How Do Wind Turbines Work?

Perhaps you’ve seen them while driving through the countryside. Or maybe you saw them just off the coast, looming large on the horizon with their spinning blades. Then again, you may have seen them on someone’s roof, or as part of a small-scale urban operation. Regardless of the location, wind turbines and wind power are becoming an increasingly common feature in the modern world.

Much of this has to do with the threat of Climate Change, air pollution, and the desire to wean humanity off its dependence on fossil fuels. And when it comes to alternative and renewable energy, wind power is expected to occupy the second-largest share of the market in the future (after solar). But just how exactly do wind turbines work?

Description:

Air turbines are devices that turn the kinetic energy of wind and changes in air flow into electrical energy. In general, they consist of the following components: a rotor, a generator, and a structural support component (which can take the form of either a tower, a rotor yaw mechanism, or both).

NASA’s Ames Research Center and the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) testing a research wind turbine in the world’s largest wind tunnel in April of 2000. Credit: NASA

A rotor consists of the blades that capture the wind’s energy and a shaft, which converts the wind energy to low-speed rotational energy. The generator – which is connected to the shaft – converts the slow rotation to high into electrical energy using a series of magnets and a conductor (which usually consists of coiled copper wire).

When the magnets rotate around with the copper wire, its produces a difference in electrical potential, creating voltage and an electric current. Lastly, there is the structural support component, which ensures that the turbine either stands at a high enough altitudes to optimally capture changes in wind pressure, and/or face in the direction of wind flow.

Types of Wind Turbines:

At present, there are two main types of wind turbines – Horizontal Axis Wind Turbines (HAWT) and Vertical Axis Wind Turbines (VAWT). As the name would imply, horizontal wind turbines have a main rotor shaft and electrical generator at the top of a tower, with the blades pointed into the wind. The turbine is usually positioned upwind of its supporting tower, since the tower is likely to produce turbulence behind it.

Vertical axis turbines (once again, as the name implies) have the main rotor shaft arranged vertically. Typically, these are smaller in nature, and do not need to be pointed in the direction of the wind in order to rotate. They are thereby being able to take advantage of wind that is variable in terms of direction.

A Darrieus wind turbine, located in Martigny, Switzerland. Credit: Wikipedia Commons/Lysippos

In general, horizontal axis wind turbines are considered more efficient and can produce more power. While the vertical model generates less electricity it can be placed at lower elevations and needs less in the way of components (particularly a yaw mechanism). Wind turbines can also be divided into three general groups based on their design, which includes the Towered, Savonius, and Darrieus models.

The towered model is the most conventional form of HAWT, consisting of a tower (as the name would suggest) and a series of long blades that sit ahead of (and parallel to) the tower. The Savonis is a VAWT model that relies on contoured blades (scoops) to capture wind and spin. They are generally low-efficiency, but have the benefit of being self-starting. These sorts of turbines are often part of rooftop wind operations or mounted on sea vessels.

The Darrieus model, also known as an “Eggbeater” turbine, is named after the French inventor who pioneered the design – Georges Darrieus. This VAWT model employs a series of vertical blades that sit parallel to the vertical support. They are generally low efficiency, require an additional rotor to start turning, produce high-torque, and place high stress on the tower. Hence, they are considered unreliable as designs go.

History of Development:

Wind power has been used for thousands of years to push sails, power windmills, or to generate pressure for water pumps. The earliest known examples come from Central Asia, where windmills used in ancient Persia (Iran) have been dated to between 500 – 900 CE. The technology began to appear in Europe during the Middle Ages, and became a common feature by the 16th century.

The first automatically operated wind turbine, built in Cleveland in 1887 by Charles F. Brush. Credit: Wikipedia Commons

By the 19th century, with the development of electrical power, the first wind turbines capable of generating electricity were built. The first was installed in 1887 by Scottish academic James Blyth to light his holiday home in Marykirk, Scotland. In 1888, American inventor Charles F. Brush built the first automated wind turbine to power his home in Cleveland, Ohio.

By the early 20th century, wind turbines began to become a common means of powering homes in remote areas (such as farmsteads). In 1941, the first megawatt-class wind turbine was installed in Vermont and attached to the local utility grid. In 1951, the UK installed its first utility-grid connected wind turbine in the Orkney Islands.

By the 1970s, research and development into wind turbine technology advanced considerably thanks to the OPEC crisis and protests against nuclear power. In the ensuing decades, associations and lobbyists dedicated to alternative energy began to emerge in western European nations and the United States. By the final decade of the 20th century, similar efforts emerged in India and China due to growing air pollution and rising demand for clean energy.

Wind Power:

Compared to other forms of renewable energy, wind power is considered very reliable and steady, as wind is consistent from year to year and does not diminish during peak hours of demand. Initially, the construction of wind farms was a costly venture. But thanks to recent improvements, wind power has begun to set peak prices in wholesale energy markets worldwide and cut into the revenues and profits of the fossil fuel industry.

Cross-section of a vertical wind turbine. Credit: energy.gov

According to a report issued by the Department of Energy in March of 2015, the growth of wind power in the United States could lead to even more highly skilled jobs in many categories. Titled “Wind Vision: A New Era for Wind Power in the United States”, the document indicates that by 2050, the industry could account for as much as 35% of the US’ electrical production.

In addition, in 2014, the Global Wind Energy Council and Greenpeace International came together to publish a report titled “Global Wind Energy Outlook 2014”. This report stated that worldwide, wind power could provide as much as 25 to 30% of global electricity by 2050. At the time of the report’s writing, commercial installations in more than 90 countries had a total capacity of 318 gigawatts (GW), providing about 3.1% of global supply.

This represents a nearly sixteen-fold increase in the rate of adoption since the year 2000, when wind power accounted for less than 0.2%. Another way to look at it would be to say that the market share of wind power has doubled four times in less than 15 years. This places it second only to solar power, which doubled seven times over in the same period, but still trails wind in terms of its overall market share (at about 1% by 2014).

An offshore wind farm located off the coast of Belgium. Credit: Wikipedia Commons/Hans Hillewaert

In terms of its disadvantages, one consistently raised issue is the effect wind turbines have on local wildlife, and the disturbance their presence has on the local landscape. However, these concerns have often been shown to be inflated by special interest groups and lobbyists seeking to discredit wind power and other renewable energy sources.

For instance, a 2009 study released by the National Renewable Energy Laboratory determined that less than 1 acre per megawatt is disturbed permanently by the construction of large-scale wind farms, and less than 3.5 acres per megawatt are disturbed temporarily. The same study concluded that the impacts are relatively low on bird and bat wildlife, and that the same conclusions hold true for offshore platforms.

All over the world, governments and local communities are looking to wind power in order to meet their energy needs. In an age of rising fuel prices, growing concerns over Climate Change, and improving technology, this is hardly surprising. At its current rate of adoption, it is likely to be one of the largest sources of energy by mid-century.

And be sure to enjoy this video about wind turbines, courtesy of NASA’s Lewis Research Center:

We have written many interesting articles on wind turbines and wind power here at Universe Today. Here’s What is Alternative Energy?, What are Fossil Fuels?, What are the Different Types of Renewable Energy?, Wind Power on the Ocean (with Help from Space), and Could the World Run on Solar and Wind Power?

For more information, check out How Stuff Works’s article about the history and mechanics of wind power and NASA’s Greenspace page.

Astronomy Cast also has some episodes that are relevant to the subject. Here’s Episode 51: Earth and Episode 308: Climate Change.

Sources:

What Are Fossil Fuels?

The term “fossil fuels” is thrown about quite a lot these days. More often than not, it comes up in the context of environmental issues, Climate Change, or the so-called “energy crisis”. In addition to be a major source of pollution, humanity’s dependence on fossil fuels has led to a fair bit of anxiety in recent decades, and fueled demands for alternatives.

But just what are fossil fuels? While most people tend to think of gasoline and oil when they hear these words, it actually applies to many different kinds of energy sources that are derived from decomposed organic material. How humanity came to be so dependent on them, and what can we look to in order to replace them, are some of the biggest concerns facing us today.

Definition:

Fossil fuels refers to energy sources that are formed as a result of the anaerobic decomposition of living matter that contains energy as a result of ancient photosynthesis. Typically, these organisms have been dead for millions of years, with some dating back as far as the Cryogenian Period (ca. 650 million years ago).

The Bryan Mound Strategic Petroleum Reserve, located in Brazoria Country, Texas. Credit: energy.gov

Fossil fuels contain high percentages of carbon and stored energy in their chemical bonds. They can take the form of petroleum, coal, natural gas, and other combustible, hydrocarbon compounds. Whereas petroleum and natural gas are formed by the decomposition of organisms, coal and methane are the results of the decomposition of terrestrial plants.

In the case of the former, it is believed that large quantities of phytoplankton and zooplankton settled on the bottoms of seas or lakes millions of years ago. Over the course of many millions of years, this organic matter mixed with mud and was buried under heavy layers of sediment. The resulting heat and pressure caused the organic matter to become chemically altered, eventually forming carbon compounds.

In the case of the latter, the source was dead plant matter that was covered in sediment during the Carboniferous period – i.e. the end of Devonian Period to the beginning of the Permian Period (ca. 300 and 350 million years ago). Over time, these deposits either solidified or became gaseous, creating coal fields, methane and natural gases.

Modern Uses:

Coal has been used since ancient times as a fuel, often in furnaces to melt metal ores. Unprocessed and unrefined oil has also been burned for centuries in lamps for the sake of lighting, and semi-solid hydrocarbons (like tar) were used for waterproofing (largely on the bottoms of boats and on docks) and for embalming.

Widespread use of fossil fuels as sources of energy began during the Industrial Revolution (18th – 19th century), where coal and oil began replacing animal sources (i.e. whale oil) to power steam engines. By the time of the Second Industrial Revolution (ca. 1870 – 1914), oil and coal began to be used to power electrical generators.

The invention of the internal combustion engine (i.e. automobiles) increased demands for oil exponentially, as did the development of aircraft. The petrochemical industry emerged concurrently, with petroleum being used to manufacture products ranging from plastics to feedstock. In addition, tar (a leftover product from petroleum extraction) became widely used in the construction of roads and highways.

Fossil fuels became central to modern manufacturing, industry and transportation because of how they produce significant amounts of energy per unit mass. As of 2015, according to the International Energy Agency (IEA) the world’s energy needs are still predominantly provided for by sources like coal (41.3%) and natural gas (21.7%), though oil has dropped to just 4.4%.

The fossil fuel industry also accounts for a major share of the global economy. In 2014, global coal consumption exceeded 3.8 billion metric tons, and accounted for US $46 billion in revenue in the US alone. In 2012, global oil and gas production reached over 75 million barrels per day, while the global revenue generated by the industry reached about US $1.247 trillion.

Countries of the world ranked in terms of their annual production of oil. Credit: Wikipedia Commons/Ali Zifan

The fossil fuel industry also enjoys a great deal of government protection and incentives worldwide. A 2014 report from the IEA indicated that the fossil fuel industry collects $550 billion a year in global government subsidies. However, a 2015 study by the International Monetary Fund (IMF) indicated that the real cost of these subsidies to governments worldwide is around US $5.3 trillion (or 6.5 % of global GDP).

Environmental Effects:

The connection between fossil fuels and air pollution in industrialized nations and major cities has been evident since the Industrial Revolution. Pollutants generated by the burning of coal and oil include carbon dioxide, carbon monoxide, nitrogen oxides, sulfur dioxide, volatile organic compounds and heavy metals, all of which have been linked to respiratory illnesses and increased risks of disease.

The burning of fossil fuels by humans is also the largest source of emissions of carbon dioxide (about 90%) worldwide, which is one of the main greenhouse gases that allows radiative forcing (aka. the Greenhouse Effect) to take place, and contributes to global warming.

In 2013, the National Oceanic and Atmospheric Administration announced that CO² levels in the upper atmosphere reached 400 parts per million (ppm) for the first time since measurements began in the 19th century. Based on the current rate at which emissions are growing, NASA estimates that carbon levels could reach between 550 to 800 ppm in the coming century.

If the former scenario is the case, NASA anticipates a rise of 2.5 °C (4.5 °F) in average global temperatures, which would be sustainable. However, should the latter scenario prove to be the case, global temperatures will rise by an average of 4.5 °C (8 °F), which would make life untenable for many parts of the planet. For this reason, alternatives are being sought out for development and widespread commercial adoption.

Alternatives:

Due to the long-term effects of fossil fuel-use, scientists and researchers have been developing alternatives for over a century. These include concepts like hydroelectric power – which has existed since the late 19th century – where falling water is used to spin turbines and generate electricity.

Since the latter half of the 20th century, nuclear power has also been looked to as an alternative to coal and petroleum. Here, slow-fission reactors (which rely on uranium or the radioactive decay of other heavy elements)  are used to heat water, which in turn generates steam to spin turbines.

Since the mid-2oth century, several more methods have been proposed that range from the simple to the highly sophisticated. These include wind power, where changes in airflow pushes turbines; solar power, where photovoltaic cells convert the Sun’s energy (and sometimes heat) into electricity; geothermal power, which relies on steam tapped from the Earth’s crust to rotate turbines; and tidal power, where changes in the tides push turbines.

The spherical tokamak MAST at the Culham Centre for Fusion Energy (UK). Photo: CCFE

Alternative fuels are also being derived from biological sources, where plant and biological sources are used to replace gasoline. Hydrogen is also being developed as a power source, ranging from hydrogen fuel cells to water being used to powering internal combustion and electric engines. Fusion power is also being developed, where atoms of hydrogen are fused inside reactors to generate clean, abundant energy.

By the middle of the 21st century, fossil fuels are expected to have become obsolete, or at least declined significantly in terms of their use. But from a historical standpoint, they have been associated with the largest and most prolonged explosions in human growth. Whether humanity will survive the long-term effects of this growth – which has included an intense amount of fossil fuel burning and greenhouse gas emissions – remains to be seen.

We have written many articles about fossil fuels for Universe Today. Here’s What is an Enhanced Greenhouse Effect?, Gases in the Atmosphere, What Causes Air Pollution?, What if We Burn Everything?, What is Alternative Energy?, and “Climate Change is Now More Certain Than Ever,” New Report Says

If you’d like more info on Fossil Fuels, check out NASA’s Earth Observatory. And here’s a link to NASA’s Article on Safeguarding our Atmosphere.

Astronomy Cast also has some episodes that are relevant to the subject. Here’s Episode 51: Earth and Episode 308: Climate Change.

Sources:

What is Alternative Energy?

In recent years, alternative energy has been the subject of intense interest and debate. Thanks to the threat of Climate Change, and the fact that average global temperatures continue to rise year after year, the drive to find forms of energy that will reduce humanity’s reliance on fossil fuels, coal, and other polluting methods has naturally intensified.

While most concepts for alternative energy are not new, it has only been in the past few decades that the issue has become pressing. And thanks to improvements in technology and production, the costs of most forms of alternative energy has been dropping while efficiency has been increasing. But just what is alternative energy, and what is the likelihood of it becoming mainstream?

Definition:

Naturally, there is some debate as to what “alternative energy” means and what it can be applied to. On the one hand, the term can refer to forms of energy that do not increase humanity’s carbon footprint. In this respect, it can include things as nuclear facilities, hydroelectric power, and even things like natural gas and “clean coal”.

Residential solar panels in Germany. Credit: Wikimedia Commons/ Sideka Solartechnik.
Residential solar panels in Germany. Credit: Wikimedia Commons/ Sideka Solartechnik

On the other hand, the term is also used to refer to what are currently considered to be non-traditional methods of energy – such as solar, wind, geothermal, biomass, and other recent additions. This sort of classification rules out methods like hydroelectric, which have been around for over a century and are therefore quite common to certain regions of the world.

Another factor is that alternative energy sources are considered to be “clean”, meaning that they don’t produce harmful pollutants. As already noted, this can refer to carbon dioxide but also other emissions like carbon monoxide, sulfur dioxide, nitrogen oxide, and others. Within these parameters, nuclear energy is not considered an alternative energy source because it produces radioactive waste that is highly toxic and must be stored.

In all cases, however, the term is used to refer to forms of energy that will come to replace fossil fuels and coal as the predominant form of energy production in the coming decades.

Types of Alternative Energy:

Strictly speaking, there are many types of alternative energy. Once again, definitions become a bit of a sticking point, and the term has been used in the past to refer to any method that was considered non-mainstream at the time. But applying the term broadly to mean alternatives to coal and fossil fuels, it can include any or all of the following:

Hydroelectricity: This refers to energy generated by hydroelectric dams, where falling water (i.e. rivers or canals) are channeled through an apparatus to spin turbines and generate electricity.

A nuclear power plant, releasing hot steam as a byproduct of its slow fission process. Credit: Wikipedia Commons/Emmelie Callewaert

Nuclear Power: Energy that is produced through slow-fission reactions. Rods of uranium or other radioactive elements heat water to generate steam, which in turn spins turbines to generate electricity.

Solar Power: Energy harnessed directly from the Sun, where photovoltaic cells (usually composed of silicon substrate, and arranged in large arrays) convert the Sun’s rays directly into electrical energy. In some cases, the heat produced by sunshine is harnessed to produce electricity as well, which is known as solar-thermal power.

Wind Power: Energy generated by air flow, where large wind-turbines are spun by wind to generate electricity.

Geothermal Power: Energy generated by heat and steam produced by geological activity in the Earth’s crust. In most cases, this consists of pipes being placed in the ground above geologically active zones to channel steam through turbines, thus generating electricity.

Tidal Power: Energy generated by tidal harnesses located around shorelines. Here, the daily changes in tides causes water to flow back and forth through turbines, generating electricity that is then transferred to power stations along the shore.

Biomass: This refers to fuels that are derived from plants and biological sources – i.e. ethanol, glucose, algae, fungi, bacteria – that could replace gasoline as a fuel source.

Hydrogen: Energy derived from processes involving hydrogen gas. This can include catalytic converters, where water molecules are broken apart and reunited by electrolysis; hydrogen fuel cells, where the gas is used to power internal combustion engines or heated and used to spin turbines; or nuclear fusion, where atoms of hydrogen fuse under controlled conditions to release incredible amounts of energy.

The Mega Ampere Spherical Tokamak (MAST) reactor at the Culham Centre for Fusion Energy (UK). Credit: CCFE

Alternative and Renewable Energy:

In many cases, alternative sources of energy are also renewable. However, the terms are not entirely interchangeable, owing to the fact that many forms of alternative energy rely on a finite resource. For instance, nuclear power relies on uranium or other heavy elements that must be mined.

Meanwhile, wind, solar, tidal, geothermal and hydroelectric power all rely on sources that are entirely renewable. The Sun’s rays are the most abundant energy source of all and, while limited by weather and diurnal patters, are perennial – and therefore inexhaustible from an industry standpoint. Wind is also a constant, thanks to the Earth’s rotation and pressure changes in our atmosphere.

Development:

Currently, alternative energy is still very much in its infancy. However, this picture is rapidly changing, owing to a combination of political pressure, worldwide ecological disasters (drought, famine, flooding, storm activity), and improvements in renewable energy technology.

For instance, as of 2015, the world’s energy needs were still predominantly provided for by sources like coal (41.3%) and natural gas (21.7%). Hydroelectric and nuclear power constituted 16.3% and 10.6%, respectively, while “renewables” (i.e. solar, wind, biomass etc.) made up just 5.7%.

In Denmark, wind power accounts for 28% of electrical production and is cheaper than coal power. Credit: denmark.dk

This represented a significant change from 2013, when the global consumption of oil, coal and natural gas was 31.1%, 28.9%, and 21.4%, respectively.  Nuclear and hydroelectric power made up 4.8% and 2.45, while renewable sources made up just 1.2%.

In addition, there has been an increase in the number of international agreements regarding the curbing of fossil fuel use and the development of alternative energy sources. These include the Renewable Energy Directive signed by the European Union in 2009, which established goals for renewable energy usage for all member states for the year of 2020.

Basically, the agreement stated that the EU fulfill at least 20% of its total energy needs with renewables by 2020, and that at least 10% of their transport fuels come from renewable sources by 2020. In November of 2016, the European Commission revised these targets, establishing that a minimum of 27% of the EUs energy needs come from renewables by 2030.

In 2015, the United Nations Framework Convention on Climate Change (UNFCCC) met in Paris to come up with a framework for greenhouse gas mitigation and the financing of alternative energy that would go into effect by 2020. This led to The Paris Agreement, which was adopted on December 12th, 2015 and opened for signatures on April 22nd (Earth Day), 2016, at the UN Headquarters in New York.

The Krafla a geothermal power station located i0n Iceland. Credit: Wikipedia Commons/Ásgeir Eggertsson

Several countries and states have also been noted fore their leadership in the field of alternative energy development. For instance, in Denmark, wind power provides up to 140% of the country’s demand for electricity, with the surplus being provided to neighboring countries like Germany and Sweden.

Iceland, thanks to its location in the North Atlantic and its active volcanoes, achieved 100% reliance on renewable energy by 2012 through a combination of hydroelectricity and geothermal power. In 2016, Germany’s policy of phasing out reliance on oil and nuclear power resulted in the country reaching a milestone on May 15th, 2016 – where nearly 100% of its demand for electricity came from renewable sources.

The state of California has also made impressive strides in terms of its reliance on renewable energy in recent years. In 2009, 11.6 percent of all electricity in the state came from renewable resources such as wind, solar, geothermal, biomass and small hydroelectric facilities. Thanks to multiple programs that encourage switching to renewable energy sources, this reliance increased to 25% by 2015.

Based on the current rates of adoption, the long-term prospects for alternative energy are extremely positive. According to a 2014 report by the International Energy Agency (IEA), photovoltaic solar power and solar thermal power will account for 27% of global demand by 2050 – making it the single largest source of energy. Similarly, a 2013 report on wind power indicated that by 2050, wind could account for up to 18% of global demand.

The IEA’s World Energy Outlook 2016 also claims that by 2040, natural gas, wind and solar will eclipse coal and oil as the predominant sources of energy. And some even go as far to say that – thanks to developments in solar, wind, and fusion power technology – fossil fuels will become obsolete by 2050.

As with all things, the adoption of alternative energy has been gradual. But thank to the growing problem of Climate Change and rising demand for electricity worldwide, the rate at which clean and alternative methods are being adopted has become exponential in recent years. Sometime during this century, humanity may reach the point of becoming carbon neutral, and not a moment too soon!

We have written many articles about alternative energy for Universe Today. Here’s What are the Different Types of Renewable Energy?, What is Solar Energy?, How Does a Wind Turbine Work?, Could the World Run on Solar and Wind Power?, Where does Geothermal Power Come From? and Compromises Lead to Climate Change Deal.

If you’d like more info on Alternative Energy, check out the Alternative Energy Crops in Space. And here’s a link to Alternative Energy Technologies to Control Climate Change.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Sources:

What are the Different Types of Renewable Energy?

Renewable energy is becoming an increasingly important issue in today’s world. In addition to the rising cost of fossil fuels and the threat of Climate Change, there has also been positive developments in this field which include improvements in efficiency as well as diminishing prices.

All of this has increased the demand for alternative energy and accelerated the transition towards cleaner, more sustainable methods of electrical power. However, it is important to note that are many kinds – biomass, solar, wind, tidal, and geothermal power – and that each has its own share of advantages and drawbacks.

Biomass:

The most widely used form of renewable energy is biomass. Biomass simply refers to the use of organic materials and converting them into other forms of energy that can be used. Although some forms of biomass have been used for centuries – such as burning wood – other, newer methods, are focused on methods that don’t produce carbon dioxide.

Biomass - which involves converting organic materials into energy - can come from a variety of sources. Credit: ecoble.com
Biomass – which involves converting organic materials into energy – can come from a variety of sources. Credit: ecoble.com

For example, there are clean burning biofuels that are alternatives to oil and gas. Unlike fossil fuels, which are produced by geological processes, a biofuel is produced through biological processes – such as agriculture and anaerobic digestion. Common fuels associated with this process are bioethanol, which is created by fermenting carbohydrates derived from sugar or starch crops (such as corn, sugarcane, or sweet sorghum) to create alcohol.

Another common biofuel is known as biodiesel, which is produced from oils or fats using a process known as transesterification – where acid molecules are exchanged for alcohol with the help of a catalyst. These types of fuels are popular alternatives to gasoline, and can be burned in vehicles that have been converted to run on them.

Solar Power:

Solar power (aka. photovoltaics) is one of the most popular, and fastest-growing, sources of alternative energy. Here, the process involves solar cells (usually made from slices of crystalline silicon) that rely on the photovoltaic (PV) effect to absorb photons and convert them into electrons. Meanwhile, solar-thermal power (another form of solar power) relies on mirrors or lenses to concentrate a large area of sunlight, or solar thermal energy (STE), onto a small area (i.e. a solar cell).

Initially, photovoltaic power was only used for small to medium-sized operations, ranging from solar powered devices (like calculators) to household arrays. However, ever since the 1980s, commercial concentrated solar power plants have become much more common. Not only are they a relatively inexpensive source of energy where grid power is inconvenient, too expensive, or just plain unavailable; increases in solar cell efficiency and dropping prices are making solar power competitive with conventional sources of power (i.e. fossil fuels and coal).

The Ivanpah Solar Power Facility in California, showing its three towers delivering concentrated solar power. Credit: Wikipedia commons/Sbharris
The Ivanpah Solar Power Facility in California, showing its three towers delivering concentrated solar power. Credit: Wikipedia commons/Sbharris

Today, solar power is also being increasingly used in grid-connected situations as a way to feed low-carbon energy into the grid. By 2050, the International Energy Agency anticipates that solar power – including STE and PV operations – will constitute over 25% of the market, making it the world’s largest source of electricity (with most installations being deployed in China and India).

Wind Power:

Wind power has been used for thousands of years to push sails, power windmills, or to generate pressure for water pumps. Harnessing the wind to generate electricity has been the subject of research since the late 19th century. However, it was only with major efforts to find alternative sources of power in the 20th century that wind power has become the focal point of considerable research and development.

Compared to other forms of renewable energy, wind power is considered very reliable and steady, as wind is consistent from year to year and does not diminish during peak hours of demand. Initially, the construction of wind farms was a costly venture. But thanks to recent improvements, wind power has begun to set peak prices in wholesale energy markets worldwide and cut into the revenues and profits of the fossil fuel industry.

According to a report issued this past March by the Department of Energy, the growth of wind power in the United States could lead to even more highly skilled jobs in many categories. Titled “Wind Vision: A New Era for Wind Power in the United States”, the document indicates that by 2050, the industry could account for as much as 35% of the US’ electrical production.

In Denmark, wind power accounts for 28% of electrical production and is cheaper than coal power. Credit: denmark.dk
In Denmark, wind power accounts for 28% of the country’s electrical production, and is now cheaper than coal power. Credit: denmark.dk

In addition, last year, the Global Wind Energy Council and Greenpeace International came together to publish a report titled “Global Wind Energy Outlook 2014”. This report stated that worldwide, wind power could provide as much as 25 to 30% of global electricity by 2050. At the time of the report’s writing, commercial installations in more than 90 countries had a total capacity of 318 gigawatts (GW), providing about 3% of global supply.

Tidal Power:

Similar to wind power, tidal power is considered to be a potential source of renewable energy because tides are steady and predictable. Much like windmills, tide mills have been used since the days of Ancient Rome and the Middle Ages. Incoming water was stored in large ponds, and as the tides went out, they turned waterwheels that generated mechanical power to mill grain.

It was only in the 19th century that the process of using falling water and spinning turbines to create electricity was introduced in the U.S. and Europe. And it has only been since the 20th that these sorts of operations have been retooled for construction along coastlines and not just rivers.

Traditionally, tidal power has suffered from relatively high cost and limited availability of sites with sufficiently high tidal ranges or flow velocities. However, many recent technological developments and improvements, both in design and turbine technology, indicate that the total availability of tidal power may be much higher than previously assumed, and that economic and environmental costs may be brought down to competitive levels.

Credit: Carnegie Wave Energy
Artist’ concept of a series of the Carnegie Wave Energy’s tidal system, where buoys anchored to the sea floor and use swells to move a series of pumps. Credit: Carnegie Wave Energy

The world’s first large-scale tidal power plant is the Rance Tidal Power Station in France, which became operational in 1966. And in Orkney, Scotland, the world’s first marine energy test facility – the European Marine Energy Center (EMEC) – was established in 2003 to start the development of the wave and tidal energy industry in the UK.

In 2015, the world’s first grid-connected wave-power station (CETO, named after the Greek goddess of the sea) went online off the coast of Western Australia. Developed by Carnegie Wave Energy, this power station operates under water and uses undersea buoys to pump a series of seabed -anchored pumps, which in turn generates electricity.

Geothermal:

Geothermal electricity is another form of alternative energy that is considered to be sustainable and reliable. In this case, heat energy is derived from the Earth – usually from magma conduits, hot springs or hydrothermal circulation – to spin turbines or heat buildings. It is considered reliable because the Earth contains 1031 joules worth of heat energy, which naturally flows to the surface by conduction at a rate of 44.2 terawatts (TW) – more than double humanity’s current energy consumption.

One drawback is the fact that this energy is diffuse, and can only be cheaply harnessed in certain locations. However, in certain areas of the world, such as Iceland, Indonesia, and other regions with high levels of geothermal activity, it is an easily accessible and cost-effective way of reducing dependence on fossil fuels and coal to generate electricity. Countries generating more than 15 percent of their electricity from geothermal sources include El Salvador, Kenya, the Philippines, Iceland and Costa Rica.

The Krafla a geothermal power station located i0n Iceland. Credit: Wikipedia Commons/Ásgeir Eggertsson
The Krafla a geothermal power station located in Iceland. Credit: Wikipedia Commons/Ásgeir Eggertsson

As of 2015, worldwide geothermal power capacity amounts to 12.8 gigawatts (GW), which is expected to grow to 14.5 to 17.6 GW by 2020. What’s more, the Geothermal Energy Association (GEA) estimates that only 6.5 percent of total global potential has been tapped so far, while the IPCC reported geothermal power potential to be in the range of 35 GW to 2 TW.

Issues with Adoption:

One problem with many forms of renewable energy is that they depend on circumstances of nature – wind, water supply, and sufficient sunlight – which can impose limitations. Another issue has been the relative expense of many forms of alternate energy compared to traditional sources such as oil and natural gas. Until very recently, running coal-fired or oil-powered plants was cheaper than investing millions in the construction of large solar, wind, tidal or geothermal operations.

However, ongoing improvements made in the production of solar cells, wind turbines, and other equipment – not to mention improvements made in the amount of energy produced – has resulted in many forms of alternative energy becoming competitive with other methods. All over the world, nations and communities are stepping up to accelerate the transition towards cleaner, more sustainable, and more self-sufficient methods.

We have written many interesting articles on alternative energy on Universe Today. Here’s What is Alternative Energy?, What is Solar Energy? and Where does Geothermal Energy Come From?, Could the World Run on Solar and Wind Power?, and Harvesting Solar Power from Space.

You should also check out the National Renewable Energy Laboratory and Renewable Energy Policy Project.

Astronomy Cast also has an episode on the subject. Here’s Episode 51: Earth.

Sources:

Where Does Geothermal Energy Come From

Earth's core.

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You may not have heard much about geothermal energy but it is one of the hottest alternative energy commodities around. It is a renewable and clean energy source that will be around for a long time. However where does geothermal energy come from? The answer is the earth itself. The world geothermal comes from the Greek words geo which means earth and therme which means heat. Basically geothermal energy is heat energy harvested from the Earth itself.

Geothermal heat is produced by the core of the Earth itself. You may not think that energy to be much when compared to the sun but you would be wrong in some aspects. The Earth’s core alone is 11,000 degrees. That is hotter than the surface of the sun. The Earth’s geothermal energy is created by the decay of radioactie materials in the core and in the surrounding layers of rock.

However this still doesnt tell us how this energy becomes accessible. The deepest mankind can even go with the best technology is around 11 km. The answer is plate tectonics. bounadaries and faults are cracks in the Earth’s crust where magma rises near or to the surface. Geothermal plants take advantage of this fact using water heated by this volcanic activity to produce electric power.

The main place where geothermal energy can be used have not only volcanic activity but also enough ground water to be used to power the turbines that generate power. Prime areas are near volcanoes, hot springs, and geysers. Large volcanic islands like Greenland have vast resources in terms of geothermal energy. In the end the most common location for geothermal reservoirs will be where ever there are major plate boundaries with a lot of seismic and volcanic activity.

The benefits of geothermal energy is already being discussed in nations like Iceland as way to reduce reliance on foreign oil. Geothermal is abundant where it can be accessed and can easily produce energy on par with the output of other types of energy production such as nuclear reactors. The best part is that it is clean energy. There is no way it can produce pollution that can harm the environment. The only risk is that drilling in active volcanic area can make them vulnerable to earthquakes.

In the end Geothermal still one of the best possible sources of clean energy on the planet. As the technology improves for accessing it more homes around the world will have the opportunity to be powered by this renewable energy resource.

We have written many articles about geothermal energy for Universe Today. Here’s an article about Geothermal Energy, and here’s an article about how geothermal energy works.

If you’d like more info on Earth, check out NASA’s Solar System Exploration Guide on Earth. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Sources:
http://www.eia.gov/kids/energy.cfm?page=geothermal_home-basics
http://en.wikipedia.org/wiki/Geothermal_energy
http://www.clean-energy-ideas.com/articles/what_is_geothermal_energy.html