Understanding the technology in the world is a way that we can gain a level of control in our lives. Choices we make about the products and services we choose can be more informed, satisfying, and economical. Among the four major forms of technology, I discuss in this column – transportation, production, communication, and energy – energy technology enables us to enjoy consumer products, has an influence on prices we pay, and greatly impacts the environment we live in. Among the different types of energy, renewable energy has evolved into a technical term we hear nearly daily about in the news and product advertisements.

Remember that “renewable” energy sources are those that can be renewed, or produced, repeatedly. They are not “inexhaustible” in the sense that they last forever, like the sun or wind or rain, but in a theoretical sense they can be renewed repeatedly, forever. Renewable energy comes from plants and animals that are still living or have lived in recent history. These plants and animals are used for the biological material they produce, particularly the element of carbon.

Carbon is a unique element because of how it can combine with other atoms and energy in a variety of special ways. It has especially great relationships with two other famously powerful elements: oxygen and hydrogen. These three elements provide the building blocks for all sorts of energy sources that we rely on to power our world. The continuous movement of carbon, typically attached to either oxygen, hydrogen, or both, throughout the Earth and atmosphere is called the carbon cycle. The carbon cycle is another one of those technical terms that is good to understand, since it serves as the foundation for so many sources of energy.

The carbon cycle is continuous, like a merry-go-round, so let’s pick a point to jump onto the ride while we follow the carbon – the carbon in the atmosphere. Carbon is flying around in our atmosphere mostly attached to oxygen in the form of carbon dioxide. That’s one carbon atom attached to two oxygen atoms. Carbon dioxide (CO2) makes up approximately 0.04% of the Earth's atmosphere. While this seems like a small amount, even a small percentage of CO2 can have a significant impact on the climate due to its greenhouse gas properties. Luckily for us, and perhaps the most amazing thing about carbon, oxygen, and hydrogen is how they are involved with the sun and plants in the process of photosynthesis. Let’s take a moment to remember photosynthesis.

Photosynthesis occurs inside chloroplasts, which are inside the cells, of plants when energy from sunlight is absorbed by chlorophyl in the chloroplasts and is used to build complex chains of carbon and hydrogen molecules. You may think of these complex chains like long, complex stacks of different Lego building blocks that are all snapped together, with the sun providing the energy for the construction. These long chains are called — you guessed it — hydrocarbons. And plants store up millions of billions of hydrocarbon molecules in their leaves, branches, trunks, and roots.

Okay, now back to the carbon cycle. Once fixed inside of a plant there are many paths that the carbon can take.

The plant may be eaten by animals (including humans), and the carbon eventually is either exhaled back into the atmosphere as carbon dioxide or passed out, still as a hydrocarbon, in urine and feces. Remarkably, human and animal waste can be used to produce methane (which is hydrocarbon) that can be burned for fuel or used to make fertilizers or soils to feed more plants.

Plants may be harvested by humans to make products, such as furniture or fabrics, in which case the carbon is trapped until that product is disposed of in a landfill. There the carbon will remain trapped for a long time until the product decays when eaten by bacteria and fungus, producing methane which is a type of hydrocarbon. Bacteria and fungus will absorb carbon as a nutrient from dead plants and animals and decompose them as they eat. Some landfills are equipped with technology to collect and burn the methane, releasing it back into the atmosphere. Unburned methane is a very destructive greenhouse gas.

Dead plants may be used as fuels to burn, either directly or indirectly. Wood can be made into charcoal for burning or burned directly. Corn, soybeans, sorghum, and other plant crops can be put into a digester where bacteria and fungus can create liquid methanol which can be added to gasoline to make gasohol. Once burned in a car the carbon will return to the atmosphere as carbon dioxide or carbon monoxide.

Many plants just die and fall back to Earth. Plants that die and get buried under ground, under very specific conditions and after extremely long periods of time, can turn into coil, oil, and natural gas. And hopefully by now you know that when these “fossil fuels” are burned for energy they release massive amounts of carbon back into the atmosphere.

We have now completed the carbon cycle full circle, following carbon in its loop until it gets back to where it started. Whew, what a journey. No wonder we have a hard time comprehending all this! Stay tuned in while we continue learning about technology and how it impacts our lives.

Kurt Wolter has studied and taught technology, including production, transportation, energy, and communication, for over 30 years. He enjoys trying to understand technology and its past, present, and future while also attempting journalism. He can be reached at technohistory100@gmail.com.