Proposed Hydroelectric Power Scheme in Pennsylvania - Case Study Example

Proposed Hydroelectric Power Scheme in Pennsylvania As energy becomes a catchphrase in the society, business, and industry today, energy alternatives are increasingly becoming popular. Hydroelectric energy remains one of the key options to meet the world’s growing demand for energy; and it forms the basis and focus of this paper. When designing or developing a hydroelectric energy scheme, or even a power plant, there are a myriad of considerations and factors that exist, irrespective of whether the concerns are local or global. Such considerations and factors are addressed in these paper; these include technical, economic, costs, and environmental considerations, as well as addition of generating capabilities of hydroelectric power. This paper focuses specifically on the Pennsylvania region. Table of Contents 1Introduction 5 1.1Problem Definition 6 2Review of Existing Hydroelectric energy schemes 6 2.1Environmental Consideration 9 2.2Economic Considerations 11 3The proposed Hydroelectric Power Scheme - Building of the Hydropower plant 13 3.1Technical and engineering Considerations 15 3.2Specifications for the proposed hydropower plant 16 3.3Development configuration 20 4Conclusion 21 5References 23 Tables Table 1: Environmental Sustainability Factors[7] 15 Table 2: The flow is needed in order to achieve the 2500kW threshold 16 Figure 1: Irafoss Hydroelectric Power Plant in Iceland 7 Figure 2: Dinorwig and Electric Mountain Power Station in Wales 8 Figure 3: The Flat Rock Dam on Schuylkill River, Manayunk, PA 9 Figure 4: Power Potential in Pennsylvania Rivers[7] 14 Figure 5: the complete schematic of the proposed power plant with all the required components 17 Figure 6: Horizontal Ossberger Turbine 19 Figure 7: Development configurations 21 1 Introduction Hydroelectric power or energy is generated from the energy released from water falls or dams. Simply put, water falls as a result of gravity; this results in kinetic energy which is converted into mechanical energy, which using turbines can in turn be converted into electrical energy that is usable. In ancient times, the Greeks generated energy by using wooden wheels to convert kinetic water energy into mechanical energy[1]. The first hydroelectric power generating plant was built in the United States of America in 1882, using fast flowing river water. In time, humans began developing dams and reservoirs to store water at locations considered convenient to utilize and exploit the power capacity and capability of water. Since then, hydroelectric power generation has overseen a myriad of transformations, both engineering and structural [2]. These resulted in a much more complicated hydroelectric energy power plant design process. Hydroelectric energy generations plants vary based on size and location, and as such, are categorized on that basis. Particularly, they are classified based on size and fit into four different categories which include mini, small, micro, and large. For instance, a hydroelectric power generating plant that generates less than 100kW is considered as a Micro-sized plant; typically, such a capacity is enough to serve about1 to 2 houses. Then, there is the mini-sized power plants which have a power generating capability of between 100kW and 1MW; this apparently can serve a small factory or an isolated community [2], [3]. A small power plant on the other hand has the capability of generating between 1MW and 30 MW of electricity, and can supply and serve the regional grid with electricity. The Large power plant category has the capability of generating more than 30MW of electricity. In the United States today, hydroelectric power contributes or constitutes more than 10% of the total energy produced and consumed in the US. The US has the potential to generate approximately 30,000MW of hydroelectric power; this potential, apparently can only be exploited if the US utilizes close to 5,600 unexploited hydroelectric sites [4]. These sites are undeveloped as a result of environmental, institutional, and legal constraints. Pennsylvania, for instance, has the capability of generating more than 5.5 million MWhr of electricity, which will eventually, only account for 4% of the total electricity produced in the commonwealth. 1.1 Problem Definition The United States Hydropower Resource Assessment Final Report (2012), reports that there are more than 104 hydropower projects each with a potential capacity of 2,218 MW. Manayunk Flat Rock Dam is among these sites; it is located in Philadelphia County, Pennsylvania in the Schuylkill River, particularly, the Delaware River basin. It is the hydroelectric power plant that this research or report focuses to discuss. Manayunk Flat Rock Dam has a potential electricity generating capacity of 2500kW [5]. The dam and the canal were built in 1819, but the dam collapsed, and thus, they were later rebuilt in 1977. It is built right on top of a previously, naturally existing fall. The canal apparently, provide transportation in the region for anthracite coal, since it enabled boats to avoid the rapids; furthermore, the water was previously used to power the Venice Island mills, and island that was created by the canal. Even today, boaters still use the canals’ slack water for recreation [4], [5]. 2 Review of Existing Hydroelectric energy schemes A perfect example of hydroelectric energy scheme is the Irafoss power plant located in Iceland. It is in fact, one of the power stations along River Sog. It was designed to generate and supply electricity to Iceland’s capital city, Reykjavik. Irafoss hydroelectric power plant harnesses its power from thee Kistifiss and the Irafoss falls, all which as located along the lower Sog [3]. The two falls both have a combined height of 38 meters [1]. Irafoss hydroelectric power plant went online in 1954; at the time, it utilized 2 turbines, each of which generated 16 MW. The power plant, however, was expanded in 1963, an expansion that saw the addition of another turbine, a third turbine, which has power generating capacity of 17.5 MW. It is interesting to note that one of the generators used at the power plant was manufactured in the US. Figure 1: Irafoss Hydroelectric Power Plant in Iceland Another important hydroelectric power plant is the Dinorwig and Electric Mountain Power Station in Wales, UK; it is not a fully-fledged electric power station per se; it is more of a pump storage facility [1]. A pump storage facility apparently uses basics mechanics in which two reservoirs that are at different altitudes are used. In the event of excess energy, especially during non-peak hours, water is pumped back into the upper reservoir so as to fulfill the demands of the peak. Consider Figure 2, which shows a schematic of the workings of the plant. The plant has the capability and capacity to generate about 1350 MW of power; in fact, the turbines and pumps are able to reach maximum capacity in less than 15 seconds [3]. Figure 2: Dinorwig and Electric Mountain Power Station in Wales These are effective hydroelectric energy schemes in their respective locations; this paper however, aimed at proposing a hydroelectric energy scheme for a region in Pennsylvania. This report purposes to show the effectiveness of building a hydroelectric energy plant in Pennsylvania, USA. It examines the electric power potential of the Manayunk Flat Rock Dam. Technical, costs, environmental and economic factors are put into considerations, as had earlier been mention [5]. A development site is then proposed, this is where the proposed hydroelectric power scheme will be implemented. Environmental consideration for any hydroelectric energy scheme are first addressed; particularly, the effects on fauna and flora-both drawback and benefits that will accrue as a result of implementing the energy scheme. Economic impacts on the immediate region, environment, as well as technical or engineering specification that will satisfy the implementation of an efficient hydroelectric energy scheme, which will produce the correct amount of power. Figure 3: The Flat Rock Dam on Schuylkill River, Manayunk, PA 2.1 Environmental Consideration The implementation of a hydroelectric power scheme has significant implications on the environment, particularly on biological, physical, as well as on humans in an immediate region. The construction of dam along a river is usually meant for hydropower generation, however, this is not the only reason; other reasons may include flood control and so forth. This is quite different from the implementation of a coal energy scheme, in which a coal power station is only built for the purpose of power generation [2]. The proposed site for the implementation of the hydropower scheme has a pre-existing dam, as such; the environment implications of such a project will be minimal. Constructing a hydropower plant significantly affects the physical environment. For instance, the ecosystem and river will be affected with the construction of a dam. This is because a dam stops the free flow of water, since a lot of water will accumulate in the new reservoir behind the dam. As a result, the surrounding land which might have been used for a myriad of purposes such as agriculture, residential development or forestry immediately becomes unusable. At time, particularly, in this proposed site, endangered flora and fauna are thus threatened [2], [5]. Dam construction also significantly impacts on the life of plants and animals. Aqua also sprouts in the surrounding environment; this is a negative biological effect, especially in semi-tropical and tropical regions. For instance, Lake Brokopondo in Surinam became an area inundated with water hyacinth, a rather unpleasant and irritating weed. Weeds may in turn result in massive water loss. Diseases such as schistosomasis and malaria somewhat increase since weeds only provide favorable condition for the mosquitoes as well as other insects that spread diseases. The problem with weeds can be controlled however, that would be expensive and difficult. When hydroelectric power projects are proposed, usually animals get a lot of attention from the general public and the media. For instance, before the commissioning of the Volta Dam hydroelectric power scheme in Africa saw a massive rescue operation of animals, which had to be transported to safer areas, away from the project site. In such instances, some animals such as giraffes or elephants are too big making the whole process more expensive and difficult. It is important to note that there are instances where creation of dams create new habitat for some fish species; a good example is when the Lake Nasser Dam was constructed, the production of fish increased almost four types [1]. The building of dams however, also makes completing the life cycle of some kinds of fish becomes impossible. This include fish species such as the anadromous fish, specifically salmon which are hatched in freshwater upstream; eel on the other hand are catadromous fish which studies show are hatched at sea and spend most of their life upstream in fresh water. It is clear that these fish rely on rivers and streams to get from one environment to the other, and as such creating a dam is likely to hinder their movement and lifecycle. Specifically, this is true in the Pacific Northwest in the US. A number of measures exist which can be taken to help reduce such effects on fish life as a result of hydroelectric power schemes. The most used and obvious measure has been to create diversion passage using better screens to capture fish; this reduces the number of fish passing through turbines. However, there have been advances in the development of power turbines to develop turbines that are much more fish friendly [1], [2]. 2.2 Economic Considerations When considering implementing a hydroelectric energy scheme in Pennsylvania, it is important to consider the economic impacts of constructing a power plant to the local community as well as the entire region. It is also important to put into consideration the global economic effects of such an important renewable energy source. Generally, most of the energy consumed globally are derived from oil, as a result, all other form of energy sources such as hydroelectric energy are affected by global oil prices. When oil prices are low, the demand for alternative energy sources reduces, and while oil prices are high, the demand for alternative energy subsequently increases [6]. Renewable alternative energy sources such as nuclear, hydroelectric, wind, and solar increased in use, more power plants were built and more demand was placed on these alternative renewable energy sources. An important economic factor that must be considered when designing a proposal of a hydroelectric energy scheme is the effect on GDP, Gross Domestic Product of a region or country, especially with regards to the years of the operation of the scheme. Operational, maintenance, development, and electricity generation costs are also important economic factors that must be considered when proposing a hydroelectric energy scheme [6]. It is important to consider whether or not a proposed hydroelectric power plant development site is developed; does a dam already exist? If not, then there are several things that are imperative to consider such as land, equipment, land rights, bridges, waterways, structures, roads, improvements, reservoirs, and railroads. In area or sites that are already developed, the only development costs that are considered are that of equipment, structures, and improvements. Flat Rock Dams, the current selected site for the proposed energy scheme, which is located along the Schuylkill River, in Philadelphia, PA, it is complete and has a preexisting site. Therefore, the only development costs that are considered are that of equipment, structures, and improvements. It is important to note that there is no electricity generation plant in that site. In order to redesign and improve the site, it is important to understand the surrounding environment, and the economics behind the process of construction and maintenance of the dam and the distribution of power [5]. The Manayunk town, where the Flat Rock Dam is located, has for years have been dependent on the Schuylkill River, for both trade and travel. The pre-existing dam, is apparently currently owned the Bureau of Abandoned Mines Reclamation, BAMR under The Pennsylvania Department of Environmental Protection [7]. A picnic area and a boat launch are maintained on the dam by the Lower Merion Township; this provides recreational access to the dam and pool. Currently, a controversy exists with regards to the use of powerboats. Based on the debate on the environment and the economics surrounding the dam, the question thus arise, should the proposed hydroelectric power scheme on the dam be maintained as is or should it be developed to its full potential? 3 The proposed Hydroelectric Power Scheme - Building of the Hydropower plant The chosen development site must be reviewed based on engineering and technical considerations. The location or the site must be geologically sound; this implies that it must be able to hold the dam’s weight, the water behind the dam in a way that will damage the surrounding are either physically, scenically, or in any other way. Most electricity is usually used through peak demand times; this has thus made meeting of peak demand for electricity a major priority that most electricity providers have addressed almost with the same response. In order to meet the power surge, most electricity companies in the US use natural gas-powered power plants [4]. However, natural gas combustion produces a lot of gases that pollute the environment [1–3]. Thus, this report proposes the use of water instead of natural gas to meet the peak demand; this is because water decreases the reliance on non-renewable fuel energy, and does not also pollute the pollute the environment since it does not produce or release volatile organic compounds such as NOx or SOx emissions. In the US, the Department of Energy relies on the expertise of Idaho National Environmental and Engineering Laboratory to study hydroelectric power generation potential of sites throughout the country. As a result, there is information regarding potential hydropower generation sites in each state, including Pennsylvania, which lists numerous site variables that have been considered with regards to determining each site [7]. According to that information, the major rivers available in Pennsylvania for damming include Beaver, Ohio, Allegheny, Delaware, Susquehanna, and Monongahela. Figure 4: Power Potential in Pennsylvania Rivers[7] Manayunk, Flat Rock Dam was shown to be a solid site for the development of a hydroelectric power plant. It was based on ninety points that are detailed in the Table 1; they provide a solid backing as to why Manayunk, Flat Rock Dam is suitable for the proposed hydroelectric power plant Table 1: Environmental Sustainability Factors[7] 3.1 Technical and engineering Considerations Designing a hydroelectric power scheme will require a number of equipment and elements that must be considered. The size of the dam, depth and size of the retention basin, diameter and length of the penstock, control gates and weir, inlet valves, generators, turbines, excitation equipment, transformers, and their efficiencies must all be examined. Head or elevation and the stream flow must also be established [1], [2]. The proposed hydroelectric power scheme has the capability to achieve a maximum drop of 6.5 meter or 22 feet, with an average stream flow of 257.63 cubic meters or 9180 cubic feet per second. The proposed hydroelectric power scheme can achieve electricity power of 2500kW. Based on this information, the calculations in Table 2 shows how much flow is needed in order to achieve the 2500kW threshold. Table 2: The flow is needed in order to achieve the 2500kW threshold The calculations indicate that only 19% of the stream flow will be diverted in order to generate the required 2500kW of electric power needed. The scheme will not divert more than the 19% that is needed to create the required amount of electricity flow, away from the rushing water and the aesthetics of the dam. This is because the selected region is a highly recreational area and as such, it is important to maintain those functions. 3.2 Specifications for the proposed hydropower plant The main dam for the proposed hydropower scheme already exists; this is because the site chose already had a pre-existing dam. The exact place where the power plant will sit will have a 21 feet head. It is important to note that the dam is an important part of the power plant because it controls the water. It dams the water, making it possible to determine the amount of water that will be required to generate electric power. Figure 5 shows the complete schematic of the proposed power plant with all the required components. Figure 5: the complete schematic of the proposed power plant with all the required components Building a power plant form ground up requires that the dam be the first to be built. Given that in this case the dam already exists, it will only be redesign and improved in order to match up the specifications required. The size of the retention basin, where the water will sit must be redesigned in order to ensure that the dam does not collapse. The water flow rate as well as the sediment load is also determined in order to determine the approximate lifetime of the dam. Intake is the dam’s entrance system for the water. The amount of water entering the dam system is controlled by the control gate and the valves. Different inlet valve designs exist; these include rotary or spherical, thruflow, and butterfly. For this scheme, the thruflow design is chosen since it has less leakage and head loss than the rotary or the butterfly. The intake weir controls where the water enters the dam and is also responsible for the diversion of the water [1], [2]. It also helps to keep out solid materials and sediments from entering the dam system. There are three types of intake that exist, among them the side intake with weir, without weir, and the bottom intake. The side weir with no intake is cheap and requires no complex machinery and only needs regular repairs and maintenance. This type of intake is however no suitable for river that have great flow fluctuations since at low water flows, very little water is diverted. The side intake with weir has the weir either completely or partially submerged in water, thus, it requires very little maintenance; however, with low water flow, diversion cannot happen properly. In the bottom design, the weir is completely submerged, as a result, it is useful in rivers that have fluctuating water flows; it allows extra water to pass over the weir. The location of the dam for the proposed plant would require the use of the side intake design with a weir. This is because it allows better flexibility, as such; it would be the most economic and effective. The tunnel that carries the water to the turbines from the intake is referred to as the penstock. In deciding the material to be used to build the penstock, there are a myriad of factors that must be put into consideration. These include the design pressure, weight, and surface roughness, jointing method, ease of installation, soil type, terrain, weather conditions, site accessibility, maintenance and design life, and likelihood of structural damage, relative cost, and availability [1], [2]. It is efficient to make the right choice especially with regards to what the surrounding soil can do to the penstock through degradation; this may result in the penstock costing more than 40% of the total cost of developing the power plant. Water flowing through the penstock reaches and turns the turbines. Different turbine models exists, which mostly depend of the company in which the turbine is purchased. Common designs include the reaction and impulse turbines. Examples of impulse turbines include Turgo, multi-jet Pelton, Pelton, and cross-flow designs. On the other hand, reaction turbine deigns include the propeller, Kaplan, and Francis. Turgo or Pelton are suitable for high head, Francis, cross-flow, or multi-jet are suitable for medium head, while Kaplan, cross-flow, or Propeller, are ideal for low head. Given this proposed hydroelectric energy scheme has a medium head, the best and most suitable design would be the cross-flow. For it to work better with the set-up of our design, it must be horizontal. The specific type of cross-flow turbine design that will be used is the Ossberger, which has up to 86% efficiency, and can operate in the head ranges between 1 to 200 meters and with flows ranging between 0.025 and 13 cubic meters per second [2]. Based on these specifications and in order to generate the maximum amount of electric power, four of the Ossberger cross-flow turbines will be used. They are relatively slow and move at an average of 20 to 80 revolutions per second. Figure 6: Horizontal Ossberger Turbine It is a partial and radial admission steam turbine which is considered as a slow speed turbine. Apparently, the guide vanes divulge to the water jet, a rectangular cross-section. Water flows through the cylindrical rotor’s blade ring, first from the outside, then from the inward, and later passes through the inward rotor form the inside outward. As required by the specifications in this case, the Ossberger turbine is built in as a multi-cell turbine, with a nominal division of 1:2 [1]. With this division, any water flow from 1/6 through to 1/1 admission is processed at the maximum efficiency. 3.3 Development configuration Figure 7 shows the development configurations that the canal and the river with the power plant may have. Based on how the canal and the dam look in this proposed scheme, design be, the one with the extended fall canal is considered as the better option. This is because the scheme will allow the maximum utilization of the stated area. Figure 7: Development configurations 4 Conclusion This report, after extensive examination and review of existing hydroelectric energy schemes has been able to determine the feasibility of designing and implementing a hydroelectric power scheme/plant at Manayunk Flat Rock Dam. As has been discussed most environmental concerns that affect the implementation a hydroelectric power plant stem from the ground-up construction of dam, they will not be an issue for this proposed scheme, given that the chosen location/site already has an existing dam. This scheme will only, partially disrupt the volume of water flowing into the dam, and most importantly will only utilize about 19% of the flow. This scheme will also benefit the community economically, since it will not only provide power, but also employment opportunities. The construction cost for this proposed scheme is low given that there is no need for constructing a new dam. Based on these considerations, the proposed scheme would be a promising project. It would be considered a small hydroelectric energy scheme given that it would only have the potential of producing electric power of 2500kW. 5 References [1] M. Rodger, Hydroelectric Power: Power from Moving Water. Boston, MA: Crabtree Publishing Company, 2010. [2] J. Sherman, Hydroelectric Power. Mankato, Minnesota: Capstone Press, 2004. [3] European Commission - Reasearch and Innovation, “Hydropower,” European Commission - Reasearch and Innovation, 2013. [Online]. Available: http://ec.europa.eu/research/energy/eu/index_en.cfm?pg=research-hydropower. [Accessed: 05-Apr-2014]. [4] US Department of Energy, “Hydropower Topics,” Energy Efficiency and Renewable Energy, 2009. [Online]. Available: http://www.eere.energy.gov/RE/hydropower.html. [Accessed: 03-Apr-2014]. [5] A. M. Conner and J. E. Francfort., “U.S. Hydropower Resource Assessment for Pennsylvania,” Philadelphia, PA, 1997. [6] B. K. Edwards, The Economics of Hydroelectric Power, 3rd ed. Hoboken, New Jersey: Edward Elgar Publishing, 2003. [7] Idaho National Engineering and Environmental Laboratory, “Pennsylvania Hydropower Resource Database Listing,” Idaho National Engineering and Environmental Laboratory, 2001. [Online]. Available: http://hydropower.id.doe.gov/resourceassessment/pa/paappdpage64.shtml. [Accessed: 04-Apr-2014]. Read More