Australian University Unveils New Carbon-Trapping Bricks 142
FirephoxRising writes "A research pilot plant in Newcastle will trial world-first technology that turns carbon emissions into bricks and pavers for the construction industry. More efficient and stable than storing gas in the ground, the new method will sequester carbon and can work anywhere, unlike geo-sequestration which is site specific."
Calcium carbonate (Score:5, Informative)
Re: Bringing coal to Newcastle! (Score:2, Informative)
OP here. It's not, of course, coal, else it would be used for fuel. It's some flavor of carbonate.
It takes all the energy initially extracted by burning the coal in the first place to convert the CO back into coal, whereas making nice stable carbonates is (depending on the metal's original form, of course) likely exothermic.
Re:Turning CO2 into carbonates? (Score:5, Informative)
It's been a while since I did chemistry, but calcium carbonate can be made from calcium oxide and carbon dioxide in the presence of water. I think that's more or less how it's done in sea creatures. So you've got:
CaO + H2O + CO2 --> CaCO3 + H2O
I believe the reaction takes place spontaneously when you dissolve calcium oxide and CO2 in water. To check, add up the standard enthalpy of formation for both sides. The water cancels, of course, leaving:
635 kJ/mol + 393.5 kJ/mol --> 1207 kJmol
Right is more negative than the left so the reaction is exothermic. Calcium carbonate is basically limestone or marble, so a nice building material, mixed with other stuff to stabilize it against acid rain. Leaving the question of where you get the CaO.
Having done all that work, I found this: http://www.globalccsinstitute.com/publications/novel-co2-capture-taskforce-report/online/54351 [globalccsinstitute.com].
Looks like the reactions are all exothermic, but you have to come up with the minerals, which means mining a ton and a bit of rock for every ton of coal you burn. But you get building materials out of the bargain too.
Re:Turning CO2 into carbonates? (Score:2, Informative)
Calcium carbonate and acid rain equals water soluble gypsum. Not cool to use as an exterior material.
Re:Turning CO2 into carbonates? (Score:5, Informative)
A bit of digging finds that they are reacting Olivine (Magnesium silicate) with CO2 giving Magnesium Carbonate.
This reaction has been studied for years as a sequestration reaction for CO2 but traditionally it needs high pressure and moderate temperature to get reasonable
conversion of the Olivine. The team at Newcastle Uni have come up with a method to produce Magnesium Carbonate (Dolomite) at much more modest reaction conditions.
I think I know what this is about. (Score:4, Informative)
The article says they have spent 6 years researching the technology. 6 years ago is also when German researchers published their discovery: http://en.wikipedia.org/wiki/Hydrothermal_carbonization [wikipedia.org] (The German version of the Wikipedia article is much more informative.)
As far as I know, it started with a researcher wondering how exactly the Earth produced coal and oil and discovering that for almost a century nobody had done any new experiments. So he did some, adding some of today's knowledge.
It turns out that if you put water and basically arbitrary organic waste (wood, grass cuttings, leaves, entire weeds, whatever) into a pressure cooker, add some citric acid as a catalyser and then heat it to 200 degrees Celsius, then you get an exothermic reaction which makes the stuff keep that temperature without further input of energy. Provided you are not using an ordinary pressure cooker (which will explode) but some special thingy.
You stop the reaction after 8-12 hours and filtrate the water to get the product. Depending on the precise time you stop, you can create topsoil, oil, brown coal or low-quality stone coal. While the method doesn't seem to produce any excess heat, you can theoretically make an industrialised country CO2 neutral by treating all of its green waste that way and storing the resulting low-quality coal underground, e.g. in an old coal mine.