Abstract: The purpose of this project is to present an overview of renewable energy sources,Guest Posting major technological developments and case studies, accompanied by applicable examples of the use of sources. Renewable energy is the energy that comes from natural resources: The wind, sunlight, rain, sea waves, tides, geothermal heat, regenerated naturally, automatically. Greenhouse gas emissions pose a serious threat to climate change, with potentially disastrous effects on humanity. The use of Renewable Energy Sources (RES) together with improved Energy Efficiency (EE) can contribute to reducing energy consumption, reducing greenhouse gas emissions and, as a consequence, preventing dangerous climate change. At least one-third of global energy must come from different renewable sources by 2050: The wind, solar, geothermal, hydroelectric, tidal, wave, biomass, etc. Oil and natural gas, classical sources of energy, have fluctuating developments on the international market. A second significant aspect is given by the increasingly limited nature of oil resources. It seems that this energy source will be exhausted in about 50 years from the consumption of oil reserves in exploitation or prospecting. “Green” energy is at the fingertips of both economic operators and individuals. In fact, an economic operator can use such a system for both own consumption and energy trading on the domestic energy market. The high cost of deploying these systems is generally depreciated in about 5-10 years, depending on the installed production capacity. The “sustainability” condition is met when projects based on renewable energy have a negative CO2 or at least neutral CO2 over the life cycle. Emissions of Greenhouse Gases (GHG) are one of the environmental criteria included in a sustainability analysis, but is not enough. The concept of sustainability must also include in the assessment various other aspects, such as environmental, cultural, health, but must also integrate economic aspects. Renewable energy generation in a sustainable way is a challenge that requires compliance with national and international regulations. Energy independence can be achieved: – Large scale (for communities); – small-scale (for individual houses, vacation homes or cabins without electrical connection).
Keywords: Environmental Protection, Renewable Energy, Sustainable Energy, The Wind, Sunlight, Rain, Sea Waves, Tides, Geothermal Heat, Regenerated Naturally.
Introduction
The purpose of this project is to present an overview of renewable energy sources, major technological developments and case studies, accompanied by applicable examples of the use of sources.
Renewable energy is the energy that comes from natural resources: The wind, sunlight, rain, sea waves, tides, geothermal heat, regenerated naturally, automatically.
Greenhouse gas emissions pose a serious threat to climate change, with potentially disastrous effects on humanity. The use of Renewable Energy Sources (RES) together with improved Energy Efficiency (EE) can contribute to reducing energy consumption, reducing greenhouse gas emissions and, as a consequence, preventing dangerous climate change.
At least one-third of global energy must come from different renewable sources by 2050: The wind, solar, geothermal, hydroelectric, tidal, wave, biomass, etc.
Oil and natural gas, classical sources of energy, have fluctuating developments on the international market. A second significant aspect is given by the increasingly limited nature of oil resources. It seems that this energy source will be exhausted in about 50 years from the consumption of oil reserves in exploitation or prospecting.
“Green” energy is at the fingertips of both economic operators and individuals.
In fact, an economic operator can use such a system for both own consumption and energy trading on the domestic energy market. The high cost of deploying these systems is generally depreciated in about 5-10 years, depending on the installed production capacity.
The “sustainability” condition is met when projects based on renewable energy have a negative CO2 or at least neutral CO2 over the life cycle.
Emissions of Greenhouse Gases (GHG) are one of the environmental criteria included in a sustainability analysis, but is not enough. The concept of sustainability must also include in the assessment various other aspects, such as environmental, cultural, health, but must also integrate economic aspects.
Renewable energy generation in a sustainable way is a challenge that requires compliance with national and international regulations.
Energy independence can be achieved:
Large scale (for communities)
Small-scale (for individual houses, vacation homes or cabins without electrical connection)
Today, the renewable energy has gained an avant-garde and a great development also thanks to governments and international organizations that have finally begun to understand its imperative necessity for humanity, to avoid crises and wars, to maintain a modern life (we can’t go back to caves).
Materials and Methods
The Geothermal Energy Potential
Geothermal energy is defined as the natural heat coming from within the Earth, captured for electricity, space heating or industrial steam. It is present anywhere beneath the earth’s crust, although the highest temperature and therefore the most desirable resource, is concentrated in regions with active or young geologically active volcanoes.
The geothermal resource is clean, renewable, because the heat emanating from the Earth’s interior is inexhaustible. The geothermal energy source is available 24 h a day, 365 days a year. By comparison, wind and solar energy sources are dependent on a number of factors, including daily and seasonal fluctuations and climate variations. For this reason, the energy produced from geothermal sources is, once captured, more secure than many other forms of electricity. Heat that continually springs from within the Earth is estimated to be equivalent to 42 million megawatts (Stacey and Loper, 1988). One megawatt can supply the energy needs of 1000 homes.
Geothermal energy originates from the thermal waters, which in turn extract their heat from the volcanic magma from the depths of the earth’s crust. The Earth’s thermal energy is therefore very large and is virtually inexhaustible, but it is very dispersed, very rarely concentrated and often too deep to be exploited industrially. Until now, the use of this energy has been limited to areas where geological conditions allow a transport medium (liquid or gaseous water) to “transfer” heat from hotspots from the depth to the surface, thus giving rise to geothermal resources.
The environmental impact of the use of geothermal energy is rather small and controllable. In fact, geothermal energy produces minimal atmospheric emissions. Emissions of nitrogen oxide, hydrogen sulphide, sulfur dioxide, ammonia, methane, dust and carbon dioxide emissions are extremely small, especially when compared to emissions from fossil fuels.
However, both water and condensed steam from geothermal power plants contain different chemical elements, including arsenic, mercury, lead, zinc, boron and sulfur, the toxicity of which obviously depends on their concentration. However, most of these elements remain in solution, in water that is re-injected into the same tank from which fermented water or steam was extracted. The most important parameter in the use of this type of energy is the temperature of the geothermal fluid, which determines the type of geothermal energy application. It can be used for heating or to generate electricity.
Going from the surface of the earth to the depth, it is noticed that the temperature increases progressively with the depth, with 3°C on average for every 100 m (30°C/km). It is called the geothermal gradient. For example, if the temperature after the first few meters below ground level, which on average corresponds to the average annual outdoor air temperature, is 15°C then it can reasonably be assumed that the first temperature will be 65-75°C at 2000 m Depth, 90-105°C at 3000 m and so on for the next few thousand meters.
Regions of interest for geothermal energy applications are those where the geothermal gradient is higher than normal. In some areas, either due to the volcanic activity of a recent geological age, or due to the cracked cracks of hot water at depths, the geological gradient is significantly higher than the average, so temperatures of 250-350°C are recorded at depths of 2000-4000 m.
A geothermal system consists of several main elements: a heat source, a reservoir, a carrier fluid that provides heat transport, a recharge area and a rock to seal the aquifer. The heat source may be a very high magmatic intrusion (> 600°C) that has reached relatively low depths (5-10 km) or, in some low temperature systems, the normal Earth’s temperature, which, as explained earlier, increases with the depth.
The tank is a volume of permeable rocks from which the carrier fluid (water or steam) extracts heat. The reservoir is generally covered by either impermeable layers or rocks whose low permeability is due to the self-sealing phenomenon consisting in the deposition of minerals in the pores of the rocks. The tank is connected to a surface recharge area through which the meteoric waters can replace the fluids leaving the tank through springs or by extraction to boreholes. The geothermal fluid is water, in most cases meteoric, liquid or gaseous, depending on temperature and pressure. Water often carries along with chemicals and gases such as CO2, H2S, etc. The mechanism underlying geothermal systems is generally governed by fluid convection. Convection occurs due to heating and thermal expansion of fluids in a gravitational field. The low density heated flame tends to rise and be replaced by a cooler, high density fluid coming from the edge of the system. Convection, by its nature, tends to increase the temperature at the top of the system, while the bottom temperature decreases. Frequently, a distinction is made between geothermal systems dominated by water and vapor-dominated systems. In water-dominated systems, liquid water is the continuous fluid phase controlling the pressure. Vapors may be present, generally as discrete bubbles. These geothermal systems, whose temperature may vary from 225°C, are the most widespread in the world. Depending on the temperature and pressure conditions, they can produce hot water, water-steam mixtures, wet steam, or, in some cases, dry steam. In vapor-dominated systems, liquid and vapor co-exist in the reservoir with continuous steam controlling the pressure. Geothermal systems of this type, of which the best known are Larderello in Italy and The Geysers in California, are quite rare and are high-temperature systems.
Generating electricity is the most important use of high pressure geothermal resources (> 150°C). Medium and low temperature resources are suitable for various applications. The classic Lindal Diagram (1973) shows the possible uses of geothermal fluids at different temperatures. Fluids at temperatures below 20°C are rarely used under very particular conditions, or in heat pump applications (DiPippo, 2004).
In the case of temperatures below 90°C, geothermal waters can be used directly rather than f