Renewable Energy Sources
Everyday, energy is used for several purposes like lighting, running machines, transportation, commercial operations and other industrial and household purposes. With the level of technology nowadays, people rely heavily on energy to run their gadgets and make their life easier and more convenient. Along with it, the biggest part of the progress that the world has attained from being traditional to being industrial belongs to the massive use of energy. Without energy, most inventions probably will not succeed and high tech machines will just be garbage for people. Indeed, energy is very vital to human’s life.
As technology gets better and better, energy consumption also increases in the same way. According to survey, the world’s energy consumption is expected to increase 40-50 percent by 2010. Along with this is the increase in the global carbon dioxide emission by 50-60 percent (SEI 2009). If this increase will continue, there is a great possibility that our world will not only suffer from global warming but people will also suffer from unclean atmosphere causing a lot of health diseases. Imagine a world full of carbon emissions from burning fossil fuels – it will seem like the earth will soon be a dangerous place to live in.
Future generations will be forced to migrate. The question is: where will the people migrate if the earth, the only planet suitable for human being is now devastated by human activities? Terrible isn’t it? That is why we, people of the present should think twice now and consider ways of saving the earth. Since energy emissions contribute much to the devastation of earth, people should take note of energy sources that will not only benefit people but will also benefit the environment in a friendly and caring way. In other words, let us consider renewable energy sources.
2. Kinds of Renewable Sources There are five types of renewable energy source: biomass, water, wind, solar and geothermal. Each type has its own benefits and way of producing electricity. A. Biomass Energy Biomass energy is the energy stored in organic materials that come from living things like animals and plants. It is usually generated from wood, crops, manure and other wastes (Illustration 1-1). Since wastes are always present and people can always grow trees and plants, biomass is therefore considered as a renewable energy source (EIA 2006).
Production of Biomass Energy Biomass energy is created when biomass is burned and the chemical energy stored in it is released in the form of heat (TPI, 2007). There are three types of biomass energy. They are: 1) Fibre Fuel; 2) Ethanol and Methanol and 3) Biogas. 1. Fibre Fuel Perhaps the oldest way of producing biomass energy is through burning of wood and wood waste that produces fibre fuel. The heat coming from the burning wood can be used to heat homes and industries, cook food and it can even run a steam engine for a manufacturing plant (EIA 2006).
A good example is the use of wood waste of paper manufacturing companies to run their steam engine machines. The use of fibre fuel caused a lot of savings because they can just use their wood waste to produce electricity for the plant (TPI 2007). 2. Biofuel Biofuels like ethanol, methanol and biodiesel are highly flammable alcohols that are generated from plant sugars or plant fibers through refineries. Ethanol and methanol are produced by putting plant materials like corn, wheat, potato skins, rice, sugar cane, sugar beets, and yard clippings in refineries where heated tanks called digesters are present (TPI 2007).
Illustration 1-2 shows the digesters that are used to generate ethanol and methanol. Biodiesel, on the other hand are generated from vegetable oils, fats, or greases such as recycled restaurant grease The digesters contain chemicals or yeasts that react on plant materials and transform them into alcohol. To produce fuel, the alcohol is extracted and purified (EIA 2006). Ethanol and methanol, when mixed with gasoline makes good petroleum for trucks, buses and cars due to their cleaner burn and high power deliverance. Illustration 1-3 shows a bus in Sweden that uses ethanol as gasoline (TPI 2007).
Biodiesel, aside from its cleaner burn is safer and is the most widely used petroleum in the US nowadays (EIA 2006). 3. Biogas Illustration 1-4 shows how biogas is generated from any garbage that comes from plant and animal products. To produce biogas, plant materials and animal wastes are mixed with water in the biogas generator. The tank is then covered and sealed to produce the bacteria known as “methanogenic” needed to breakdown the materials and produce methane, the main ingredient for biogas. After several weeks, biogas is then formed, collected at the top of the tank and stored in balloon like bags for future use (EIA 2006).
Another way to produce biogas is through landfills where large amount of garbage is present. The landfill is covered with leak-proof cap and the biogas produced is collected through pipes by the landfill gas purification plant. This is shown in Illustration 1-5. The biogas produced from landfills is used to run machines to heat buildings (TPI 2007). B. Wind Energy Wind can be simply described as air in motion and it is caused by the unequal heating of the earth’s surface by the sun. Like biomass, wind is also renewable because there will always be wind as long as there is sun.
Because wind is just everywhere, it can be easily used as a source of electricity (TPI 2007). In places like along coastlines and mountains where wind is very abundant, wind is highly used to provide mechanical energy to run machines and farm equipment (EIA 2006). Production of Wind Energy The simplest way to produce wind energy is by capturing it using sails or wind turbines (EIA 2006). In the past, wind turbines can only be found at windmills in farms. Illustration 2-1 shows the windmills that are used in Europe in 1900’s.
Today wind turbines can also be found in several rural areas (TPI 2007). There are two types of wind turbines used in capturing the wind. The first one is the vertical axis wind turbine that has blades that goes from top to bottom and looks more like giant egg beaters. The other is the horizontal axis wind turbine whose blades looks more like airplane propellers. Among the two, it is the horizontal axis wind turbine that is used widely due to its efficiency in capturing wind (EIA 2006). To generate electricity from the wind, air is first captured by the blades of the wind turbine.
The wind turbine blades are connected to a shaft and the shaft is connected to a generator inside the wind turbine like what is shown in Illustration 2-2. The blades, upon capturing the wind will start to rotate and will start to generate mechanical energy (EIA 2006). This mechanical energy will then be transferred to the generator and the generator will transform it to electricity. Wires that are connected to the generator will carry the electricity to any appliance attached to it or to batteries where it is stored for future use (TPI 2007). Illustration 2-3 shows a sample of a single-use wind turbine in a farm.
Wind Energy for Commercial Purpose For commercial purposes, several giant wind turbines having height of 90 meters are built in wind farms like the one in the Horse Hollow Wind Energy Center in Texas. It has 421 wind turbines that are running 24 hours a day to generate enough electricity to power 220,000 homes per year (TPI 2007). Another can be seen in Alberta as shown in Illustration 2-4. Unlike other energy generating sources, wind turbines are preferred due to its reliability, efficiency and low cost. It also creates no air pollution making it the world’s fastest-growing new energy source.
On the other hand, wind farm should also be planned well. Factors such as season, wind speed and altitude must be considered when establishing a wind farm to ensure that maximum amount of energy can be generated (TPI 2007). C. Solar Energy Solar energy is also one of the most useful energy sources. Solar energy is simply defined as the energy in the form of sun’s rays or solar radiation that reaches the earth. Like the other renewable sources, solar energy can be converted to other forms of energy like heat and electricity that can be used for several purposes (EIA 2006). Production of Solar Energy
There are currently two ways of converting solar energy to electricity. The first one is through photovoltaic cells or solar cells (Illustration 3-1) and the second is through solar power plants. The difference between the two is that photovoltaic cells change sunlight directly to electricity by capturing the sun’s rays. Photovoltaic cells are made from silicone wafers connected by wires that are capable of capturing the sun’s rays as seen in Illustration 3-2. These are most commonly used in calculators, lighted road signs, emergency phones and in other remote areas (TPI 2007).
Since photovoltaic cells are easy to install in any size allowed and because they create no air and water pollution, many commercial facilities are starting to appreciate its benefits especially in Europe where solar roofs are used in building (Illustration 3-3). In a larger scale, solar energy can be used for telecommunication purposes and in lighting system of a community (TPI 2007). Meanwhile, since only a small amount of electricity can be generated from a single photovoltaic cell, several cells are linked together by wires to form an array of photovoltaic cells that are more capable of producing electricity (EIA 2006).
On the other hand, solar power plants indirectly produce electricity by means of first heating a fluid using the heat from the solar thermal collectors. The solar thermal collectors are just like photovoltaic cells in function – they also capture the sun’s rays and heat. When the fluid is hot enough, it is now used to power generators that produce electricity (TPI 2007). Solar Energy during Night Time Since solar energy comes from the sun’s rays, photovoltaic cells are useless during night time where the sun’s rays are not present.
It should be noted that the amount of energy generated or captured by the photovoltaic cells depends on how sunny it is (EIA 2006). Therefore, in order to use solar energy efficiently, storage of solar energy is necessary. Storage can be done by using rechargeable batteries that have or that are attached to photovoltaic arrays (EIA 2006). Illustration 3-4 shows the batteries that are capable of recharging and discharging at many several cycles for continuous use. The energy stored in batteries can be used for household and industrial purposes, depending on the size and energy capacity of the batteries.
The only downside of using batteries in running appliances is that the power from the batteries are direct current (DC) and are usually lower than the 110V alternating current (AC) required by most of the appliances (EIA 2006). To solve this problem, people use a device called a “power inverter” that is capable of converting the batteries’ power to 110V AC suitable for the appliances (TPI 2007). D. Water Energy Among all the renewable sources that are used to generate electricity, it is hydropower or water energy that has the biggest part.
The use of water to generate electricity dated back thousands of years ago when native people used it to turn paddle wheel to grind grains (EIA 2006). Since the source of hydropower is water, hydroelectric power plants must be located on a water source. Among all kinds of water source, streams and rivers are the most powerful and efficient in generating electricity due to their intense water current and flow(EIA 2006). Production of Water Energy Water energy is basically formed through the use of water turbines.
In the past, waterwheels are used to capture the energy of moving water and use it to provide power to mills that grind grains and cut lumber (Illustration 4-1). In rural and remote areas, waterwheels are also used to generate electricity (EIA 2006). To start the mill, a gate is simply opened to let the water flow over the top of the wheel. The water pouring on the wheels usually came from a small dam and reservoir, called the millpond. The water wheel is then connected to a massive millstone or metal saw blade by means of a system of gears.
The flow of the water generates mechanical energy for the mill. If the waterwheel is connected to an electric generator, the mechanical energy can be converted to electricity as shown in Illustration 4-2 (EIA 2006). Small Scale Hydropower One of the most efficient and environmentally friendly ways to generate electricity in small scale is by using a device called a micro-hydro turbine. Illustration 4-3 shows a micro-hydro water turbine system. The turbine has a diameter of 10 cm and it consists of spoon shaped cups arranged around the center of a wheel.
The wheel is then attached to a shaft that turns when jets of high speed water pass to it. The electricity generated by the spinning shaft is enough to power a variety of machines including electrical generators, woodworking tools, pumps, fans and more (TPI 2007). Since micro-hydro is easy to install and to maintain, a lot of people are considering the use of this machine especially to those who live near water sources (EIA 2006). Furthermore, its parts are also cheap making it ideal for areas where establishment of complex structures are difficult and expensive (Illustration 4-4).
Lastly, micro-hydro produces no pollution and it does not need a huge dam or reservoir to run (TPI 2007). Large Scale Hydropower For large scale hydropower, bigger bodies of water are used to generate higher volume of electricity (Illustration 4-5). Hydroelectric facilities often depend on a dam to raise the water level in the reservoir. The water from this reservoir is then allowed to flow through huge pipes to a building that houses several water turbines (TPI 2007). The water flows at a high speed causing the turbines to spin fast as well.
The turbines are linked to huge generators that are capable of generating electricity as the turbines turn. The electricity is carried to cities and towns that are located hundreds or thousands of kilometers away from the turbine plant (TPI 2007). E. Geothermal Energy Geothermal energy can be simply described as the heat from within the earth. Since the earth consists of several hot layers, this results to the production of steam and hot water that are used to generate heat and electricity.
Like the other sources of renewable energy mentioned earlier, geothermal energy is also renewable because the water is replenished by rainfall and the heat is continuously produced inside the earth. People around the world especially those living in colder areas such as Alaska use geothermal energy to heat their homes and to produce electricity by digging deep wells and pumping the heated underground water or steam to the surface. In addition, people can make use of the stable temperatures near the surface of the earth to heat and cool buildings.
Production of Geothermal Energy Geothermal energy is generated in the earth’s core, about 4,000 miles below the surface. The entire earth is composed of several layers (inner core, outer core, mantle, crust) with each layer having different temperature levels (EIA 2006). It must be noted that the temperatures hotter than the sun’s surface are generated inside the earth by the slow decay of radioactive particles, a process that happens in all rocks. Illustration 5-1 shows how geothermal energy is produced while Illustration 5-2 shows a geothermal heat utility in New Mexico.
To generate electricity, a type of machine called a geothermal heat pump is used (Illustration 5-3). The function of the geothermal heat pump is almost the same as the function of a common refrigerator (EIA 2006). Like the refrigerator, the heat pump uses a compressor, sealed tubing for gathering and dispersing heat and a gas called the refrigerant. A network of tubes is buried deep in the soil near the plant or the house. The compressor motor is then responsible for circulating the refrigerant around the network of tubes.
The heat from the surrounding soil warms the liquid refrigerant in the buried tubes, changing its form to gas. As soon as the liquid turns to gas, it enters the compressor that squeezes it and raising its temperature and pressure. The hot refrigerant circulates through radiators inside the plant or house, releasing the heat gathered from the soil. After releasing heat, the refrigerant turns back to its liquid form and the process starts again (TPI 2007). Illustration 5-4 shows the system used to generate safe geothermal energy.
During summertime, the flow of the refrigerant can be reversed causing the heat pup system to cool the house or the plant. Heat from the house or plant is collected and returned back to the soil, resulting to a highly efficient air conditioning system (TPI 2007). 3. Conclusion After getting acquainted with the five types of renewable energy sources, people should really start considering the use of these energy sources. Wherever they live: whether along a body of water, in a windy area or sunny place, there is always an option that can be used to generate electricity.
As discussed earlier, the affordability of putting up renewable energy machines makes it more competitive and more preferred over nuclear and fossil fuel energy source. Aside from the fact that fossil fuels and nuclear energy sources speed up the depletion of ozone layer and global warming, fossil fuel layers are getting thinner and thinner due to its consumption and it will take hundreds or even thousands of years to obtain the same amount again in the earth’s layer. Nuclear source on the other hand, has nuclear emissions that are very dangerous to human’s health once mistakenly treated.
On the other hand, the cost for putting up preventive measures is high and in the same manner, the cost for covering all the damages that can be obtained once the danger happened is higher. So why should people settle for something that will be dangerous for them in the long run if they can settle for something that will benefit not only them, but also the environment and the future generation? Isn’t it fulfilling enough for people if with the little decision that they can do, they can generate a worldwide benefit?
Perhaps, if there is any precious gift that we can give to our future generation, it will be the opportunity to live peacefully and healthfully in a world that has no pollution and no dangerous emissions. By working to achieve a cleaner atmosphere, people of the present can prepare a brighter future for the next generations. That is why it is very important that people should intensify their use of renewable energy sources due to its life fulfilling benefits. People should remember that their initial investment can pay them a lot in the long run.
By working together in supporting and intensifying the use of renewable energy source, people can ensure a safer and enjoyable place to live. References: Energy Information Administration. (2006). Renewable Energy. Energy Kids Page. From http://www. eia. doe. gov/kids/energyfacts/sources/renewable/solar. html SEI Organization (2009). Energy Facts. Solar Energy International Website. From: http://www. solarenergy. org/resources/energyfacts. html The Pembina Institute. (2007). Renewable Energy Basics. Re-energy. ca. From http://www. re-energy. ca/t_renewablebasics. shtmlSample Essay of RushEssay.com