I would like to open by saying that this is a follow up to a previous post strangely enough entitled “Rehab for the our oil addiction, the first of 12 steps” (the first step was methanol). To be honest I have no idea how many steps there will actually be, I just liked the old title and it is a good idea to serialize articles.
So here we go again!
As that I am a fan of delivering bad news bluntly, they is no way to cut 75% of our Middle East oil imports, by 2025, unless… well hmm… unless we start producing enough oil on our own. Here is the problem with that, even if we made the entire state of Alaska into one giant pump jack and juiced all the seals and caribou for oil we still couldn’t met our energy needs. There is one way that we could get enough oil, well it’s not technically oil it is oil shale. You can think of oil shale is kind of halfway between oil, coal, and a rock. What it is, is less important then the fact that between the US and Canada there is enough of it to feed our energy needs for a couple hundred years 1.2 trillion barrels worth. (Coal, which will be step three of 12 (if I have the time and interest), is also a resource that we have enough of to last hundreds of years.)
The problem with oil shale is how to separate the useful part (kerogen) from the part that is worthless rock and do it cheaply and cleanly. Right now they cook the rocks and that makes most of semi-liquid hydrocarbons flow out, but that is costly and a lot of good carbon is lost or left unextracted. Plus, as I said the stuff is semi-liquid so it clogs everything up. However, for most things that are mined (oil shale is mined) the mineral is extracted from the ore, using a solvent (hard to believe but cyanide is a solvent). So it would be nice if there was a solvent that could extract the hydrocarbons from oil shale. Well there are lots of organic solvents will do it, but organic solvents are bad because most of them are made from oil and would be lost during the extraction, so the solvent costs would make extraction to costly to be practical. (Plus the ultimate goal would be in situ solvent extraction of the hydrocarbons, and could imagine what the EPA would say when asked if it was ok to pump massive amounts of say carbon tetrachloride in the deposit?) There is one carbon-based molecule that isn’t considered organic, yep you guessed it (or not) carbon dioxide (CO2). Mostly people only know of CO2 the gas and CO2 the solid (dry ice), but under pressure when cooled CO2 can turn into a liquid and if kept under pressure it remains liquid at high temperatures (>93 C). (You’ve seen liquid CO2 trucks on the road it’s called NuCO2, you can find the fill port on your local fast food restaurant just look for a 6x6” stainless steel box at about eye level, but I digress.) Liquid CO2 is one of the finest solvents of hydrocarbons there is, and even better to get the stuff dissolved in it back out all you do is release the pressure at the CO2 turns back into a gas.
My idea is that the oil shale material be ground fine and the hydrocarbons extracted using liquid CO2. The extracted material can then be pumped to the hydrogenator or cracker or column still, still dissolved in the CO2 (thus reducing the clogging problems.) The CO2 is then recovered, scrubbed (since it will contain a small amount of gaseous hydrocarbons (CH4) and lots of sulfur compounds (which means the extracted hydrocarbons are less sour and therefore will burn cleaner)), liquefied, and reused. The remaining material which is greater reduced in volume can then be retorted if sufficient carbon remains to be worthwhile, but if (probably) not then it can be burned in a rotary furnace (similar to the kilns used to make Portland Cement) to provide energy for the plant, and clinker that comes out the end can be ground to produce a commercial abrasive, left whole and used as filler for concrete, or if we get hard enough up, would be a medium grade aluminum ore.
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