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Permalink Reply by The_Baron on July 14, 2009 at 3:47

The question isn't "can it be done?". Its "How much is it going to cost."

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Permalink Reply by P.G. on July 14, 2009 at 5:42

How much will it cost on a per house benefited basis for those solar panels they'd like to install out in the desert?
I doubt if there would be much cost difference whether they were installed directly on each roof or clumped together out in the desert.

I heard that baking soda thing would be comparable cost wise with what they are spending on scrubbers already plus they would have a marketable product as a by-product.

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Permalink Reply by The_Baron on July 14, 2009 at 6:52

much more expensive than scrubbers, this would be as an alternative to underground sequestering.

The amount of baking soda would flood the market, but it is an interesting idea. My only question is "where to get all the sodium-hydroxide?"

Sodium hydroxide is produced (along with chlorine and hydrogen) via the chloralkali process. This involves the electrolysis of an aqueous solution of sodium chloride. The sodium hydroxide builds up at the cathode, where water is reduced to hydrogen gas and hydroxide ion:

The substance is a strong base, it reacts violently with acid and is corrosive in moist air to metals like zinc, aluminum, tin and lead forming a combustible/explosive gas (hydrogen) - see ICSC 0001). Attacks some forms of plastics, rubber or coatings. Rapidly absorbs carbon dioxide and water from air. Contact with moisture or water may generate heat.

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Permalink Reply by Mac Davis on July 14, 2009 at 8:38

1) What happens to the chlorine from making sodium hydroxide?
2) How much energy is consumed by producing the sodium hydroxide relative to the energy produced from burning the coal?
3) What do you do with the baking soda?

For every ton of coal, you would get 7 tons of Baking Soda, and 2 tons of chlorine.
For every cubic foot of coal you would get about 3.5 cubic feet of baking soda.

We use about 3 tons of coal per person per year in the US, so that's 21 tons of baking soda per person per year. You'd have a cube of baking soda about 6 feet on a side for every person in the US for every year.

You have 6 tons of chlorine per person as well. That's around 2 billion tons of chlorine per year in the US.

We mine a LARGE volume of coal, so you're going to have 3.5 times as much volume of baking soda. Imagine for every train full of coal you see, you have 3.5 trains full of baking soda going somewhere.

US consumption of chlorine is around 11 million tons. That still leaves about 2 billion tons of chlorine per year in the US to dispose of. It appears that consumption of sodium bicarbonate is less than 1 million tons per year.

Baking soda is not particularly toxic, but it is mildly alkaline. Sufficient concentrations in water or soil will kill plants. You'd have to store large quantities of baking soda somewhere and protect it from rain so that it doesn't wash away or end up in the ground water, soil, or surface water.

I don't know what the heck you'll do with 6 tons of chlorine per person per year. Or around 2 billion tons of chlorine per year produced in the US. Chlorine is nasty and toxic. You'd have to figure out something to react it with to make it safe.

For every ton of CO2 this process disposes of, you get around 2 tons of baking soda and 2 tons of chlorine. Is this really less damaging to the environment than 1 ton of CO2?

OK, it may be a good idea on a small scale as long as you can otherwise use the chlorine and baking soda, but it's not even a drop in the bucket in terms of CO2 production from coal fired power plants.

Note: Some of my chemical calculations may be off, I did it pretty quick, but it's still going to be only a few percent of the total CO2 production for the US.

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