seawater. And this exist.

It seems to me that Calera’s problem is the dependence on extra produced magnesium hydroxide if produced on a larger scale and outside of their today’s plant site. Right so?
What is the magnesium hydroxide requirement per ton of Calera cement?
What then if the magnesium hydroxide input stems from magnesium containing waste material for which supply there was no or few additional CO2 output necessary? And possibly made available to nearby cement-companies using the calera process and for example by-product gypsum which is typically also associated with this type of magnesium containing waste.
Calera today’s trials follow already this production pattern if they are located at a former magnesium and refractory production site! If the production pattern fits, then Calera’s claim is right. Why to make a secret about the needed production and raw material pattern for this process?

There helps perhaps a look into the history of the Calera Moss Landing site in California: “The National Refractories and Minerals Corporation (formerly Kaiser Refractories, and hereafter Discharger) operates a seawater magnesia (magnesium oxide, MgO) plant at Moss Landing. Seawater containing Magnesium Chloride MgCl2 is pumped from Moss Landing Harbor and combined with Dolomite [CaMg(C03)2] to form Magnesium hydroxide [Mg(OH)2], which is sold as an environmental pH control product or burned to form magnesia, also an end product.”
http://calview.casil.ucdavis.edu/casil/etc/catalog/126_821.html

Peter

Magnesium hydroxide recycled from the chloride?  A couple of glaring problems with this. 
Firstly, where is the magnesium chloride obtained from? This salt exists naturally in seawater and evaporite-derived deposits, but these are limited or highly dilute.  Of course, you can react magnesian rocks with HCl, but HCl production has a large carbon footprint.  Sec
Secondly, you need a base (hydroxide) to convert the chloride to the hydroxide.  There are no natural deposits of strong bases.  So, you would have to use sodium hydroxide (too expensive and it has a large carbon footprint) or go back to calcining limestone (large carbon footprint), etc.

You appear to be saying that by using a magnesium hydroxide byproduct from another industry, you can ignore the carbon footprint associated with its production.  This is highly deceptive, and amounts to the same Greenwash that Calera is undertaking.

To cut a long story short - HOWEVER YOU MAKE MAGNESIUM HYDROXIDE, IT WILL HAVE A LARGE CARBON FOOTPRINT.  THERE IS NO WAY AROUND THIS.

Also, you are confusing magnesium hydroxide and Portland cement.  Portland cement specs specifically limit the amount of magnesium, and manufacturers are very careful to control the limestone feed so as to minimize magnesium.  Magnesium oxide and hydroxide are deleterious to Portland cement - it causes expansion, cracking, etc.

You are definitely right for bashing on Calera for their secretive practices.  The company’s ideas will inevitably be used by other companies whether it patents them or not.  It doesn’t pay to be secretive, and ideas spread faster if things are open.

Secrecy, I’ve found, can actually be somewhat destructive. There was a company called Montalvo Systems that took the security issue to the maximum. They had no releases and refused to talk at all. Former employees talked about how the need to stay secret ended up consuming quite a bit of mental bandwidth.

Reply to Peter Arnold

To clarify - Calera does not produce a cement.  Lat year, when they started, they claimed they made a cement.  Then they changed their story and said they made a mineral admixture for cement.  Their latest story is that they are making aggregate for concrete.

Magnesium hydroxide is a rather uncommon mineral - because of its reactivity.  Similarly, for magnesium oxide.  So, if you want to make magnesium hydroxide you typically take magnesium carbonate and calcine it to make the oxide, then react this with water to make the hydroxide.
The reactions are:
MgCO3——-> MgO + CO2
MgO + H2O———> Mg(OH)2
You release CO2 when you calcine magnesium carbonate - plus you produce CO2 from the process energy expenditures for calcining and reacting with water.

However Calera is obtaining magnesium hydroxide or oxide - whether they produce it themeslves or buy it from another company, the fact is that they are using a chemical which has a large positive carbon footprint.  Trying to hide this is Greenwash, pure and simple!

Also, you cannot react Dolomite with seawater to form magnesium hydroxide.  You have to calcine to Dolomite to Dolime (a mix of CaO and MgO) - this reacts with seawater to precipitate magnesium hydroxide (magnesium hydroxide is much less soluble than calcium hydroxide).  The former Kaiser process then calcined the hydroxide to the oxide.  All in all, very energy-intensive chemistry with a large carbon footprint.  The reactions are: 
CaCO3/MgCO3—-> CaO/MgO + 2CO2
CaO/MgO + 2H2O + MgCl2——->  2Mg(OH)2 + CaCl2
Mg(OH)2——-> MgO + H2O

Calera must be in dire straits - now they are dissolving olivine in hydrochloric acid and using the Mg/Ca stream from this, along with sodium hydroxide as base, to precipitate CO2.

They have also re-invented the electrolytic cell for the production of sodium hydroxide from brine.

Calera would have people believe that these energy/resource-intensive processes are “Green”. 

Yet more proof of the Calera Scam.

See their patent application WO/2009/086460 (METHODS OF SEQUESTERING CO2)