Clean Coal and Cement that eats CO2

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I am sure you have heard the commercials or even heard Obama talk about Clean Coal. I don’t believe that clean coal exists at this time.

There are some sequestration experiments going on now where they pump CO2 deep underground, but no one really knows if that will work or if the gases will percolate up sometime. Besides the Carbon and the green house gases, coal is also notorious for putting mercury and other toxic chemicals in our water and air. Even if we can clean the exhaust there is a huge problem with mining. Strip mining destroys the land and mountaintop removal has filled up thousands of miles of headwaters, creeks, and rivers with the tailings. Even if the exhaust gases are scrubbed and filtered from the stacks there are thousands of tons toxic waste that gets stored somewhere. Recently one of these storage sites broke through the containment spreading millions of tons of toxic waste over the countryside.

Lately Algae has shown a lot of promise for creating oil. There are claims of 100,000 gallons of oil from algae per acre. See: http://www.biodieselnow.com/forums/p/18449/136155.aspx
The algae forms this oil by pulling CO2 out of the air, in effect sequestering it in the oil. Algae grows like crazy when CO2 is added to the water. Why not bubble the coal exhaust through water and create fuel from the algae? Algae also does well, when combined with sewage or farm animal waste. It uses the nitrogen for fertilizer. The NOX in the coal exhaust might also act as fertilizer. Another neat thing about algae is it doesn’t need clean water to grow.

Lately there is research indicating that coal can be used to produce cement and that the cement can sequester CO2. If you take the exhaust and bubble it through seawater or water with lime added, it forms carbonates which can be used to make cement and this cement will sequester CO2. Regular cement creates a ton of CO2 for each ton of cement made, and it uses a lot of energy to heat it. The cement from exhaust sequesters half a ton of CO2 for each ton made, and it can use the heat from the coal plant, and also reduces the need for cooling towers. See: http://www.treehugger.com/files/2009/01/hot-trick-climate-action.php
Fly ash has been used to make a type of cement for a long time, or it can be added to regular cement to enhance properties. By bubbling the exhaust through water a lot of this fly ash will become slurry and might combine with the carbonates to make a great cement.
By placing magnesium silicates in the mix Novacem makes cement that sequesters CO2. See: http://www.guardian.co.uk/environment/2008/dec/31/cement-carbon-emissions

With some, or a combination of all of these new technologies, we might actually be able to clean up coal, and reduce the CO2 from cement production which is one of our largest CO2 emitters.

Our new energy director said that if we all paint our roofs white and have white roads, it will reflect sunlight and “cut carbon emissions by as much as taking all the world’s cars off the roads for 11 years”. See: http://money.cnn.com/2009/07/13/news/economy/white_roofs/index.htm

The blacktop we now use for paving, absorbs sunlight and gets very hot. Concrete would reflect sunlight and keep our cities much cooler. Concrete also lasts 4-5 times as long as asphalt does, and new techniques like roller compacted concrete, has brought the cost of cement down to about the same cost as asphalt. However concrete is an environmental disaster because of all of the CO2 it creates. Now if we can make concrete that sequesters CO2 it makes a lot of sense to start building roads and houses (save trees) with this versatile material.

If we stop using Asphalt which is made from oil, and if we can grow biofuels from algae we would significantly reduce our dependence on foreign oil.

Posted on August 24, 2009 · in USA

Tagged as: Carbon Emissions • CO2 • ghg