A method developed at Aalto University in Finland makes it possible to use microbes to produce butanol suitable for biofuel and other industrial chemicals from wood biomass.
Butanol is particularly suited as a transport fuel because it is not water soluble and has higher energy content than ethanol.
Most commonly used raw materials in butanol production have so far been starch and cane sugar. In contrast to this, the starting point in the Aalto University study was to use only lignocellulose, otherwise known as wood biomass, which does not compete with food production.
Another new breakthrough in the study is to successfully combine modern pulp -- and biotechnology. Finland's advanced forest industry provides particularly good opportunities to develop this type of bioprocesses.
Wood biomass is made up of three primary substances: cellulose, hemicelluloses and lignin. Of these three, cellulose and hemicellulose can be used as a source of nutrition for microbes in bioprocesses. Along with cellulose, the Kraft process that is currently used in pulping produces black liquor, which can already be used as a source of energy. It is not, however, suitable for microbes. In the study, the pulping process was altered so that, in addition to cellulose, the other sugars remain unharmed and can therefore be used as raw material for microbes.
When wood biomass is boiled in a mixture of water, alcohol and sulphur dioxide, all parts of the wood -- cellulose, hemicellulose and lignin -- are separated into clean fractions. The cellulose can be used to make paper, nanocellulose or other products, while the hemicellulose is efficient microbe raw material for chemical production. Thus, the advantage of this new process is that no parts of the wood sugar are wasted.
In accordance with EU requirements, all fuel must contain 10 per cent biofuel by 2020. A clear benefit of butanol is that a significantly large percentage -- more than 20 per cent of butanol, can be added to fuel without having to make any changes to existing combustion engines. The nitrogen and carbon emissions from a fuel mix including more than 20 per cent butanol are significantly lower than with fossil fuels. For example, the incomplete combustion of ethanol in an engine produces volatile compounds that increase odour nuisances in the environment. Estimates indicate that combining a butanol and pulp plant into a modern biorefinery would provide significant synergy benefits in terms of energy use and biofuel production.
The project run by Aalto University is part of the Tekes' BioRefine programme. Tekes is the Finnish Funding Agency for Technology and Innovation.
The Biorefine programme is developing new competence based on national strengths and related to the refining of biomass. The overall aim of the project is to increase the refining value of forest residues that cannot be utilised in, for example, the pulp process. The research has been developed by Professor Aadrian van Heiningen and Tom Granstr�m and a group of researchers at Aalto University.
Results of findings have been published in scientific journals such as Bioresource Technology. The developed technology has been patented.
Source : http://www.sciencedaily.com/
A Portuguese energy company called Enersis is funding a commercial wave energy project in Northern Portugal. Construction of Pelamis Offshore Wave Energy Project will begin at the end of October 2006. The project will use Pelamis wave generator technology (manufactured by Ocean Power Delivery) to harness energy from the ocean. After two decades of research and testing at the Lisbon Technical Institute, the first stage of this ocean energy project is intended to produce 2.25 megawatts and power homes through the nation�s state-run electrical grid system. Ocean Power Delivery is considered to be the world�s leading ocean energy company.
�This project, begun in 2003, is now in the world vanguard,� said Rui Barros, Enersis director of new projects. �Of all the varieties of renewable energy, perhaps harnessing the waves is the only one where Portugal might have a real future,� he said. With its geographical position and extensive coastline giving access to the larger and more powerful Atlantic waves, official estimates from Portugal�s State Secretariat for Industry and Innovation have predicted wave power could account for up to 30 percent of the country�s gross domestic product by 2050. Renewable energy experts have determined wave farms in Portugal could yield as much as three times as much energy as that produced by a wind turbine park for the same investment cost.
A report published by the Portuguese Wave Energy Center has confirmed the long-term economic benefits of wave energy for the country and calls on the government to put in place a strategy to attract foreign investment into Portuguese wave power ventures. �The utilization of wave energy may have a significant socio-economic impact on Portugal, namely regarding renewables, creation of job opportunities, opportunity of exportation of equipment and services, innovation and development of technology, as well as companies dedicated to the exploitation of other oceanic resources,� the report says.
Relatively new in development, modern research into wave power had its beginnings in response to the 1973 oil crisis. Professor Stephen Salter of the University of Edinburgh pioneered research into wave energy with his prototype machine �Salter�s Duck.� Though the duck remains a laboratory prototype, the machine remains the standard for wave energy. The experimental device converted around 90 percent of the wave power by bobbing up and down on the surface of the water � like a duck. Despite its early promise though, setbacks and a general lack of government support saw the project shelved.
However, with the Portuguese system set to be the world�s first commercial wave energy venture, the exploitation of wave power has found itself back on the renewable energy agenda.
Following the Enersis announcement, other countries naturally suited to the development of wave power have expressed their interest in introducing the technology. Following his recent visit to Aguadoura, Scottish Executive Enterprise Minister Nicol Stephen announced that a portion of the 8 million pounds already set aside for renewable marine energy in Scotland would now be directed towards installing the Pelamis wave devices at the European Marine Energy Center in Orkney.
�I am committed to supporting Scotland�s huge wave and tidal energy resource. Scotland has a real opportunity to be a world leader in this field,� said the minister shortly after his visit to view the wave energy project in northern Portugal. �The opportunity now exists to create a multi-million pound industry based in Scotland, employing thousands of highly skilled people,� he said.
However, environmental group Friends of the Earth, while supporting the minister�s announcement, sounded a warning that any delays in introducing the wave power technology could lead to an exodus of Scottish expertise.
�Wave and tidal power could supply a fifth of U.K. energy needs and Scotland is ideally placed to generate significant amounts of this pollution-free energy,� said Friends of the Earth chief executive Duncan McLaren. �However, there is a danger that unless we see full-scale devices in our waters soon that the world-leading expertise Scotland has built up will rapidly depart these shores,� he said.
As part of the government supported alternative energy plan, another 28 wave power devices will be installed in Portugal within a year, reaching a target of 22.5 megawatts of electricity produced using wave energy. The project is supported by state run power company Energias de Portugal.
Source : http://wavepowerplant.blogspot.com/
More than a dozen advanced reactor designs are in various stages of development. Some are evolutionary from the PWR, BWR and PHWR designs above, some are more radical departures. The former include the Advanced Boiling Water Reactor (ABWR), two of which are now operating with others under construction, and the planned passively safe ESBWR and AP1000 units (see Nuclear Power 2010 Program).
The Integral Fast Reactor (IFR) was built, tested and evaluated during the 1980s and then retired under the Clinton administration in the 1990s due to nuclear non-proliferation policies of the administration. Recycling spent fuel is the core of its design and it therefore produces only a fraction of the waste of current reactors.
The Pebble Bed Reactor, a High Temperature Gas Cooled Reactor (HTGCR), is designed so high temperatures reduce power output by doppler broadening of the fuel's neutron cross-section. It uses ceramic fuels so its safe operating temperatures exceed the power-reduction temperature range. Most designs are cooled by inert helium. Helium is not subject to steam explosions, resists neutron absorption leading to radioactivity, and does not dissolve contaminants that can become radioactive.
Typical designs have more layers (up to 7) of passive containment than light water reactors (usually 3). A unique feature that may aid safety is that the fuel-balls actually form the core's mechanism, and are replaced one-by-one as they age. The design of the fuel makes fuel reprocessing expensive.
The Small Sealed Transportable Autonomous Reactor (SSTAR) is being primarily researched and developed in the US, intended as a fast breeder reactor that is passively safe and could be remotely shut down in case the suspicion arises that it is being tampered with.
The Clean And Environmentally Safe Advanced Reactor (CAESAR) is a nuclear reactor concept that uses steam as a moderator � this design is still in development.
The Hydrogen Moderated Self-regulating Nuclear Power Module (HPM) is a reactor design emanating from the Los Alamos National Laboratory that uses uranium hydride as fuel.
Subcritical reactors are designed to be safer and more stable, but pose a number of engineering and economic difficulties. One example is the Energy amplifier.
Thorium based reactors. It is possible to convert Thorium-232 into U-233 in reactors specially designed for the purpose. In this way, thorium, which is more plentiful than uranium, can be used to breed U-233 nuclear fuel. U-233 is also believed to have favourable nuclear properties as compared to traditionally used U-235, including better neutron economy and lower production of long lived transuranic waste.
Advanced Heavy Water Reactor (AHWR)� A proposed heavy water moderated nuclear power reactor that will be the next generation design of the PHWR type. Under development in the Bhabha Atomic Research Centre (BARC), India.
KAMINI � A unique reactor using Uranium-233 isotope for fuel. Built in India by BARC and Indira Gandhi Center for Atomic Research (IGCAR).
India is also planning to build fast breeder reactors using the thorium � Uranium-233 fuel cycle. The FBTR (Fast Breeder Test Reactor) in operation at Kalpakkam (India) uses Plutonium as a fuel and liquid sodium as a coolant.
Source : http://nuclear-powerplants.blogspot.com/
Just as many conventional thermal power stations generate electricity by harnessing the thermal energy released from burning fossil fuels, nuclear power plants convert the energy released from the nucleus of an atom, typically via nuclear fission.
When a relatively large fissile atomic nucleus (usually uranium-235 or plutonium-239) absorbs a neutron, a fission of the atom often results. Fission splits the atom into two or more smaller nuclei with kinetic energy (known as fission products) and also releases gamma radiation and free neutrons. A portion of these neutrons may later be absorbed by other fissile atoms and create more fissions, which release more neutrons, and so on.
This nuclear chain reaction can be controlled by using neutron poisons and neutron moderators to change the portion of neutrons that will go on to cause more fissions. Nuclear reactors generally have automatic and manual systems to shut the fission reaction down if unsafe conditions are detected.
A cooling system removes heat from the reactor core and transports it to another area of the plant, where the thermal energy can be harnessed to produce electricity or to do other useful work. Typically the hot coolant will be used as a heat source for a boiler, and the pressurized steam from that boiler will power one or more steam turbine driven electrical generators.
There are many different reactor designs, utilizing different fuels and coolants and incorporating different control schemes. Some of these designs have been engineered to meet a specific need. Reactors for nuclear submarines and large naval ships, for example, commonly use highly enriched uranium as a fuel. This fuel choice increases the reactor's power density and extends the usable life of the nuclear fuel load, but is more expensive and a greater risk to nuclear proliferation than some of the other nuclear fuels.
A number of new designs for nuclear power generation, collectively known as the Generation IV reactors, are the subject of active research and may be used for practical power generation in the future. Many of these new designs specifically attempt to make fission reactors cleaner, safer and/or less of a risk to the proliferation of nuclear weapons. Passively safe plants (such as the ESBWR) are available to be built and other designs that are believed to be nearly fool-proof are being pursued. Fusion reactors, which may be viable in the future, diminish or eliminate many of the risks associated with nuclear fission.
There are two types of nuclear power in current use:
* The Radioisotope thermoelectric generator produces heat through passive radioactive decay. Some radioisotope thermoelectric generators have been created to power space probes (for example, the Cassini probe), some lighthouses in the former Soviet Union, and some pacemakers. The heat output of these generators diminishes with time; the heat is converted to electricity utilising the thermoelectric effect.
* Nuclear fission reactors produce heat through a controlled nuclear chain reaction in a critical mass of fissile material. All current nuclear power plants are critical fission reactors, which are the focus of this article. The output of fission reactors is controllable. There are several subtypes of critical fission reactors, which can be classified as Generation I, Generation II and Generation III. All reactors will be compared to the Pressurized Water Reactor (PWR), as that is the standard modern reactor design.
Pressurized Water Reactors (PWR)
These reactors use a pressure vessel to contain the nuclear fuel, control rods, moderator, and coolant. They are cooled and moderated by high pressure liquid water. The hot radioactive water that leaves the pressure vessel is looped through a steam generator, which in turn heats a secondary (non-radioactive) loop of water to steam that can run turbines. They are the majority of current reactors, and are generally considered the safest and most reliable technology currently in large scale deployment. This is a thermal neutron reactor design, the newest of which are the VVER-1200, Advanced Pressurized Water Reactor and the European Pressurized Reactor. United States Naval reactors are of this type.
Boiling Water Reactors (BWR)
A BWR is like a PWR without the steam generator. A boiling water reactor is cooled and moderated by water like a PWR, but at a lower pressure, which allows the water to boil inside the pressure vessel producing the steam that runs the turbines. Unlike a PWR, there is no primary and secondary loop. The thermal efficiency of these reactors can be higher, and they can be simpler, and even potentially more stable and safe. This is a thermal neutron reactor design, the newest of which are the Advanced Boiling Water Reactor and the Economic Simplified Boiling Water Reactor.
Pressurized Heavy Water Reactor (PHWR)
A Canadian design (known as CANDU), these reactors are heavy-water-cooled and -moderated Pressurized-Water reactors. Instead of using a single large pressure vessel as in a PWR, the fuel is contained in hundreds of pressure tubes. These reactors are fueled with natural uranium and are thermal neutron reactor designs. PHWRs can be refueled while at full power, which makes them very efficient in their use of uranium (it allows for precise flux control in the core). CANDU PHWRs have been built in Canada, Argentina, China, India (pre-NPT), Pakistan (pre-NPT), Romania, and South Korea. India also operates a number of PHWRs, often termed 'CANDU-derivatives', built after the Government of Canada halted nuclear dealings with India following the 1974 Smiling Buddha nuclear weapon test.
Reaktor Bolshoy Moschnosti Kanalniy (High Power Channel Reactor) (RBMK)
A Soviet design, built to produce plutonium as well as power. RBMKs are water cooled with a graphite moderator. RBMKs are in some respects similar to CANDU in that they are refuelable during power operation and employ a pressure tube design instead of a PWR-style pressure vessel. However, unlike CANDU they are very unstable and large, making containment buildings for them expensive. A series of critical safety flaws have also been identified with the RBMK design, though some of these were corrected following the Chernobyl accident. Their main attraction is their use of light water and un-enriched uranium. As of 2010, 11 remain open, mostly due to safety improvements and help from international safety agencies such as the DOE. Despite these safety improvements, RBMK reactors are still considered one of the most dangerous reactor designs in use. RBMK reactors were deployed only in the former Soviet Union.
Gas Cooled Reactor (GCR) and Advanced Gas Cooled Reactor (AGR)
These are generally graphite moderated and CO2 cooled. They can have a high thermal efficiency compared with PWRs due to higher operating temperatures. There are a number of operating reactors of this design, mostly in the United Kingdom, where the concept was developed. Older designs (i.e. Magnox stations) are either shut down or will be in the near future. However, the AGCRs have an anticipated life of a further 10 to 20 years. This is a thermal neutron reactor design. Decommissioning costs can be high due to large volume of reactor core.
Liquid Metal Fast Breeder Reactor (LMFBR)
This is a reactor design that is cooled by liquid metal, totally unmoderated, and produces more fuel than it consumes. They are said to "breed" fuel, because they produce fissionable fuel during operation because of neutron capture. These reactors can function much like a PWR in terms of efficiency, and do not require much high pressure containment, as the liquid metal does not need to be kept at high pressure, even at very high temperatures. BN-350 and BN-600 in USSR and Superph�nix in France were a reactor of this type, as was Fermi-I in the United States. The Monju reactor in Japan suffered a sodium leak in 1995 and is pending restart earliest in February 2010. All of them use/used liquid sodium. These reactors are fast neutron, not thermal neutron designs. These reactors come in two types:
Lead cooled
Using lead as the liquid metal provides excellent radiation shielding, and allows for operation at very high temperatures. Also, lead is (mostly) transparent to neutrons, so fewer neutrons are lost in the coolant, and the coolant does not become radioactive. Unlike sodium, lead is mostly inert, so there is less risk of explosion or accident, but such large quantities of lead may be problematic from toxicology and disposal points of view. Often a reactor of this type would use a lead-bismuth eutectic mixture. In this case, the bismuth would present some minor radiation problems, as it is not quite as transparent to neutrons, and can be transmuted to a radioactive isotope more readily than lead. The Russian Alfa class submarine uses a lead-bismuth-cooled fast reactor as its main power plant.
Sodium cooled
Most LMFBRs are of this type. The sodium is relatively easy to obtain and work with, and it also manages to actually prevent corrosion on the various reactor parts immersed in it. However, sodium explodes violently when exposed to water, so care must be taken, but such explosions wouldn't be vastly more violent than (for example) a leak of superheated fluid from a SCWR or PWR. EBR-I, the first reactor to have a core meltdown, was of this type.
Pebble Bed Reactors (PBR)
These use fuel molded into ceramic balls, and then circulate gas through the balls. The result is an efficient, low-maintenance, very safe reactor with inexpensive, standardized fuel. The prototype was the AVR.
Molten Salt Reactors
These dissolve the fuels in fluoride salts, or use fluoride salts for coolant. These have many safety features, high efficiency and a high power density suitable for vehicles. Notably, they have no high pressures or flammable components in the core. The prototype was the MSRE, which also used Thorium's fuel cycle to produce 0.1% of the radioactive waste of standard reactors.
Aqueous Homogeneous Reactor (AHR)
These reactors use soluble nuclear salts dissolved in water and mixed with a coolant and a neutron moderator.
Source : http://nuclear-powerplants.blogspot.com/
What are Geothermal Power Plants?
There are three geothermal power plant technologies being used to convert hydrothermal fluids to electricity. The conversion technologies are dry steam, flash, and binary cycle. The type of conversion used depends on the state of the fluid (whether steam or water) and its temperature. Dry steam power plants systems were the first type of geothermal power generation plants built. They use the steam from the geothermal reservoir as it comes from wells, and route it directly through turbine/generator units to produce electricity. Flash steam plants are the most common type of geothermal power generation plants in operation today. They use water at temperatures greater than 360�F (182�C) that is pumped under high pressure to the generation equipment at the surface. Binary cycle geothermal power generation plants differ from Dry Steam and Flash Steam systems in that the water or steam from the geothermal reservoir never comes in contact with the turbine/generator units.
Types of Geothermal Power Plants
Dry Steam Power Plants
This is the earliest form of geothermal power plant, which directs steam into turbines to produce electricity. Excess heat from the production well is channeled back into the reservoir via an injection well. This type of generator was first used in 1904, to generate electricity in Lardarello, Italy, where it still stands today, fully operational. The United States have also built dry steam power plants, including those in Northern California geysers.
Steam plants use hydrothermal fluids that are primarily steam. The steam goes directly to a turbine, which drives a generator that produces electricity. The steam eliminates the need to burn fossil fuels to run the turbine. (Also eliminating the need to transport and store fuels!) This is the oldest type of geothermal power plant. It was first used at Lardarello in Italy in 1904, and is still very effective. Steam technology is used today at The Geysers in northern California, the world's largest single source of geothermal power. These plants emit only excess steam and very minor amounts of gases.
Flash Steam Power Plants
Hot springs above 1750�C may is used to power Flash Steam Power Plants. These hot fluids are channeled to a low pressure flash tank, magnifying its steam formation. This flash steam is then used to power turbines, activating the generator to produce electricity. Excess heat is returned to the reservoir by means of an injector well. One example of a flash steam power plant is the Cal-Energy Navy I, located in Coso Geothermal Field, California.
Hydrothermal fluids above 360�F (182�C) can be used in flash plants to make electricity. Fluid is sprayed into a tank held at a much lower pressure than the fluid, causing some of the fluid to rapidly vaporize, or "flash." The vapor then drives a turbine, which drives a generator. If any liquid remains in the tank, it can be flashed again in a second tank to extract even more energy.
Binary-Cycle Power Plants
This type of power plant use a completely different method compared with the above systems, where the steam from production wells does not directly come into contact with the turbines. Steam is used to heat working fluids in the heat exchanger, which then generates flash steam. This steam is then used to power the turbines and generator to produce electricity. Steam from the heat exchanger is what�s called Binary / Secondary Fluid. This is a closed loop system, where no excess heat is released into the air.
BCPP is able to be operated in low temperatures, between 90-1750�C. One example of this technology is the Mammoth Pacific Binary Geo-Thermal Power Plants in Casa Diablo geothermal field. This technology is a glimpse of future geothermal technology, one that will be used in the future.
The Agency For the Assessment and Application Technology (BPPT) has built a prototype 2KW binary cycle power plant with hydrocarbon as its primary fluid. BPPT has also planned to develop small scale power plants between 2010-2014 which includes a 1 MW binary cycle power plant (targeted for 2014) through a 2 KW prototype (2008) and 100 KW pilot project (2012), and the development of condensing turbine power plant technology with a capacity of 2-5 MW (2011 and 2013).
Most geothermal areas contain moderate-temperature water (below 400�F). Energy is extracted from these fluids in binary-cycle power plants. Hot geothermal fluid and a secondary (hence, "binary") fluid with a much lower boiling point than water pass through a heat exchanger. Heat from the geothermal fluid causes the secondary fluid to flash to vapor, which then drives the turbines. Because this is a closed-loop system, virtually nothing is emitted to the atmosphere. Moderate-temperature water is by far the more common geothermal resource, and most geothermal power plants in the future will be binary-cycle plants.
The Future of Geothermal Electricity
Steam and hot water reservoirs are just a small part of the geothermal resource. The Earth's magma and hot dry rock will provide cheap, clean, and almost unlimited energy as soon as we develop the technology to use them. In the meantime, because they're so abundant, moderate-temperature sites running binary-cycle power plants will be the most common electricity producers.
Before geothermal electricity can be considered a key element of the U.S. energy infrastructure, it must become cost-competitive with traditional forms of energy. The U.S. Department of Energy is working with the geothermal industry to achieve $0.03 to $0.05 per kilowatt-hour. We believe the result will be about 15,000 megawatts of new capacity within the next decade.
source:http://www.geothermalpowerplant.com/
There are many advantages and disadvantages of nuclear power. There are also ethical concerns as well as political concerns. The following article addresses many of the major advantages and disadvantages to nuclear power.
There are many advantages and disadvantages of nuclear power. There are also ethical concerns as well as political concerns. The following article addresses many of the major advantages and disadvantages to nuclear power.
Advantages of Nuclear Power:
* Nuclear power plants don't take up much space. This allows them to be placed in already developed areas and the power does not have to be transferred over long distances.
* It doesn't pollute in a very direct way. It is cleaner than many other forms of energy production. This is in reference to greenhouse gas emissions which are released into the atmosphere. There is a waste product as described below.
* Another advantage of nuclear power is that nuclear energy is by far the most concentrated form of energy, so it can be produced in large quantities over short periods of time.
* The possibility for long term production is great since new reactors, where costly can be made when the old ones wear out. Oil reserves and other fossil type fuels are likely to run out at some point.
Disadvantages of Nuclear Power:
* Nuclear Power generates radiation, which can be harmful or even fatal to infected people.
* A nuclear meltdown can often occur which will release massive amounts of radiation into the community.
* Extremely radioactive nuclear waste is produced by nuclear power plants. This stuff can�t be just thrown out. The US plans to move all its nuclear was to an underground dump by the year 2010. Currently it is stored in the plants.
* Nuclear waste dumps can spontaneously combust without warning.
* Nuclear reactors only last for about forty to fifty years, so where they are extremely productive, they break down and are costly to replace.
* There are international dangers too. Some reactors produce plutonium which can be used to make nuclear weapons. If the whole world were to use these, they would have unlimited access to nuclear weapons.
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Geothermal energy is the energy obtained from the earth(geo) from the hot rocks present inside the earth. It is produced due to the fission of radioactive materials in the earth�s core and some places inside the earth become very hot. These are called hot spots. They cause water deep inside the earth to form steam. As more steam is formed, it gets compressed at high pressure and comes out in the form of hot springs which produces geothermal power.
To harness this geothermal energy, two holes are dug deep into the earth and cold water is pumped through the first one and steam comes out through the second long pipe which helps in generating electricity. The holes dug for harnessing geothermal energy result in lesser emission of greenhouse gases than due to burning of fossil fuels. Thus if used at a larger scale and more efficiently, it gives a hope to reduce global warming.
Geo-thermal energy is one of the rare forms of energy which is not directly or indirectly from solar energy. In areas where hot springs are found, hot springs baths are very common and enjoyable form of recreation. However, they need to be in a controlled environment since they cannot be accessed without proper supervision. We have earlier seen how it is harnessed, the process involved is a long and expensive one and not feasible in some areas.
Construction of geothermal energy plants can affect the seismic stability to a large extent. Even though there are lesser emissions, digging deep holes causes seismic disturbances which have led to earthquakes.
Now lets discuss advantages and disadvantages of Geothermal Energy.
Advantages of Geothermal Energy
1) It is a renewable source of energy.
2) By far, it is non-polluting and environment friendly.
3) There is no wastage or generation of by-products.
4) Geothermal energy can be used directly. In ancient times, people used this source of energy for heating homes, cooking, etc.
5) Maintenance cost of geothermal power plants is very less.
6) Geothermal power plants don't occupy too much space and thus help in protecting natural environment.
7) Unlike solar energy, it is not dependent on the weather conditions.
Disadvantages of Geothermal Energy
1) Only few sites have the potential of Geothermal Energy.
2) Most of the sites, where geothermal energy is produced, are far from markets or cities, where it needs to be consumed.
3) Total generation potential of this source is too small.
4) There is always a danger of eruption of volcano.
5) Installation cost of steam power plant is very high.
6) There is no guarantee that the amount of energy which is produced will justify the capital expenditure and operations costs.
7) It may release some harmful, poisonous gases that can escape through the holes drilled during construction.
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Geothermal energy comes from within the earth. It may be the result of the decay of radioactive substances, chemical reactions, friction from the movement of the continents or heat present when the earth formed.
Most of this heat is at depths beyond the reach of current technology. One of the most famous examples of geothermal energy is the geyser Old Faithful in Yellowstone National Park in the United States.
The four basic forms of geothermal energy are dry steam, hot water (or wet steam), hot dry rock and geopressurized systems. Dry steam occurs only in a few places, but it is the only one of the forms that is in commercial use.
Dry steam
The Geysers plant north of San Francisco, California, uses dry steam to run turbine generators, producing more than 500 megawatts of electric power. Operators pipe dry steam from natural underground reservoirs through a conventional steam turbine generator to produce electricity. The system converts the steam to water in a condenser and returns the water to the earth.
Hot water
Hot rock far beneath the earth's surface heats underground water to temperatures up to 2,200 degrees Fahrenheit. Pressure keeps the water in liquid form. The hot water flows to the surface through wells. Deprived of its pressure, it becomes steam to drive a steam turbine directly or to heat another fluid to run a turbine. Hot water geothermal energy provides central heating for all the buildings in Reykjavik, Iceland.
Hot dry rock
Extracting energy from subterranean hot dry rock means introducing a heat exchange fluid (water) to carry the heat from the rock to the power plant. Scientists inject water deep into fractured hot rock. Then they use the heated water as geothermal water for conversion to useful energy.
Geopressurized systems
Reservoirs of hot water mixed with methane gas, trapped underground, offer the energy potentials of both pressure and burnable methane, as well as the heat energy available from any geothermal resource.
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Hydroelectric energy is the electrical energy derived from hydro (water) power. It is a non-conventional or alternate source of energy.
How hydroelectric energy is generated?
Before discussing advantages and disadvantages of Hydroelectric power, let�s first understand how a hydroelectric power plant works to understand its merits and demerits better. Flowing water possesses kinetic energy. Traditionally, this energy was used to drive water mills to grind pulses etc. Modern day methods have modified this use for a bigger purpose- generation of electricity. When rain falls on high grounds in hilly areas, it flows down in the form if rivers and reaches the sea level. This water is stopped in between and stored in large reservoirs or damns. The dams are at a height and thus water now contains potential energy. This water is then made to flow to large turbines. The water flows with high speed and pressure and rotates turbines, which in turn generates electricity. The water stream follows its natural course, once out of the generator. This is how a hydroelectric power plant can convert the potential energy of stored water in a reservoir of a tall dam into electric energy.
The main reason for using this form of energy for electricity generation is the fact that it is an alternate source of energy and can bring a relief to the use of conventional energy sources. Other advantages of hydro energy are discussed below.
Hydroelectric Power
Hydroelectric power uses the energy of moving water to make electricity. Fuel for a hydro plant is renewable and costs nothing. Another benefit is that hydro plants do not affect air quality.
Hydro plants generated 33 percent of the electricity in the US in the 1920s. Today they generate more electricity than 60 years ago, but account for only 13 percent of the US total. The percentage is smaller because total electric generation from other sources has increased over time.
In a hydropower system, dams on a river capture its power and direct the fast-flowing water through turbines and turning generators to produce electricity. The difference between the water levels above and below the turbine and the rate of water flow determine the amount of power generated.
Run-of-the-river plants use the natural flow of the stream. This greatly limits their potential to produce electricity in a controlled manner because the flow usually varies during the year. To avoid this, some dams store water upstream in a reservoir and then release it as needed.
Advantages of Hydroelectric Energy
1) It is a non-polluting source of energy.
2) It has lower operational cost compared to fossil fuel-based generation plants.
3) Can be easily transmitted through wires to long distances.
4) Dams made for generation of Hydroelectricity also help in irrigation projects.
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When it comes to the future, solar energy is looking strong. People are now realizing that in the long term, solar energy provides a financially viable option. The upfronts costs might be high, but in the long term, everyone can save money by using solar energy. Here are some of the major advantages of solar energy.
Saving money is something that everyone is looking to achieve when it comes to solar energy. The great advantage of solar energy is that it utilizes a free energy resource; the sun. By utilizing the power of the sun, solar energy systems can create electricity. In fact, even if extra energy is produced, this can actually be sold to utility providers at a profit. Solar energy does not just save people money, but it can also make them money too.
A lot more people these days are focused on doing what is right for the environment. This includes things like producing energy. Power plants use a lot of non-renewable energy resources to provide our homes with power. Solar energy systems do not damage the environment in any way, so are good for the future of the planet.
One of the major advantages of solar energy is the lack of maintenance that is required in the long term. The systems do need slight maintenance every now and then, but in the long term, the costs are minimal. This means that once the initial investment has been made, there is little that a owner of a solar energy system really needs to do.
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A method developed at Aalto University in Finland makes it possible to use microbes to produce butanol suitable for biofuel and other industrial chemicals from wood biomass.
