Capturing Carbon Dioxide 10/29/19

Science Opinion by Richard Bleil

Today I read an article about MIT engineers producing a new cement that can cut carbon dioxide. According to this article, carbon dioxide from cement constitutes 30% of the total US emissions (which seems high to me). The way that they are cutting it is two-fold; first, it uses renewable energy to produce the heat necessary to process and create the cement, and second, the new cement captures the carbon dioxide.

Maybe I should write a bit about what cement is in a future blog. But for now, I want to focus on capturing carbon dioxide. See, there is a lot of effort right now on this approach to reducing the gas in the atmosphere, even to the point where some countries have built plants to do just this.

The real problem with carbon dioxide is that it has very low potential energy. There’s a reason that it is the final product in organic oxidation reactions. Organic compounds have a lot of stored potential energy. This is why we eat organic matter to survive; our bodies break down the sugars and starches and proteins to release the stored energy in these molecules. That energy is captured and used for our metabolic and catabolic processes, and the breakdown occurs under very well controlled steps, each step reducing the amount of stored potential energy, until carbon dioxide is finally produced, which we exhale during respiration. The reason carbon dioxide is the final product is because there is just no significant energy that can be extracted from it, so it becomes waste.

The amount of energy our bodies extract from organic matter is exactly the same amount of energy we get out of these same materials when we just burn them outright. The only difference is that in our bodies the processed is controlled, while open fire burning releases all of that energy at once.

There are a few ways to capture carbon. Recently a US senator made a statement to the effect that increased carbon dioxide is good for our plant because it inspires plant growth. Well, he’s not exactly wrong, but it’s still a stupid comment to make. Yes, plants do absorb carbon dioxide, and that is one way to capture the gas, but there are two problems with this. First of all, we continually eat into the plant life on this planet. The rain forest fires in Brazil is a prime example of risking our own lives for profit, as the Brazilian rain forest is one of the last few great carbon dioxide scrubbing forests left in the world, and the fires have been to a great extent intentionally started to clear land for industry. The second problem is that absorbing carbon dioxide by plants does not remove the gas from the active carbon cycle.

And herein lies the problem. By relying on fossil fuels as long as we have, we’ve been the focus of a great uncontrolled scientific experiment. See, coal, oil and gases like methane trapped deep under the earth’s surface represent a carbon source that has been removed, nearly entirely, from the carbon cycle. Left untouched, the carbon dioxide levels in the atmosphere should be fairly constant, or at least very slowly fluctuating as events like gas escape from underground pockets and volcanic eruptions being the major sources of new carbon dioxide release. Compared with the amount of carbon dioxide already in the atmosphere, such events would be a minor source at best. As it is, coal, gas and oil based power plants, fossil fuel burning vehicles, oil and gas based heating and other human processes (both industrial and personal) adds tremendous amounts of carbon dioxide into the atmosphere, and continues to do so every day.

Another way to capture carbon dioxide is to turn it into some kind of stone, like limestone, or other such longer-term product. I say longer-term because, while these products might remove the carbon dioxide from the atmosphere for a very long time, it is still only a temporary fix. See, even stones like limestone have higher potential energy than carbon dioxide, and it’s only a matter of time (perhaps thousands of years) before the carbon dioxide again escapes these “traps”. Limestone statues, for example, in Eastern Europe show this. These statues, truly great works of art, have been eaten away by acid rain.

Here’s the story. Before the end of the second war to end all wars, the Eastern European nations were open for travel, and the art in their architecture was free to see with breathtaking details and a true celebration of the human form. After the war, when the “iron curtain” fell, the prevailing governments restricted travel, and didn’t want to spend money, so they chose the inexpensive way to do, well, pretty much everything, including energy production. Most of their energy came from coal burning plants, and these coal burning plants used cheap coal contaminated with elements like sulfur. As the sulfur burned, it created sulfur dioxide and sulfur trioxide, which in water (like the water droplets in rain), it turns into sulfurous and sulfuric acid. This rain would react with the limestone, converting the calcium carbonate into calcium sulfate (which dissolved and was washed away) and carbon dioxide. Today, these same statues are humanoid in form and vaguely have faces left, but the art is gone.

Nope, if we want to save the planet, we must stop relying on these carbon reserves. Renewable energy and conservation. I fear that is the only way, whether we want to face it or not.