Generating electricity

A power station (also referred to as a generating station, power plant, powerhouse, or generating plant) is an industrial facility for the generation of electric power. Most power stations contain one or more generators, a rotating machine that converts mechanical power into electrical power. The relative motion between a magnetic field and a conductor creates an electrical current. Most power stations in the world burn fossil fuels such as coal, oil, and natural gas to generate electricity. Others use nuclear power, but there is an increasing use of cleaner renewable sources such as solar, wind, wave and hydroelectric.

Coal-fired power stations

Image: http://www.cmu.edu

Coal is first milled to a fine powder, which increases the surface area and allows it to burn more quickly. In these pulverised coal combustion systems, the powdered coal is blown into the combustion chamber of a boiler where it is burnt at high temperature. The hot gases and heat energy produced converts water – in tubes lining the boiler – into steam. The high pressure steam is passed into a turbine containing thousands of propeller-like blades. The steam pushes these blades causing the turbine shaft to rotate at high speed. A generator is mounted at one end of the turbine shaft and consists of carefully wound wire coils. Electricity is generated when these are rapidly rotated in a strong magnetic field. After passing through the turbine, the steam is condensed and returned to the boiler to be heated once again. The electricity generated is transformed into the higher voltages (up to 400,000 volts) used for economic, efficient transmission via power line grids. When it nears the point of consumption, such as our homes, the electricity is transformed down to the safer 100-250 voltage systems used in the domestic market.

Gas turbine power stations

The use of gas turbines for generating electricity dates back to 1939. Today, gas turbines are one of the most widely-used power generating technologies. Gas turbines are a type of internal combustion engine in which burning of an air-fuel mixture produces hot gases that spin a turbine to produce power. It is the production of hot gas during fuel combustion, not the fuel itself that the gives gas turbines the name. Gas turbines can utilize a variety of fuels, including natural gas, fuel oils, and synthetic fuels. Combustion occurs continuously in gas turbines, as opposed to reciprocating internal combustion engines, in which combustion occurs intermittently.

Diesel generators

A diesel generator is the combination of a diesel engine with an electric generator (often an alternator) to generate electrical energy. . A diesel compression-ignition engine often is designed to run on fuel oil, but some types are adapted for other liquid fuels or natural gas. Diesel generating sets are used in places without connection to a power grid, or as emergency power-supply if the grid fails, as well as for more complex applications such as peak-lopping, grid support and export to the power grid.

In South Africa it costs about R2.35 per kilowatt hour to generate electricity with diesel generators as opposed to less than 50 cents per kilowatt hour to generate power at coal power stations.

Powerships

Image: http://www.karadenizenergy.com

The Karadeniz Energy Group developed its “Power of Friendship” project for countries in the Middle East, Africa and Asia.Some African countries, notably Ghana, get electricity from Powerships, which are essentially floating power stations.According to Karadeniz its power ships are “high technology floating power plants designed and constructed to fulfil the urgent electricity needs of the countries through rental contracts or power purchase agreements (PPA)”. Power ships are delivered to the client countries as a complete power plant ready to operate immediately. Power ship capacities range from 45MW to 500MW, and are delivered between 60 days and 180 days after ordering to provide medium-term solutions with contracts of between 2 years to 5 years. 

Biomass electricity

Biomass is biological material derived from living, or recently living organisms. It most often refers to plants or plant-based materials . As an energy source, biomass can either be used directly via combustion to produce heat, or indirectly after converting it to various forms of biofuel like methane gas or transportation fuels like ethanol and biodiesel. The main contributors of waste energy are municipal solid waste, manufacturing waste, and landfill gas. Energy derived from biomass is projected to be the largest non-hydroelectric renewable resource of electricity in the US between 2000 and 2020. The biomass power generating industry in the United States, which consists of approximately 11,000 MW of summer operating capacity actively supplying power to the grid, produces about 1.4 percent of the U.S. electricity supply.

Engine generated electricity

Image: Electro Elmadan

An engine-generator is the combination of an electrical generator and an engine mounted together to form a single piece of equipment. This combination is also called an engine-generator set or a gen-set. In many contexts, the engine is taken for granted and the combined unit is simply called a generator. In addition to the engine and generator, engine-generators generally include a fuel supply, a constant engine speed regulator (governor) and a generator voltage regulator, cooling and exhaust systems, and lubrication system. Engine-generators are available in a wide range of power ratings. Regardless of the size, generators may run on gasoline, diesel, natural gas, propane, bio-diesel, sewage gas or hydrogen. The smaller units are built to use gasoline (petrol) as a fuel, and the larger ones have various fuel types, including diesel, natural gas and propane (liquid or gas).

A dynamo is an electrical generator that produces direct current with the use of a commutator. A commutator is the moving part of a rotary electrical switch in certain types of electric motors and electrical generators that periodically reverses the current direction between the rotor and the external circuit. Dynamos were the first electrical generators capable of delivering power for industry, and the foundation upon which many other later electric-power conversion devices were based, including the electric motor, the alternating-current alternator, and the rotary converter. Today, the simpler alternator dominates large scale power generation, for efficiency, reliability and cost reasons. A dynamo has the disadvantages of a mechanical commutator. Also, converting alternating to direct current using power rectification devices (vacuum tube or more recently solid state) is effective and usually economic. An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature.

Image: http://poradu.pp.ua

A magneto is an electrical generator that uses permanent magnets to produce alternating current. Unlike a dynamo, there is no commutator and so they cannot produce direct current. They are categorised as a form of alternator, although they are usually regarded as distinct from most other alternators, which use field coils rather than permanent magnets. Magnetos have advantages of simplicity and reliability, but are inefficient owing to the weak magnetic flux available from their permanent magnets. This restricted their use for high-power applications. Some magnetos did find use as telephone magnetos in early telephones, particularly for ringing. The most common application for magnetos was as an ignition magneto, in spark-ignition petrol engines, ranging from early cars to aircraft (for reliability) and small engines such as chainsaws.

Fuel cell generated electricity

A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent. F;uel cells are different from batteries in that they require a continuous source of fuel and oxygen/air to sustain the chemical reaction whereas in a battery the chemicals present in the battery react with each other to generate an electromotive force . Fuel cells can produce electricity continuously for as long as these inputs are supplied. There are many types of fuel cells, but they all consist of an anode, a cathode and an electrolyte that allows charges to move between the two sides of the fuel cell. Electrons are drawn from the anode to the cathode through an external circuit, producing direct current electricity. As the main difference among fuel cell types is the electrolyte. In addition to electricity, fuel cells produce water, heat and, depending on the fuel source, very small amounts of nitrogen dioxide and other emissions.

Fuel cells are used for primary and backup power for commercial, industrial and residential buildings and in remote or inaccessible areas. They are also used to power fuel-cell vehicles, including forklifts, automobiles, buses, boats, motorcycles and submarines.

Source: Wikipedia

Manufacturers of fuel cells and fuel cell products

A list of 200 companies and organizatons in the fuel cell industry, from developers to component manufacturers to hydrogen suppliers and system integrators, can be ECR International found on the  Fuel Cells Organization's website.

Polymer Electrolyte Membrane or Proton-Exchange Membrane (PEM) fuel cell.

• Intelligent Energy
• Ballard Power
• Plug Power
• ITM Power
• Quantum Fuel Systems Technologies Worldwide
• EFO
• Doosan Fuel Cell America

Alkaline Fuel Cells (AFCs) have a solution of potassium hydroxide in water as an electrolyte which allows the precious metal catalyst of PEM fuel cells to be replaced by a variety of non-precious metals.

• AFC Energy

Molten Carbonate fuel cells (MCFCs) use a high temperature salt mixture suspended In an inert ceramic matrix as an electrolyte.

• Fuel Cell Energy

Solid Oxide Fuel Cells (SOFCs) use a solidceramic as the electrolyte.

• Ceres Power
• Ceramic Fuel Cells

The Chamber of Mines of South Africa has installed a 100kW base load platinum fuel cell which has been running well since December 18, 2014. Fuel cell electric vehicles now have comparable ranges to conventional vehicles (>600 kms) and only a three minute filling time (compares to 100km range for a pure electric vehicle and 3-9 hour charging time for the batteries) and which emits no pollutants during driving. These FCEV’s, like the Toyota Mirai are now being sold in Japan and California and could revolutionise automotive travel. The Mirai can also be used as a back-up generator for home use (during load-shedding).

Toyota Mirai cutaway showing the electric traction motor and power control unit in the front, the fuel cell stack in the middle, and the nickel-metal hydride traction rechargeable battery above the hydrogen storage tanks in the rear.

Nuclear power stations

Image: http://www.ijrte.org

A nuclear power plant is a thermal power station in which the heat source is a nuclear reactor. A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Nuclear reactors usually rely on uranium to fuel the chain reaction. As is typical in all conventional thermal power stations the heat is used to generate steam which drives steam turbines  connected to an  electric generator which produces electricity. As of 23 April 2014, the International Atomic Emergy Agency  reported that there are 435 nuclear power reactors in operation operating in 31 countries. Nuclear power plants are usually considered to be base load stations, since fuel is a small part of the cost of production. Since nuclear fission creates radioactivity, the reactor core is surrounded by a protective shield. This containment absorbs radiation and prevents radioactive material from being released into the environment. In addition, many reactors are equipped with a dome of concrete to protect the reactor against both internal casualties and external impacts. The amount of free energy contained in nuclear fuel is millions of times the amount of free energy contained in a similar mass of chemical fuel such as gasoline, making nuclear fission a very dense source of energy. Nuclear fission is the main process generating nuclear energy. Nuclear currently makes up 11% of the global energy mix, according to the World Nuclear Association.

Nuclear betavoltaic electricity generation are generators of electric current, in effect a form of battery, which use energy from a radioactive source emitting beta particles (electrons). The terms atomic battery, nuclear battery, tritium battery and radioisotope generator are used to describe a device which uses energy from the decay of a radioactive isotope to generate electricity. Like nuclear reactors they generate electricity from atomic energy, but differ in that they do not use a chain reaction. Compared to other batteries they are very costly, but have extremely long life and high energy density, and so they are mainly used as power sources for equipment that must operate unattended for long periods of time, such as spacecraft, pacemakers, underwater systems and automated scientific stations in remote parts of the world. Recent progress has prompted some to suggest using betavoltaics to trickle-charge conventional batteries in consumer devices, such as cell phones and laptop computers. A common source used is the hydrogen isotope, tritium. Unlike most nuclear power sources, which use nuclear radiation to generate heat, which then is used to generate electricity (thermoelectric and thermionic sources), betavoltaics use a non-thermal conversion process; converting the electron-hole pairs produced by the ionization trail of beta particles traversing a semiconductor.

Manufacturers of betavoltaic batteries

• City Labs Inc. is a manufacturer of long-life Tritium betavoltaic batteries for microelectronics, sensors, and other small devices.

Hydroelectric power stations

Source: http://www.sunyjcc.edu

Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy, accounting for 16 percent of global electricity generation Hydropower is produced in 150 countries, with the Asia-Pacific region generating 32 percent of global hydropower in 2010. China is the largest hydroelectricity producer with around 17 percent of domestic electricity use. 

Source: http://www.cgee.org.br

The cost of hydroelectricity is relatively low, making it a competitive source of renewable electricity. It is also a flexible source of electricity since the amount produced by the station can be changed up or down very quickly to adapt to changing energy demands. However, damming interrupts the flow of rivers and can harm local ecosystems, and building large dams and reservoirs often involves displacing people and wildlife. Once a hydroelectric complex is constructed, the project produces no direct waste, and has a considerably lower output level of the greenhouse gas carbon dioxide (CO2) than fossil fuel powered energy plants. 

Micro hydro is a type of hydroelectric power that typically produces up to 100 kW of electricity using the natural flow of water. These installations can provide power to an isolated home or small community.

Lucid Energy's LucidPipe™ Power System harnesses the untapped energy potential of moving water in pipelines to produce electricity.

Pumped-storage hydroelectricity  is a type of hydroelectric energy storage used by electric power systems for load balancing. The method stores energy in the form of gravitational potential energy of water, pumped from a lower elevation reservoir to a higher elevation. Low-cost off-peak electric power is used to run the pumps. During periods of high electrical demand, the stored water is released through turbines to produce electric power. Although the losses of the pumping process makes the plant a net consumer of energy overall, the system increases revenue by selling more electricity during periods of peak demand, when electricity prices are highest.

Wave power electricity

Source: http://www.mpoweruk.com/hydro_power.htm

Wave power  is the transport of energy by ocean surface waves, and the capture of that energy to do useful work – for example, electricity generation, water desalination, or the pumping of water (into reservoirs). A machine able to exploit wave power is generally known as a wave energy converter (WEC). Wave power is distinct from the diurnal flux of tidal power and the steady gyre of ocean currents.Wave-power generation is not currently a widely employed commercial technology, although there have been attempts to use it since at least 1890.In 2008, the first experimental wave farm was opened in Portugal, at the Aguçadoura Wave Farm..The major competitor of wave power is offshore wind power.

The UK Energy Ministry approved planning and construction is expected to start sometime in 2017 of a six-mile-long barrier wall that will enclose a huge amount of water in an artificial “tidal lagoon”. This planned power plant in Wales will use the rise and fall of ocean tides to generate enough electricity. 420 gigawatt hours per year, to power 155,000 homes for 120 years.

Osmotic power

Osmotic power or salinity gradient power is the energy available from the difference in the salt concentration between seawater and river water. Two practical methods for this are reverse electrodialysis (RED) and pressure retarded osmosis (PRO). Both processes rely on osmosis with ion specific membranes. The key waste product is brackish water. This by product is the result of natural forces that are being harnessed: the flow of fresh water into seas that are made up of salt water. The technologies have been confirmed in laboratory conditions. They are being developed into commercial use in the Netherlands (RED) and Norway (PRO). The cost of the membrane has been an obstacle. A new, lower cost membrane, based on an electrically modified polyethylene plastic, made it fit for potential commercial use. Other methods have been proposed and are currently under development. Among them, a method based on electric double-layer capacitor technology.and a method based on vapor pressure difference.

Source: http://www.dutchwatersector.com

Solar power generated electricity

Source: http://www.alternative-energy-news.info/technology/solar-power

Photovoltaic (PV) is the direct conversion of light into electricity and a method of converting solar energy into direct current electricity using semiconducting materials that exhibit the photovoltaic effect

A solar cell, or photovoltaic cell, is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon. Solar cells are the building blocks of photovoltaic modules, otherwise known as solar panels. A solar panel refers to a photovoltaics (PV) module, a set of solar photovoltaics modules electrically connected and mounted on a supporting structure. A PV module is a packaged, connected assembly of solar cells. Solar panels can be used as a component of a larger photovoltaic system to generate and supply electricity in commercial and residential applications. Each module is rated by its DC output power under standard test conditions, and typically ranges from100 to 320 watts. Concentrated solar power (also called concentrating solar power, concentrated solar thermal, and CSP) systems generate solar power by using mirrors or lenses to concentrate a large area of sunlight, or solar thermal energy, onto a small area. Electricity is generated when the concentrated light is converted to heat, which drives a heat engine (usually a steam turbine) connected to an electrical power generator or powers a thermochemical reaction (experimental as of 2013).

Scientists at Stanford University have improved the efficiency of a revolutionary solar cell by around 100 times. Unlike standard photovoltaic cells, which only capture light energy, Stanford’s new device captures both light and heat, potentially boosting solar cell efficiency towards 60% — way beyond the 30-40% limit of traditional silicon photovoltaic solar cells.

The Solar Thermal Energy Research Group (STERG) at Stellenbosch University has been developing a unique South African CSP technology. CSP is able to provide dispatchable, clean energy at utility scale, with the added benefit of high localisation potential and socio-economic beneficiation. In early 2014 the team won a grant from the Technology Innovation Agency to showcase the technology in a 100kW pilot facility. The technology takes a simple and fresh approach to overcome the challenges that are currently faced in heliostat fields.

Google's Project Sunroof computes how much sunlight hits your roof in a year. It takes into account:

• Google's database of aerial imagery and maps
• 3D modeling of your roof
• Shadows cast by nearby structures and trees
• All possible sun positions over the course of a year
• Historical cloud and temperature patterns that might affect solar energy production

Rawlemon  has created a spherical sun power generator prototype called the beta.ray. The technology will combine spherical geometry principles with a dual axis tracking system, allowing twice the yield of a conventional solar panel in a much smaller surface area. The futuristic design is fully rotational and is suitable for inclined surfaces, walls of buildings, and anywhere with access to the sky. It can even be used as an electric car  charging station.

Manufacturers of solar panels.

• Trina Solar (China) is a global leader in photovoltaic modules, solutions and services. Founded in 1997 as a PV system integrator, Trina Solar today drives smart energy together with installers, distributors, utilities and developers worldwide.
• Yingli Green Energy (China)
• Canadian Solar
• Jinko Solar (China)
• JA Solar (China)
• Sharp Solar ( Japan)
• ReneSola 
• First Solar (USA) is an American photovoltaic (PV) manufacturer of rigid thin film modules, or solar panels, and a provider of utility-scale PV power plants and supporting services that include finance, construction, maintenance and end-of-life panel recycling.
• Hanwha SolarOne (China)
• SunPower (USA) and Kyocera (Japan)

• SolarCity, the company co-founded by Elon Musk, now produces the world's most efficient rooftop solar panels with a module efficiency of just over 22 percent. SolarCity CEO Lyndon Rive said that the company is shooting for a cost of around 55 cents per watt. It plans to build the 360 watt panels in its 1 GW solar panel plant in Buffalo, New York, set to open in 2016.

Source: http://www.alternative-energy-news

Wind power generated electricity

Wind power is extracted from air flow using wind turbines to produce electrical power. A generator inside the nacelle (a housing at the top of a wind turbine mast for the generating components, including the gearbox, drive train, and brake assembly) converts the wind power into electricity. Wind power as an alternative to fossil fuels, is plentiful, renewable, widely distributed, clean, produces no greenhouse gas emissions during operation, and uses little land. The net effects on the environment are generally less problematic than those from non-renewable power sources. Large wind farms can consist of hundreds of individual wind turbines which are connected to the electric power.transmission network. Gansu Wind Farm, the largest wind farm in the world, has several thousands of turbines. Onshore wind is an inexpensive source of electricity, competitive with or in many places cheaper than coal, gas or fossil fuel plants. Offshore wind is steadier and stronger than on land, and offshore farms have less visual impact, but construction and maintenance costs are considerably higher. Small onshore wind farms can feed some energy into the grid or provide electricity to isolated off-grid locations.

Wind power is very consistent from year to year but has significant variation over shorter time scales. It is therefore used in conjunction with other sources to give a reliable supply.

As of 2014, Denmark had been generating around 40% of its electricity from wind and at least 83 other countries around the world are using wind power to supply their electricity grids. Wind power capacity has expanded rapidly to 336 GW in June 2014, and wind energy production was around 4% of total worldwide electricity usage.

South Africa increased its installed wind-energy capacity to above 1 GW in 2015, new Global Wind Energy Council (GWEC) figures show, making it the largest wind-energy producer in Africa, followed by Morocco, whose installed capacity stood at 787 MW in 2015. South Africa’s wind growth has been stimulated primarily by government’s Renewable Energy Independent Power Producer Procurement Programme, through which 6 300 MW of renewable-energy capacity has been procured since 2011. Prices for wind have also fallen from R142c/kWh in the first bid window in 2011, to 65c/kWh in the fourth bid window. Print Send to Friend 7 1 GWEC reports that the country installed 483 MW in 2015, helping to raise the installed capacity of the Africa and Middle East region to nearly 3 300 MW. However, the story of 2015 was the surge in Chinese installations, with an “astonishing” 30.5 GW added in the year, raising the total global wind capacity installed last year to 63 GW, a year-on-year market growth of 22%. China also moved past the European Union (EU) as the leading wind market, with 145.1 GW installed compared with the EU's 141.6 GW. “The Chinese government's drive for clean energy, supported by continuous policy improvement, is motivated by the need to reduce dependence on coal which is the main source of the choking smog strangling China's major cities, as well as growing concern over climate change,” GWEC said. Total global capacity reached 432.4 GW at the end of 2015, representing cumulative growth of 17%. "Wind power is leading the charge in the transition away from fossil fuels,” GWEC secretary-general Steve Sawyer enthused, adding that new markets were opening up across Africa, Asia and Latin America. "2015 was a big year for the big markets  – China, the US, Germany and Brazil, all set new records,” Sawyer added. "But there is a lot of activity in new markets around the world and I think in 2016 we'll see a broader distribution.”

Vortex generated electricity, Instead of capturing energy via the circular motion of a propeller, takes advantage of what’s known as vorticity, an aerodynamic effect that produces a pattern of spinning vortices. The Vortex’s shape was developed computationally to ensure the spinning wind (vortices) occurs synchronously along the entirety of the mast. In its current prototype, the elongated cone is made from a composite of fibre glass and carbon fibre, which allows the mast to vibrate as much as possible (an increase in mass reduces natural frequency). At the base of the cone are two rings of repelling magnets, which act as a sort of non-electrical motor. When the cone oscillates one way, the repelling magnets pull it in the other direction, like a slight nudge to boost the mast’s movement regardless of wind speed. This kinetic energy is then converted into electricity via an alternator that multiplies the frequency of the mast’s oscillation to improve the energy-gathering efficiency. There are no gears, bolts, or mechanically moving parts. It’s less expensive to manufacture, totally silent, and safer for birds since there are no blades to fly into. Its turbine would cost around 51 percent less than a traditional turbine whose major costs come from the blades and support system. It is being developed by Vortex Bladeless.

Manufacturers of wind turbine generators

• Siemens German manufacturer who became established with the creation of the world’s first offshore wind power plant in 1991 in Denmark. Siemens occupies a leading position within onshore wind power, having been awarded the world’s largest single onshore order to date,: a 1,050 MW order from MidAmerican Energy in the USA for a series of onshore wind power plants in Iowa.

• Sinovel Chinese manufacturer, who has manufactured more than 5 600MW of wind turbines in operation and is currently the 2nd largest turbine manufacturer in the world and holds a global market share of 11.1%

• Vestas Danish manufacturer started producing wind turbines in 1979 and have since gained a market-leading position with more than 64 GW of installed wind power and more than 42 GW under service globally.

• Honeywell The American Honeywell wind turbine is a gearless wind turbine that measures just 6 feet (1.8 m) in diameter, weighs 185 lbs (84 kgs) and produces up to 1500 kWh per year depending on height and location. It has a start-up speed as low as 0.5 mph (0.2 m/s), with an auto shut off at 38 mph (17.0 m/s), traditional gearbox turbines require minimum wind speeds of 7.5 mph (3.5 m/s) to cut in and start generating power.

• A Dutch renewable energy start-up called The Archimedes has a new class of small-scale wind turbine -- one that is almost silent and is far more efficient at converting wind into energy. The company states that the Liam F1 turbine could generate 1 500 kWh of energy per year at wind speeds of 5m/s, enough to cover half of an average household's energy use.

Geothermal generated electricity

Geothermal electricity is electricity generated to geothermal energy. Technologies in use include dry steam power stations, flash steam power stations and binary cycle power stations. Dry steam stations are the simplest and oldest design. They directly use geothermal steam of 150°C or greater to turn turbines. Flash steam stations pull deep, high-pressure hot water into lower-pressure tanks and use the resulting flashed steam to drive turbines. They require fluid temperatures of at least 180°C, usually more. Geothermal electricity generation is currently used in 24 countries, while geothermal heating is in use in 70 countries.

As of 2015, worldwide geothermal power capacity amounts to 12.8 gigawatts (GW), of which 28 percent or 3,548 megawatts are installed in the United States. International markets grew at an average annual rate of 5 percent over the last three years and global geothermal power capacity is expected to reach 14.5–17.6 GW by 2020. Based on current geologic knowledge and technology, the Geothermal Energy Association (GEA) estimates that only 6.5 percent of total global potential has been tapped so far, while the IPCC reported geothermal power potential to be in the range of 35 GW to 2 TW.[2] Countries generating more than 15 percent of their electricity from geothermal sources include El Salvador, Kenya, the Philippines, Iceland and Costa Rica.

Geothermal power is considered to be a sustainable, renewable source of energy because the heat extraction is small compared with the Earth's heat content. The greenhouse gas emissions of geothermal electric stations are on average 45 grams of carbon dioxide per kilowatt-hour of electricity, or less than 5 percent of that of conventional coal-fired plants.

Piezoelectricity

Piezoelectricity is the electric charge that accumulates in certain solid materials (such as crystals, certain ceramics, and biological matter such as bone, DNA and various proteins) in response to applied mechanical stress. The word piezoelectricity means electricity resulting from pressure. Piezoelectricity is found in useful applications such as the production and detection of sound, generation of high voltages, electronic frequency generation, microbalances, to drive an ultrasonic nozzle, and ultra fine focusing of optical assemblies. It is also the basis of a number of scientific instrumental techniques with atomic resolution, the scanning probe microscopies and everyday uses such as acting as the ignition source for cigarette lighters, push-start propane barbecues, and quartz watches.

Press a lighter switch and you'll hear a clicking sound and see sparks appear. What you're doing, when you press the switch, is squeezing a piezoelectric crystal, generating a voltage, and making a spark fly across a small gap.

Manufacturers of piezoelectric materials and products

• PI Ceramic GmbH has been developing and manufacturing piezo ceramic materials and components since 1992 for standard and OEM solutions: Piezo components, ultrasonic transducers, actuators and system solutions.

• APC International Ltd. is a supplier of piezoelectric ceramic shapes, piezoelectric transducers, piezo devices, and piezo application support services. APC’s piezo products include: piezoelectric ceramics in standard and custom shapes, piezoelectric materials (PZT materials), stack actuators, ultrasonic air transducers, piezo nebulizers, piezo buzzers, piezo disc benders, bending actuators, piezo ignitors, ultrasonic cleaning transducers, piezo sensors, and custom transducers.

• Soundpower Corporation flagship product is the Power-Generating Floor,. While output varies depending on the number of tiles, a step by a person weighing 60 kilograms normally generates 0.1 Watt of power. In addition to its Power-Generating Floors, there are two other pillars to the company's operations: sound power and vibration power. Sound-power generation is a means by which the energy from speech and noise vibrations is turned into electricity. Soundpower is now at work developing various applications for this technology, including mobile phones that can be charged during conversations and sound-insulating walls that generate electricity from the sound of passing cars.

• Goodyear tires, that use heat and vibration to recharge the battery, still a concept, would harvest heat from several different processes, and then feed that back into the batteries. At the core of the concept is a layer of piezoelectric material underneath the rubber of the tire. Piezoelectric materials can generate electricity from the application of mechanical force, but in this instance, the 'thermo-piezoelectric' material takes excess heat from the outside of the tire and converts it into electricity.

Conversion of Heat to Electricity Using Multiferroic Alloys

University of Minnesota engineering researchers recently discovered a new alloy material, Ni45Co5Mn40Sn10, that converts heat directly into electricity. Researchers say the material could potentially be used to capture waste heat from a car's exhaust that would heat the material and produce electricity for charging the battery in a hybrid car. Other possible future uses include capturing rejected heat from industrial and power plants or temperature differences in the ocean to create electricity. The new material created by the researchers begins as a non-magnetic material, which then becomes strongly magnetic when the temperature is raised a small amount. When this happens, the material absorbs heat and spontaneously produces electricity in a surrounding coil.

Static electricity

Static electricity is an imbalance of electric charges within or on the surface of a material. The charge remains until it is able to move away by means of an electric current or electrical discharge. Static electricity is named in contrast with current electricity, which flows through wires or other conductors and transmits energy. A static electric charge is created whenever two surfaces contact and separate, and at least one of the surfaces has a high resistance to electrical current and is therefore an electrical insulator.

A 40-year plan for energy