What’s So Great About Carbon?

Anyone who has ever read science fiction (and perhaps other people as well) knows that life on earth is carbon based.

There is a reason for that. Carbon is a supple element. It can easily bond with other carbon. and when they do so they form strong bonds. Carbon to carbon bonds are found in everything from graphite to diamonds. Their different strength is based on the structure of those bonds, in the way they are joined.

Graphite is formed from stacked sheets of carbon chains, while diamonds are crystals of carbon. Think of a ream of paper. It’s easy to peel the sheets apart, but very hard to tear the whole stack. That’s like the carbon sheets which form graphite. You can make it stronger by adding another ream, but that doesn’t change how easily you can separate the sheets. That makes it ideal for scraping a bit off the tip (writing) while not breaking the point (usually.)

Now imagine a crystal whose sides are made from those reams of paper. The only way to break it apart is to weasel your way into a corner. Diamonds are formed from crystals within crystals making one of the strongest bonds on earth. Both graphite and diamonds are only carbon (presuming there aren’t any impurities which only happens in my imagination), but if you are interested in writing a book it’s better to line your pocket with carbon sheets rather than carbon crystals.

Within our bodies carbon also joins with other atoms to form many of the molecules we need to live, including DNA, proteins and sugars. In fact, carbon is so important it is the definition of organic. Chemically speaking an organic molecule is simply one which contains carbon (it’s a bit more complicated, but for us civilians that definition works.) Organic chemistry is the study of carbon.

Silicon is another atom which strongly bonds to itself. It has properties similar to carbon. Hence sci-fi aliens are often silicon based.

While carbon is necessary for life, too much of it is inimical to life. The reason we should worry about the amount of carbon in the air is because that same ease of bonding means carbon readily joins with oxygen to form CO2 (carbon dioxide) and hydrogen to form CH4 (methane) and other dangerous gases.

Carbon sequestration (also know as carbon fixation) is the process of taking carbon out of the air by creating bonds with liquids or solids so the carbon is no longer available to join with gases in the atmosphere. One way to sequester carbon is to put CO2 under pressure until it becomes liquid then injecting the liquid into porous rock. That essentially reverses the natural process.

Hydrocarbons are molecules made entirely of H (hydrogen) and C (carbon.) CH4 is the simplest hydrocarbon. You probably know it as methane. Butane and propane are also examples of hydrocarbons.

Million of years ago marine plants and animals (full of carbon) died and decomposed on the ocean bottom. The bacteria responsible for the decomposition used most of the oxygen, nitrogen and other elements leaving behind a mess made up mainly of carbon and hydrogen. Eventually this was covered with layers of sand and silt until the weight of time – actually it was the weight of the sediment and the ocean above it- created enough pressure to liquefy hydrocarbons and other compounds creating what we now call fossil fuels.

It is that same carbon, from those original plants and animals, that is released into the air when those fossil fuels are burned. That is the problem, we release in moments all the carbon that had been sequestered for millions of years. Now we need to find a way to put the genie back in the bottle, or, rather, the carbon into the ground.

That discussion will wait for another post – although action to remove carbon from the air cannot wait.