In a documented essay of 600 - 900 words please address the following questions, in your own words: * First discuss how energy can be converted from one form to another, giving specific examples * Define what we mean by fossil fuels and explain why there are an attractive source of energy * Describe two different energy alternatives to fossil fuels in detail. Discuss how they work, how they compare with fossil fuels, and their relative advantages and disadvantages.
"Energy can be defined as the ability to do work" (Tillery, B., Enger, E., Ross, F., Integrated Science 2009 Custom Edition, Page 59). In strict scientific terms, it is classified into two main forms: kinetic energy and potential energy. Kinetic energy is defined as the energy of a moving object. Examples include a swinging pendulum, a thrown ball, and a piece of paper blowing in the wind. Potential energy is defined as the energy in matter due to position. It is typically referred to as ‘stored’ energy such as the energy in a spring or a stretched elastic band. There are actually various forms of potential energy including gravitational potential energy, elastic potential energy, chemical potential energy, and electrical potential energy. “Energy can be categorized into five forms: (1) mechanical, (2) chemical, (3) radiant, (4) electrical, and (5) nuclear” (Tillery, B., Enger, E., Ross, F., Integrated Science 2009 Custom Edition, Page 62). Mechanical energy is the energy created by the physical movement of an object. Chemical energy is that which is “released during a chemical reaction” (Tillery, B., Enger, E., Ross, F., Integrated Science 2009 Custom Edition, Page 62). Radiant energy “is the energy of electromagnetic waves” (www.sciencedaily.com/articles/r/radiant_energy.htm). Electrical energy “is another form of energy from electromagnetic interactions” (Tillery, B., Enger, E., Ross, F., Integrated Science 2009 Custom Edition, Page 63). Nuclear energy is “…the energy released by a nuclear reaction” (wordnetweb.princeton.edu/perl/webwn ). Kinetic energy can be converted to potential energy and potential energy can be converted into kinetic energy. “Any form of energy can be converted to another form “(Tillery, B., Enger, E., Ross, F., Integrated Science 2009 Custom Edition, Page 64). List of examples of energy conversions:
1. Electric Generator (Mechanical Energy into Electrical Energy) 2. Electric Motor (Electrical Energy into Mechanical Energy) 3. Steam Engine (Heat Energy into Mechanical Energy)
4. Diesel or Petrol Engine (Chemical Energy into Mechanical Energy) 5. Stove (Chemical Energy of oil or LPG into Heat Energy)
6. Electric Bulb (Electrical Energy into Heat and Light Energy) http://wiki.answers.com/Q/List_of_examples_of_energy_conversions#ixzz1KTFKGRsB 7. Solar Cell (radiant energy to mechanical energy)
There are various sources of energy and these possess a multiplicity of functions. Today energy is used as a source of production. Currently petroleum, coal, and natural gas are the most widely used energy forms. These three energy sources are referred to as fossil fuels. “It was estimated by the Energy Information Administration that in 2007 primary sources of energy consisted of petroleum 36.0%, coal 27.4%, natural gas 23.0%, amounting to an 86.4% share for fossil fuels in primary energy consumption in the world” (http://en.wikipedia.org/wiki/Fossil_fuel) “Fossil fuels are fuels formed by natural resources such as anaerobic decomposition of buried dead organisms” (http://en.wikipedia.org/wiki/Fossil_fuel). They are extremely attractive because “they can be burned (oxidized to carbon dioxide and water), producing significant amounts of energy per unit weight” (http://en.wikipedia.org/wiki/Fossil_fuel). While fossil fuels are most widely used, alternate forms of energy are currently being sought after because these fuels are non-renewable and pose a threat to the environment. Two examples of these alternatives sources include solar energy and hydrogen. Solar energy is derived from radiant light and heat from the sun. Currently there are two methods used for solar energy conversion: the solar thermal method and the photovoltaic method. Both require the use of solar panels to collect heat from the sun. The solar thermal method is currently the most popular form of solar panel available. It uses the sun’s energy to directly generate heat. Solar panels are used to collect the heat from the sun. This heat is captured and then transferred to water tanks for heating and distribution through the rest of the house. This means that production maximizes absorption of the heat generated by sun throughout the day, so energy is available for night time use as well. Thermal collectors (tubes) are used to absorb this energy. “The in-direct alternative to this production method is using anti-freeze instead of water. Once the sun has warmed this liquid, the heat gained from this process is transferred to water held in a tank.” (http://www.biofuelswatch.com/how-does-solar-energy-work/)
“The photovoltaic method directly transfers the sun’s power into electricity. This process uses solar cells, or photovoltaic cells to trap the sun’s heat. They are often silicon-based with wide surface area for maximum heat absorption from the sun’s rays. This method traps electricity directly, instead of using the warmth created from the sun in the thermal method. The number of these cells which is contained in one panel differs depending on the size of the panel, but these cells can be interlinked and combined for a greater production power” (http://www.biofuelswatch.com/how-does-solar-energy-work/). While there are two methods of production, they differ in two other ways: direct and indirect energy. They are dependent on the methods used to harvest the sun’s rays. In the case of direct solar power only one step is used to transform sunlight into usable energy. This is the electromagnetic radiation method. Examples include solar cells, power towers, or fiber optic cables which absorb sunlight. Indirect solar energy involves more than one process in order to obtain usable solar energy. Biofuel/biomass is an example, as it is made from plants which use photosynthesis to harvest the sun and convert it into chemical energy. Hydroelectric dams and wind turbines also function through indirect solar means, as water and wind can be sun powered. Ocean thermal energy conversion (OTEC) is an indirect result of solar power, as the sun warms the ocean and causes different wave movements with the help of the wind. In addition to these types of technologies there are also active and passive systems/applications. Active applications require a solar collector “in which sunlight heats air, water, or some liquid. The liquid or air is pumped through pipes in a house to generate electricity, or it is used directly for hot water” (Tillery, B., Enger, E., Ross, F., Integrated Science 2009 Custom Edition, Page 70). Passive applications only require direct sunlight without the aid of additional energy.
Solar energy as an alternate source of energy has many advantages. The power source of the sun is absolutely free, production produces no pollution; after the initial cost, it is cost effective; most systems do not require any maintenance during their lifespan, which means you never have to put money into them; most systems have a life span of 30 to 40 years; most systems carry a full warranty for 20 to 30 years or more; in 35 states, solar energy can be fed back to the utilities to eliminate the need for a storage system as well as eliminating or dramatically reducing your electric bills; and they can be custom made for the consumer’s particular needs. “The primary disadvantage to solar energy is the upfront cost”. In addition to this “a solar energy installation requires a large area for the system to be efficient in providing a source of electricity. Pollution can be a disadvantage to solar panels, as pollution can degrade the efficiency of photovoltaic cells. Solar energy is only useful when the sun is shining. The location of solar panels can affect performance, due to possible obstructions from the surrounding buildings or landscape” (http://www.clean-energy-ideas.com/articles/disadvantages_of_solar_energy.html). Hydrogen is a diatomic gas” that can be used for energy directly in a fuel cell or burned to release heat” (Tillery, B., Enger, E., Ross, F., Integrated Science 2009 Custom Edition, Page 70). It is very high in energy. In the case of a fuel cell, hydrogen and oxygen are combined to produce electricity, heat, and water. “Fuel cells are often compared to batteries. Both convert the energy produced by a chemical reaction into usable electric power. However, the fuel cell will produce electricity as long as fuel (hydrogen) is supplied, never losing its charge” (http://www.renewableenergyworld.com/rea/tech/hydrogen).
While hydrogen is high in energy, it exists in limited supply – in trace amounts. It must therefore be obtained by a chemical reaction. Rather than being used to produce energy, it can be used as a means to store energy for later use, thus acting as a transporter of energy. Both of these alternative sources of energy have their advantages and disadvantages. In comparison to