Long Distance Trains.

Long distance trains travel between cities or regions within a country, or from one country to another. They are usually long trains, with coaches designed as restaurants to provide catering services to passengers embarking on the journey. There are also sleeping coaches and facilities such as bathrooms and toilets for the passengers. They are also widely used as tourist trains to ferry tourists over long distances especially when they want to see the countryside in the country they travel to. The speed for trains travelling these long distances have increased dramatically with the introduction of high speed trains for these routes. High speed trains are now very popular in China where most travellers prefer using them than taking flights due to the efficiency of these trains and their convenience. We will examine the different typed of long distance trains in subsequent posts.

Types of Long distance trains.

  1. High Speed Rail
  2. Intercity Trains
  3. Regional Trains
  4. Higher Speed Trains.

Passenger Trains.

Passenger trains carry passengers over long distances and are usually long and fast. A growing type of passenger train used for long distances is the high speed rail. These trains can run at speeds up to 500km/hour. To achieve these speeds, a technology called magnetic levitation has been in research and development to be deployed. These trains can be self powered or multiple units of cars or coaches or a combination of locomotives and unpowered coaches. Passenger trains travel between stations or depots where passengers may embark or disembark. These trains operate on fixed schedule and usually get their supply of power from head- end power, which is usually located at the head of a train. The power source, usually a locomotive or generator car, at the front or ‘ head’ provides electricity used for heating, lighting, electrical and other hotel needs. A separate diesel generator located in the train’s head may also be used to supply power to the entire train. Passenger trains consist of the driver, conductor and other staff responsible for the operation and maintenance of the train for the whole duration of the journey. The trains are built with steel on the exterior and the interior built to look like the interior of airplanes, though with more space for ordinary passengers. Passenger trains were first used in the 19th century, powered by coal and steam. Later trains were powered by diesel electric engines. Modern passenger trains which are high speed trains are powered by trains which run purely on electricity, connected to overhead cables. An example of this type of electric propulsion system is the traction motor. A traction motor is an electric motor used for propulsion of a vehicle such as locomotives. Traction motors are used in electrically powered rail vehicles, (electric multiple units) and other electric vehicles such as electric milk flats, elevators, roller coasters, conveyors, trolley buses, vehicles with electric transmission systems such as diesel electric locomotives, electric hybrid vehicles, battery electric vehicles. Traction motors include direct current(DC) and alternating current (AC) motors. Direct current traction motors were used for so many years in electric and diesel electric propulsion of locomotives, but the invention of high powered semiconductors ( thyristors and the IGBT) has now made practical the use of much simpler higher reliability Alternating Current(AC) induction motors known as asynchronous traction motors.

Trains.

Trains are a series of connected cars running on rail tracks. The tracks are made of iron resting on concrete bars laid on the ground continuously over long distances. Trains are used to transport cargo and passengers over long distances and difficult terrain. Most trains are powered by diesel electric engines, but can also be powered by steam, pneumatics, gas turbines or batteries. The track usually consist of two running rails with a fixed spacing, and may be supplemented by additional rails such as electric conducting rails and rack rails. Monorails and maglev guideways may also be used.

Types of Trains.

  1. Passenger trains
  2. Long Distance Trains
  3. High Speed Rail
  4. Intercity Trains
  5. Regional Trains
  6. Higher Speed Trains
  7. Short distance trains
  8. Commuter trains
  9. Rapid transit trains
  10. Trams.
  11. Light rail
  12. monorail
  13. Mine trains
  14. Maglev
  15. Railcar
  16. Heritage trains.

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Osmotic Power Station

Osmotic power is the energy available from the difference in the salt concentration between seawater and river water. Two practical methods used are reverse electrodialysis and pressure retarded osmosis. Both processes rely on osmosis with membranes. The key waste product is brackish water. The technology of generating electricity by osmotic method was invented in 1973. The technology has been confirmed in the laboratory and are being developed for commercial use in Norway and the Netherlands. A membrane is usually used during the power generation process. Other technologies are being developed that could complement or replace membranes such as electric double layer capacitor technology and vapour pressure difference.

Methods Used.

These are:

  1. Pressure Retarded Osmosis
  2. Reversed Electrodiaysis
  3. Capacitive Method
  4. Vapour pressure Differences
  5. Solar Pond
  6. Boron Nitride Nanotubes.

Pressure Retarded Osmosis

In this method seawater is pumped into a pressure chamber that is at a pressure lower than the difference between the pressure of saline water and freshwater. Freshwater is also pumped into the pressure chamber through a membrane, which increases both the volume and pressure of the chamber. As the pressure differences are compensated, it drives the turbine producing electricity.

Reverse Electro dialysis

This is another method that is being studied and developed. It is basically the creation of a salt battery. It has been described as an array of alternating anion and cation exchange membranes which can be used to generate electricity from the free energy of a river or seawater.

Capacitive Method.

This method has so far only been tested in the laboratory. With this method energy can be extracted from the mixing of saline water and freshwater by cyclically charging up electrodes in contact with saline water, followed by a discharge in freshwater. Since the amount of electrical energy which is needed during the recharging step is less than what is gotten out during the discharging step each completed cycle effectively produces energy.

Vapour pressure differences.

Vapour pressure differences are of two types, open cycle and closed cycle. Both of these methods do not require membranes. The open cycle is similar to the open cycle in ocean thermal energy conversion. In a closed cycle the primary power source originates from a thermal difference, as part of a thermodynamic heat cycle. In this method water vapour is dissolved in a deliquescent salt water mixture using osmotic power as an intermediary.

Solar Pond.

This method does not harness osmotic power only solar power. Sunlight reaching the bottom of the pond is absorbed as heat. The effect of natural convection where heat rises is blocked using density differences between the three layers that make up the pond, in order to trap heat. It is made up of three zones, the upper convection zone, the stable gradient zone and the bottom thermal zone. The stable gradient zone acts as an insulator for the bottom layer as it blocks natural convection. This water from the lower layer the storage zone is pumped out and the heat generated is used to drive a turbine producing electricity.

Boron Nitride Nanotubes.

A research team built an experimental system using boron Nitride that produced much greater power than Statoil prototype. It used an impermeable and electrically insulating membrane that was pierced by a single boron nitride nanotube with an external diameter of a few dozen nanometers. With this membrane separating salt water and freshwater the team was able to measure the electric current passing through the membrane using two electrodes immersed in the fluid on the other side of the nanotube. The results show that the device was able to generate electric current on the order of a nanoampere.

Biomass Power Plants

Biomass is fuel derived from organic materials, a renewable and sustainable source of energy used to create electricity. Some examples of biomass fuels include; forest debris, scrap lumber, crops such as sugar cane, manure, waste residue. With a constant supply of waste from construction and demolition activities to wood not used in paper making to municipal solid waste, green energy production can continue indefinitely. Biomass is a renewable source of fuel because waste residues will always exist( in form of scrap wood, mill residues and forest resources) and properly managed forests will always have trees and crops and the residual biological matter from those crops.

BIOMASS POWER

Biomass power is carbon neutral electricity derived from the burning of renewable organic waste that would otherwise be dumped on landfill sites, openly burned or left in the forests. In biomass power plants the organic waste such as wood waste are burned and produces heat. The heat generated produces steam when water is heated. The steam is then used to drive a turbine which is connected to a generator that produces electricity.

Conversion Types

There are several methods used for converting biomass for practical use as fuels. These are;

  1. Thermal conversion
  2. Chemical conversion
  3. Biochemical conversion
  4. Electrochemical conversion

Thermal Conversion

This process uses heat as the dominant mechanism to upgrade biomass into a better and more practical fuel. The methods include torrefaction, pyrolysis and gasification. There are other less common and more experimental processes like hydrothermal upgrading. Some have been developed for use on high moisture content biomass including aqueous slurries and allow them to be converted into more convenient forms.

Chemical Conversion

A range of chemical processes can be used to convert biomass into forms that are convenient to store, transport and use, or to exploit some property of the process itself. Many of these processes are based on similar coal based processes like the Fischer- Topsche synthesis. Biomass can be converted into multiple commodity chemicals.

Biochemical Conversion

As biomass is an organic material, many highly efficient biochemical processes have developed in nature to breakdown the molecules of which biomass is composed. Many of these conversion processes can be harnessed. In these processes microorganisms are used in the conversion processes which include; anaerobic digestion, fermentation and composting. Glycoside hydrolases are also used in the degradation of biomass such as polysaccharides present in starch and lignocellulose. Thermostable enzymes are also increasingly used especially for biomass that require thermal treatment for efficient degradation.

Electrochemical Conversion

Biomass can be converted to electricity directly via electrochemical oxidation of the material. This can be performed in a direct carbon fuel cell, direct liquid fuel cell such as direct ethanol fuel or direct methanol fuel cell, direct formic acid fuel cell and microbial fuel cell. The fuel can also be consumed indirectly using a fuel cell system containing a reformer which converts the biomass into a mixture of CO and H2 before it is consumed in the fuel cell.

Hydro Electric Power Plants

Hydro electric power plants utilize water in huge reservoirs to generate electricity. A dam is usually built across a body of water, creating a reservoir behind it. The dam is built with huge turbines located inside the dam. Outlets are created for the water from the reservoir to flow to the other side of the river when the reservoir is full. The outlets are opened and closed when required. When the outlets are opened, water rushes in at high speeds and drives the turbines. The turbines are connected to alternators which produce electricity. The cost of hydroelectricity is low, making it a competitive source of renewable energy. The hydro station consumes no water at all, unlike gas or coal stations. It is a flexible source of electricity, as this source of energy generation can be varied upwards or downwards rapidly, to adapt to changing energy demands. Once this plant is constructed, it produces no waste and its emission of greenhouse gases is considerably lower than other power generating plants like coal or gas.

Generating Types

1. Conventional

2. Pumped storage

3. Run of the river

4. Tide.

1. Conventional

This involves the use of dams through which water flows at high pressure to drive a series of turbines. The turbines are connected to a generator which produces electricity. As the turbines rotate, they drive the generator to produce electricity. The amount of electricity produced varies with the water flow, thus huge amounts of electricity are produced during the rainy season and the amount drops during the dry season where there is little or no rain.

Pumped Storage

This method produces electricity to supply when the demand is high by moving water between reservoirs at different elevations. At times of low demand of electricity, the excess generation capacity is used to pump water into the higher reservoir. When the demand increases, water is released back into the lower reservoir through a turbine. This method currently provide the most commercially important means of large scale energy grid storage and improve the daily capacity factor of the generation system.

Run of The River.

These hydroelectric stations are those with small or no reservoir capacity, so that only water coming from upstream is available for generation at the moment. Any oversupply must pass unused. A constant supply of water from a lake or reservoir upstream is a significant advantage in choosing sites for this hydro plant type.

Tide.

This power station utilizes the daily rise and fall of the ocean tides to generate electricity. It allows for construction of reservoirs which are dispatchable to generate power during high demand periods. Tidal power generation is viable in small parts of the world, and research and development are ongoing on these sites to determine how much electricity can be developed using this technology.

A hydroelectric Dam.

Solar Power Plants

Solar power is the conversion of energy from the sun to electricity. The process involves the use of photovoltaics or concentrated solar power or both. Concentrated solar power systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. Photovoltaic cells convert light to an electric current using the photovoltaic effect . Photovoltaic cells where meant to power small devices like calculators and remote homes powered by an off grid photovoltaic system mounted on the rooftop. Commercial concentrated solar power plants were first developed in the 1980s and have continued to expand since.

Types

They are basically two types:

1. Photovoltaic systems

2.Concentrated Solar Power.

Photovoltaic Systems

Photovoltaic systems use solar panels placed either on rooftops or ground mounted solar farms converting sunlight directly to electrical power. This system consist of a photovoltaic cell that converts light into electric current using the photovoltaic effect. The photovoltaic effect is the creation of voltage and electric current in a material upon exposure to light. It is a physical and chemical phenomenon. The photovoltaic effect is similar to the photoelectric effect. In either of these cases, light is absorbed causing the excitation of an electron or charge carrier to a higher energy state. The difference between the two is that the photoelectric effect is used when the electron is ejected out of the material. Photovoltaic effect is used when the excited charge carrier is still contained within the material. In most photovoltaic applications the radiation in sunlight,and the devices are called solar panels. The array of a photovoltaic power system produces direct current (DC) power which fluctuates with the Sun’s intensity. For practical use this usually requires conversion to certain desired voltages or alternating current (AC) through the use of inverters. Multiple solar cells are connected inside modules. Modules are wired together to form arrays, then tied to an inverter which produces power at the desired voltage and for AC the desired frequency or phase.

Concentrated Solar Power.

Concentrated solar power also called concentrated solar thermal uses lenses or mirrors and tracking systems to concentrate sunlight,then using the resulting heat to generate electricity from conventional steam driven turbines. A wide range of these technologies exist among which are the parabolic trough, the compact linear Fresnel reflector, the Stirling dish and the solar power tower. In all of these systems a working fluid is heated by a concentrated sunlight and then used to generate electricity or store power. Thermal storage efficiency allows up to 24 hour electricity generation.

Hybrid Systems

A hybrid system combines photovoltaic and concentrated power system with one another or with other forms of generation such as diesel,wind and biogas. The combined form of generation may enable the system to modulate power output as a function of demand or at least reduce the fluctuating nature of solar power and the consumption of non- renewable fuel. Hybrid systems are most often found on Islands.

A solar power plant.

Nuclear Power Plants

A nuclear power plant is a thermal station whose heat source is a nuclear reactor. As with thermal stations, the heat generated is used to produce steam which is used to drive a turbine. The turbine is connected to a generator which produces electricity. As the turbine rotates, it drives the generator that produces electricity. As of today there are 31 countries that use nuclear power to produce electricity and more countries are expected to build their own nuclear power plants in future. Nuclear power plants are considered less expensive to maintain due to the low fuel cost, but initial capital cost for construction of these plants is usually very high.

Operations

The conversion to electrical energy usually takes place indirectly. The fission process in the reactor heats the reactor coolant. The coolant may be water, gas or liquid metal, depending on the type of reactor. The coolant then goes to the steam generator and heats water to produce steam. The high pressure steam is then fed to the steam turbine. As the steam impacts on the turbine blades, the turbine rotates and acts as a prime mover to the generator and the generator produces electricity.

The Nuclear Reactor

It is the heart of the station. The reactor’s core produces heat by nuclear fission and this heat increases the temperature of the coolant as it is pumped through the reactor to reduce its temperature. The heated coolant is then transferred to the steam generator where it converts the water to steam. This steam is used to drive the turbine which acts on the generator to produce electricity. After the steam turbine has expanded and partially condensed the steam, the steam is passed to a condenser where it is condensed. The condensate is then pumped back into the steam generator to begin the whole cycle again. Nuclear reactors employ uranium to fuel the fission process. Uranium is a heavy metal found on earth, in sea water and rocks. Since nuclear fission creates radioactivity the reactor core is surrounded by a protective shield. This shield absorbs radiation and prevents radioactive materials from being released into the environment. Many reactors are also protected by dome of concrete to protect against internal impact and external casualties.

A Nuclear power station.
How Nuclear power plants work.

Wind Turbines.

Wind turbines also known as wind energy converter are used to convert the kinetic energy of the wind into electrical energy. They come in two types, vertical and horizontal. The smallest turbines are used for charging batteries for domestic use while the larger ones are used to generate electricity for homes. Wind farms which refer to a large array of turbines are used by countries as an alternative source of electricity to reduce their reliance on coal,fuel oil and other fossil fuels. Wind turbines are classified by the wind speed they are designed for from Class 1 to Class 3.Wind turbines can rotate from either a horizontal or vertical axis and can also include blades or be without blades. The horizontal axis blades are however more common than the vertical ones.

Horizontal axis

These large blades mounted at the top of the tower produce the majority of wind power electricity generated in the world today. The turbines have the main rotor shaft and electrical generator at the top of the tower and must be pointed to the wind. Small turbines are pointed by a simple wind vane,while large turbines use a wind sensor coupled with a yaw system. Most have a gearbox, which turns the slow rotation of the blades into quicker rotation suitable for electricity generation. Some turbines do not need a gearbox and are called direct drive meaning they couple the rotor directly to the generator without a gearbox as intermediary. These direct drive turbines are more advantageous compared with the turbine with gearbox. They eliminate the gear speed increaser which is susceptible to significant accumulated fatigue torque loading, reliability issues and high cost of maintenance.

Vertical axis

These have the main rotor shaft arranged vertically. One advantage is that the turbine does not have to be pointed directly to the wind to be effective, which is an advantage on a site where the wind is highly variable. It is also an advantage when it is attached to a building where it is less steerable. The generator and gearbox can be placed close to the ground, using a direct drive from the rotor assembly to the ground based gearbox improving accessibility for maintenance. However it generates far less power overtime.

Recent innovations

Wind turbine rotor blades are being made longer to increase efficiency. They are required to be stiff, strong light and resistant to fatigue. Materials with these properties are composites such as polyester and epoxy, while glass fiber and carbon fiber are used for reinforcements. Construction may employ manual layup or injection moulding. Wind turbine parts other than the rotor blades(including the rotor hub, gearbox,frame and tower) are largely made of steel. Smaller turbines have begun using aluminium alloys for the components to make the turbine lighter and more efficient. Prestressed concrete has been increasingly used in the material for the tower, but still requires much reinforced steel to meet the strength requirements of the turbine. Setup gearboxes are being increasingly replaced by variable speed generators, which require magnetic materials. This will require a greater supply of rare earth mineral called neodymium. These technological innovations point to a more reliable wind turbine with increased capacity for electricity generation.

A wind turbine.

Geothermal power plants

These plants generate electrical power using geothermal energy. The plant types include; Dry steam power stations, flash steam power stations and binary cycle power stations. This electric generation type is currently used in 26 countries. Statistics show that worldwide generation capacity of geothermal plants amount to 12.8 gigawatts and projected to reach 18 gigawatts by 2020. Geothermal power is considered to be sustainable and renewable source of energy because the heat extraction is small compared to the heat’s content. The amount of greenhouse emissions is small compared to coal fired and other power plants.

Working Principle

Geothermal power stations are similar to other steam turbine thermal power stations in that heat from a fuel source(in this case the Earth’s core) is used to heat water or other working fluid. The working fluid is then used to turn a turbine of a generator producing electricity.

Types of Geothermal plants

1. Dry Steam Power Stations

They are the simplest and oldest design. This type is not often found, but is the most efficient. This system may have a liquid reservoir but steam is used as the working fluid. This plant uses dry steam of 150 deg Celsius to turn the turbines connected to a generator. As the turbines rotate, electricity is generated. The steam then moves to a condenser where it is cooled to liquid form and recirculated back into the system to continue the process.

Flash Steam Power Stations.

These stations move deep high pressure hot water into low pressure tanks and use the resulting flashed steam to drive turbines. They require temperatures of at least 180 degree Celsius or more. This type is most commonly used today. In this power plant the hot water flows up through wells in the ground under its own pressure. As it flows upward the pressure decreases and some of the hot water boils into steam. The steam then separates from the water and is used to drive the turbine which causes the generator to produce electricity.

Binary Cycle Power Stations

These power station types are the most recent technology. They can accept fluid temperatures as low as 57degree Celsius. The hot geothermal water is passed by a secondary fluid with a much lower boiling point then water. This causes the secondary fluid to flash vapourize and drive the turbine. This is the most common type being constructed today and has a thermal efficiency of 10-13%.

A geothermal power plant.

Coal fired power plants.

Coal fired power plants utilize coal to generate electricity. They are the most commonly used of all power plant types. They have been used for so many years by countries in Europe and the US but because of global warming concerns and environmental pollution these plants are being closed down in phases and replaced by other power plant types. They are however still being built in Asia but expectation is that the construction of new plants will slow and will be replaced by other power plants.

Generation principle.

Coal fired plants use coal which has been grounded into powder form and burned in a furnace with a boiler. The heat from the furnace converts boiler water into steam. The steam then moves from the boiler under high pressure and impacts on a set of turbine blades. The turbine is connected to a generator which produces electricity. As the turbine blades rotate, the generator produces electricity. Thus chemical energy stored in coal is converted to thermal energy produced by steam from the boiler which is then converted to mechanical energy of the rotating turbine blades and electrical energy produced by the generator.

Transportation of coal

Coal is delivered by rail, barge, trucks,collier ship or slurry pipeline. Generating stations are sometimes built close to a mine, where it is not feasible or very expensive to transport the coal. Hence the coal can be delivered to the mine by conveyor belt or diesel- electric trucks. A large coal train may be 2km long and contain 140 cars with each car each carrying 100 tonnes of coal. This is the amount usually required for large power plants especially during periods of high demand for electricity such as during winter periods when these plants will be supplied with three to five trains a day.

Collier ships which carry up to 40,000 tons of coal may take several days to offload their cargo. Some collier ships may have their own conveyor belt to offload their cargo, others may depend on equipment from the plant. To transport coal through the inland waterways, coal is loaded unto barges which rely on tugboats to move them through these waters to the site of the power plant.

Coal is still the cheapest power generation plant to build, with governments around the world still subsidizing their building and construction and it will take years of investment in other sources of power generation to rid the world from coal power plants.

Coal fired power plant.
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Power Plants.

Power plants are large, complex structures built to generate electric power. They may be also called power stations or generating stations and may have several generators for generating electric power. There are several types of power plants available for use and will be discussed subsequently. Power stations contain generators which convert rotary mechanical energy into electric power. Others however rely on renewable energy sources such as wind and the sun which store electrons in large batteries and utilized when the coal fired or oil fired power generation plant experiences failure.

Types of power plants

The types include;

  1. Coal fired power plant
  2. Geothermal power plants
  3. Wind turbines
  4. Nuclear power plants
  5. Solar power plants
  6. Hydro Electric power plants
  7. Biomass
  8. Osmotic power station.

Classification

The power plant types are further classified into renewable energy plant sources and non renewable plants sources.

The renewable power plants sources include; solar, wind, hydro electric, biomass.

The non renewable power plants sources include, coal, gas,oil fired. The types and classification of these plants will be discussed subsequently. These sources of power generation have been used for at least one hundred years and research and development are still ongoing to replace most of the non renewable sources of energy with cleaner and cheaper ones.

Satellites

A satellite is an object that has been placed in space, revolving in an orbit. Satellites are classed into natural satellites and artificial satellites. Natural satellites include, the sun, moon, stars, artificial satellites are the objects made by man and placed in orbits in outer space and used for communication and geographical survey of the earth. These artificial satellites are constructed in special laboratory- like rooms before being transported to launch sites and loaded on to rockets which transport them into space. Satellites find many applications for civil and military purposes including earth observation, communication, navigation, space telescope, space station, human spacecraft. Their communication and navigation purpose include the GPS which is used by both the military and the general populace. Satellite orbit vary according to their purpose including low Earth orbit, polar orbit and geostationary. The non military application of satellites are basically of three types; These are fixed satellites, mobile satellite systems and scientific research satellites. The fixed satellites offer trillions of voice, data and video transmissions tasks across countries and continents between certain points on the Earth’s surface. Mobile satellite systems help connect remote regions, vehicles, ships aircraft with the rest of the world and with other communication units, mobile or stationary while also serving as navigation systems. Scientific research satellites provide information such as the weather,land survey and other scientific research such as earth science, marine science and scientific data on the earth’s atmosphere. So many countries are now capable of building and launching their own satellites. They include, New Zealand, France, China, Britain, Japan,United States, North Korea, Iran, South Korea, Russia. More countries are also acquiring the technique of building and launching satellites. Private companies are now building and launching their own satellites such as Tesla. There are increasing dangers posed to satellites from kinetic kills using rockets to jamming. Several countries such as the United States, China and Russia have demonstrated the ability to destroy satellites in space using anti- satellite rockets. Jamming of satellites have also been carried out by militant organizations to spread propaganda messages and to pilfer classified information. However, governments and satellite operators have strengthened the communication networks and now have sophisticated systems that enable pinpoint the source of any foreign carrier in their networks and deal effectively to solve the problem.

Submarines

Submarines are vessels designed to move underwater. They are capable of independent operations with inbuilt power plants capable of supplying power to the vessel for extended periods. Submarines are different from submersibles which are usually launched from submarines or bigger surface ships and are not capable of operating independently from the mother vessel. Submarines are classed into two types according to their propulsion system; conventional submarines and nuclear powered submarines. The conventional submarines are powered by diesel electric engines and used for a wide variety of applications including for civilian purposes such as research of marine life underwater, laying of communication cables underwater and for military submarines used for coastal defense. Nuclear powered submarines are however exclusively used by the military for open seas patrol because of their unlimited range. These vessels are usually refuelled once every 25 years so their ability to stay submerged for months underwater without surfacing is greatly enhanced. They carry missiles and other offensive weapons and are usually difficult to detect on the open seas. These vessels are usually large with tonnages exceeding 16,000 tons to provide enough space for the missiles they carry and the crew onboard manning the vessel. They are part of a country’s strategic nuclear deterrence force and ensure the survivability of a country’s nuclear weapons in case of an attack. Nuclear submarines are propelled by nuclear reactors which provide heating to water that produces steam needed to propel the vessel. Conventional submarines are usually powered by diesel electric generators that provide propulsion power to the vessel. In newly built submarines, air independent propulsion is now employed for propulsion.

Quantum Computers.

These are futuristic computers. This because the technology behind these computers are in the testing phase and so have not yet been deployed for real time applications. These computers are said to solve mathematical problems many times faster than any supercomputer being used anywhere in the world. To put it in context, Google says it has developed a quantum computer capable of performing a calculation in 200 seconds that will take a conventional computer 10,000 years to perform. While this claim has been disputed by other tech companies also building or researching their own quantum computers, it shows the potential of the quantum computers. Countries are also heavily investing in quantum computing technology. China which has also built its own quantum computers is also building the infrastructure needed to effectively deploy this technology.In 2017 China launched a satellite into space to be used as an experiment to demonstrate the effectiveness of quantum communications. Conventional computers employ the use of numerical keys to encrypt data. Quantum computers make use of photons. Photons are particles of light and a photon can be made to represent 0,1 and other values all at once. A quantum computer can manipulate these particles to perform many calculations simultaneously, vastly increasing the speed at which it can solve complex problems such as cracking encryption. The 2017 Chinese experiment demonstrated how quantum communications will operate. The satellite beamed photons to two different ground stations 1200 kilometres apart. The photons then became entangled. The entangled photons could serve as unhackable keys to encrypted transmissions. The potential use of this technology in civilian and military applications is enormous. It means that hostile countries will not be able to access sensitive civilian and military information to be used against target countries. This technology is not expected to be deployed until after a decade. However rapid advances in research and development could shorten this timeline.