ENERGY 101 -
Before you woke this morning, you were using energy, as quiet in bed you that may have appeared. Not only was your body and brain using energy just to remain alive, but you likely had energy being used by your support systems -- home heating/air conditioning, refrigerator, smartphone, waterheater, etc. The food you ate yesterday to keep you alive today had some element of energy used in growing it, packaging it, preparing it, and transporting it to your store/home or restaurant where you ate it. There is a complex system of energy expenditure to keep us at a basic level of life. Then, there's the energy we use once we're awake and active, including work, travel, exercise, and special interests or hobbies.
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We now consume energy at rates far above that of our ancestors. Ancestral man, with a slighter stature and population insignificant in comparison to ours today, had little impact on energy available to him at the time. His energy needs in a foraging societies were primarily filled by the provision of food, and his annual consumption averages did not go above 5–7 GJ/capita. Per capita, it's likely on an order of 25 to 30 times greater today, as we rely on huge energy resources such as petroleum to support our lifestyles. On its own, this would not be significant with respect to Earth's sustainability were it not coupled with a huge human population today of about 8 billion vs. maybe hundreds of thousands of humans in early ancestral times. Ancestral man relied primarily on energy simultaneously derived from the sun in the form of plants (photosynthesis) and animals which also consumed energy largely via photosynthetically derived foods.
No other creature is more dominant now in energy use than humankind.
So, let's have a quick review.
Energy is all around us, either in use moving things, being moved, or ready to be used (kinetic). We can't live without it, but we can live better by using it more responsibly. Human life on Earth will survive if we minimize fossil fuel use, maximize renewables, and practice energy conservation.
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By 2015, fossil fuels still accounted for 86% of the world’s primary energy, just 4% less than a generation ago, in 1990.[En1-1]. By turning to these rich stores we have created societies that transform unprecedented amounts of energy. This transformation brought enormous advances in agricultural productivity and crop yields; it has resulted first in rapid industrialization and
urbanization, in the expansion and acceleration of transportation, and in an even more impressive growth of our information and communication capabilities; and all of these developments have combined to produce long periods of high rates of economic growth that have created a great deal of real affluence, raised the average quality of life for most of the world’s population, and eventually produced new, high-energy service economies.
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Fossil fuels are considered non-reneweable in that their natural creation time requires millions of years. Fossil fuel is a naturally occurring carbon compound found in the Earth's crust that has been produced by anaerobic (without free oxygen) conditions and high pressures acting upon dead organisms - yes organisms whose life and energy originally came from the sun. Typically found at depths beneath the Earth surface or ocean floor of tens of meters to kilometers, these fossil fuel deposits are often occur in large agglomerations of gas, liquid or solid matter - millions of years worth of stored sun energy.
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So, just what is energy? We can't see it, smell it, or taste it, but it is essential for life. Energy is described as the capacity of doing work. That's a clue -- if energy is used, some action takes place. In fact, energy is always associated with motion. Even if we don't see motion, an object at rest will have potential energy that can be changed to kinetic energy in an object in motion. Energy can be transferred from one form to another. For example, an electric heater transfers electrical energy to heat energy, The first law of thermodynamics states that energy cannot be created or destroyed, it can only be changed from one form to another. This principle is known as the conservation of energy.
The largest contributor to Earth energy is the sun. Some 71% of solar energy directed at Earth is absorbed by the Earth's systems, the remaining 29% is reflected back and never enters the Earth's atmosphere. At any moment, about 16,300kwh of solar energy arrives on Earth for every person. Only a third of that falls on land, yet that's still 2,000 times as much as we need per person. Solar panels covering less than 0.01% of the land area could supply all of our energy needs. There are some technical limits to that, like replacing jet fuel and some distribution issues; however, with solar costs coming down, and better efficiencies still on the horizon, although not a perfect solution for all of our energy, it is quick and significant.
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Of the sun's energy that lands on our planet, around 2% is converted into wind energy,[En1-3] mostly inaccessible, high up in the jet stream. Most of the low-altitude wind is far out at sea, too far for offshore wind farming. Even on land and coastal waters, only a small part can be harnessed because of geographical constraints. A wind farm larger than 10 turbines can generate only around 1 Watt per square metre of land. And wind doesn't blow in concert with our electrical needs.
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From 2005 through 2019 the world increased energy production by 28%. Unfortunately, most of that increase was in fossil fuels. Moving to renewables at a rate sufficient to reduce CO2 emissions is difficult as long as a growing population is supported with growing energy production primarily fossil in fuels.
Footnotes
[En1-1] bp Statistical Review of World Energy 2021
[En1-2] Helmenstine, Anne Marie, Ph.D. "10 Types of Energy and Examples." ThoughtCo, Feb. 16, 2021, thoughtco.com/main-energy-forms-and-examples-609254.
[En1-3] Smil, Vaclav. Energy Transitions: Global and National Perspectives, 2nd edition, Praeger, 2016