Photosynthesis and Energy

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How it works

Energy is very important and plays a substantial role in life itself, but where does energy come from, and how does energy work? Of course, the answer is simple: photosynthesis. With this reading, you will learn what photosynthesis is, how it works, the energy it creates, and how energy is stored and used. Finally, you will learn about different types of energy and the benefits those energy sources have.

The process of photosynthesis begins when a plant receives carbon dioxide from the surrounding atmosphere, which humans and animals output, to inhale oxygen. Once water reaches the plants, it is transferred from the leaves to the stem, which will eventually be united with sunlight. The green color of the leaf, also known as chlorophyll, traps energy. Finally, the energy delivered by the sun transforms the water into molecules of hydrogen and oxygen. (“A Step-by-step Guide to Understand the Process of Photosynthesis,” 2018)

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When the hydrogen and oxygen molecules are released, the hydrogen combines with the carbon dioxide to make food for plants, while the oxygen molecule is discarded. The discarded oxygen molecules are beneficial to any living organism that needs oxygen to survive. As far as survival goes, we humans need both oxygen and energy. Photosynthesis gives food or energy to the plants, but how does that help us as humans? It’s a sort of cycle: the plants get energy, which is transferred to humans either through consuming plants directly or consuming an animal that eats those plants. This is how energy reaches humans. (“A Step-by-step Guide to Understand the Process of Photosynthesis,” 2018)

The energy that we get from food enters our body and fuels our cells so that they can generate and maintain their biological order to stay alive. For our cells to extract energy from the food we eat, they must break down certain molecules such as proteins, lipids, and polysaccharides into smaller components during digestion. Proteins are broken down into amino acids, polysaccharides into sugars, and fats into fatty acids and glycerol. After the molecules have been broken down, any sugar molecules are converted to pyruvate molecules. During this conversion, two types of activated carrier molecules are produced: adenosine triphosphate, also known as ATP, and nicotinamide adenine dinucleotide, also known as NADH. The production of ATP redistributes the energy from the breakdown of sugars and fats into a form more convenient for use elsewhere in the body. (Alberts, 1970)

There are five different ways that energy can be stored in the body: ATP, Creatine phosphate (also known as PCr), glycogen, fat, and proteins. When it comes to muscle contraction, your body will use ATP, which is stored in the muscle itself and liver. Once that energy is used, it needs to be replaced, and that is where PCr comes into play. Creatine phosphate’s main job is to replenish the ATP that was previously used; unfortunately, there is only enough PCr in the body to last a few seconds. A prime example of this would be if you’re running and you use what seems to be your last bit of energy at the end to sprint to the finish line. Once both of these energies are depleted, the body has to replace them using its main source, which is carbohydrates. Glycogen, also known as your blood sugar, is stored in the blood and liver but is used in the muscle. Fat is your body’s emergency energy storage, but it needs oxygen to be converted and it is slower to refill when used. Protein does not act as a free energy source in the body; it is used in the muscles, primarily for muscle repair. (“Energy storage in the body,” 2012)

There are numerous different sources we use today to power various things like our cars or other vital parts of our lives, such as fossil fuels. Fossil fuels are the remains of dead animals or plants that the earth, over millions of years, has buried under dirt and rocks. The dirt, rocks, and heat from inside the earth, along with the pressure from being buried, transform these fossils into a sort of oil, natural gas, or even coal. Because these fossil fuels are created over millions of years, it takes a substantial amount of time for new fossil fuels to form. Hence, these sources cannot be renewed and are referred to as nonrenewable fuels. Once all of these nonrenewable energies are used up, they are gone for good. Currently, we are using fuels that were made about sixty-five million years ago. (“What are Fossil Fuels?” 2015)

As I stated before, there are three main sources of fossil fuels: coal, oil, and natural gases. Coal is primarily used in power plants and is found abundantly in Canada and also in the northern United States. There are two different places coal can be found: one is located closer to the earth’s surface (known as strip mines) and in mines that are buried deep below the earth’s surface. Power plants that use coal as an energy source make the turbines move by burning coal to create steam; this steam then causes the turbines to turn, generating energy. Another way to use coal is called Coal Coke, which is produced by baking coal in furnaces. Steel mills employ this method to smelt iron into steel. The higher temperatures needed for this process help the steel become more flexible, making it advantageous for creating bridges and other structures. (“What are Fossil Fuels?” 2015)(“Use of Coal,” 2018)

The next source of energy that we get from fossil fuels is oil or petroleum. This source is found in deposits below the Earth’s surface. Companies that require this oil or petroleum need to use drills to reach these deposits. The oil is then pumped from below using oil rigs. Once the oil has been acquired, it must be refined so it can be split up into different products we use on a daily basis. The crude black oil that gets drilled from below the Earth’s surface is split up for different products by being heated. These products that the oil is turned into can vary between gasoline, diesel fuel, and other fuels, to items such as toothbrushes and plastic bottles. (“What are Fossil Fuels?” 2015)

The final source of energy that is provided by fossil fuels is natural gases. Natural gases are made up of a highly flammable gas we know as methane, which is composed of hydrogen and carbon atoms. Natural gases are also extremely light compared to the air that we breathe. These gases are located close to underground petroleum deposits, with the most effective way of obtaining the natural gases being to pump them from below the surface and send them through a pipeline system. Natural gases are used all over the world, except in Bermuda because it isn’t considered economical to transport these natural gases through pipelines. However, the United States is able to safely ship propane gas to Bermuda because it is easier to transport under high pressure. (“What are Fossil Fuels?” 2015)

The advantages of fossil fuels are that we as humans don’t have a hard time finding or refining the product that is used to make oil. Fossil fuels are far more energy-dense than that of biofuels or electricity. But, of course, there are also disadvantages. The disadvantages of fossil fuels are that the very limited supply we have means that we will run out of them eventually. Once the source becomes limited, prices for the products will skyrocket, and eventually, they won’t even be available. (“The Chemistry of Biofuels” 2010)

Another source of energy that we use on an everyday basis is biofuels. These fuels are made from biological matter such as trees, agricultural wastes, crops, or grass. Biofuels are produced from all sorts of carbon sources that can be reproduced rapidly, the best example being plants. These fuels don’t contain sulfur and give off low carbon monoxide and toxic emissions. They are also a substitute for fossil fuels. Biofuels can increase energy security and reduce greenhouse gases by providing an alternative to fossil fuels. To better understand biofuels, we must also understand their history. (“What are Biofuels?”)

Biofuels have been around since the early 1800s. During this time period, camphene and alcohol were the most common fuels used for lamps. Although biofuels were definitely a viable source of energy, they didn’t become common until around the 1990s. Samuel Morey was one of the first people to run an internal combustion engine using alcohol, which occurred in 1826. Soon after, the first Otto-cycle to run using ethanol-infused alcohol was created by Nicklaus Otto in 1860. At the time of the civil war, alcohol was being taxed so heavily that the use of fossil fuels became much more common than that of biofuels. The tax hike on alcohol was eventually repealed by President Roosevelt to make ethanol more competitive. (“What are Biofuels?”)

As I pointed out previously, biofuels are made from plant or animal products. But how, you may ask? Some products of biofuel start by extracting sugars or starch from crops and begin the fermenting process to make the alcohol that is needed. Of course, other biofuels are made from the decaying of animals and plants and catching the gases that result from the decaying animals or plants. As I continue, you must know that there are three different generations of biofuels. The first generation is produced only from food crops, the second generation is called advanced biofuels, and the third generation refers to biofuels made from algae (“The Chemistry of Biofuels”, 2010).

The first generation of biofuels contains products that are directly produced from food crops such as corn, sugar cane, soybeans, and vegetable oil. Corn is most certainly the most used for the world’s supply of ethanol and most of that corn used comes from the United States. Sugar cane falls in as a close second when it comes to the primary source for the production of ethanol. Second-generation biofuels are a little harder to explain. The difference between first and second generation biofuels is that the feedstock for second generation biofuels are not used for food crops. For example, waste vegetable oil would be considered a second-generation biofuel because it was already used as a food source and is no longer needed. The third generation biofuels are fuels produced by algae. The list of fuels that can be made from algae is astounding. Algae can produce fuels like biodiesel, butanol, gasoline, methane, ethanol, vegetable oil, and jet fuel. On top of the long list of fuels that algae can make, it can also produce outstanding yields. Numbers like 9,000 gallons of biofuel per acre (“The Chemistry of Biofuels”, 2010).

The advantages of biofuels are unlike fossil fuels. They are a renewable energy source because crops or algae are used, it can be considered an unlimited resource. Biofuels can be more friendly to our environment if they are produced in a careful manner. If biofuels are produced in the correct way, they can reduce greenhouse gases. These fuels are much safer than fossil fuels because biofuels are biological molecules which means they are biodegradable. Another advantage of biofuels is it can be made completely sulfur-free so there is no side effect like acid rain that you get with fossil fuels when burning coal (“The Chemistry of Biofuels”, 2010).

The disadvantages of biofuels are that they are now being grown regionally because some plants and crops just grow better in more suitable climates than others, so we can’t grow everything right where we need it. Also, when watering plants, the less we need the better because water is very limited so growing plants or crops in the right regions makes it much easier for the plant to survive on what little water may be given if it’s in the perfect climate. There is only so many places that crops can be grown and of course, feedstock is a major player in the game of biofuels. Burning biofuels contributes to global warming because they are mostly made up of carbon and hydrogen molecules and produce carbon dioxide. Biofuels are among the promising replacements for fossil fuels, unfortunately, they are not a permanent fix. They will only slow global warming, not stop or reverse it (“The Chemistry of Biofuels”, 2010).

In conclusion, there are so many factors that go into energy and our lives. Life on earth would be a much different place if we didn’t have these sources of energy. Something as tiny as sunlight and photosynthesis, which simply give us the oxygen we need to survive, is mind-blowing. These plants and sunlight not only give us oxygen but also energy to go about our everyday lives. Learning about the differences between fossil fuels and biofuels, the products used to make them, and the various types we use in this day and age that are provided from these two large energy sources is intriguing. Moreover, understanding the numerous types of energy we have, their various uses, where in the body they are stored, adds another level of appreciation. It’s not just mind-blowing to learn all these different processes I thought I already knew; it’s fascinating to delve deeper and learn more than I anticipated.


“A Step-by-Step Guide to Understanding the Process of Photosynthesis.” BiologyWise, BiologyWise, 16 May 2018,

Alberts, Bruce. “How Cells Obtain Energy from Food.” Current Neurology and Neuroscience Reports, U.S. National Library of Medicine, 1 Jan. 1970,

“Energy Storage in the Body.” LoneSwimmer, 1 Oct. 2012,

“What Are Fossil Fuels?” What Is Electricity?, 2015,

“Use of Coal.” Factors Affecting Gasoline Prices – Energy Explained, Your Guide To Understanding Energy – Energy Information Administration, 13 July 2018,

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“What Are Biofuels?” Biofuels – Creative Discovery Museum,

“The Chemistry of Biofuels.”, 2010,

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Photosynthesis and Energy. (2019, Sep 17). Retrieved from