Top five renewable energy sources

Renewable energy has started making headlines with many energy experts looking at various renewable energy sources such as solar energy, wind energy, geothermal energy, hydro power, and biomass. Renewable energy is very important because it offers alternative to using fossil fuels, not just in terms of reducing harmful greenhouse gas emissions but also to replace depleting oil, coal and natural gas. Renewable energy also improves our energy security and our energy independence, and is extremely abundant, practically limitless, meaning that the future will no doubt belong to renewable energy.

SOLAR ENERGY

Solar energy is the most abundant energy source on our planet but the world currently uses a tiny fraction of the totally available solar energy. Solar energy technologies are still connected with high costs, and do not offer satisfactory efficiency, though things are certainly improving very fast.

Solar energy is environmentally friendly renewable source of energy. Harnessing solar energy doesn't result in increase of harmful CO₂ emissions. The other advantage of solar energy is that the Sun is virtually unlimited source of energy that could supply with ease our current as well as the future energy demand, even with the predicted global population growth, as for instance covering just 4% of the world's desert area with solar panels would be enough to supply all of the world's electricity.

The downside of solar energy is that solar panels are still connected with relatively high costs, there are many ongoing solar researchers and hopefully science will soon find solutions to improve economics and efficiency of solar power technologies.

In 2012, solar energy accounted for less than 0.03% of the world's total energy supply, which is way too little, given its enormous potential. Despite this small number solar energy sector is constantly growing, and solar energy industry is one of the fastest growing industries in the world. The largest photovoltaic market in the world is still Germany.

Generally speaking, solar power plants have positive environmental impact. Harnessing solar energy doesn't contribute to climate change, acid rains or any form of pollution. This however doesn't mean there are no downsides to solar power plants, for instance manufacturing solar panels involves some toxic materials and the fact that huge solar power require lot of land for construction, and lot of water for cooling purposes.

Solar power plant.

WIND ENERGY

Wind energy has very long tradition as people were using wind energy for more than 5000 years to propel sailboats and sailing ships. These days wind energy is mostly used to generate electricity by using wind turbines. Wind power is one of the fastest growing renewable energy markets, even despite the stagnation in recent years, after losing its popularity to solar energy. Wind farms are no longer being built only on land but also offshore and offshore wind energy could in years to come become dominant way of harnessing wind energy.

Wind energy is ecologically acceptable renewable energy source that does not contribute to climate change or air pollution. Wind turbine prices are constantly decreasing and wind is certainly becoming cost-competitive on global energy market, as it currently represents one of the few renewable energy sources that could actually compete with fossil fuels in terms of economics.

Wind energy is intermittent energy source, and in times when wind doesn't blow we need another backup energy option to ensure constant energy supply for reliable power delivery. Large wind turbines with huge blades can sometimes lead to bird deaths if not equipped with radars. Sometimes it is difficult to integrate wind turbines into existing environment because they can disrupt visual effect of certain landscape.

Wind farms represent a group of interconnected wind turbines on one location which is used for production of electricity. At this moment, the world's largest wind farm is The Roscoe Wind Farm, with the output of 780 MW, in the US state of Texas.

Wind energy has overall positive environmental impact since there are no emissions involved. Certain environmental drawbacks are still present such as the fact that large, fast rotating blades can kill many birds if not equipped with radar, large wind turbines can also create noise pollution which can have negative effect on wildlife in nearby area.

Wind power plant.

GEOTHERMAL ENERGY

Geothermal energy also has relatively long history of use and refers to power extracted from heat stored in the Earth. This heat comes from the radioactive decay of various elements beneath the Earth's surface, volcanic activity, and also from solar energy that was absorbed at the surface. People were first using geothermal energy for bathing, though today geothermal energy is mostly used to generate electricity, though there also some countries that use geothermal energy for heating purposes in form of geothermal heating.

Geothermal energy is renewable energy source that cannot be depleted since earth is in constant state of producing heat (though there can be a factor of temporary local depletion), and it does not produce harmful carbon emissions nor it contributes to air pollution like fossil fuels (coal, oil, and natural gas do). Geothermal energy is clean, cost effective, reliable, sustainable, and environmentally friendly source of energy. Unlike solar and wind energy geothermal energy isn't intermittent energy source and is thus very reliable in terms of supply and delivery.

Geothermal power plants are very expensive to be built costing twice as much compared to coal and natural gas fired plants. High construction and drilling costs are the main reason why geothermal energy is being harnessed in only 24 countries of the world, as it is only being economically acceptable in areas with suitable amount of hot rocks at just the right depth for drilling. Once the drilling technologies become more technologically advanced geothermal energy will likely become much more competitive to fossil fuels.

Three basic types of geothermal power plants are: 1.dry steam plants where steam is piped directly from a geothermal reservoir to turn the generator turbines. 2. flash steam plants that takes the high-pressured hot water from deep inside the Earth and convert it to steam to turn the generator turbines. 3. binary cycle power plants that transfer the heat from geothermal hot water to another liquid, and afterwards the second liquid is turned into the steam that turns the generator turbines.

Geothermal energy is overall environmentally friendly source of energy. Existing geothermal electric plants emit an average of 122 kilograms (269 lb) of CO2 per megawatt-hour of electricity, which represents an amount negligible compared to fossil fuel fired plants. Harnessing geothermal energy has minimal land and freshwater requirements which are drawbacks of solar energy. The only potential environmental threat comes from fluids drawn from the deep earth as they carry a mixture of gases, such as carbon dioxide (CO2), hydrogen sulfide (H2S), methane (CH4) and ammonia which can (if not treated properly) add to global warming, air pollution, and acid rain.

Geothermal power plant.

HYDROPOWER

Hydropower is renewable energy source that has very long history of use, mostly in form of waterwheels and mills. Hydropower is today the most widely spread renewable energy source on global scale supplying around 20% of total global electricity.

Hydropower is renewable energy source that doesn't pollute our planet with harmful greenhouse gas emissions like this is the case with oil, coal and natural gas. Hydropower plants have long lifespan and relatively low maintenance costs since modern technology has enabled that almost everything is automated. Hydropower is very efficient source of energy, and doesn't suffer from intermittency like solar and wind do.

As already mentioned above, hydropower is still the most important renewable energy source on global scale, accounting for approximately 20% of the world's electricity. China currently leads the way in hydroelectricity generation, mostly because of its massive hydropower projects such as Three Gorges Dam.

The largest hydroelectric power plant in the world is Three Gorges Dam in China, with the capacity of 22.5 GW, the second ranked is Itaipu Dam, located between Brazil and Paraguay with the capacity of 14 GW.

The massive hydroelectric power plants can have negative impact on environment if not thoroughly planned and carefully constructed as this was the case with the construction of Three Gorges Dam that led to massive flooding and other negative environmental consequences.

Hydro power plant.

BIOMASS 

Biomass is renewable energy source that refers to biological material deriving from living, or recently living organisms such as wood, waste or biofuels. The five different energy resources from which the biomass derives are wood, waste, garbage, landfill gases, and alcohol fuels.

Biomass is abundant and widely spread source of energy that can be found in almost every corner of the world. Biomass is often said to be carbon neutral energy option, though there are many ongoing studies that still argue whether biomass is really carbon neutral or not. Biomass is also connected with CO2 emissions like fossil fuels are, though it does not contribute to global warming like fossil fuels do because burning of biomass which releases CO2 emissions is said to practically balance the CO2 absorbed by the plants during its growth. Biomass is becoming increasingly popular energy source on global scale, with many countries opening new biomass facilities. Wood is still the most popular form of biomass on global level, though there are many ongoing researches that aim to find the adequate solutions to turn waste and garbage into useful form of energy.

Biomass is said to satisfy today around 4% of US energy needs with more than half of this referring to biomass form using wood. The 2011 US study said that the currently existing biomass power generating industry in the United States has the capacity for around 11,000 MW.

The largest biomass power plant in United States is The New Hope Power Partnership, Florida with the capacity of 140 MW. Biomass power plant size is often driven by biomass availability in close proximity as transport costs of the fuel play a key factor in the plant's economics.

Since wood is the most common form of biomass, unsustainable biomass production could also lead to deforestation which together with the fact that biomass releases CO2 emissions represents environmental drawback of using more biomass.

Biomass power plant.

Hydropower – good to know

The worldwide use of hydropower is constantly growing, and has increased by 5,2% in period between 2009 and 2010. At the end of 2010 global hydropower capacity accounted to a record 3,427 terawatt-hours, contributing to more than 16 percent of globally produced electricity.

The hydropower still has relatively low costs, in average around 3 to 5 U.S. cents per kilowatt-hour and it is also one of the most reliable energy sources in the world.

The flexibility of hydropower plants is often neglected advantage of hydropower because many people tend to forget the fact that hydroelectric power plants can be ramped up and down very quickly to adapt to demands in energy supply.

Itaipu dam, Brazil.

Hydropower is by no means a perfect source of energy because huge dams can create soil erosion, interrupt the flow of the rivers, flooding and they also often lead to displacement of people and wildlife.

Many energy experts agree that future looks bright for hydropower because of its good cost parity with fossil fuels and also because its climate benefits. Many countries with adequate water resources could use hydropower to reduce their amount of greenhouse gas emissions.
 
China is still the world’s largest hydropower producer and will likely further expand its lead in global hydro use in the coming years. The Chinese produced 721 terawatt-hours in 2010, roughly accounting for 17 % of domestic electricity use. China's total installed hydropower capacity, at the end of 2010 was 213 gigawatts (GW). China it is also the home to world's largest hydroelectric power plant, the Three Gorges Dam and plans to add another 140 GW of new hydropower capacity by 2015

Hydropower is widely used source of energy as there are at least 150 countries currently using some form hydropower. Hydropower could be a good clean energy choice for Africa because Africa has good hydropower potential and very little of installed hydropower capacity.

Here are also some interesting details from the latest Worldwide Institute Watch study:

• Five countries -   China, Brazil, the United States, Canada, and Russia accounted for approximately 52 percent of the world's installed hydropower capacity in 2010.
• There are now three hydropower plants larger than 10 GW: the Three Gorges Dam in China, Itaipu Hydroelectricity Power Plant in Brazil, and Guri Dam in Venezuela.
• A total of $40-45 billion was invested in large hydropower projects worldwide in 2010.

Solar energy in Nevada and California - Water shortage

United States is feeling the consequences of recession and more rural countries like Nevada are among worst hit areas. Many believed that a salvation from recession came from a German developer, Solar Millennium who last year famously announced plans to build two large solar farms (Nevada is one of the sunniest U.S. states) that would harness the sun to generate electricity, and in process create hundreds of jobs for people that lost their jobs because of recession.

But then all of the sudden things became problematic because of the water use. The Germans announced that its preferred method of cooling the solar power plants would consume 1.3 billion gallons of water a year which equals about 20 percent of this desert valley’s available water and would very likely cause water shortage.

However the public opinion in this matter is still not united. Some are looking forward to this hoping to make money by selling water rights to the company while others are concerned about not only the facts that this project could result in water shortage problem, but also what this project is going to do Nevada's environment.

Many people accept renewable energy as something that is flawless but everything in this world has its flaws, and so does the renewable energy. One of these flaws is definitely demand for huge amount of water. Many of the proposed solutions to the nation’s energy as well as environmental problems in form of certain types of solar farms to biofuels refineries to cleaner coal plants, windmills, could consume billions of gallons of water every year, and water is as many of you know the most precious resource on this planet.

Water is big problem for new solar projects in Nevada.

Water could very easy become major hurdle in renewable energy development, not only in United States but globally too because renewable energy and water are in many cases very closely connected. Conflicts over water could undermine the future of many renewable energy projects so don't expect this Nevada's project to be just an exception. Therefore the most likely to succeed are most water-efficient renewable technologies that could use water shortages could give them a competitive edge over cost effectiveness.

If we take a look at California we can see that many solar developers have already been forced to switch to less water-intensive technologies because local officials were worried about potential water shortages and therefore not giving them green light to go with projects. And many other big solar projects across the country are also having problems over water consumption with local communities.

Joni Eastley, chairwoman of the county commission in Nye County, Nevada, which includes Amargosa Valley, said at one hearing that her area had been “inundated” with requests from renewable energy developers that “far exceed the amount of available water.” Local authorities definitely do not want to gamble with the question of water, and this is where all troubles are starting.

Many of these new solar energy projects include building solar thermal plants because this is cheaper technology compared to the solar panels we could often seen on roofs on some buildings. Solar thermal plants are specific because they have mirrors that heat a liquid to create steam that afterwards drives an electricity-generating turbine. Here is used the same principle as in the fossil fuel power plant, namely that the steam must be condensed back to water and cooled for reuse.

The conventional method uses so called „wet cooling“. The working principle is as follows: Hot water flows through a cooling tower where the excess heat evaporates along with some of the water so the water has to be replenished constantly. An opposite procedure called „dry cooling“, uses fans and heat exchangers, basically the same thing as the car’s radiator. Dry cooling needs far less water, but has big disadvantage in high costs and reduced efficiency, so many energy companies driven by profits at the end decide for wet cooling projects.

But the water issue could put much more emphasis on dry cooling projects and the ones that could profit the most are definitely photovoltaic power plants.

Photovoltaic power plants are typically more expensive and less efficient than solar thermal farms but require a relatively small amount of water, mainly to wash the panels, and this could turn out to be their big advantage in years to come compared to projects like Solar Millennium.



California is U.S. state that mostly uses solar energy .California's current plans include 35 large-scale solar projects that should be enough to generate 12,000 megawatts of electricity, which is output equal to about 10 nuclear power plants. These projects would of course use water, some less, some more, and this could also turn out to be problem in upcoming years.

Some projects wouldn't use as much water like for instance BrightSource Energy’s dry-cooled Ivanpah project in Southern California that would consume an estimated 25 million gallons a year, mainly to wash mirrors. If all projects were like this then there wouldn't be a big deal about it but some projects like for instance wet-cooled solar trough power plant that is barely half Ivanpah’s size and was proposed by the Spanish developer Abengoa Solar would draw enormous 705 million gallons of water in an area of the Mojave Desert that already very rarely receives rainfall.

Publicly most known dispute is the dispute over a proposed wet-cooled trough plant that NextEra Energy Resources, plans to build in a dry area east of Bakersfield, California.

NextEra wants to tap freshwater wells to supply the 521 million gallons of cooling water each year to the plant, despite a California's policy against the use of drinking-quality water for power plant cooling.

This issue has become so big that has even moved into the California Legislature, where a special bill has been introduced to allow renewable energy power plants to use drinking water for cooling if certain conditions are met.

Water disputes have already forced Solar Millennium to abandon one of their wet cooling projects that was intended for a solar power plant in Ridgecrest, California, after the local water district refused to supply the 815 million gallons of water a year the project would need. The company at the end decided to dry cool two other massive Southern California solar trough farms it wants to build in the Mojave Desert to avoid further disputes with local communities.

The words “we will not do any wet cooling in California because there are simply no plants being permitted here with wet cooling.”, that Rainer Aringhoff, president of Solar Millennium’s American operations said are really the reality of future solar energy projects in California, and many expect the same in Nevada.

This doesn’t many that things will go smooth for solar projects that use less water as even solar projects with low water consumption face hurdles. For instance Tessera Solar is planning a large project in the California desert that would use only 12 million gallons per year, mainly to wash mirrors. But because it would draw its water upon a severely depleted aquifer, Tessera will probably have to buy rights to 10 times that amount of water and then retire the pumping rights to the water it does not use. To avoid all of this, Tessera has agreed to fund improvements to a local irrigation district in exchange for access to reclaimed water because they have to find water to continue with their projects even though they are low water users.

Water is particularly scarce in American west, and even big energy demand can't at this point justify enormous use that some solar energy projects would require. Yes these projects would likely create thousands of new jobs for local population, and would help relieve the consequences of recession, but would cause even bigger water scarcity across these mostly desert areas.

Finding balance between need for new renewable energy projects and new jobs and scarce water resources on the other side won't be easy even in this early stage of solar energy sector development whether alone when U.S. would start getting 20 or more percent from renewables.

Water is not a problem in some parts of Nevada. Hoover Dam on Colorado River.

Water could soon turn out to become the most precious resource in the world so future renewable energy projects would definitely have to ensure working principles that would use far less water in order to be successful.

Yes we definitely need energy from renewable energy sources but we much more need water that is key ingredient to all life on our planet. Science and technology would definitely have to work hard to ensure new working principles for renewable energy projects or otherwise these new energy projects will have even bigger price that currently fossil fuels have.

Yes fossil fuels do pollute the planet but at least they do not need so much water to operate, and big renewable energy projects will need to show much more than their ecological component to become fully acceptable.

Many prominent people in U.S. believe that era of water scarcity awaits America in years to come and the least thing we need is energy projects with massive water consumption. Scientists have recently stated that in San Diego within the next 13 years Lake Mead and Lake Powell along the Colorado River, the two largest reservoirs in the southwest United States, could become “dead pool” mud puddles due to climate change, population growth, and profligate use.

In California for instance California Governor Arnold Schwarzenegger declared a statewide water emergency, and Nevada isn't looking much better so really the last thing that U.S. needs are largely water consuming renewable energy projects. Don't get me wrong I'm pro renewable energy project but only if their price isn't too high, and since we are here talking about enormous amounts of water, their price is definitely too high.

China to double hydropower capacity in one decade

China has many times expressed desire to stop being used as the synonym for pollution due to heavy industrialization and the excessive use of fossil fuels, most notably coal. China is still heavily dependent on fossil fuels but is also investing huge resources into its renewable energy sector in order to become greener in years to come. One of the most dominant renewable energy sectors is definitely hydropower.

China's hydropower capacity is currently somewhere around 172,000 megawatts, which is the largest in the world, mostly due to different hydropower project like Three Gorges Dam. But china isn't planning to stop at this level and is in fact expected to nearly double its hydropower capacity to 300,000 megawatts by 2020. At least this is what state media said, as the nation powers ahead with the development of renewable energy sources.

Three Gorges Dam.

Water resources minister Chen Lei, who was quoted by the official Xinhua news agency as giving the target, also said hydropower would play a more important role in China's strategy for energy security in the future. Of course it still remains to be seen whether future Chinese hydropower project will be built with less problems than lest say China's infamous Three Gorges Dam that in the end turned out to be more negative than positive project despite huge potential.

One thing is sure though China definitely needs more developed renewable energy sector, and hydropower projects if properly done could be of great help to China to become greener and stop being labelled as the world's biggest poluter that contributes mostly to climate change problem.

If we take a look at the current China energetic data we can see that China is still heavily dependent on highly-polluting coal that satisfies 70 percent of its energy needs. China would definitely like to change this ratio and is therefore giving tremendous economic boost to some renewable energy sectors, most notably wind and hydropower energetic projects.

Of course China isn't only doing this to save its environment and global climate, there is also the question of energy demand that will become even bigger in years to come. Any energy source that has enough potential should be exploited as much as possible, especially if this energy source turns out to be ecologically friendly energy source.

China can definitely use its huge hydropower advantages but should also learn a lot from past mistakes to ensure prominent place for hydropower sector in future energy supply.

China's hydropower sector had its peak in 80s, and was even referred to as the "country's only renewable energy that could be tapped on a large scale" but some problems with the construction of Three Gorges Dam stopped China's hydropower miracle. It will be really interesting to see whether hydropower still has enough to jump back as the best alternative to fossil fuels in China, and whether Chinese has learned something from their past mistakes.

Africa – High wind energy potential not used enough

According to many energy experts Africa has huge energy potential but very few African countries are really using wind energy. The three countries that are using wind energy the most are Egypt, Morocco and Tunisia but even these countries have been slow to push for more investments in wind energy sector.

These three countries supply around 95 percent of the 563 megawatts of total installed capacity on the black continent. Wind energy sector has already started paying up mostly because of demand from Europe, where countries are under pressure to reduce CO₂ emissions so they turn to different renewable energy sectors.

South Africa could soon be joining these three North-African countries as the country's new energy minister Dipuo Peters said how South Africa wants independent power producers to add 400 MW from wind to the grid within the next three years.

Egypt, on the other hand has set a target for wind to make up 12 percent of its total energy by 2020, with wind farms adding 7,200 MW to the grid.


Wind energy could also become important energy source for eastern and western Africa, especially after serious droughts raised doubts about the reliability of hydro sources the regions currently largely depend on. Kenya's Lake Turkana Wind Power already announced how it plans to produce 300 MW of electricity by 2012 from wind power in the north of the country.

These plans, if they fulfill will only use small share of Africa's total wind energy potential. This is because African countries have based their economies on coal which means that countries should reform their energy sectors and upgrade transmission and distribution networks to better wind power use. This will of course be hard to do, especially given lack of political will, and most of all available funds, in many African countries.

But still, countries like Egypt are showing that renewable energy policy definitely has its advantages, and that African countries should set more ambitious targets to better exploit of not only wind energy but other renewable energy sectors too. This example should be followed in other African countries, especially in Africa's richest country South Africa that according to Nano Energy, an energy consultancy has wind energy potential of at least 60,000 MW but is not doing enough to use it because of fossil fuels dominance, and lack of political will.

Funds for using wind energy sector shouldn't be really a big problem, because many EU countries are offering loans with favorable interest payments for investments to renewable energy sector. Start-up capital can be easily found; all what countries must show is political will on more emphasis to renewable energy sector.

Wind energy isn't only renewable energy source that Africa can build upon, Africa also gets vast amounts of sunlight throughout the whole year, and so solar energy is another option to consider. With proper politics and wise investments Africa could soon become very important source of renewable energy, capable to not only supply its energy needs, but also to satisfy large share of EU energy demand.

Tidal power (tidal energy) facts

Tidal energy is the utilization of the sun and moon's gravitational forces - as the tide is the result of their influences.

Tidal energy is a type of energy that produces electricity and other forms of power through the use of water.

Tidal energy is energy that could be obtained from the changing sea levels. In other words, tidal energy is a direct result of tide shifting from low to high.

Tidal energy is one of the oldest forms of energy. Tide mills, in use on the Spanish, French and British coasts, date back to 787 A.D. Tide mills consisted of a storage pond, filled by the incoming tide through a sluice and emptied during the outgoing tide through a water wheel.

The tide moves a huge amount of water twice each day and although the tidal energy supply is reliable and plentiful, converting it into useful electrical power is not easy.

There are two basic theories on how to convert tides into power. The first involves converting the power of the horizontal movement of the water into electricity. The second involves producing energy from the rise and drop of water levels.

La rance tidal power plant.

Tidal energy is considered to be a renewable source of energy since it only uses the energy from the changing of the tides instead of burning or consuming any form of energy source.

Although the technology required to harness tidal energy is well established, tidal power is expensive, and there is only one major tidal generating station in operation. This is a 240 megawatt station at the mouth of the La Rance river estuary in France.

The major advantage of tidal energy is its economical benefits. For example, tidal energy does not require any fuel. Tides rise and fall every day in a very consistent pattern.

The technology required to convert tidal energy into electricity is very similar to the technology used in traditional hydro-electric power plants - dam, gates and turbines.

There are three prototypes of tidal energy devices: horizontal axis turbine, vertical axis turbine, and oscillating devices.

The cost of tidal energy is very site specific, and influenced by geography, distance to grid, and speed and volume of the current.

The altering of the ecosystem at the bay is the biggest drawback of tidal power. Damages like reduced flushing, winter icing and erosion can change the vegetation of the area and disrupt the balance.

Tidal energy underwater turbine.

Tidal energy is not on the list of sustainable energy technologies the UN agencies even though for islanders it is our best hope for large amounts of affordable clean power.

Stream tidal energy is harnessed from currents – horizontal water movement which is created by the rise and fall of tides.

Turbines, similar to wind turbines, can be anchored to the sea bed to generate electricity from tidal currents.

Tidal energy is at its most efficient where the height of the tide, mass of water being moved, and the speed of its movement are all at their optimum level.

Tidal energy is perceived as having the potential to provide a reliable source of green energy because it is predictable and guaranteed, unlike wind turbines, which are dependent on the weather.

Tidal energy has an efficiency of 80% in converting the potential energy of the water into electricity.

Tidal power can provide secondary benefits such as bridges and roads, which are built over the tidal generators.

Tidal power changes the sedimentation and turbidity (how clear the water is) of the water system.

Mozambique keen to use hydropower

Mozambique is keen to use hydropower for satisfying the country's energy needs. Therefore Mozambique will finally take control of the biggest dam in sub-Saharan Africa, Cahora Bassa, which is second biggest dam in Africa (just behind Egypt's Aswan dam), that was in Portugal's hands more than 30 years after Portugal's colonial power ended.

President of Mozambique Armando Guebuza said: "We are finally going to be able to use the dam to satisfy energy needs of our country" and government spokesman Luis Covane added that "given its production capacity of more than 2000 MW Cahora Bassa is important for the development of clean and ecologically-sound energy, not only in Mozambique but for a big Part of Southern Africa as well". This Aswan dams covers an area of 2000 square kilometers (800 square miles) and its capacity should be enough for neighboring countries like South Africa, Zimbabwe, Zambia and Malawi.

For 82 % of the dam that is in hands on Portugal Mozambique will have to pay total sum of 950 million dollars and they already handed initial 250 million dollars and were given another 14-month grace period to take care of the rest. The last tranche of payment should be transferred to Portugal as we speak as Mozambique launched an international appeal for funds in order to finance the purchase. This Mozambique example is really one fine example of clean energy use in poor countries which should really be an example for all other developing countries to try to work on their clean and renewable energy sources instead of being oriented on "dirty" energy sources like are fossil fuels. This particularly refers to coal which often takes dominant place in developing countries because it's relatively cheap energy source.

It's really nice to see that importance of renewable energy sources is stressed in poor African countries too as they are starting to see their significance in upcoming years, and not only economical but what's more important ecological.

Mozambique is keen to use hydropower. Click on picture for full size.

Hydropower facts

Hydropower is the most significant renewable energy source.

Hydropower is the only renewable energy source that is in some measure competitive with fossil fuels.

Hydropower is the force of energy of moving water.

Hydropower is clean renewable energy source that doesn't pollute environment.

Hydropower uses the Earth's water cycle to generate electricity because movement of water as it flows downstream creates kinetic energy that can be then converted into electricity.

Hydropower doesn't pollute the air but construction and work of the dams can affect natural water systems and also affect wildlife and fish population.

Hydropower generates in the USA about nine percent of total energy supply.

Hydropower - Dam (click on picture for full size).

Hydropower's air emissions are negligible because there are no fuels burned.

Hydropower requires the use of dams which can alter river ecosystems.

Hydropower use needs to be carefully balanced with preservation of ecosystems that are altered by changes of water flow.

Hydropower can't be used in all areas because it needs fast flowing water throughout whole year.

Hydropower is very efficient energy source because some turbines can achieve efficiency of 95 % and more.

Hydropower today provides about 20 % of the world's electricity and is the main energy source for more than 30 countries.

Hydropower's advantage over other renewable energy sources is the fact that average rainfall is highly predictable and therefore output is reliable and river flow doesn't fluctuate from minute to minute like is the case with wind energy.

Hydropower is renewable energy source that doesn't cause global warming because it doesn't releases dangerous greenhouse gases.

Hydropower produce no air pollutants that cause acid rain and smog.

US hydropower map (click on picture for full size).

Hydropower has been exploited for millenia.

Hydropower can have negative ecological impacts, especially on fisheries and water ecosystems, this especially applies to large-scale hydropower.

Hydropower's installations can act as the barrier to fish movements and can kill or damage fish population.

Hydropower is the least expensive renewable energy source in the USA.

Hydropower's large-scale projects are criticized for altering river ecosystems, killing fish and affecting the water quality.

Hydropower needs more researching in order to decrease its negative environmental impacts on river ecosystems.

Hydropower in USA is used especially in the northwestern United States .

Hydropower's primary use is to produce electricity.

Hydropower can also be used for water supply, flood control, irrigation and even recreation purposes.

Hydropower accounts for 70 % of produced electricity in northwestern United States.

Hydropower can be used anywhere in the world where there's falling water.

Hydropower - working principle (click on picture to enlarge).