How Is Power Generated With Hydroelectricity?

Hydroelectric power energy from falling water. Hydro electric power means getting energy from flowing water. This method of energy generation is viewed as very environmentally friendly by many people, since no waste happens during energy generation. However, hydroelectric power can have a deep impact on the surrounding environment, leading some people to question the help of hydroelectric power as a method of clean energy generation.

Hydroelectric power is used to run water as an energy source and mostly in grind corn. Hydroelectricity produced enough power light for two paper mills and a house. Nearly ally of the hydroelectric power stations, provide around 20% of the worlds electricity. The Origin of Hydro Power was first used in Ancient Egypt. They used flowing water to make a machine work and grind their crops. The Size of the Hydro power plants today range in size from some hundred kilowatts to several hundred megawatts. Some of the larger plants have capacities up to 10,000 megawatts and supply electricity to millions of people.

Over 80 percent of all electricity produced by renewable sources is produced by large hydroelectric dams. With low carbon dioxide emissions and working costs, hydropower is an important part of a climate friendly energy mix. More sustainable sources, such as wave and tidal power, could save the standing of water based energy production.

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Hydropower accounts for around 20% of the world’s electricity generation, and a little over 2 percent of the world’s total energy supply. Although dams often have big environmental and social impacts, the World Wide Fund for Nature estimates that another 370 Giga watts of large, medium, or small hydroelectric capacity could be developed without unacceptable impacts by 2050.

The energy output

Because most dams use gravity, a hydroelectric dam’s energy output depends largely on the height difference between the tank water source and the outflow. Water flow along the rivers is another important factor, as is the age and efficiency of a dam. Many of the world’s older dams will need to be upgraded or repowered in the coming decades to improve efficiency, which will be expensive but could eventually add another 30 GW to the global energy mix.

Environmental impact

Large hydroelectric dams have a number of negative impacts on the local environment and human society. Dams disrupt river ecosystems and passages, killing aquatic life that gets caught in turbine blades. Dams also create artificial reservoirs, which floods farmland and forests, and displaces wildlife and people. Hydroelectric projects are also susceptible to fluctuations in river flows and rainfall. Which depends on energy from the Volta River Dam, has suffered severe energy shortages in recent years because of lack of rainfall.

The key environmental problem with hydroelectric power is that blocking changes the natural environment. The flow of a river is basically changed when a dam is installed, posing problems for fish and aquatic plants on both sides of the dam. However, there are some arguments in support of hydroelectric power. Once installed, a hydroelectric power plant does not generate any emissions or waste, making it very much preferable to something like a coal fired power plant. The technology of hydroelectric power is also always being improved, and sometimes simple measures like fish ladders can moderate the impact of a dam.

How it works….

1. Hydroelectric power, or hydroelectricity, is generated by the force of falling water. It’s one of the cleanest sources of energy and it’s also the most reliable and costs the least.

2. Water is needed to run a hydroelectric power-generating unit. The water is held behind a dam, forming an artificial lake. The force of the water being released from the reservoir through the dam spins the blades of a giant turbine. The turbine is connected to the generator that makes electricity as it spins. After passing through the turbine, the water flows back into the river on the other side of the dam. Basically the exciter powers the rotator.

3. Electricity is produced by spinning electromagnets within a generator’s wire coil that creates a flow of electrons. To keep the electromagnets spinning, hydroelectric stations use falling water. Hydroelectric power plants convert the kinetic energy contained in falling water into electricity. The energy in flowing water is ultimately derived from the sun, and is therefore constantly being renewed. As the rotator and its magnetic field turn, an electric charge is created in the stator.

4. Energy contained in sunlight evaporates water from the oceans and deposits it on land in the form of rain. Differences in land elevation result in rainfall runoff, allowing some of the original solar energy to be captured as hydroelectric power. Most hydroelectric stations use either the natural drop of the river or build a dam across the river to raise the water level and provide the drop needed to create a driving force. Water at the higher level goes through the intake into a pipe, called a penstock, which carries it down to the turbine. A transformer increases the voltage of the current coming from the starter.

The turbine is a type of water wheel that converts the water’s energy into mechanical power. The turbine is connected to a generator, when the turbine is set in motion it causes the generator to rotate, producing electricity. The falling water, having served its purpose, exits the generating station through the draft tube and the tailrace where it rejoins the river.

Building a dam means flooding a lot of land. The sun evaporates water from the sea to the lakes. This forms clouds and falls as rain in the mountains which then keeps the dam supplied with water. For free. Gravitational potential energy is stored in the water above the dam. Because the height of the water it will get to the turbines at a higher pressure. This means that people can extract a great deal of energy from it. The water then flows down to the river as normal.

There is another way of using the hydroelectric power is to build the station next to a fast flowing river. However using this way may cause a problem which when you do the arrangement the flow of the water cannot be controlled and water cannot be stored.

Advantages…

Once the dam is built, energy is almost free.

No waste or pollution produced

It is more reliable than wind, solar and wave power

Water can be stored above the dam

Hydroelectric power stations can increase to full power quickly.

Electricity can be generated all the time.

Disadvantages…

It is very expensive to build

Building a large dam will flood a very large area upstream which can cause problems for animals

Hard to find a suitable site.

Water quality can be effected which have an impact on plants.

Hydroelectric power is renewable. It is renewable in the sense that people cannot take away the source of the energy by using them. The sun provides water by evaporation from the sea. No fuel is needed in this generation. Also energy of the tides will not go away if the power is used.

Efficiency

The equation for hydro electric power is P = Q X H X 0.18 X E

The p is for power in watts.

The Q is the flow rate in gallons per minute

The H is vertical relief measured in feet

0.18 is a unit conversion constant

The E is the efficiency of the turbine

The micro hydroelectric turbines are an efficiency of 50%. However for the mini hydroelectric applications the efficiency is a bit higher usually around 65%.

The Cost

The costs of the hydro electric power is everything concerning hydro, the costs are site specific, they will depend on the head available such as the higher the head the smaller the turbine needed to generate the same level of power. The high head machines can be also be connected directly to the generator without the need for the belts. Hydroelectric power is attractive because it’s cheap for the consumer average price in the PNW is around 4 cents per KWH this is 3 times less than the national average.

Low costs to the consumer reflect relatively low operating costs of the Hydro Facility. Most of the cost is in building the dam

Operating costs about 0.6 cents per KWH

Coal Plant averages around 2.2 cents per KWH which reflects costs of mining, transport and distribution.

Energy density in stored important water is high, so one liter of water per second on a turbine generates 720 watts of power. If this power can be continuously generated for 24 hours per day for one month then the total number of KWH per month is then:

720 watts x 24 hours/day x 30 days/month = 518 Kwh/month.

Power generating capacity is directly relative to the height the water falls. For a fall of say only 3m, 30 times less electricity would be generated but this is just for a miniscule flow rate of 1 kg/sec.

Solar Power- Energy from the Sun

Solar power is energy which comes from the sun. People have used sun for drying clothes and foods for thousands of years but only now people have been able to use it for generating power. The sun is about 150 million kilometres away and very powerful.

Just a tiny fraction of the suns energy that hits the earth is enough to meet all the power needs many times over. Every minute enough energy gets to the earth to meet the demands for a whole year.

Solar power is energy which comes from the sun. This energy is very powerful and hits the earth regardless of whether or not we take advantage of it. Even the tiny percentage of sunlight that touches the earth is plenty to meet the energy and power needs of the entire human population more than 8,500 times over.

Energy from the sun is converted into solar power using solar collectors. Solar panels consist of solar cells designed to capture energy from the sun. The solar panels used in heating air and liquid are different from those used to provide electricity. To absorb the highest possible amount of solar energy, solar panels must be pointed at the sun.

Energy from the sun can be converted into solar power in two ways. The first way involves the use of solar thermal applications. Solar thermal applications use the sun’s energy to provide direct heat to air or liquid. Solar thermal panels can be used for both housing and larger scale applications.

The second way of obtaining solar power involves the use of photoelectric applications. Photoelectric applications use photovoltaic cells in converting energy from the sun into electricity. Photovoltaic cells are considered low maintenance and well suited to remote applications. They use semiconductors like silicon to convert energy from the sun into electricity.

How solar power works…

Solar cells- the Photovoltaic (Photo means light and voltaic means electricity) which convert light directly into electricity, for example in sunny weather you can get enough power to run a 100w light bulb from just one square metre of solar panel. Solar cells provide the energy to run satellites that orbit the earth.

Solar water heating- this is where heat from the sun is used to heat water in glass panels. This means people do not use so much gas and electricity to heat water at home. Water is pumped through pipes in the panel, the pipes are painted black, and so they get hotter when the sun shines on them.

Solar furnaces- it uses a huge collection of mirrors to concentrate the suns energy into a small space and produce very high temperatures. Solar furnaces are very huge “solar cookers”. A solar cooker can be used in hot countries to cook food.

Solar energy isn’t all about generating electricity:

For example, photo luminescent products store light energy. They’re also called “self-luminous” and are a useful source of emergency lighting in the event of a sudden power outage.

The advantages of solar power are…

Solar energy is free – it needs no fuel and produces no waste or pollution.

In sunny countries, solar power can be used where there is no easy way to get electricity.

Handy for low-power uses such as solar powered garden lights and battery chargers, or for helping your home energy bills.

The disadvantages of solar power are…

Doesn’t work at night.

Very expensive to build solar power stations, although the cost is coming down as technology improves.

Can be unreliable unless you’re in a very sunny climate.

Solar cells are expensive

Solar power is renewable. The Sun will keep on shining anyway, so it makes sense to use it.

3 main ways to use it:-

Sun heats water in panels on your roof

Solar cells “photovoltaic cells” make electricity from sunlight

Solar furnace

Solar power isn’t much use unless you live somewhere sunny

Doesn’t cause pollution, doesn’t need fuel.

Basics of solar power

The amount of power generated by solar cells is determined by the amount of light falling on them, which is depending on the weather and time of day. Sometimes there will be too much power, other times these won’t be enough. In this case the system battery can be damaged if it was overcharged or over discharged. The smallest system may have only 12 volts of light, but in bigger systems 23o or 110 volts will probably be needed. An invert is used to transform the low voltage Direct Current generated by the solar panel into mains voltage Alternate current.

The costs of solar power

Solar power is currently selling for between £3 and 35 per watt of rated power output. A typical panel that you might install on your roof would be rated for between 100 and 300 watts and therefore will cost between about £400 and around £1500 or so.

A complete solar power system also needs some other components and will have some installation costs and so the total installed cost of a solar system is usually in the range of £8 – 10 per watt of rated power. Most home sized systems are rated in the 1000 to 10,000 watt range and therefore cost between about £8000 and £100,000 to install. Many states offer refunds and tax savings that can reduce this cost by as much as 50%.These systems will normally generate between about £300 and £2500 worth or electricity per year.

Solar panels are expected to last between 30 and 50 years and so these systems will likely generate between £9000 and £120,000 worth of electricity over their life time. This will be different widely though based on local electricity costs and may well increase greatly in the future if electricity rates rise.

Energy efficiency

Energy efficiency saves money, where solar energy saves even more money. The efficiency rating of solar panels is fairly low for instance the amount of the suns energy converted into electricity. Depending on the situation it can range from 5% to 15%, although there have been some recent breakthroughs in technology which has increased this to 40%. However it will be some years before this technology becomes money making available in the solar panels we fit to our homes.

When calculating how many solar panels you need for your home, you don’t need to be too concerned about the efficiency rating of your panel because photovoltaic solar panels are specified by their energy generating capacity. For example, 100 watt panels will output 100 watts of energy under ideal conditions. So if you are looking to produce 1kw per hr of energy you will need 10 x 100 watt panels.

Solar panels range in their energy output. normally they range from 30 to 205 watts. If you are DIY then pay special interest in calculating your energy requirements. If you are getting a company to draw up plans for you then they will take care of this calculation.

There are three main types of solar photovoltaic cells and these are polycrystalline, mono crystalline and thin film. Each has different efficiency ratings when converting the suns energy into electricity and they all have their advantages and disadvantages.

The main difference between them is size and price. The more efficient technologies like mono crystalline panels are more efficient than the other two and so the panels are smaller and take up less space when comparing like for like in energy output but they are more expensive.

So before you decide which panels to go for, you need to calculate your energy requirements, establish how much you want to invest and then go and compare the different panels.

There are many other aspects that can affect the efficiency of your panels. We find the following to be the most common: how often you clean them, are they infrared, how much sun do they get and how hot do they get. It is a surprise to many people that for most panels their efficiency drops when the temperature starts to go above 25 Deg Celsius. If you want a hot water heater conversion then solar thermal panels are a lot more efficient.

In summary, on face value solar energy does not seem very efficient, although it is improving year on year. However, don’t get too tied up about the efficiency of the panels, focus more on the output, size and level of investment.

Sustainability

Solar energy will burn for billions of years; it won’t run out any time soon. This is sustainable because it will not reduce in the near future. They use primarily silicon, which is one of the richest materials on earth. But they can also use other things, like metals (copper, silver, gold), and some toxic chemicals (arsenic, cadmium) etc. The sustainability of these materials are recyclable, and it is thought 99% of a solar cell can be recycled. But the production of them does has some toxic site affects, which means we have to balance the clean energy production of the cells with the bad by products of their manufacturing process.

Appropriate energy

The biggest gains are usually found in lighting. Solar power doesn’t have to be used for heating, but it would help. However, electricity is a bad way of heating things, but you can use solar power to heat water. Most houses are not designed for energy efficiency especially old houses. Normally light bulbs waste a lot of energy, that’s because they work by getting hot. It’s like getting a little light and a lot of heat. Always use low energy lamps. However in low voltage lamps if your solar power is small and you don’t have a big inverter, then you will be better off with low voltage lamps.

Tidal power

Coming and going of the tides gives this form of renewable energy a different advantage over other sources that are not as predictable and reliable, such as wind or solar. The Department of Trade and Industry has stated that almost 10% of the United Kingdom’s electricity needs could be met by tidal power.

Tides come and go is because it is all to do with the gravitational force of the Moon and Sun, and also the rotation of the Earth.

This diagram shows how the gravitational attraction of the moon and sun affect the tides on Earth. The size of this attraction depends on the mass of the object and its distance away. The moon has the greater effect on earth even with having less mass than the sun because it is so much closer. The gravitational force of the moon causes the oceans to swell along an axis pointing directly at the moon. The rotation of the earth causes the rise and fall of the tides. When the sun and moon are in line their gravitational attraction on the earth combine and cause a spring tide. When they are as positioned in the first diagram above, 90° from each other, their gravitational attraction each pulls water in different directions, causing a neap tide.

The rotational period of the moon is around 4 weeks, while one rotation of the earth takes 24 hours; this results in a tidal cycle of around 12.5 hours. This tidal behaviour is easily predictable and this means that if harnessed, tidal energy could generate power for defined periods of time. These periods of generation could be used to offset generation from other forms such as fossil or nuclear which have environmental consequences. Although this means that supply will never match demand, offsetting harmful forms of generation is an important starting point for renewable energy.

Tidal energy is a type of energy that produces electricity and other form of power through the use of water. Tidal energy is the energy that could be obtained from changing sea levels. It is a direct result of tide changing from low to high. The two basic theories on how to convert tides into power are:

Is involves in converting the power of the horizontal movement of the water into electricity.

Involves producing energy from the rise and drop of water levels.

LIKE THIS!

Most are at the concept proving stage and have links to universities such as Plymouth, Manchester and Imperial College. Technologies in development include:

Use of a shore based oscillating water column,

Trapping and compressing air in successive waves to build enough compression to drive a turbine

Using pressure differences under wave crests to drive water flows through turbine chambers

Floating buoys that use the kinetic energy of the buoy’s rise and fall to drive a turbine

Using the motion of joints in an articulated structure to drive hydraulic rams that power motors.

There are different types of turbines that are available for use in a tidal barrage. A bulb turbine is one in which water flows around the turbine. If a repair is required then the water must be stopped which causes a problem and is time consuming with possible loss of generation. When rim turbines are used, the generator is mounted at right angles to the to the turbine blades, making access easier. But this type of turbine is not suitable for pumping and it is difficult to control its performance. The blades of this turbine are connected to a long tube and are leaning at an angle so that the generator is sitting on top of the barrage.

The turbines in the barrage can be used to pump extra water into the basin at periods of low demand. This usually works with cheap electricity prices, generally at night when demand is low. The company therefore buys the electricity to pump the extra water in, and then generates power at times of high demand when prices are high so as to make a profit.

HOW IT WORKS

Step 1: First a place must be chosen for the plant to be built

Step 2: Then it must be tested to make sure the waves are big enough to produce enough electricity to make up for the price.

Step 3: After this they must build the power plant

Step 4: Then they have to test it to make sure it works

Step 5: The tidal power plant should do the following: The waves should go into the plant. The pressure of the waves should turn the turbines making electricity.

It would cost at least £15 billion to build a tidal power. However there would be a number of benefits, including protecting a large stretch of coastline against damage from high storm tides and providing an already made road bridge. Although the drastic changes to the currents in the estuary could have a huge affects on the economic and huge number of birds that feed on the mud, so when the tides goes out the birds would have no where to feed.

Efficiency of tidal power

The benefit of tidal range power is its remarkable efficiency: once constructed, up to 80% of the potential energy of the water ‘captured’ which can be converted to electricity with no greenhouse emissions. Tidal energy is also attractive from the point of view of energy security which makes uses of resources naturally available on and around the stores.

Economics

The capital required to start construction of a barrage has been the main awkward block to its deployment. It is not an attractive plan to a saver due to long payback periods. This problem could be solved by government funding or large organisations getting involved with tidal power. In terms of long term costs, once the construction of the barrage is complete, there are very small maintenance and running costs and the turbines only need replacing once around every 30 years. The life of the plant is unclear and for its entire life it will receive free fuel from the tide. The economics of a tidal barrage are very complicated. The optimum design would be the one that produced the most power but also had the smallest barrage possible.

Social Impact

The building of a tidal barrage can have much social cost on the surrounding area. During the building of the barrage, the amount of traffic and people in the area will increase and will last for a few years. The barrage can be used as a road or rail link, providing a time saving method of crossing the bay or estuary. There is also the possibility of include wind turbines into the barrage to generate extra power. The barrage would affect shipping would have to be made to allow ships to pass through.

The biggest disadvantages of tidal barrages are the environmental and ecological affects on the local area. This is very difficult to expect, each site is different and there are not many projects that are available for comparison. The change in water level and possible flooding would affect the plants around the coast, having an impact on the aquatic and shore ecosystems. The quality of the water in the basin or estuary would also be affected, the remains levels would change, affecting the turbidity of the water and therefore affecting the animals that live in it and depend upon it such as fish and birds. Fish would certainly be affected unless condition was made for them to pass through the barrage without being killed by turbines. All these changes would affect the types of birds that are in the area, as they will travel to other areas with more favourable conditions for them.

These effects are not all bad, and may allow different species of plant and creature to grow in an area where they are not normally found. But these issues are very fine and need to be independently assessed for the area.

Advantage

Once tidal power is built it is free.

It doesn’t produced no green house gases or other waste

It needs no fuel

It produces electricity

Its not expensive to maintain

Tides are totally predictable

Offshore turbines are not ruinously expensive to build and do not have large environmental impact.

Unlike wind and solar power production using the tidal forces is constant and predictable.

No Waste produced

Sustainability of energy production.

Easy and not expensive to maintenance.

Has little impact on the environment.

Tidal energy turbines are dropped into deep water, so they are not a danger to ships.

Tidal power cannot be used up

Disadvantages

A barrage across an estuary is very expensive to build and effects wide areas

Many birds rely on the tide uncovering the mud flat so that they can feed and Fish can’t travel

Only provides power for around 10 hours a day- when the tide is actually moving in and out

There are few suitable sites for tidal barrage.

Heavier that wind turbines

More expensive than wind turbines.

Usually producing power for around 10 hours each day. This is the time frame in which the tide is actually moving in or out.

Tidal energy has potential to become a possible option for large scale, base load generation. Tidal Streams are the most attractive method, having reduced environmental and ecological impacts and being cheaper and quicker to be installed.

Tidal barrage is where a dam or barrage is built across an estuary or bay that experiences an enough tidal range. This tidal range has to be in overload of 5 metres for the barrage to be possible. The purpose of this dam or barrage is to let water flow through it into the basin as the tide comes in. The barrage has gates in it that allow the water to pass through. The gates are closed when the tide has stopped coming in, trapping the water within the basin creating a hydrostatic head. As the tide moves away out with the barrage, gates in the barrage that contain turbines are opened, the hydrostatic head causes the water to come through these gates, driving the turbines and generating power. Power can be generated in both directions through the barrage but this can affect efficiency and the economics of the project.

The structure of a barrage requires a very long national engineering project. The barrage will have environmental and ecological impacts not only during building but will change the area affected forever. Just what these impacts will be is very hard to measure as they are site specific, and each barrage is different. There are different types of turbines that are available for use in a tidal barrage. A bulb turbine is one in which water flows around the turbine. If protection is required then the water must be stopped which causes a problem and is time consuming with possible loss of generation. When rim turbines are used, the generator is mounted at right angles to the to the turbine blades, making access easier. But this type of turbine is not suitable for pumping and it is difficult to control its performance.

Bulb Turbine

Rim Turbine

Tubular Turbine

The turbines in the barrage can be used to pump extra water into the basin at stages of low order. This usually matches with cheap electricity prices, generally at night when the order is low. The company therefore buys the electricity to pump the extra water in, and then generates power at times of high claim when prices are high so as to make a profit. This has been used in Hydro Power, and in that context is known as pumped storage.

The economical effects of tidal power are when they start building of a barrage has been the main uncertain block to its use. It is not an attractive to a saver due to long payback periods. This problem could be solved by government funding or large organisations getting involved with tidal power. In terms of long term costs, once the building of the barrage is complete, there are very small maintenance and running costs and the turbines only need replacing once around every 30 years. The life of the plant is unclear and for its entire life it will receive free fuel from the tide. The economics of a tidal barrage are very complicated. The best design would be the one that produced the most power but also had the smallest barrage possible.

Social impact

The building of a tidal barrage can have many social costs on the surrounding area. During building of the barrage, the amount of traffic and people in the area will increase a lot and will last for a number of years. The barrage can be used as a road or rail link, providing a time saving method of crossing the area. There is also the possibility of including wind turbines into the barrage to generate extra power. The barrage would affect shipping and navigation and but would have to be made to allow ships to pass through.

Wind power

A wind power is the conversion of wind energy into a useful form of energy. Such as people use wind turbine to make electricity, wind mills for mechanical power, wind pumps for pumping water or dra