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I think that tidal (and wave) power is a great option as a renewable energy resource. I live in Australia so we have lots of oceans and an absence of baseload high quality viable renewable energy sources (solar chimney technology is getting there but still could not be considered to be a baseload source due to variation in sunlight intensities). Tidal has the benefit of being able to be predicted well in advance (we have tide charts after all) and in equatorial regions tides can be huge. Wind was at the same stage as tidal 30 years ago and is now a viable source. From a microgeneration perspective small communities throughout Asia and the Pacific would benefit from the ability to install a small tidal turbine (rated to say 500kW) that would reduce the need to use diesel generators which cost far more than $0.04/ kWh. I definitely think that governments need to invest strongly on tidal energy.

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Some farms in remote areas have wind mills for power generation and there are also some commercially run wind farms. I copied the stuff below from a alternative energy page.

“South Australia’s ninth wind farm just opened on the Barunga Ranges near Snowtown. Its 47 turbines, installed by Trust Power of New Zealand, (who already operate that countries largest wind farm at Tararua), are said to have the capacity to deliver over 98MW of electricity. The company reckon this output should provide sufficient power for around 70,000 Australian households.

Not only was this project completed ahead of schedule, but it allows the state of South Australia to claim that they now produce almost 60% of Australia’s wind power. Additionally it means that South Australia is poised to meet Prime Minister Kevin Rudd’s target for all states to produce 20% of their energy from renewable sources by 2020.”

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1KW will run quite a few low energy lamps, plus a computer, TV or HiFi etc.

It would not run an electric kettle or or anything else much in the way of heating appliances.

The BIG problem you will have is that a ‘1KW’ wind generator will probably only average 100W on a good day.

Look very carefully at the ratings and figures of the device before you spend any money.
Some of the generators on sale only give the headline rating if mounted on a tall mast on top of a hill & with a gale force wind…

They put windfarms in open spaces & on tall masts for good reason. The airflow near buildings & obstructions is generally so turbulent it’s a waste of time trying to use a small wind generator in a town.

Do some research and find reports from other people who have bought the one you are looking at first, otherwise you are likely to pay out more than you can save in electricity over the lifetime of the machine.

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There are a multitude of misconceptions about the Amish. Here are just a few:

The Amish don’t use any modern technology – FALSE. The Amish are selective about the technology they use. They tend to reject technology that they feel would have a significant negative impact on their lifestyle, but are accepting of technology they do not see a problem with. Also, what technology is accepted and what is rejected depends on the Amish affiliation and each individual church community.

The Amish feel electricity is evil – FALSE. This has to be the most ridiculous of all the misconceptions. Most Amish (but not all) do not want electricity supplied by utility companies in their homes. They do, however, use some electrical devices where they can generate the power themselves through the use of gasoline generators or battery (which they charge using solar or wind power). They also do not want natural gas lines into their homes from utility companies, but readily use bottled gas (propane).

The Amish produce all of their own food and clothing – FALSE. I live in an area with a very large Amish population. I see Amish people in supermarkets and department stores all the time. The local Walmarts have tie ups for the horse and carriages.

The Amish do not use modern medicine or doctors – FALSE. The Amish have no aversion to modern medical practices or medicines at all. They go to doctors when they need to. They are hospitalized when it is required. Some Amish women still use midwives for birthing, but many use doctors and give birth in hospitals, especially for difficult pregnancies.

The Amish live communally without any outside contact – FALSE. Amish families live in their own private homes on their own private land. They own private businesses or work outside of the homes and manage their own finances. They keep bank accounts and take out loans for homes or business. They participate in many community activities with the general public, especially those that involve charity work.

The Amish don’t pay taxes – FALSE. The Amish pay all income, property, and sales taxes. They can claim an exemption from Social Security with-holdings under certain circumstances (are self employed or work for an Amish owned business), but if they do then they can never collect any SSI benefits either, and are therefore not a burden to the SSI system.

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Hey X, what you’ve been reading is basically correct, you are looking at probably 10 + years for your financial payback. If that is what you are after, probably better to spend a few dollars making your living space a bit more efficient, which will cut down on your current electric bill, and put the rest in long term bonds. You’ll get your money back faster with the investment.

We live in a home that is completely powered by the wind and sun. It still has the utility company connected, which I now use as my storage battery for excess power, and then I can draw on them if I need extra down the road. There is a small fee for that too. The original reason we got involved is because at the time, our power was always going out at inconvenient times, and later for environmental reasons. If, as you say, the cost benefit ratio is too unbalanced, you might as well stick to nuclear, then I’m guessing environmental benefits are not of interest to you. Lots of people grow tomatoes in their garden even though it’s easier and cheaper to buy them at the store, or the farmers market if you want fresh. For them it’s therapuetic to make something of their own, and provide at least a sustainable patch of green grass in a world of commercial vegetable fields. The only difference between them and us is we just grow electrons in our garden, even though it is probalby cheaper to buy them commercially, from the nuclear plant, or someplace else. There is also the fact that our home has not been without power for even a minute the last 13 years now, but it’s hard to put a price tag on something like that.

If you really think you might want to get involved a little without having to bet the farm, try starting small like we did 13 years ago. A couple of golf cart batteries, one 70 or so watt panel and a few miscellaneous parts and we were lighting our kitchen and bath and running a few small electronics, like a radio, cell phone charger and so on. And within months when the next power outage came, those items continued to function, free of charge or gasoline. Home Power Magazine liked our small starter idea so much years ago they ran a small article on it. If you subscribe, you can use their online archive search engine and look for an article called, “Small System First.” If you’re handy with stuff around the house, it might be a good project for you. Check out the magazine and some other sources below. Good luck X, and take care, Rudydoo

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Will any one in your household object to noise and vibration from even a small wind turbine? If so, the turbine needs to be on a separate tower, not attached to the house.
Are there any nearby tall trees? If so, the cost of a tower taller than the trees may be 80% the total cost. Trees reduce the average wind speed. Worse trees cause variation in the wind speed from one second to the next. This increases the wear on moving parts in your turbine. Electrical watts out is proportional to the 4 th power of the wind speed = 6 mile per hour winds produce very little electricity.
Did you check your location for frequent high wind speed? If not you may be very disappointed in the watthours you get. Neil

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The energy policy of India is characterized by tradeoffs between four major drivers:

Rapidly growing economy, with a need for dependable and reliable supply of electricity, gas, and petroleum products;
Increasing household incomes, with a need for affordable and adequate supply of electricity, and clean cooking fuels;
Limited domestic reserves of fossil fuels, and the need to import a vast fraction of the gas, crude oil, and petroleum product requirements, and recently the need to import coal as well; and
Indoor, urban and regional environmental impacts, necessitating the need for the adoption of cleaner fuels and cleaner technologies.
These trade-offs are often difficult to achieve. For example, the supply of adequate, yet affordable electricity generated and used cleanly is a continuing challenge because expansion of supply, and adoption of cleaner technologies, especially renewable energy, often means that this electricity is too expensive for many Indians, particularly in rural areas.

In recent years, these challenges have led to a major set of continuing reforms and restructuring.

1 Energy conservation
2 Electricity industry
3 Alterative bio-diesel sources
4 Wind power showcase
5 Oil
6 Nuclear power
7 Solar Energy
8 Policy framework

Energy conservation
Energy conservation has emerged as a major policy objective, and the Energy Conservation Act 2001, was passed by the Indian Parliament in September 2001. This Act requires large energy consumers to adhere to energy consumption norms; new buildings to follow the Energy Conservation Building Code; and appliances to meet energy performance standards and to display energy consumption labels. The Act also created the Bureau of Energy Efficiency to implement the provisions of the Act.

Electricity industry
The electricity industry has been restructured by the Electricity Act 2003, which unbundles the vertically integrated electricity supply utilities in each state of India into a transmission utility, and a number of generating and distribution utilities. Electricity Regulatory Commissions in each state set tariffs for electricity sales. The Act also enables open access on the transmission system, allowing any consumer (with a load of greater than 1 MW) to buy electricity from any generator. Significantly, it also requires each Regulatory Commission to specify the minimum percentage of electricity that each distribution utility must source from renewable energy sources.

Alterative bio-diesel sources
The President of India, Dr. Abdul Kalam, is one of the strong advocaters of Jatropha cultivation for production of bio-diesel.[1] In his recent speech, the President said that out of the 60 million hectares (600,000 km²) of waste land that is available in India over 30 million hectares (300,000 km²) are suitable for Jatropha cultivation. Once this plant is grown the plant has a useful lifespan of several decades. During it life Jatropha requires very little water when compared to other cash crops. For plan for supplying incentives to encourage the use of Jatropha has been implemented.

Wind power showcase
The once-impoverished village of Muppandal benefited from the building of the nearby Muppandal wind farm, a renewable energy source, which supplies the villagers with electricity for work.[2][3] The village had been selected as the showcase for India’s $2 billion clean energy program which provides foreign companies with tax breaks for establishing fields of wind turbines in the area. Now huge power-producing windmills tower over the palm trees. The village has attracted wind energy producing companies creating thousands of new jobs, dramatically raising the incomes of villagers.[4] The suitability of Muppandal as a site for wind farms stems from its geographical location as it has access to the seasonal monsoon winds.[2]

Oil
Because of political instability in the Middle East and increasing domestic demand for energy, India is keen on decreasing its dependency on OPEC to meet its oil demand, and increasing its energy security. Several Indian oil companies, primarily lead by ONGC and Reliance Industries, have started a massive hunt for oil in several regions in India including Rajasthan, Krishna-Godavari river basin[5] and north-eastern Himalayas. The proposed Iran-Pakistan-India pipeline is a part of India’s plan to meet its increasing energy demand.

Nuclear power
While India is self-sufficient in thorium, possessing 24% of the world’s known and economically available thorium,[6] it possesses a meager 1% of the similarly calculated global uranium reserves.[7] The United States-India Peaceful Atomic Energy Cooperation Act is expected to greatly help India in obtaining a steady supply of sufficient nuclear energy in the longer run.

Solar Energy
India’s theoretical solar potential is about 5000 TW·h per year (i.e. 600 GW), far more than its current total consumption. Currently solar power is prohibitive due to high initial costs of deployment. However India’s long-term solar potential could be unparalleled in the world because it has the ideal combination of both high solar insolation and a big potential consumer base density. [8][9] A major factor influencing a regions energy intensity is the cost of energy consumed for temperature control. Since cooling load requirements, unlike heating, are roughly in phase with the sun’s intensity, cooling from intense solar radiation could make perfect energy-economic sense in the subcontinent, whenever the required technology becomes competitively cheaper.

Policy framework
A long-term energy policy perspective is provided by the Integrated Energy Policy Report 2006 which provides policy guidance on energy-sector growth.

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Regenrative braking is the most effective way of topping up the battery by recapturing waste energy and already used on most electric cars and hybrids

Solar pannels could contribute something, but would increase the weight of the vehicle, and probably drag too.

A generator trailer is a well tried solution = instant hybrid for long journies, but without carrying the weight & complexity for normal travel. Http://www.evalbum.com/2312

the first question to ask is given that an electic car can travel 200 miles before recharging and then recharged in 10 minutes http://www.phoenixmotorcars.com is this really “excessive downtime”. The driver should take a 10minute break too after 200 miles.

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A generator is a generator. It doesnt matter if you have an ox pulling the sucker around. You just need gears to change the direction of your mechanical energy. Maybe your question is how do you make a generator?

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Its sad that Singaporeans should ask such questions. We are so timid. At the very worst you get a fine for installing green equipments. Take a MRT ride where you can see many terrace houses. You will find many with solar roofs.Their owners are not languishing in Changi prison. As for wind power, Singapore is not windy whole year round. Best stick with solar panels.

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That’s a really great career to look at, especially with a high focus being placed on alternative energy nowadays. I think I can help you answer some of your questions:

-Do you have to have a degree to be a wind energy technician?
It really depends on where you go. Some schools may offer degrees while others offer certification programs.

-Is a degree needed
It really depends on where you are applying. But often times with a lot of jobs, experience is key.

-Job Requirements
Wind turbine technician combine their knowledge of mechanics, hydraulics, meteorology, composites, and computer science when servicing and maintaining large, commercial-scale turbines. Essentially, they maintain wind turbines and ensure they are working properly.

People that study wind energy basically learn these things, all of which can tie into their job requirements:
* DC Circuits and AC Circuit Fundamentals
* Computer Fundamentals
* Technical Mathematics
* Hydraulics
* Principles of Wind
* Safety Theory
* Electromechanical/Safety Practicum
* Applied Wind Physics

Here’s a link to a blog article from a school that offers the program going into some fun facts about wind energy and wind technicians http://blog.pcitraining.edu/?p=37

Hope this helps you out, good luck with your project!

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Hey Brian, interesting question, and one that gets to the heart of many renewable energy myths today. Your explanation might have a couple apples vs oranges. The sun produces much more power than 120,000 terawatts, or terawatts per year, but I’m not sure if TW/Y represents either of those. Total electrical energy use on our globe is about 15 terawatts continuously, or 132,000 TW hours each year. Since solar panels are about 12 to 14 % efficient today, it would take an area of 192 square miles to produce that much power. Problem is, you would need it to work 24/7, and most places on our globe are dark at night. Accomodating for night time, and twilight hours in the morning and evening when the panels would be operating below peak power, the number jumps to about 890 square miles, or about 39,000,000 acres. That sounds huge, but consider that Rhode Island takes up over 1500 square miles, and is one of the smallest states in the US, really that scenario is feasible. The fact is we are never going to do that. The cost, the enourmous demand for silicone, wiring, grids, and so on make it totally impractical. There is also the fact that Rhode Island is pretty cloudy.

Now enter the Germans, they have a fantastic plan to mine solar power from the Sahara Desert. It doesn’t involve solar panels, instead they are going to use solar thermal collectors that will heat oil to several hundred degrees, which will be circulated back into huge insulated tanks, then the hot oil will be used to boil water into steam ,which will turn a steam turbine. This idea has several advantages. First, since we can use both the light of the sun, and its resultant heat as opposed to a silicone panel, which uses only the incoming photons, the efficiency jumps to about 60%. Second, since oil does not boil until around 550 degrees, we can use the stored hot oil well into the night until it cools substantially. Now we have access to solar power at night. And the concentrators and oil(which gets continuously recycled each day) cost much less per unit power than any panel in production today. Since the efficiency is much higher, they will only need 30 to 40 square miles to power all of Europe. If you want to check it out, google, “North African Solar Project,” and read some of the resulting websites. If the system works as well as they plan, it will run most of Western Europe, and then we will probably have one in our desert southwest a few years later. This concentrator will not offset any wildlife, beyond a few scorpions and rattlesnakes living in the far out areas of the desert, and since they will be using sea water to boil into steam, the byproduct of the electrical production will be fresh water. That fresh water will be used for irrigation to farm small quantities of sunlight intensive farm stock in what is now a completely dry desert. Adding small amounts of plant life to the northwest corner of the desert where none exists now will not alter the climate, but does offer another opportunity for carbon to be converted to oxygen, reducing the CO2 content of the atmosphere slightly. There will be jobs there, installation, technicians, maintenance and operations, and as long as the sun shines in the desert, we won’t run out of fuel.

We’ve been powering our home for 11 years now on wind and solar power. I’ve learned many things during that time. One item is that there are two things in large supply in solar power, the sun, and missinformation. Lots of people have been posting interesting “facts” here about solar and wind power, having never laid a hand on a panel or wind turbine. Wind turbines do not kill as many birds each year as living room windows do, powering homes with solar panels does not require massive amounts of space, silicone panels do not need massive amounts of toxic chemicals to manufacture them, and people do not get cancer from spinning wind turbines. These are just a few of my favorites, there are many more. If you want to learn more about this technology, check out some sources below. Take care Brian, Rudydoo

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Electricity supply is produced by large Power Generation Stations and sold to the distribution Companies who then distribute and sell it to the users.
The Power Generation Stations, consist of various types of Industrial Plants:
1…Burning of Fossil Fuels…Oil, Coal or Gas which are used to produce vast amounts of high pressure, high temperature (superheated) steam. This steam is used to drive (rotate at high speed), huge Steam Turbines which are connected to large Power Generators that produce the Electricity into a ‘Power Grid’ network which feed the electrical companies who then supply the Industrial and domestic users.

2..Combustion Gas Turbines use the Energy of an Expanding mixture of Superheated Air and Combustion Gases to drive high speed turbines that drive Power Generators….and so on..as above.

3..Use of Rivers or Lakes behind dams. The huge volumes of flowing water from these sources provides massive amounts of Kinetic Energy which is utilised to drive large Water Turbines which, in turn drive Power Generators….the rest is as above.

4..Wind Turbines are used to do exactly he same thing…A large ‘Propeller’ type windmill drives a generator…etc.

5..Nuclear Power plants use the tremendous heat of atomic fission to produce vast amounts of high pressure, high temperature (superheated) steam. This steam is used to drive (rotate at high speed), huge Steam Turbines…etc.

In each case, the Kinetic Energy of the power source is converted to Mechanical Energy (Turbine) and then into Electrical Energy (Generator)..

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Answer #3 was sort of right. You are correct, because of the variances in speed, those generators tend to be DC machines. From the wind turbine the “juice” is fed to inverters that can be phase controlled as well. The DC, after conversion to true sine wave AC, and phase locked to the grid system, and it’s voltage adjusted for the feed point where it will be added in, is switched into the grid system at that point. Best use, unless you have millions to invest in wind turbines and the hardware to go with it, is to use the power at your home, yourself.

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Its difficult to give a complete answer here.
Firstly we have to say that however you build your project it will be extremely difficult to make it green.
The reason is that the amount of Carbon you release will be enormous compared to the amount released by a commercial power station producing the same amount of electricity.
So from a commercial point of view have you looked at the price you will get from the buyer??
I assume you are in the uk.
If you look into selling to “the grid” you might find that the price will be very low indeed.
The amount you could get would depend on when you generated, ie were you only on at peak times,
If you produce electricity only now and again which is the most likely case I expect the amount you would get paid would not cover the cost of the diesel to power your loader and the man’s wages.
First check what you could get paid for the power you produce and when it is produced.

(it would most likely be very very little) It is not legitimate to look at what you are charged for electricity.

So your best plan I believe is to generate enough electricity for yourself and forget about export.

The problem with this normally is that you have to have your power station going 24/7.
Thats a lot of work.
What you could do is build a mini hydro scheme.
This is done very little but is very green.
The draw back is that you need two enomous ponds of water separated in height by about 10 feet (min).
You have a water wheel which runs 24/7 producing your electricity.
This is powered by water running from your top pond to the bottom one.

Now once per day you need to pump up the water from the bottom pond to the top. You can do this with very simple steam lift system.
Anyone with basic engineering skills could build this system.
If you could make your ponds big enough you can run your wood/steam powered lift system less often.

BTW solar is the best way to heat your pool. Very inexpensive effective systems now available. DIY systems cannot compete here.

Solar or wind could also be used to pump water to the top pool. This method means you dispense with batteries which are only 70% efficient and not Green. They are expensive and need to be replaced every 5 years making small projects using batteries. .
Micro-Hydro is the way to go. You will not find much on the web. You are welcome to mail me if you want to know more.

I know you will be disappointed in not being able to sell your power but the cost of the equipment compared to the payback time would make it a bad plan.
(like I say it would also be very un eco freindly)

Good luck with whatever you try.

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As of 2007, the cost of solar power was 38 cents per kwh while the costs of coal power was 0.6 cents per kwh. It isn’t a matter of what one man could afford but what if everyone’s power bill went up to 63 times what they are now.

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Wind power provides very little net energy. It is a non-starter. The use of plastics in wind turbines (as in ALL turbines) is a non-issue and completely misses the point.

Wind energy is a tempting IDEA but a disappointing reality. Wind power is so unreliable and variable that equivalent standby power has to be available all the time, wasting energy. Wind turbine construction is heavily subsidised and the electricity produced (even without allowing for the hidden cost of standby cover) is so expensive it is uneconomical. Power companies only buy wind generated power because they HAVE to by law and they cover the excessive cost by charging us more for ALL our electricity. If it wasn’t for the subsidies (direct grants plus subsidies through us paying more for conventional power) there would be no wind energy in the UK. It is an appalling waste of money that could be better spent on more productive, more economical, more reliable power generation using other technologies.

Tidal power is stronger and totally predictable but receives only a fraction of the subsidy of wind power. Ignoring ideology and looking for a realistic practical solution, we need to be building nuclear power capacity plus clean-burn coal fired power stations with tidal power as a longer term source.

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The ability to generate electricity is measured in watts. Watts are very small units, so the terms kilowatt (kW, 1,000 watts), megawatt (MW, 1 million watts), and gigawatt (pronounced “jig-a-watt,” GW, 1 billion watts) are most commonly used to describe the capacity of generating units like wind turbines or other power plants.

Electricity production and consumption are most commonly measured in kilowatt-hours (kWh). A kilowatt-hour means one kilowatt (1,000 watts) of electricity produced or consumed for one hour. One 50-watt light bulb left on for 20 hours consumes one kilowatt-hour of electricity (50 watts x 20 hours = 1,000 watt-hours = 1 kilowatt-hour).

The output of a wind turbine depends on the turbine’s size and the wind’s speed through the rotor. Wind turbines being manufactured now have power ratings ranging from 250 watts to 5 megawatts (MW).

Example: A 10-kW wind turbine can generate about 10,000 kWh annually at a site with wind speeds averaging 12 miles per hour, or about enough to power a typical household. A 5-MW turbine can produce more than 15 million kWh in a year–enough to power more than 1, 400 households. The average U.S. Household consumes about 10,000 kWh of electricity each year.

Example: A 250-kW turbine installed at the elementary school in Spirit Lake, Iowa, provides an average of 350,000 kWh of electricity per year, more than is necessary for the 53,000-square-foot school. Excess electricity fed into the local utility system earned the school $25,000 in its first five years of operation. The school uses electricity from the utility at times when the wind does not blow. This project has been so successful that the Spirit Lake school district has since installed a second turbine with a capacity of 750 kW. (For further information on this project, see at the Web site of the International Council for Local Environmental Initiatives.)

Wind speed is a crucial element in projecting turbine performance, and a site’s wind speed is measured through wind resource assessment prior to a wind system’s construction. Generally, an annual average wind speed greater than four meters per second (m/s) (9 mph) is required for small wind electric turbines (less wind is required for water-pumping operations). Utility-scale wind power plants require minimum average wind speeds of 6 m/s (13 mph).

The power available in the wind is proportional to the cube of its speed, which means that doubling the wind speed increases the available power by a factor of eight. Thus, a turbine operating at a site with an average wind speed of 12 mph could in theory generate about 33% more electricity than one at an 11-mph site, because the cube of 12 (1,768) is 33% larger than the cube of 11 (1,331). (In the real world, the turbine will not produce quite that much more electricity, but it will still generate much more than the 9% difference in wind speed.) The important thing to understand is that what seems like a small difference in wind speed can mean a large difference in available energy and in electricity produced, and therefore, a large difference in the cost of the electricity generated. Also, there is little energy to be harvested at very low wind speeds (6-mph winds contain less than one-eighth the energy of 12-mph winds).

admin answers:

Geothermal power is power extracted from heat stored in the earth and comes from radioactive decay of minerals and from solar energy absorbed at the surface. It’s used to heat up baths and for generating electricity. Geothermal power is cost effective, reliable, and environmentally friendly, but has previously been geographically limited to areas near tectonic plate boundaries.Geothermal wells tend to release greenhouse gases trapped deep within the earth, but these emissions are much lower than those of conventional fossil fuels. As a result, geothermal power has the potential to help mitigate global warming if widely deployed instead of fossil fuels. As of 2004, five countries (El Salvador, Kenya, the Philippines, Iceland, and Costa Rica) generate more than 15% of their electricity from geothermal sources.

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It’s a big piece, but I hope you get all the info u need =)

1. The process of harnessing energy from the ocean’s tide is very similar to that of harnessing water through a hydroelectric dam. However, the dam needed for this process is much larger. Installed within the dam are turbines. The movement and flow of the tide in and out from the shore is then used to turn those turbines and create the power needed.

(2,3,4 question) There are two ways at present of using tidal power:

Barrage systems: This system, built like a dam across a river, holds back the water till the tide has gone out, then uses the potential energy of the water to turn turbines in the barrage. This is an expensive system with many disadvantages.

Tidal Stream systems. This consists of using turbines, rather like wind turbines, to use the kinetic power of the moving water to generate electricity. This is easier and cheaper to install.

There are three Barrage systems operating throughout the world.

One large 240 MW plant on the Rance River in France, and two small plants,

one in the Bay of Fundy in Canada, and

another in Kislaya Guba in Russia.
There is only one Tidal Stream system working commercially:

A fullsize turbine prototype, SeaGen, was installed in Strangford Lough in Northern Ireland in 2008, with a capacity of 1.2 MW.
A large number of smaller tidal stream pilot schemes are being trialled.

-In Hammerfest, Norway a turbine, generating 300 kW, started in 2003.
-A 300 kW Periodflow marine current propeller type turbine was tested in Devon, England in 2003.
-Since April 2007 a prototype project in the East River in New York City has been running.
-An Open-Centre Turbine, has a prototype being tested at the European Marine Energy Centre (EMEC), in Orkney, Scotland.
-A Gorlov turbine, an improved helical design, is being prototyped on a large scale in S. Korea.
-Neptune Renewable Energy has developed Proteus which uses a barrage of vertical axis crossflow turbines for use mainly in estuaries.
-During 2003 a 150kW oscillating hydroplane device, the Stingray, was tested off the Scottish coast.
-Successful commercial trials of highly efficient shrouded tidal turbines on the Gold Coast, Queensland, Australia in 2002.
-Shrouded turbines are being installed for a remote Australian community in northern Australia, two small turbines will provide 3.5 MW.
-Another larger 5 meter diameter turbine, capable of 800 kW in 4 m/s of flow, is planned as a tidal powered desalination showcase near Brisbane Australia in October 2008.
-The Hydro Venturi, is being tested in San Francisco Bay.
-In April 2008, a turbine-generator unit (TGU) prototype was successfully tested at Cobscook Bay and Western Passage tidal sites near Eastport, Maine.
-Trials in the Strait of Messina, Italy, started in 2001 of the Kobold concept.

(4,6,7) Tidal energy use harnesses the water flow created primarily by the moon orbiting the Earth. As water is pulled toward the gravity of the moon, currents are created that can turn generator turbines.

Volumes have been written about tides and their effects on our planet. This Wikipedia Tides article is a good primer on the subject. It is noteworthy that all tidal energy does not come from the moon. About a third of it comes from the gravitational influence of our sun.

The interplay of gravitational fields of the moon and the sun combined with the rotation of Earth, creates a twice a day ebb and flow of the tides of our world that varies in height and strength.

Those variations in height and strength are completely predictable. As we’ll see later, that predictability is an important aspect of tidal energy use.

Though renewable, practical tidal energy use will be limited. Tidal flows are global, but the key to using them economically is finding either natural high tidal flow areas, or large tidal basins that can be easily dammed to channel water through turbines. _________________________________________________________________

ENVIRONMENTAL FRIENDLINESS –

Tidal energy use involving dams creates many of the same environmental concerns as damming rivers. Tidal dams restrict fish migration and cause silt build up which affects tidal basin ecosystems in negative ways.

Systems that take advantage of natural narrow channels with high tidal flow rates have less negative environmental impact than dammed systems. But they are not without environmental problems.

Both systems use turbines that can cause fish kills. But these are being replaced by new, more fish friendly turbines. The art and science of environmentally friendly hydro engineering is well advanced and will certainly be applied to any tidal energy project.

But even with dams, the environmental impact of tidal energy projects may prove to be smaller than our use of any other energy resource. Economics will severely limit the number of tidal energy projects. ______________