A Guide To The Energy Of The Earth

Understanding Energy and Its Laws

Energy is a ubiquitous physical quantity that adheres to precise natural laws. Our universe contains a finite amount of energy which is neither created nor destroyed but can be transformed into different forms such as kinetic or potential energy. Each form of energy has unique properties and formulas. For instance, a 6 Watt bulb in an LED desk lamp transfers 6 Joules of light energy per second.

Energy Flow in Earth’s Systems

Energy is integral to the functioning of our planet and its systems, including the atmosphere, hydrosphere, lithosphere, and biosphere. Energy moves in and out of these systems, and during any energy transfer between them, some energy is inevitably lost to the surroundings in the form of heat, light, sound, vibration, or movement.

Sources of Earth’s Energy

Our planet’s energy comes from both internal and external sources. Internal sources include geothermal energy from radioactive isotopes and rotational energy from the spinning of the Earth. The Sun, however, is the major external source of energy, driving systems like our weather and climate. Sunlight warms the surface and atmosphere in varying amounts, causing convection, producing winds, and influencing ocean currents. Infrared radiation radiating out from the warmed surface of the Earth gets trapped by greenhouse gases, further affecting the energy flow.

The Sun as a Source of Energy for Organisms

The Sun is also the major source of energy for organisms. Plants, algae, and cyanobacteria use sunlight to produce organic matter from carbon dioxide and water, powering the biosphere’s food chains. We release this food energy using chemical reactions like combustion and respiration. At each level in a food chain, some energy is stored in newly made chemical structures, but most is lost to the surroundings as heat, like your body heat, released by your digestion of food.

Energy Flow in Food Chains

As plants are eaten by primary consumers, only about 10% of their total energy is passed on to the next level. Since energy can only flow in one direction in a food chain, from producers on to consumers and decomposers, an organism that eats lower on the food chain is more efficient than one higher up. So eating producers is the most efficient level at which an animal can get its energy. However, without continual input of energy to those producers, mostly from sunlight, life on Earth as we know it would cease to exist.

Human Energy Consumption

We humans spend our energy doing a lot of things besides eating. We travel, we build, we power all sorts of technology. To do all this, we use sources like fossil fuels: coal, oil, and natural gas, which contain energy that plants captured from sunlight long ago and stored in the form of carbon. When we burn fossil fuels in power plants, we release this stored energy to generate electricity.

Generating Electricity

To generate electricity, heat from burning fossil fuels is used to power turbines that rotate magnets, which in turn create magnetic field changes relative to a coil of wire, causing electrons to be induced to flow in the wire. Modern civilization depends on our ability to keep powering that flow of electrons. Fortunately, we aren’t limited to burning non-renewable fossil fuels to generate electricity. Electrons can also be induced to flow by direct interaction with light particles, which is how a solar cell operates. Other renewable energy sources, such as wind, water, geothermal, and biofuels can also be used to generate electricity.

The Importance of Energy Efficiency

Global demand for energy is increasing, but the planet has limited energy resources to access through a complex energy infrastructure. As populations rise, alongside rates of industrialization and development, our energy decisions grow more and more important. Access to energy impacts health, education, political power, and socioeconomic status. If we improve our energy efficiency, we can use our natural resources more responsibly and improve quality of life for everyone.