Hydro power

Hydroelectric powerYul van der StapWhat isHydroelectric powerpower generated through the energy of flowing waterHistory

Humans have been using water to power our heavy work for more than two thousand years. Ancient civilizations, including the Greeks and Romans, diverted water to push wheels that would then turn mills to grind grain for bread. Before the Industrial Revolution, water was the main power source for milling lumber and grain, and powering small machinery.This is a diagram of letheringsett watermill created before industrial revolution3HistoryFox river in Appelton, Wisconsin

Dams using hydraulic reaction turbines were first used to generate electricity in the U.S. in the 1880s (See Reference 4) Within 20 years of the first few hydroelectric dams, nearly 40 percent of the electricity in the U.S. was being produced hydroelectrically. (See Reference 3) From 1905 through the 1930s, several large dams, including the Hoover and Roosevelt dams, were added to meet the public demand for electricity in their homes. (See Reference 4) By 1940, three-quarters of the electricity for the western states came from hydroelectric power. 4History

n the mid-20th century, hydroelectric power through dams could not meet the demands of the growing U.S. population and the increase in homes that used electric lighting and appliances. New forms of power generation were developed such as nuclear power, coal, and natural gas. Currently, hydroelectric dams running at their maximum produce only enough electricity to power 10 percent of the homes in the U.S. Controversies such as the impediment of fish migration and the impact of changing a river's natural course have lead to dams having a poor image in the public eye, despite the power source being renewable and relatively nonpolluting.5Dam

I introduce you the first hydroelectric power plant: dam. We will see the video about how the dam gathers energy.6Energy transformation

7FormulaPE=pghVP=ghQ

For 1m^3/sec from head of 1m ,P=9 kW, if 90%

Potential energy=density times head times gravitaional constant times volume

Power =eta, efficiency of turbine, times pgh times Q, the flow rate.

8Advantages & disadvantagesDam +Constant rate of electricity productionLong durabilityLake can be used as irrigation purposeLeisure area-High cost of constructionDestruction of environmentAlter of natural water table level.9Run of river

A portion of river is diverted into the forebay.The purpose of the forebay is to allow large debris in the water to settle so that it will not enter the facility and damage the turbineThe water then flows into some combination of canal, where it is delivered to the powerhouse.The powerhouse contains the turbine, generator, and other mechanical and electrical equipment. The turbine converts the energy from the flowing water into mechanical energy.The turbine is connected to a generator, which transforms the rotational energy into electricity.After the water leaves the turbine, it is returned to the river through a canal.10Energy transformation

FormulaPmax =Qv2 Q=Av

Pmax =1/2Av3

if 1m3 of water flows 1ms-1 with 100% efficiency, P=0.5kWwhere v is the velocity of the water flow and Q is the volume of water flowing through the turbine per second. Q is given by Q=Av, where A is area. 12Advantages & disadvantagesRun of River +Avoids the need to build large dams to store waterprojects will operate anywhere between 65% to 90% of the time in any given yearLow potential risk of water qualityHas minimal impact on environment-Low production rateLow availability

avoids the need to build large dams to store water, allowing the project to generate as conditions, river flows and the license permitsCompany constructing run of river is taking advantage of sites that have strong head and flow duration curves, its projects will operate anywhere between 65% to 90% of the time in any given year. From an installed capacity perspective, this means that even a small project will generate a lot of kilowatt-hours.

Even though it has high efficiency and operation time, the the electricity produced is not high enough compared to other renewable power plants compared to dams or others. Like I showed you before, even with same conditions were given the dam could produce 9kW while run of river was 0.5.

13Tidal flows

14TransformationKE (water)KE (turbine)Electricity (generator)15FormulaPmax =1/2Av3

if 1m3 of water flows 1ms-1 with 100% efficiency, P=0.4kWThe maximum power output from a shrouded water turbine used in tidal energy applications is equal to the kinetic energy of the water impinging on the blades, similar to the "run of river" calculation above. Taking the efficiency of the turbine and its installation into account, the maximum output power Pmax is given by Pmax =Av3where v is the velocity of the water flow and A is the swept area of the blades.16Advantages & disadvantagestidal flow+Can harness until sun and moon existEfficiency of 80%PredictabilityProtection of coastal area-High construction costEffective only 10hrs /dayEnvironmental damage

Tidal forces have their origin in the gravitational interaction with the Moon and Sun, meaning that we could harness tidal power as long as Moon and Sun continue to exist.

The efficiency of tidal power. Tidal power belongs to the most efficient energy sources by having efficiency of approximately 80%, this is much better efficiency as compared to other more popular renewable energy sources such as solar and wind.

Tides are predictable, and this predictability is also one of the advantages that tidal power has over other energy sources because rise and fall of tides are much more cyclic than random weather patterns. This predictability gives us knowledge when the tides will be in and out.

Barrages and small dams used to harness tidal power could protect coastal areas or ship ports from dangerous tides during a stormy weather

Tidal power disadvantages:

Tidal power plants are connected with high upfront costs needed for construction, and therefore lack cost-competitiveness on global energy market.

Tidal power is intermittent source of energy that can only produce electricity during tidal surges which is in average around 10 hours each day. This means that in order for tidal power to be considered as a reliable source of energy needs to be accompanied with some effective energy storage solution.

Tidal power plants could lead to environmental damage in some cases as the frames of the turbines have potential to disrupt the movement of large marine animals. Also, the construction of tidal power plant can disrupt fish migration in the oceans.

17The endhttp://www.technologystudent.com/energy1/hydr2.htmhttp://www.mpoweruk.com/hydro_power.htmhttp://greenliving.nationalgeographic.com/history-hydroelectric-power-20128.htmlhttp://www.window.state.tx.us/specialrpt/energy/renewable/http://teeic.anl.gov/er/lhhydro/restech/desc/index.cfmhttp://www.runofriverpower.com/media/documents/CEBC_FS-RunOfRiver_WEB354.pdfhttp://hydroearth.blogspot.kr/2012/10/tidal-power-advantages-and-disadvantages.htmlhttp://www.youtube.com/watch?v=qRUl1mJQHmc&list=PLC73D6D66C6F9D747http://www.pembina.org/re/sources/hydro-powerhttp://www.youtube.com/watch?v=rnPEtwQtmGQ