All living things need energy to stay alive. The difference lies in the source of energy used. Plants get energy from the sun when their leaves soak in the sunlight and then use the energy to convert carbon dioxide and water into food. Herbivores then feed on the plants to obtain the energy from the plants they eat while carnivores get their energy from the plant eaters. This food chain powers the earth and can be also known as an energy chain.
Humans also need energy, not only for our lives, but in order to power our homes, cook our food, provide transportation and power our industries. For most of history, energy has come cheap, but there is a price to pay. Energy comes at a high cost, not only in dollars, but to the environment. Dangers include radioactive waste, acid rain, deforestation, and even flooding. The change to our global climate however is the biggest hazard. Striking the right balance between our energy needs and ensuring future supplies without damaging the environment is the goal.
Issues that may lead to environmental changes cannot be mentioned without paying attention to the controversial topic about energy, its uses and its effects on human health and the environment. Energy is evident in our daily lives in a variety of ways. It is essential for existence. The supply of energy as it transmits throughout the world varies in production, supply and use depending on the community. Aside from the energy received through food, fueling the living population, it is also necessary for the functioning of a technologically driven community.
Energy is the ability to do work. Divided into two types, potential and kinetic, it makes everything happen. Stored energy is called potential energy, while moving energy is known as kinetic energy. Within its two types, it is found in many different forms. It can be chemical energy, electrical energy, thermal energy, radiant energy, mechanical energy and nuclear energy. Alternative energy sources are neither based on splitting atoms or fossil fuels because these forms have damaging effects on the environment. Examples of such forms include solar energy, wind energy, hydropower, thermal energy, biomass and biofuels.
Energy is often categorized as either renewable or non-renewable. This, however, can be misleading, since all sources of energy are renewable, but they are renewable on widely different time scales. Fossil Fuels, for example, renew over millions of years in comparison to wind or biomass which renew on a daily to yearly scale. Another way to sort these is by income and fund. Fund resources can be withdrawn from at any rate and therefore are often drawn from much faster than they can be replenished like fossil fuels and nuclear isotopes. Income resources are in a relatively continuous supply and routinely replenish, however, we are limited at how fast we can use them. Due to the differing time scales, we commonly use the term non-renewable for fossil fuels and fissionable isotopes since they do not replenish at a useful rate for man in comparison to the term renewable in which we use to describe such sources as the sun and wind which replenish on a daily basis. Most importantly, whether you categorize energy in terms of renewable and non renewable or income and fund, all forms of energy, at some point in time, produces some environmental consequence. All choices have consequences and in order to make informed decisions, careful consideration to these consequences must be weighed. For the nature of discussing energy in the classroom to young minds, the background knowledge below classifies energy sources as either non renewable or renewable. It is vital to remind the students that energy is often classified as such based on the scale of time it takes for the energy source to renew.
Energy from nuclear power produces less air pollution than the burning of fossil fuels, however are considered more dangerous in the case of an accident. Nuclear energy is formed when a plutonium or uranium atom is split, gets bombarded by neutrons and then spilts again. Energy is released in the form of heat and the heat is then used to produce steam or generate electricity. When things go wrong however, in the case of an explosion at a nuclear plant, radioactive material is released into the environment causing widespread damage, unfavorable living conditions, health problems and even death. Although the immediate impact of nuclear fission has the least impact on the environment, it is perhaps the most potentially catastrophic in the event something goes wrong. (McLeish, "Energy Resources: Our impact on the Planet," 12-30.)
Chemical energy is the energy that is stored in atoms and molecules and released in a chemical reaction, most often heat, known as an exothermic reaction. Examples of stored energy include batteries, coal, natural gas, petroleum and biomass. This stored energy undergoes a chemical reaction then converts into thermal, light or sound energy. For example, the wood in a fireplace is stored chemical energy, but when it is ignited the energy released is transformed into heat or light energy. Fossil fuels, biomass and biodiesel are subsets of this energy source.
Fossil fuels, which are formed by preserved remains of trees, plants and microscopic remains of animals, provide the world with about seventy-five percent of its energy. When fossil fuels burn, the carbon combines with oxygen to become carbon dioxide. This is where issues of environmental hazards occur. First, the fossil fuels are used more quickly than it took for them to be formed and the carbon dioxide levels in the atmosphere then rise. Additionally, the transportations of fossil fuels raise concerns with water pollution and neighboring ecosystems in the event of a spill. Fossil fuels however will eventually become depleted and it's hard to tell exactly how much oil, coal and gas will remain available for use and how long we will have access to them. It therefore becomes necessary to start looking into alternative renewable resources to "power" our planet.
Biomass is a renewable source of energy formed from wood, plants and animal material. The issues with this type of energy is that it requires a vast amount of land space taking over the land usually used for food, as well as the wood for heat and cooking. Biomass also emits an extensive amount of greenhouse gases similar to that of coal and oil. This is because when biomass is burned the carbon dioxide released is eventually absorbed into the atmosphere, oceans and soil.
Biodiesel is a renewable energy source that is made from vegetable oils and animal fats. Most biodiesel is made from soybean oil. The biodiesel is then blended with low amounts of petroleum. It is non toxic and biodegradable producing fewer air pollutants like carbon monoxide, sulfur dioxide and hydrocarbons. On the other hand, there is an increase in the emissions of nitrogen oxides. Comparatively with petroleum diesel, biodiesel is a cleaner choice. (McLeish, "Energy Resources: Our impact on the Planet," 12-30.)
Electricity is a secondary energy source as we get it from the conversion of other sources such as coal, gas, oil, nuclear power or other natural sources of energy such as biomass. Electricity's applications are nearly limitless, as it is used in heating, lighting, communication and transportation to name a few.
Geothermal energy is heat that is generated from within the Earth's core. This heat can then be captured as steam or water and used to heat buildings or generate electricity.
These geothermal reservoirs occur naturally, but can gradually find its way to the Earth's surface in the forms of volcanoes, hot springs or geysers. The most geothermal activity occurs in an area that encircles the Pacific Ocean known as the Ring of Fire. Most of the geothermal power plants in the United States are located western states such as California, Nevada, Utah, Oregon and Hawaii. Geothermal plants' emission levels are very low, so they release less than one percent of the carbon dioxide emissions of a fossil fuel plant. The geothermal systems that get energy from lakes and rivers can be considered renewable, in comparison to the systems that get energy from traps. This type of system could only be renewable on a time scale of thousands of years. Geothermal systems can also upset the geological strata and lead to earthquakes.
Solar energy is energy that has been produced by the sun and can then be converted directly and indirectly into another form of energy such as heat and electricity. Solar energy is used for heat, agriculture and generating electrical energy. Although renewable, solar energy does have its drawbacks, such as its intermittent timing in reaching the Earth's surface and the large area required to collect it at a useful rate. Solar energy is also expensive in its conversion via photovoltaic cells. Any solar radiation that we use for energy does contribute to global warming because it is unable to reflect back to space, although not nearly as much as the combustion of fossil fuels.
Wind power is simply energy generated from moving air. Since the Earth's surface is heated irregularly it absorbs the sun's heat at different rates. The type of land and location determine the rate at which it heats. Wind energy is used to generate electricity but although renewable is not fully reliable, because it can be used only as long as the sun shines. Wind Turbines use blades to collect the wind's kinetic energy to create electricity. The wind travels over the blade which creates "lift." The blades connected to a drive shaft then turn an electric generator. This renewable resource requires careful planning in its location where high altitude is necessary like the tops of a rounded hill, open plains, shorelines and mountain gaps. Although wind speed varies depending on location, this energy source has fewer environmental issues. Wind turbines do not release emissions, and can reduce the amount of electricity produced from fossil fuel power plants. On the other hand, their size is very large and can disrupt the physical landscape of an area. Some even complain about the noise caused by the wind turbine blades. It can also be detrimental to wildlife. Wind is also contingent on global circulation which is dependent on ocean currents.
Hydropower is a renewable energy source that relies on the water cycle; where solar energy heats surface water causing evaporation, this water vapor condenses into clouds and then falls back to the surface in a form of precipitation which eventually flows through rivers and back to the oceans where it evaporates and begins the cycle again. The amount of energy derived from water is dependent on its flow. Water that moves fast from a high peak or forcefully through the water will produce more energy as it eventually is captured to turn blades in a turbine which spins a generator to produce electricity. The hydropower is produced in large facilities built by the federal government located mostly in Washington, Oregon and California. Although this electricity is considered clean energy it does present some environmental problems. Hydropower dams may obstruct fish migration and changes the natural temperature, flow and chemical properties of the water which negatively impacts its native plants and animals. Greenhouse gases like carbon dioxide and methane are also released from hydropower reservoirs and generators in amounts that can measure nearly equal to the amount generated by fossil fuels. Drought and land use change, can severely affect weather patterns. Hydropower also destroys large land areas and alters the natural flow of water (Energy Kids, http://www.eia.gov).
Enormous amounts of energy found in the sources mentioned above are used to power transportation, provide heat, generate electricity and manufacture goods in order to keep a community in flux. With this overconsumption come challenges. Part of this challenge lies in the choices made in the development and powering of the community that will not only match the energy needs of the population but is also environmentally sustainable.