Tag Archives: photosynthesis

In Defense of Carbon

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Carbon is the basic building block of life.  It is an element, indestructible.  We have the same amount of carbon on earth now as always.  It goes through a cycle.  Because it is so versatile, it can join with numerous other atoms to create complex structures.

I’m a climate change agnostic.  I know the climate changes every day and every season.  Whether human beings are changing the climate in a significant way is the subject of heated debate.  I do know humans are poisoning the environment, but the most dangerous chemicals involved are not carbon dioxide or methane.  These two are naturally occurring substances that are intimately involved in the cycles of life and death.

Organic chemistry is based on whether the compounds under study contain carbon.  Photosynthesis is the means by which plants use energy from light to convert water and carbon dioxide to food for the plant.  In this process, water is hydrolyzed (meaning broken down into its constituent atoms) with the hydrogen joining with carbon to form sugars, such as glucose and sucrose.  The sugars contain energy that fuels plant growth, maintenance and manufactures the substance of the plant itself, like cellulose.

That plants can make their own food from light, carbon dioxide and water is a marvel of solar technology, because all food ultimately comes from plants.  The mechanism of photosynthesis, according to my botany text (Botany:  An Introduction to Plant Biology, 6th edition, T., Elliot Weier, et al., 1982) took almost 200 years to be understood, and it still contains undiscovered secrets.  Researchers are now working on harnessing the 100% efficiency of plants to make electricity.  In contrast, solar panels are only between 15-20% efficient.

According to Botany, a series of discoveries beginning in 1700 led to the eventual understanding of how photosynthesis works.  In 1700, a Flemish physician and chemist Jan van Helmont grew a willow branch in measured soil and water.  It grew from five to 169 pounds in five years, but used only two ounces of soil.  In 1772, Joseph Fleming noted a sprig of mint could restore confined air that had been made impure by burning a candle, but in 1779 Jan Ingen-House noticed air was only revitalized when the green portion of the plant was exposed to light.  In 1782, Jean Sonebier discovered carbon dioxide was necessary in the “fixed air” supply of the green plant, and in 1796 Ingen-House determined the carbon went into the nutrition and structure of the plant.  In 1804, Nicholas Th. de Saussure observed water was also involved in the photosynthetic process, and in 1800 chemists discovered that carbohydrates were formed.  Experiments using “heavy oxygen” (oxygen with atomic weight of 18 rather than the usual 16) proved the oxygen liberated in photosynthesis came from water rather than CO2.

The basic chemical reaction for converting carbon dioxide and water to glucose is:

6CO2 + 6H20 +686 kcal –> C6 H12 O6 + 6O2

The oxygen is released into the atmosphere.  Plants also release water vapor through evaporation, and this induces liquids and nutrients to move upward through the xylem (the plant’s substance, including transportation “vessels”).

The glucose produced is used directly, or stored as insoluble starch.  It’s used to make cellulose and other structural components, or is combined with nitrogen, sulfur or phosphorus to make proteins.

When a plant or any life form dies, the stored carbon is either consumed by another life form or it is released as CO2 and methane (CH4), among other substances.

Igniting the hydrocarbon molecules reverses the photosynthetic process in a one-to-one ratio.  CO2 and water are re-created, and the energy bound up in the molecule is released as heat or used to do work.

The chemical reaction when the simplest hydrocarbon, methane (natural gas), is burned is:

CH4 + 2O2 –>  CO2 + 2H2O

Natural gas, oil, coal, ethanol, and plastic, to name a few, have the same carbon and hydrogen building blocks, in different combinations.  All have high energy contents and produce CO2 and water when burned.

Ethanol—which is now a federally mandated gasoline additive—has a lower energy content than gasoline so lowers gasoline efficiency. Ethanol, also called “ethyl alcohol,” is old-fashioned grain alcohol, the same substance distilled by farmers in Revolutionary War days, and the stuff that led to the Whiskey Rebellion when the whiskey tax was passed in 1791.

Plastic has a high energy content and burns hot.  Plastic waste is accumulating around the planet, in huge ocean “gyres,” as well as other bodies of water, sewage and drainage systems.  Its breakdown products are associated with endocrine (hormonal) changes in people and animals.

The main weakness of the climate change initiative is that the focus on “greenhouse gases” diverts attention from more immediate and ongoing threats to the planet.  The use of single-use packaging, for instance, uses valuable natural resources, such as paper, and environmentally harmful industrial products, such as plastic, that end up in landfill or in rivers, lakes, and oceans.

The ethanol mandate, passed in 2007, is a particularly toxic piece of legislation.  Under this scenario, farmland is used to produce corn, soy, or other carbon-containing plant matter, to be distilled into alcohol for burning in cars.  Not only does this deplete soil that might otherwise be used to grow food, but it requires massive amounts of water, time and money, so is a pox on the planet and on the engines that use it. It is particularly harmful in small engines, like lawnmowers, so conscientious users must use ethanol-free gas to protect their engines.  That Archer Daniels Midland, the main corporate beneficiary of the ethanol mandate, is set up to distill ethanol for cars as well as ethanol for drinking, should provide clues as to how regressive this mandate is.

In summary, I contend that, “climate change” includes changing the political climate to recognize that growing trees is better for the planet than giving corporations “carbon credits” not to cut them down.

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