T & D - 44) Types of Cable Installations in Electrical Network

Types of cable installations in electrical network

Introduction to installing power cables

There are a variety of ways to install power distribution cables. Each method ensures distribution of power with a unique degree of reliability, safety, economy, and quality for any specific set of conditions.

These conditions include the electrical characteristics of the power system, the distance and terrain of distribution, and the expected mechanical and environmental conditions.

1. Open-Wire

Open-wire construction consists of uninsulated conductors on insulators which are mounted on poles or structures. The conductor may be bare or it may have a thin covering for protection from corrosion or abrasion. The attractive features of this method are its low initial cost and the fact that damage can be detected and repaired quickly.

On the other hand, the uninsulated conductors are a safety hazard and are also highly susceptible to mechanical damage and electrical outages resulting from short circuits caused by birds or animals. Proper vertical clearances over roadways, walkways, and structures are critical. Exposed open-wire circuits are also more susceptible to the effects of lightning than other circuits, however, these effects may be minimized by the use of overhead ground wires and lightning arresters.

In addition, there is an increased hazard where crane or boom truck use may be involved. In some areas contamination on insulators and conductor corrosion can result in high maintenance costs.

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2. Aerial Cable

Aerial cable consists of fully insulated conductors suspended above the ground. This type of installation is used increasingly, generally for replacing open wiring, where it provides greater safety and reliability and requires less space.

Properly protected cables are not a safety hazard and are not easily damaged by casual contact.

415 volt insulated aerial bundled cables (ABC)

They do, however, have the same disadvantage as open-wire construction, requiring proper vertical clearances over roadways, walkways, and structures.

2.1 Supports

Aerial cables may be either self-supporting or messenger-supported. They may be attached to pole lines or structures. Self-supporting aerial cables have high tensile strength for this application. Cables may be messenger-supported either by spirally wrapping a steel band around the cables and the messenger or by pulling the cable through rings suspended from the messenger.

2.2 Distance

Self-supporting cable is suitable for only relatively short distances, with spans in the range of 100-150 feet. Messenger-supported cable can span relatively large distances, of over 1000 feet, depending on the weight of the cable and the tensile strength of the messenger. For this reason, aerial cable that must span relatively large distances usually consists of aluminum conductors to reduce the weight of the cable assembly.

The supporting messenger provides high strength to withstand climatic rigors or mechanical shock. It may also serve as the grounding conductor of the power circuit.

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3. Above-Ground Conduits

Rigid steel conduit systems afford the highest degree of mechanical protection available in above-ground conduit systems. Unfortunately, this is also a relatively high-cost system. For this reason their use is being superseded, where possible, by other types of conduit and wiring systems.

Where applicable, rigid aluminum, intermediate-grade steel conduit, thin-wall EMT, intermediate-grade metal conduit, plastic, fiber and asbestos-cement ducts are being used.

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4. Underground Ducts

Underground ducts are used where it is necessary to provide a high degree of safety and mechanical protection, or where above-ground conductors would be unattractive.

Underground cable duct on street

4.1 Construction

Underground ducts use rigid steel, plastic, fiber, and asbestos-cement conduits encased in concrete, or precast multi-hole concrete with close fitting joints.

Clay tile is also used to some extent. Where the added mechanical protection of concrete is not required, heavy wall versions of fiber and asbestos-cement and rigid steel and plastic conduits are direct buried.

4.2. Cables

Cables used in underground conduits must be suitable for use in wet areas, and protected against abrasion during installation.

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5. Direct Burial

Underground direct buried power cables

Cables may be buried directly in the ground where permitted by codes and only in areas that are rarely disturbed. The cables used must be suitable for this purpose, that is, resistant to moisture, crushing,soil contaminants, and insect and rodent damage. While direct-buried cable cannot be readily added to or maintained, the current carrying capacity is usually greater than that of cables in ducts. Buried cable must have selected backfill.

It must be used only where the chance of disturbance is unlikely. The cable must be suitably protected, however, if used where the chance of disturbance is more likely to occur.

Relatively recent advances in the design and operating characteristics of cable fault location equipment and subsequent repair methods and material have diminished the maintenance problem.

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6. Underwater (Submarine) Cable

Submarine cable is used only when no other cable system can be used. It supplies circuits that must cross expanses of water or swampy terrain.

6.1 Construction

Submarine cable generally consists of a lead sheathed cable and is usually armored.Insulation material should be XLP or EPR, except when paper insulation is justified because of its high resistance to, and freedom from, internal discharge or corona.

Multiconductor construction should be used, unless limited by physical factors. The lead sheathing usually consists of a copper-bearing lead material, however, other alloys may be required when special conditions warrant nonstandard sheathing. The most common type of  armoring material used for submarine cables is the spirally wrapped round galvanized steel wire.

Standard applications for submarine power cables to connect mainland areas or cities via water passages. This applies to mainland-to-island connections. Many of these networks and connections are getting older and need to be overhauled. We are constantly working on the continuous refinement of these products to reduce environmental effects (precisely during the laying process) and losses during power transmission (using new materials).

In this type of cable, asphalt impregnated jute is usually applied over the lead sheath and the wire armor is applied over the jute to reduce mechanical damage and electrolytic corrosion. An additional covering of the asphalt impregnated jute may be applied over the wire armor.

Nonmetallic sheathed cables are sometimes suitable for certain submarine applications. The cable must be manufactured specifically for submarine service and, generally, has an increased insulation thickness. The cable may require wire armor and should have electrical shielding for all voltage ratings above 600 V.

6.1 Installation

Installed underwater sea submarine cable

Submarine cable should lie on the floor of the body of water and should have ample slack so that slight shifting caused by current or turbulence will not place excessive strain on the cable. Where the cable crossing is subject to flow or tidal currents, anchors are often used to prevent excessive drifting or shifting of the cable. In addition to laying cables directly on the bottom, burying cable in a trench using the jetwater method should be considered.

Cables must be buried in waters where marine traffic is present. The depth of burial should be enough to prevent damage caused by dragging anchors, which may be in excess of 15 feet for large ships on sandy bottoms.

Warning signs located on shore at the ends of the submarine cable should be provided to prohibit anchoring in the immediate vicinity of the cable.

Grounding of Cable Systems

For safety and reliable operation, the shields and metallic sheaths of power cables must be grounded. Without such grounding, shields would operate at a potential considerably above ground. Thus, they would be hazardous to touch, and would incur rapid degradation of the jacket or other material intervening between shield and ground.

This is caused by the capacitive charging current of the cable insulation which is approximately 1 milliampere (mA) per foot of conductor length. This current normally flows at a power frequency between the conductor and the earth electrode of the cable, normally the shield. In addition, the shield or metallic sheath provides the fault return path in the event of insulation failure, permitting rapid operation of the protection devices.

Grounding Conductor

The grounding conductor, and its attachment to the shield or metallic sheath, normally at a termination or splice, should have an ampacity no lower than that of the shield.

In the case of a lead sheath, the grounding conductor must be able to carry the available fault current over its duration without overheating. Attachment to shield or sheath is frequently by means of solder, which has a low melting point; thus an adequate area of attachment is required.

Grounding Methods

The cable shield lengths may be grounded at both ends or at only one end.

If grounded at only one end, any possible fault current must traverse the length from the fault to the grounded end, imposing high current on the usually very thin shield conductor. Such a current could damage or destroy the shield, and require replacement of the entire cable rather than only the faulted section. With both ends grounded, the fault current would divide and flow to both ends, reducing the duty on the shield, with consequently less chance of damage.

There are modifications of both systems. In one, single-ended grounding may be attained by insulating the shields at each splice or sectionalizing point, and grounding only the source end of each section. This limits possible shield damage to only the faulted section.

Multiple grounding, rather than just double-ended grounding, is simply the grounding of the cable shield or sheath at all access points, such as manholes or pull boxes. This also limits possible shield damage to only the faulted section.

Resource: Electric Power Distribution Systems Operations by NAVFAC MO-201, April 1990

T & D - 2) Historical Review of Power System Stability Problems

Historical Review of Power System Stability Problems

As electric power systems have evolved over the last century, different forms of instability have emerged as being important during different periods. The methods of analysis and resolution of stability problems were influenced by the prevailing developments in computational tools, stability theory, and power system control technology. A review of the history of the subject is useful for a better understanding of the electric power industry’s practices with regard to system stability.

Power system stability was first recognized as an important problem in the 1920s (Steinmetz, 1920; Evans and Bergvall, 1924; Wilkins, 1926). The early stability problems were associated with remote power plants feeding load centers over long transmission lines.

With slow exciters and non-continuously acting voltage regulators, power transfer capability was often limited by steady-state as well as transient rotor angle instability due to insufficient synchronizing torque.

To analyze system stability, graphical techniques such as the equal area criterion and power circle diagrams were developed. These methods were successfully applied to early systems which could be effectively represented as two machine systems.

As the complexity of power systems increased, and interconnections were found to be economically attractive, the complexity of the stability problems also increased and systems could no longer be treated as two machine systems. This led to the development in the 1930s of the network analyzer, which was capable of power flow analysis of multi-machine systems. System dynamics, however, still had to be analyzed by solving the swing equations by hand using step-by-step numerical integration. Generators were represented by the classical ‘‘fixed voltage behind transient reactance’’ model. Loads were represented as constant impedance.

Improvements in system stability came about by way of faster fault clearing and fast acting excitation systems. Steady-state aperiodic instability was virtually eliminated by the implementation of continuously acting voltage regulators. With increased dependence on controls, the emphasis of stability studies moved from transmission network problems to generator problems, and simulations with more detailed representations of synchronous machines and excitation systems were required.

The 1950s saw the development of the analog computer, with which simulations could be carried out to study in detail the dynamic characteristics of a generator and its controls rather than the overall behavior of multi-machine systems.

Later in the 1950s, the digital computer emerged as the ideal means to study the stability problems associated with large interconnected systems. In the 1960s, most of the power systems in the U.S. and Canada were part of one of two large interconnected systems, one in the east and the other in the west. In 1967, low capacity HVDC ties were also established between the east and west systems. At present, the power systems in North America form virtually one large system. There were similar trends in growth of interconnections in other countries.

While interconnections result in operating economy and increased reliability through mutual assistance, they contribute to increased complexity of stability problems and increased consequences of instability. The Northeast Blackout of November 9, 1965, made this abundantly clear; it focused the attention of the public and of regulatory agencies, as well as of engineers, on the problem of stability and importance of power system reliability.

Until recently, most industry effort and interest has been concentrated on transient (rotor angle) stability. Powerful transient stability simulation programs have been developed that are capable of modeling large complex systems using detailed device models. Significant improvements in transient stability performance of power systems have been achieved through use of high-speed fault clearing, high-response exciters, series capacitors, and special stability controls and protection schemes.

The increased use of high response exciters, coupled with decreasing strengths of transmission systems, has led to an increased focus on small signal (rotor angle) stability.

This type of angle instability is often seen as local plant modes of oscillation, or in the case of groups of machines interconnected by weak links, as inter area modes of oscillation. Small signal stability problems have led to the development of special study techniques, such as modal analysis using eigenvalue techniques (Martins, 1986; Kundur et al., 1990). In addition, supplementary control of generator excitation systems, static Var compensators, and HVDC converters is increasingly being used to solve system oscillation problems.

There has also been a general interest in the application of power electronic based controllers referred to as FACTS (Flexible AC Transmission Systems) controllers for damping of power system oscillations (IEEE, 1996).

In the 1970s and 1980s, frequency stability problems experienced following major system upsets led to an investigation of the underlying causes of such problems and to the development of long term dynamic simulation programs to assist in their analysis (Davidson et al., 1975; Converti et al., 1976; Stubbe et al., 1989; Inoue et al., 1995; Ontario Hydro, 1989). The focus of many of these investigations was on the performance of thermal power plants during system upsets (Kundur et al., 1985; Chow et al., 1989; Kundur, 1981; Younkins and Johnson, 1981). Guidelines were developed by an IEEE Working Group for enhancing power plant response during major frequency disturbances (1983).

Analysis and modeling needs of power systems during major frequency disturbances was also addressed in a recent CIGRE Task Force report (1999). Since the late 1970s, voltage instability has been the cause of several power system collapses worldwide (Kundur, 1994; Taylor, 1994; IEEE, 1990). Once associated primarily with weak radial distribution systems, voltage stability problems are now a source of concern in highly developed and mature networks as a result of heavier loadings and power transfers over long distances. Consequently, voltage stability is increasingly being addressed in system planning and operating studies.

Powerful analytical tools are available for its analysis (Van Cutsem et al., 1995; Gao et al., 1992; Morison et al., 1993), and well-established criteria and study procedures are evolving (Abed, 1999; Gao et al., 1996).

Present-day power systems are being operated under increasingly stressed conditions due to the prevailing trend to make the most of existing facilities. Increased competition, open transmission access, and construction and environmental constraints are shaping the operation of electric power systems in new ways that present greater challenges for secure system operation. This is abundantly clear from the increasing number of major power-grid blackouts that have been experienced in recent years; for example, Brazil blackout of March 11, 1999; Northeast USA-Canada blackout of August 14, 2003; Southern Sweden and Eastern Denmark blackout of September 23, 2003; and Italian blackout of September 28, 2003. Planning and operation of today’s power systems require a careful consideration of all forms of system instability.

Significant advances have been made in recent years in providing the study engineers with a number of powerful tools and techniques.

A coordinated set of complementary programs, such as the one described by Kundur et al. (1994) makes it convenient to carry out a comprehensive analysis of power system stability.

How much for the geothermal energy? Impacts, hm?

Economics

Geothermal power requires no fuel, and is therefore immune to fuel cost fluctuations, but capital costs tend to be high. Drilling accounts for over half the costs, and exploration of deep resources entails significant risks.

A typical well doublet in Nevada can support 4.5 megawatt (MW) of electricity generation and costs about $10 million to drill, with a 20% failure rate.

In total, electrical plant construction and well drilling cost about 2-5 million € per MW of electrical capacity, while the levelised energy cost is 0.04-0.10 € per kW·h. Enhanced geothermal systems tend to be on the high side of these ranges, with capital costs above $4 million per MW and levelized costs above $0.054 per kW·h in 2007.

Geothermal power is highly scalable: a large geothermal plant can power entire cities while a smaller power plant can supply a rural village.

Chevron Corporation is the world’s largest private producer of geothermal electricity. The most developed geothermal field is the Geysers in California. In 2008, this field supported 15 plants, all owned by Calpine, with a total generating capacity of 725 MW.

Environmental impact

Fluids drawn from the deep earth carry a mixture of gases, notably carbon dioxide (CO2), hydrogen sulfide (H2S), methane (CH4) and ammonia (NH3).

These pollutants contribute to global warming, acid rain, and noxious smells if released. Existing geothermal electric plants emit an average of 122 kg of CO2 per megawatt-hour (MW·h) of electricity, a small fraction of the emission intensity of conventional fossil fuel plants. Plants that experience high levels of acids and volatile chemicals are usually equipped with emission-control systems to reduce the exhaust.

Geothermal plants could theoretically inject these gases back into the earth, as a form of carbon capture and storage.

In addition to dissolved gases, hot water from geothermal sources may hold in solution trace amounts of toxic chemicals such as mercury, arsenic, boron, antimony, and salt.  These chemicals come out of solution as the water cools, and can cause environmental damage if released. The modern practice of injecting geothermal fluids back into the Earth to stimulate production has the side benefit of reducing this environmental risk.

Plant construction can adversely affect land stability. Subsidence has occurred in the Wairakei field in New Zealand. Enhanced geothermal systems can trigger earthquakes as part of hydraulic fracturing. The project in Basel, Switzerland was suspended because more than 10,000 seismic events measuring up to 3.4 on the Richter Scale occurred over the first 6 days of water injection.

Geothermal has minimal land and freshwater requirements. Geothermal plants use 3.5 square kilometres per gigawatt of electrical production (not capacity) versus 32 and 12 square kilometres for coal facilities and wind farms respectively.[30] They use 20 litres of freshwater per MW·h versus over 1000 litres per MW·h for nuclear, coal, or oil.

How to determine the hydropower available at site

To determine the power available at a site, head and flow measurements must be taken. Flow is the rate at which water moves, measured in liters per minute (I/m) or gallons per minute (gpm). This can be measured by channeling the water into a pipeline, then into a container of a known volume, noting the time it takes to do so.

Head can be measured by using a transit, by siting along a level, or by using a pressure gauge at the end of the pipeline.

It is important to keep in mind that output can only be accurately determined if head and flow measurements are made correctly, so care should be taken during this process.

1.) Approximate power available at any given site can be assessed using the formula:

head (feet) x flow (gpm) / 8 — Watts
e.g., 100 feet x 30 gpm / 8 = 375 Watts

or

head (m) x flow (l/m) / 10 = Watts
e.g., 30 m x 120 I/m / 10 = 360 Watts

2.) Before considering the purchase of a Stream Engine, perform the above estimate. If it is determined that your site is viable, contact your dealer to discuss pipelines, transmission distance, and system voltage. Power from the Stream Engine is limited according to the available head.

At about 7.5 metre (25 feet), output is limited to 500 watts, 15 metre (50 feet) to 750 watts, and at a 30 metre (100 feet) head, 1000 watts can be generated, given adequate flow.

3.) The length, diameter, and type of pipeline must be determined in order to predict losses due to friction.

4.) Many factors affect system voltage including output and transmission distance. Power is usually generated at battery voltage, but where transmission distances are too great for low voltage transmission (12, 24, or 48 V), higher voltages can be generated and transformers can be effectively used to step down to battery voltage.

World’s largest wind turbine blade developed by Alstom and LM Wind Power

Global leader in power generation equipment and services, Alstom, and LM Wind Power, leading wind turbine blade supplier, have entered a strategic partnership to develop the world’s longest wind turbine blade ever produced. The new blade is a unique development designed specifically for Alstom’s next generation 6-megawatt (MW) offshore wind turbine.
Development of the blade will require more than 20,000 hours of work by LM Wind Power’s specialist teams focusing especially on aerodynamics, structural design, and production processes of this giant. The use of specifically developed material compounds will enable LM Wind Power to maximize strength and durability while producing an exceptionally light blade. Furthermore, it will feature a structural design specifically tailored for Alstom’s turbine, as well as LM Wind Power’s proprietary aerodynamic profiles based on its latest GloBlade, which offers an additional 4-5 percent of annual energy production compared to standard designs. The geometry of the new blade has already been validated in LM Wind Power’s own wind tunnel – the world’s only wind tunnel customized for aerodynamic testing of wind turbine blades.
The prototype blades will be produced in LM Wind Power’s Danish factory in Lunderskov and will be ready for installation at Alstom prototype sites in Europe to start testing during the winter of 2011.

LM Wind Power is one of the pioneers in offshore wind. Its first blades installed offshore have been operating since 1991 at the world’s first offshore wind farm, Vindeby, Denmark. Since 2004, LM Wind Power has supplied its 61.5-meter long blades for offshore. One example is the Beatrice Wind Farm Demonstrator project 25 kilometers off the coast of Scotland.
These blades are currently the world’s longest in serial production and have been installed in offshore wind farms across Europe, where they achieve very high availability.
Alstom’s 6 MW turbine has been optimized for the UK’s Crown Estate Round 3 and other North Sea markets. Two prototypes will be installed in 2011 and 2012, a per-series in 2013 (the final roll out step before full commercialization), and series production in 2014. In January Alstom and EDF Energies Nouvelles (EDF-EN) announced that, using this turbine, they would bid jointly for projects under the recently launched 3 GW French offshore wind tender.
The turbine incorporates leading edge technologies to meet the challenges of the tough marine environment and bring down the cost of energy (COE). These include the turbine’s very large rotor diameter and 6 MW power output for higher energy output. High yield helps offset wind farm investment and operating costs, lowering COE. The turbine’s weight has also been optimized to reduce installation and infrastructure costs.
The turbine features Alstom’s unique ALSTOM PURE TORQUE™ technology to protect and improve the performance of the generator. The technology protects the turbine’s drive train by deflecting unwanted stresses from the wind safely to the tower. Only turning force, or torque, is transmitted to the generator thereby boosting the turbine’s reliability.
Furthermore the turbine’s innovative permanent magnet direct drive system enables a compact, lightweight design that reduces service costs and improves operating efficiency. The system’s low number of rotating parts increases reliability, to maximize turbine availability and further reduce maintenance costs.
Alfonso Faubel, Alstom Power’s Wind business Vice President, said: “LM Wind Power’s quality technology perfectly complements our innovative wind turbine development capability. We have a partner of undoubted pedigree, a proven track record on offshore blade development and the global manufacturing presence and development resources to support our offshore growth plans. The close collaboration of both companies in offshore wind will deliver best in class technology to help bring down the COE, and a highly competitive market offering that will help us become a leader in the global offshore wind energy market.”
Roland Sundén, CEO LM Wind Power Group, said: “I am confident that Alstom’s innovative turbines flying the world’s longest blades from LM Wind Power will give them a clear COE advantage, and we are very pleased to extend our excellent working relations with Alstom into this prestigious project. The key to success in offshore, given that you have a quality wind turbine, is strength of balance sheet, project management skills and power engineering experience. LM Wind Power recognizes Alstom’s clear advantages in this respect compared to many others in offshore.”

About LM Wind Power

LM Wind Power Group is the world’s largest component supplier to the wind industry comprising a blades, brakes and service business and operating from or close to the major wind energy markets.
LM Wind Power has produced more than 130,300 blades in the course of more than 30 years corresponding to approximately 43 GW installed wind power capacity.

What happens when the wind doesn’t blow?

One of the questions most often asked about wind power is ‘what happens when the wind doesn’t blow’. In the big picture wind is a vast untapped resource capable of supplying the world’s electricity needs many times over.

In practical terms, in an optimum, clean energy future, wind will be an important part of a mix of renewable energy technologies, playing a more dominant role in some regions than in others. However, it is worthwhile to step back for a minute and consider the enormity of the resource.

Researchers at Stanford University’s Global Climate and Energy Project recently did an evaluation of the global potential of wind power, using five years of data from the US National Climatic Data Center and the Forecasts Systems Laboratory 1). They estimated that the world’s wind resources can generate more than enough power to satisfy total global energy demand.

Using only 20% of this potential resource for power generation, the report concluded that wind energy could satisfy the world’s electricity demand in the year 2000 seven times over.

After collecting measurements from 7,500 surface and 500 balloon-launch monitoring stations to determine global wind speeds at 80 meters above ground level, they found that nearly 13% had an average wind speed above 6.9 meters per second (Class 3), sufficient for economical wind power generation.

Offshore Resources

North America was found to have the greatest wind power potential, although some of the strongest winds were observed in Northern Europe, while the southern tip of South America and the Australian island of Tasmania also recorded significant and sustained strong winds. To be clear, however, there are extraordinarily large untapped wind resources on all continents, and in most countries; and while this study included some island observation points, it did not include offshore resources, which are enormous.

Scale of large wind turbines

For example, looking at the resource potential in the shallow waters on the continental shelf off the densely populated east coast of the US , from Massachusetts to North Carolina, the average potential resource was found to be approximately four times the total energy demand in what is one of the most urbanized, densely populated and highest-electricity consuming regions of the world 2).

The WBGU calculations of the technical potential were based on average values of wind speeds from meteorological data collected over a 14 year period (1979–1992). They also assumed that advanced multi-megawatt wind energy converters would be used. Limitations to the potential came through excluding all urban areas and natural features such as forests, wetlands, nature reserves, glaciers and sand dunes. Agriculture, on the other hand, was not regarded as competition for wind energy in terms of land use.

Looking in more detail at the solar and wind resource in 13 developing countries, the SWERA (Solar and Wind Energy Resource Assessment) project, supported by the United Nations Environment Programme, has found the potential, for instance, for 7,000 MW of wind capacity in Guatemala and 26,000 MW in Sri Lanka. Neither country has yet started to seriously exploit this large resource.

After this initial pilot programme, SWERA has expanded since 2006 into a larger programme with the aim of providing high quality information on renewable energy resources for countries and regions around the world, along with the tools needed to apply this data in ways that facilitate renewable energy policies and investments. The private sector is also getting into the resource-mapping business, with Seattle based 3Tier launching its ‘mapping the world’ programme in 2008, with the goal of making accessible resource assessments available for the entire world by 2010.

In summary, wind power is a practically unlimited, clean and emissions free power source, of which only a tiny fraction is currently being exploited.

Generating Power In The Future – Solar Wind Power

As the world discovers new ways to meet its growing energy needs, energy generated from Sun, which is better known as solar power and energy generated from wind called the wind power are being considered as a means of generating power.

Though these two sources of energy have attracted the scientists for a very long time, they are not able to decide, which of the two is a better source to generate power. Now scientists are looking at a third option as well.

Scientists at Washington State University have now combined solar power and wind power to produce enormous energy called the solar wind power, which will satisfy all energy requirements of human kind.

Advantages of Solar wind power.

• The scientists say that whereas the entire energy generated from solar wind will not be able to reach the planet for consumption as a lot of energy generated by the satellite has to be pumped back to copper wire to create the electron-harvesting magnetic field, yet the amount that reaches earth is more than sufficient to fulfill the needs of entire human, irrespective of the environment condition.
• Moreover, the team of scientists at Washington State University hopes that it can generate 1 billion billion gigawatts of power by using a massive 8,400-kilometer-wide solar sail to harvest the power in solar wind.
• According to the team at Washington State University, 1000 homes can be lit by generating enough power for them with the help of 300 meters (984 feet) of copper wire, which is attached to a two-meter-wide (6.6-foot-wide) receiver and a 10-meter (32.8-foot) sail.
• One billion gigawatts of power could also be generated by a satellite having 1,000-meter (3,280-foot) cable with a sail 8,400 kilometers (5,220 miles) across, which are placed at roughly the same orbit.
• The scientists feel that if some of the practical issued are solved, Solar wind power will generate the amount of power that no one including the scientists working to find new means of generating power ever expected.

How does the Solar wind power technology work?

The satellite launched to tap solar wind power, instead of working like a wind mill, where a blade attached to the turbine is physically rotated to generate electricity, would use charged copper wire for capturing electrons zooming away from the sun at several hundred kilometers per second.

Disadvantages of Solar wind power

But despite the fact that Solar wind power will solve almost all the problems that we were to face in future due to power generating resources getting exhausted, it has some disadvantages as well. These may include:

• Brooks Harrop, the co-author of the journal paper says that while scientists are keen to tap solar wind to generate power, they also need to keep provisions for engineering difficulties and these engineering difficulties will have to be solved before satellites to tap solar wind power are deployed.
• The distance between the satellite and earth will be so huge that as the laser beam travels millions of miles, it makes even the tightest laser beam spread out and lose most of the energy. To solve this problem, a more focused laser is needed.
• But even if these laser beams reach our satellites, it is very doubtful that our satellites in their present form will be able to tap them. As Greg Howes, a scientist at the University of Iowa puts it, “The energy is there but to tap that energy from solar wind, we require big satellites. There may be practical constraints in this.”