Wednesday, January 1, 2014

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 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 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 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 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 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.

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