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).
Keywords: Environmental Protection, Renewable Energy, Sustainable Energy, The Wind, Sunlight, Rain, Sea Waves, Tides, Geothermal Heat, Regenerated Naturally.
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:
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).
The Micro-Hydropower Potential
Hydroelectric power comes from the action of moving water. It can be seen as a form of solar energy because the sun feeds the water circuit in nature. Within this circuit, the water from the atmosphere reaches the surface of the earth in the form of precipitation. Part of it evaporates, but much of it penetrates the soil or becomes flowing water to the surface. Rainwater and melted snow finally end up in ponds, lakes, reservoirs or oceans where evaporation takes place permanently.
Water resources due to inland rivers are estimated at about 42 billion cubic meters per year, but under unchecked storage, it can only account for about 19 million cubic meters per year due to fluctuations in river flows.
Low-power hydropower plants are a major contributor of renewable electricity at European and world level. Worldwide, it is estimated that there is an installed capacity of 47,000 MW, with a potential - technical and economic - close to 180,000 MW.
Low-Power Hydropower Plants (HMP) are powered by natural water flow, i.e., it does not involve large-scale water capture and therefore does not require the construction of large dams and reservoirs, although they help where they exist and can be used easily. There is no international definition of the HMP and the upper limit varies between 2.5 and 25 MW depending on the country, but the 10 MW value is generally accepted and promoted by European Association of Low Power Hydro Power Plants (ESHA).
Low power plants are one of the most reliable and cost-effective technologies for producing clean electricity.
In particular, the key advantages of HMPs to wind-based, wave-based or solar power plants are:
HMPs are also environmentally friendly. Most of the time, they work on the natural course of water. Therefore, this type of water-based installation does not have the same negative environmental effects as large hydropower plants.
Small hydropower plants can be located either in mountainous areas where rivers are fast or in low-lying areas with large rivers. The four most common types of micro-power plants are presented below.
For large and medium fall schemes, channel and duct combinations are used. If the terrain is injured, the construction of the canal is difficult and then only the forced duct that can sometimes be buried is used. In the barrage arrangements the turbines are placed in or in the immediate vicinity of the dam, so that there is almost no need for the channel or the pipeline.
Another option of placing the microturbines is to use the flows from the water treatment plants.
The objective of a hydroelectric system is to convert the potential energy of the volume of water flowing from a certain height into electricity at the bottom end of the system where the power plant is located. The water level difference, known as "fall", is essential for the production of hydroelectricity; The simple rapid flow of water does not contain enough energy to produce significant electrical energy than on a very large scale such as coastal submarine currents. That is why two indicators are needed: Q water flow and H dropping. It is generally better to have a larger drop than a higher flow, because smaller equipment can be used.
Grossfall (H) is the maximum vertical distance between upstream and downstream water levels. The actual fall seen at the turbine will be somewhat lower than the gross fall, due to the loss of water in and out of the system. This low fall is called the Net Fall.
Flow rate (Q) is the volume of water passing into the unit of time, measured in m3/s. For small systems, the flow rate can also be expressed in liters/second, where 1000 l/s = 1 m3/sec. Depending on the fall, hydroelectric plants can be classified into three categories:
These categories are not strict, but are only a possible ranking system for locations.
Hydroelectric installations can also be defined as:
Generally, large-scale locations are less expensive to develop than small-fall ones, because for the same level of energy produced, the flow required by the turbine will be lower than hydro-technical constructions. For a river with a relatively high slope in a sector of its course, the level difference can be used by conducting part or all of the course and returning it to the river bed after passing through the turbine. The water can be brought directly from the source to the turbine via a pressure pipe.
Hydroelectric turbines convert water pressure into mechanical power to the shaft, which can be used to drive an electric generator or other equipment. Available electricity is directly proportional to the fall and flow rate.
The best turbines can have hydraulic efficiency in the order of 80-90% (higher than any other driving force), although it decreases with size.
The main component of a small hydropower plant is the hydraulic turbine. All of these turbines convert the falling water energy into kinetic rotation shaft energy, but confusion often arises as to which type of turbine should be used depending on the circumstances. The choice of the turbine depends on the location characteristics, especially the drop and flow, plus the desired generator speed and if the turbine has to operate under low flow conditions.
There are two main types of turbines, called "impulse" and "reactive".
The impulse turbine converts the potential energy of the water into kinetic energy through a jet that comes out of a nozzle and is projected onto the rotor cups or blades.
The reaction turbine uses pressure and water speed to create energy. The rotor is completely immersed and the pressure and speed drop from intake to exhaust. By contrast, the rotor of a pulse turbine operates in air, driven by a jet (or jets) of water.
There are 3 main types of impetus turbines: Pelton, Turbo and Cross Flow (or Banki). The main 2 types of reaction turbines are helical (Kaplan) and Francis.
Most existing turbines can be grouped into three categories:
Kaplan and propeller turbines are axial flow turbines, generally used for small falls (typically less than 16 m). The Kaplan turbine has adjustable blades and may or may not have an adjustable stator head unit. If both the rotor blades and the steering gear are adjustable, we are dealing with a 'double-tuned' turbine. If the directing device is fixed, we are dealing with a 'simple tuned' turbine. In the conventional version, the Kaplan turbine has a spiral chamber (either steel or reinforced concrete); the flow enters radially inward and makes a straight angle before entering the rotor in the axial direction. If the rotor has fixed blades, the turbine is called a propeller turbine.
Propeller turbines may have mobile or fixed devices. Turbines with nipples are used only if flow and fall are practically constant.
Bulb and tubular turbines are derived from the Kaplan and helical variants, where the flow enters and exits with minor directional changes. In the Bulb turbine, the multiplier and the generator are located in a submerged capsule. The tubular turbines allow several arrangements, namely: Straight-angle transmission, Straflo turbines with S-ducts, belt drive generators, etc. Versions with straight-angle transmission are very attractive, but they are only manufactured to a power of 2 MW.
Francis turbines are radial-flow turbine engines with fixed rotor blades and mobile guides used for mid-fall. The rotor is made up of cups with complex profiles. A Francis turbine typically includes a spiral cast iron or steel chamber to distribute water throughout the perimeter of the rotor and a series of guide elements to adjust the flow of water into the rotor.
Pelton turbines are single or multiple jet turbines, each jet being designed with a needle nozzle to control the flow. They are used for medium and large falls. The nozzle axes are on the rotor plane.
The cross-flow turbine, sometimes called the Ossberger turbine, after a company that has been manufacturing it for over 50 years, or the Michell turbine is used for a wide range of falls, overlapping with Kaplan, Francis and Pelton turbine applications. This type is very suitable for a high-flow and low drop stream.
Turbo can operate under a fall ranging from 30-300 m. Like the Pelton turbine, it is a pulsating turbine, but the blades have a different shape and the water jets hit the plane of the rotor at an angle of 20°. The water enters the rotor through one side of it and goes out through the other. The high turbo turbine speed due to its smaller diameter than other models makes it more likely to directly engage the turbine and generator. A turbine of this type may be suitable for average falls where a Francis turbine could also be used. But, unlike Pelton, the water passing through the rotor produces an axial force that requires the installation of a transmission shaft on the shaft.
The type, geometry and dimensions of the turbine will be fundamentally conditioned by the following criteria:
The efficiency of a turbine is defined as the ratio between the power delivered by the turbine (mechanical power transmitted to the axle) and the absorbed power (the hydraulic power equivalent to the flow measured under the net fall). To estimate overall efficiency, the efficiency of the turbine must be multiplied by the efficiency of the speed multiplier (if used) and the alternator.
For different types of turbines, efficiency drops rapidly below a certain percentage of nominal flow. A turbine is designed to operate close to the maximum efficiency point, typically 80% of the turbine's maximum flow and when the flow deviates from this value, the hydraulic efficiency of the turbine decreases.
The flow rate range and thus the generated energy, varies if:
In the first case, it is necessary to select a flow that allows the production of energy almost all year round. In the second case, the nominal flow should be selected so that the net profit from the sale of electricity is maximum.
The control panel is the equipment that monitors the operation of the hydropower system. The main functions of the control panel are:
A filter grating is a grate used to filter waste water. This is a useful equipment to prevent the accumulation of waste and other undesirable elements in watercourses, rivers and lakes. The basic scheme of all filter hatches is similar, but internal, external and turbine grates serve different needs. Grates can also be produced from different materials.
A simple filtration grate for a watercourse can be made of any type of barbecue material that allows water to pass but retains much of the waste. A filter of this type is usually made of the same material as whipped cream, i.e., metal or plastic.
Depending on the water course and the level of pollutants passing, the grate filter often requires regular cleaning to avoid blocking the water course. The grill is an obstacle and leads to a slight reduction of the frame. Therefore, the distance between the bars must be the maximum that allows for the collection of large enough waste for a turbine damage. The turbine manufacturer will recommend the correct dimensions.
Also, the flow rate of water near the filter grating should be relatively low, preferably below 0.3 m/s and not more than 0.5 m/s.
Manual cleaning is only feasible for small installations or locations that have permanent staff for other reasons. There is now a range of automatic cleaning equipment available to remove waste collected by filter gratings.
The most common types are:
On rivers where there are concerns about fish safety, more stringent filtering regulations are usually applied to ensure that the fish are prevented from reaching the turbine intake and will be diverted to deviation. The specific fish filtering measures are set according to the sensitivity of the location.
Several innovative fish exclusion methods are tested in the intake areas, avoiding the use of a physical filter. These include the use of electricity, bubble curtains and sounds to guide the fish. These methods offer significant advantages for the operator, avoiding obstruction of the water flow.
Historical data of flows corresponding to a fixed location are considered for the estimation of water resources, so designers use this information. Ministries dealing with Environment, Hydrology, Energy and/or Environmental Agencies (national/regional/local) or other similar organizations are usually the source of flow measurements for the most significant rivers and watercourses in European countries. The data can be used to assess the flow rate of the watercourse at the proposed location, as long as it adapts to the ratio of the proposed location to the measurement site (downstream or upstream). For the assessment of regional resources, satellite imagery is used to create the GIS database for source identification, site selection, environmental planning, Digital Terrain Modeling (DTM) and transmission line network and location classification. In general, these measurements for large-scale resource assessment are made by a team of GIS, hydrologists, hydropower experts, etc.
Geographic Information Systems (GIS) are computerized information systems used for digital representation and analysis of geographic features present on the earth's surface. The methodology for assessing the hydropower potential of a region can be done using both methods.
Remote sensing technology is an effective tool for identifying suitable locations for new hydropower projects, especially in inaccessible areas with high hydrological potential. Data from infrared remote sensing (0.8 μm - 1.1 μm) clearly provides the contrast between water and earth and is therefore best suited for mapping perennial water courses.
The only resource required for a low-power hydroelectric plant is running water available at a certain angle. Planning a HMP starts with the most accurate estimate of the fall and flow available at the proposed location. There are several methods for measuring the fall available. Some methods are more suited for low-drop locations, but they are too complicated and inaccurate for big falls. It is recommended to always take more fall measurements at each location.
The purpose of a hydrological study is to predict variation in flow over the year. Because the flow varies from day to day, a single measurement is of little use. In the absence of a hydrological analysis, a long-term measurement system can be installed. Such a system is often used to confirm the hydrological approach and is also the most reliable method of determining the actual flow rate at that location. Individual measurements are useful for verifying the hydrological predictions by sampling.
The flow measurement techniques are:
The theoretical potential for small hydropower plants and represents input data for calculations designed to estimate the technologically and economically exploitable potential.
The available potential is investigated by processing the above elements and after imposing some constraints related to:
To estimate the technological potential, the system then simulates the choice and operation of hypothetical turbines by using the following algorithms (for each hypothetical hydro power plant consisting of the available potential):
The initial valuation of investment costs and financial feasibility calculations shall be calculated:
As a result, the system suggests some parts of the watercourse where low-power hydro power plants can be installed, with optimal power and financial efficiency.
A potential installation location of a HMP is defined by the location of the water intake and the location of the power plant construction next to the watercourse. The difference in height between these two locations is defined as the hydraulic (net) fall h.
The assessment of a potential location should take into account the following features:
Low power plants have specific features different from large-scale ones, as they usually do not have large capacity upstream storage for financial reasons. It should be noted that large power plants (except those installed along the great rivers) have dams that form large accumulation basins. In this way, the natural flow of water is detached from the flow rate of the turbines, because the purpose of these large power plants is to cover the demand for energy at the peak points.
HMP, because of its low power, can’t really contribute to the peak of energy demand and building up a build-up is therefore a disproportionate financial burden without benefits in relation to the investment. Therefore, an HMP, even using a water diversion, functions as a hydroelectric plant on the water line, which means that it is to exploit the natural flow as best as possible. This is why the HMP feasibility analyzes are made using the flow curve rather than the time series of the natural course because the HMP has no accumulation but only a limited basin whose volume provides good conditions for the water supply in Pipeline and which corresponds to the flow rate for several hours.
The analysis of the technically and financially exploitable hydropower potential is done separately for each watercourse. For each course, the system provides information about:
Theoretical Potential
It is defined as the total potential energy available at selected nodes of the watercourse. The data used are: - Nodes of the watercourse; - Yearly flow rate curve at at least one point of the watercourse; - Geographic data and the system calculates: - The annual flow curve of each water node, according to the law of equal surfaces (continuity); - difference in height between nodes; - potential water potential for each branch of the watercourse.
Potential available
During the analysis of the potential of a watercourse, some availability filters are inserted, which effectively express some restrictions on the exploitation of water. Other non-energy uses of water form an important availability parameter for a river (irrigation, water supply, etc.). The system also provides some useful information on entities involved in water use rights for each part (segment) of the watercourse.
In this section, a technical and economic analysis of all the hydropower plants that may be installed on a given watercourse is made. For each potential hydroelectric plant, the following parameters are estimated:
The system continues with an assessment of possible hydro power plants based on their energy efficiency and financial feasibility and then provides the following information:
Any developer must seek professional advice before allocating significant finance for the design and construction of a small hydropower system. Involvement of professionals in this type of project can go from preliminary site evaluation, a feasibility study to complete 'turnkey' service, dealing with every aspect of development. There are also several companies that are engaged in the rental, development and operation of locations and can provide a complete package of services and financing.
An experienced professional is able to decide if a location is worth investigating more closely, based on an initial visit and discussions with the developer and others. Preliminary investigations of this type typically require 2-3 days. At this stage, a minor investment could save much more expensive and other possible complications during the development process.
A feasibility study uses accurate data and carefully analyzes costs, moving the project from the original idea to a final project that will support project financing applications and the necessary licenses. That's why it is good to hire a professional to carry out the feasibility study and the detailed project.
In a feasibility study, we must find the following key elements:
Aversa, R., Petrescu, RVV., Apicella, A., Kozaitis, S., Mirsayar, MM., Abu-Lebdeh, T., Berto, F., Akash, B., Petrescu, FIT., 2017 Triton for Nuclear Fusion, American Journal of Engineering and Applied Sciences 10(4):992-1000. DOI: 10.3844/ajeassp.2017.992.1000. Retrieved from: http://thescipub.com/abstract/10.3844/ajeassp.2017.992.1000
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Management of Renewable Energies and Environmental Protection, Part III
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.
