Renewable energy sources
Abstract
In this article I am going to present some of the ways to generate electricity with emphasis on socalled "green" energy, e.g., wind, solar and hydrostatic energy.
Introduction
The electricity that you use now was made just a moments ago, the large portion of that electrical energy is generated in thermal power station by burning some sort of fossil fuel or by splitting an atoms of plutonium or uranium. According to the EIA almost 70% of all electrical energy was generated from fossil fuels in 2011 in USA and almost 20% by nuclear fission while only 9% from hydroelectric and other renewable energy sources. You may be asking yourself "Why is that the case, why does not USA invest in power plants that utilize renewable energy?" Some say that fossil fuel lobby is responsible for that, others, on the other hand, argue that there is no need for utilizing any power source other that fossil fuels, on the basis that there is much more of it left it in the bowels of our planet. The fact of the matter is that all power plants that use renewable energy have high price(long pay off time) and/or efficiency problems. For instance it takes about 20 years for the large wind turbine to pay off. Now you can see why so few countries are willing to invest in such energy sources. I will present a few of the mostly used power stations below.
Thermal power station
Thermal power station is a type of power plant in witch water is heated to the point of boiling and then the superheated steam is driven to the steam turbines where the kinetic energy of the steam is transformed to the mechanical energy which is then used to power a generators to make electricity, the steam that comes out of the turbine is then condensed to water which is again heated to make steam, that is called the Rankine cycle. Thermal power plants can be classi ed by the type of fuel that they use in:
-fossil fuel
-nuclear
-geothermal
-solar thermal
Thermal power stations have a constant power out-put and, cannot be used to meet all of the demands for electrical energy, because fluctuations in power de-mand are quite large. To solve that problem, more than one type of power station is utilized, most frequently hydroelectric dams and some sort of thermal power stations.
Hydroelectric power stations
Also called dams are used to impound water which can be, when requested, used to power a water turbine and eventually generate electricity. Dams, unlike almost very other power plants, have a very simple, cheap and highly effcient way of storing energy and as a consequence have extremely high exibility. When the demand for electricity is low and the in low of water large, the unused water can be impounded. Water that cannot flow downstream gets accumulated before the dam.
Solar power stations
Convert sunlight into electricity that can be directly gathered from solar radiation by using so called Pho-tovoltaic cells that exploit the photovoltaic cells that exploit the photovoltaic
effect or indirectly by using mirrors to concentrate solar radiation and to boil water although that is classifed as thermal power plant. The problem with photovoltaic cells is that they give direct current (DC) while the electricity that wemostly use is alternating current(AC). That problem can be solved by using inverters, that transform DC to AC, while that approach works it reduces the efficiency of the power plant and increases the construction costs. Other than problem with transforming electricity from DC to AC there is a problem with storing energy be-cause there is a time when we have a lot of sunlight but almost no need for electricity. That problem is solved by using batteries but they are expensive and have a relatively short life-time.
Wind power stations
Use wind turbine to power generators. Wind turbine converts kinetic energy of the wind to mechanical energy which is used to power a generator. The cost of wind turbine is proportional to the torque it produces and the power of the wind turbine is proportional to the surface area that is swept by the blades but by doubling the diameter of the blades the power increases by the factor of 4 and the rotational speed halves but the torque increases by the factor of 8. As a result, the price is rising faster that the output power of the turbine. Again, there is no smart way of storing that elec-tricity, there are some radical concepts, presented by the professor Seamus Garvey that imply using a wind turbine for compressing air, that compressed air is then stored under the sea in air bags that look like big balloons. That compressed air can be used when requested to power generators. While idea seems in-tuitive and it is proven that it works it is still under development and a number of years will pass until we see one of those turbines up and running.
Conclusion
Every way of generating electricity has its pros and cons. The thermal power plants have best balance be-tween initial cost, life time and power output but the ecological footprint of such station is huge. The nu-clear power plants have somewhat smaller ecological footprint but there is no smart solution for disposing of nuclear waste. Dams, that are the third biggest pro-ducers of electricity have rather small in influence on the environment but have a rather small output power as well. Wind and solar power power plants are environmentally indierent but have problems with cost and energy storing. We can see that the impact on environment had little to none in uence in deciding which power plants were built. That is now slowly changing, as people become more environmentally aware. Expensive and ecological has become cool as it can be.
Abstract
In this article I am going to present some of the ways to generate electricity with emphasis on socalled "green" energy, e.g., wind, solar and hydrostatic energy.
Introduction
The electricity that you use now was made just a moments ago, the large portion of that electrical energy is generated in thermal power station by burning some sort of fossil fuel or by splitting an atoms of plutonium or uranium. According to the EIA almost 70% of all electrical energy was generated from fossil fuels in 2011 in USA and almost 20% by nuclear fission while only 9% from hydroelectric and other renewable energy sources. You may be asking yourself "Why is that the case, why does not USA invest in power plants that utilize renewable energy?" Some say that fossil fuel lobby is responsible for that, others, on the other hand, argue that there is no need for utilizing any power source other that fossil fuels, on the basis that there is much more of it left it in the bowels of our planet. The fact of the matter is that all power plants that use renewable energy have high price(long pay off time) and/or efficiency problems. For instance it takes about 20 years for the large wind turbine to pay off. Now you can see why so few countries are willing to invest in such energy sources. I will present a few of the mostly used power stations below.
Thermal power station
Thermal power station is a type of power plant in witch water is heated to the point of boiling and then the superheated steam is driven to the steam turbines where the kinetic energy of the steam is transformed to the mechanical energy which is then used to power a generators to make electricity, the steam that comes out of the turbine is then condensed to water which is again heated to make steam, that is called the Rankine cycle. Thermal power plants can be classi ed by the type of fuel that they use in:
-fossil fuel
-nuclear
-geothermal
-solar thermal
Thermal power stations have a constant power out-put and, cannot be used to meet all of the demands for electrical energy, because fluctuations in power de-mand are quite large. To solve that problem, more than one type of power station is utilized, most frequently hydroelectric dams and some sort of thermal power stations.
Hydroelectric power stations
Also called dams are used to impound water which can be, when requested, used to power a water turbine and eventually generate electricity. Dams, unlike almost very other power plants, have a very simple, cheap and highly effcient way of storing energy and as a consequence have extremely high exibility. When the demand for electricity is low and the in low of water large, the unused water can be impounded. Water that cannot flow downstream gets accumulated before the dam.
Solar power stations
Convert sunlight into electricity that can be directly gathered from solar radiation by using so called Pho-tovoltaic cells that exploit the photovoltaic cells that exploit the photovoltaic
effect or indirectly by using mirrors to concentrate solar radiation and to boil water although that is classifed as thermal power plant. The problem with photovoltaic cells is that they give direct current (DC) while the electricity that wemostly use is alternating current(AC). That problem can be solved by using inverters, that transform DC to AC, while that approach works it reduces the efficiency of the power plant and increases the construction costs. Other than problem with transforming electricity from DC to AC there is a problem with storing energy be-cause there is a time when we have a lot of sunlight but almost no need for electricity. That problem is solved by using batteries but they are expensive and have a relatively short life-time.
Wind power stations
Use wind turbine to power generators. Wind turbine converts kinetic energy of the wind to mechanical energy which is used to power a generator. The cost of wind turbine is proportional to the torque it produces and the power of the wind turbine is proportional to the surface area that is swept by the blades but by doubling the diameter of the blades the power increases by the factor of 4 and the rotational speed halves but the torque increases by the factor of 8. As a result, the price is rising faster that the output power of the turbine. Again, there is no smart way of storing that elec-tricity, there are some radical concepts, presented by the professor Seamus Garvey that imply using a wind turbine for compressing air, that compressed air is then stored under the sea in air bags that look like big balloons. That compressed air can be used when requested to power generators. While idea seems in-tuitive and it is proven that it works it is still under development and a number of years will pass until we see one of those turbines up and running.
Conclusion
Every way of generating electricity has its pros and cons. The thermal power plants have best balance be-tween initial cost, life time and power output but the ecological footprint of such station is huge. The nu-clear power plants have somewhat smaller ecological footprint but there is no smart solution for disposing of nuclear waste. Dams, that are the third biggest pro-ducers of electricity have rather small in influence on the environment but have a rather small output power as well. Wind and solar power power plants are environmentally indierent but have problems with cost and energy storing. We can see that the impact on environment had little to none in uence in deciding which power plants were built. That is now slowly changing, as people become more environmentally aware. Expensive and ecological has become cool as it can be.
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