1.
Environmental technology
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The term is also used to describe sustainable energy generation technologies such as photovoltaics, wind turbines, bioreactors, etc. Sustainable development is the core of environmental technologies, the term environmental technologies is also used to describe a class of electronic devices that can promote sustainable management of resources. Renewable energy is the energy that can be replenished easily, for years we have been using sources such as wood, sun, water, etc. for means for producing energy. Energy that can be produced by objects like wood, sun, wind. Water purification, The whole idea/concept of having dirt/germ/pollution free water flowing throughout the environment, many other phenomena lead from this concept of purification of water. Water pollution is the enemy of this concept, and various campaigns. Air purification, Basic and common green plants can be indoors to keep air fresh because all plants remove CO2. The best examples are, Dypsis lutescens, Sansevieria trifasciata, sewage treatment is conceptually similar to water purification. Sewage treatments are very important as they purify water per levels of its pollution, the most polluted water is not used for anything, and the least polluted water is supplied to places where water is used affluently. It may lead to other concepts of environmental protection, sustainability etc. Environmental remediation is the removal of pollutants or contaminants for the protection of the environment. This is accomplished by various chemical, biological, and bulk movements, solid waste management is the purification, consumption, reuse, disposal and treatment of solid waste that is undertaken by the government or the ruling bodies of a city/town. Egain forecasting is a method using forecasting technology to predict the future impact on a building. By adjusting the heat based on the weather forecast, the system eliminates redundant use of heat, thus reducing the energy consumption, Energy conservation is the utilization of devices that require smaller amounts of energy in order to reduce the consumption of electricity. Reducing the use of electricity causes less fossil fuels to be burned to provide that electricity, principles, Green syndicalism Sustainability Sustainable design Sustainable engineering Scientists continue to search for clean energy alternatives to our current power production methods. Some technologies such as anaerobic digestion produce renewable energy from waste materials, the global reduction of greenhouse gases is dependent on the adoption of energy conservation technologies at industrial level as well as this clean energy generation. That includes using unleaded gasoline, solar energy and alternative fuel vehicles, since industrial use of energy accounts for 51% of worldwide energy usage improving energy efficiency in this field is a top priority for environmental technology companies around the globe. Greasestock is an event held yearly in Yorktown Heights, New York which is one of the largest showcases of environmental technology in the United States, EUCETSA - European Committee of Environmental Technology Supplier Associations Related Norway Online resources How Silicon Valley could become the Detroit of electric cars
2.
Efficient energy use
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Efficient energy use, sometimes simply called energy efficiency, is the goal to reduce the amount of energy required to provide products and services. For example, insulating a home allows a building to use less heating and cooling energy to achieve, installing fluorescent lights, LED lights or natural skylights reduces the amount of energy required to attain the same level of illumination compared with using traditional incandescent light bulbs. Improvements in energy efficiency are generally achieved by adopting an efficient technology or production process or by application of commonly accepted methods to reduce energy losses. There are many motivations to improve energy efficiency, reducing energy use reduces energy costs and may result in a financial cost saving to consumers if the energy savings offset any additional costs of implementing an energy efficient technology. Reducing energy use is seen as a solution to the problem of reducing greenhouse gas emissions. Energy efficiency and renewable energy are said to be the pillars of sustainable energy policy and are high priorities in the sustainable energy hierarchy. Energy efficiency has proved to be a strategy for building economies without necessarily increasing energy consumption. For example, the state of California began implementing energy-efficiency measures in the mid-1970s, including building code, during the following years, Californias energy consumption has remained approximately flat on a per capita basis while national US consumption doubled. In general, up to 75% of the electricity used in the US today could be saved with efficiency measures that cost less than the electricity itself. The same holds true for this is home and there is 78% of electricity uses D in your home-owners, in fact, researchers at the US Department of Energy and their consortium, Residential Energy Efficient Distribution Systems have found that duct efficiency may be as low as 50–70%. The US Department of Energy has stated there is potential for energy saving in the magnitude of 90 Billion kWh by increasing home energy efficiency. Other studies have emphasized this.2 percent average growth anticipated through 2020 in a business-as-usual scenario, international standards ISO17743 and ISO17742 provide a documented methodology for calculating and reporting on energy savings and energy efficiency for countries and cities. Modern appliances, such as, freezers, ovens, stoves, dishwashers, installing a clothesline will significantly reduce ones energy consumption as their dryer will be used less. Current energy efficient refrigerators, for example, use 40 percent less energy than conventional models did in 2001, in the US, the corresponding figures would be 17 billion kWh of electricity and 27,000,000,000 lb CO2. According to a 2009 study from McKinsey & Company the replacement of old appliances is one of the most efficient global measures to reduce emissions of greenhouse gases. Modern power management systems also reduce energy usage by idle appliances by turning them off or putting them into a low-energy mode after a certain time, many countries identify energy-efficient appliances using energy input labeling. The impact of energy efficiency on peak demand depends on when the appliance is used, for example, an air conditioner uses more energy during the afternoon when it is hot. Therefore, an efficient air conditioner will have a larger impact on peak demand than off-peak demand
3.
Recycling
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Recycling is the process of converting waste materials into new materials and objects. It is an alternative to conventional waste disposal that can save material, Recycling can prevent the waste of potentially useful materials and reduce the consumption of fresh raw materials, thereby reducing, energy usage, air pollution, and water pollution. Recycling is a key component of waste reduction and is the third component of the Reduce, Reuse. There are some ISO standards related to recycling such as ISO15270,2008 for plastics waste, recyclable materials include many kinds of glass, paper, and cardboard, metal, plastic, tires, textiles, and electronics. The composting or other reuse of biodegradable waste—such as food or garden waste—is also considered recycling, materials to be recycled are either brought to a collection centre or picked up from the curbside, then sorted, cleaned, and reprocessed into new materials destined for manufacturing. However, this is difficult or too expensive, so recycling of many products or materials involves their reuse in producing different materials instead. Another form of recycling is the salvage of materials from complex products, either due to their intrinsic value. Recycling has been a practice for most of human history. In pre-industrial times, there is evidence of bronze and other metals being collected in Europe. Paper recycling was first recorded in 1031 when Japanese shops sold repulped paper, in Britain dust and ash from wood and coal fires was collected by dustmen and downcycled as a base material used in brick making. In 1813, Benjamin Law developed the process of turning rags into shoddy and mungo wool in Batley and this material combined recycled fibers with virgin wool. The West Yorkshire shoddy industry in such as Batley and Dewsbury lasted from the early 19th century to at least 1914. Industrialization spurred demand for materials, aside from rags, ferrous scrap metals were coveted as they were cheaper to acquire than virgin ore. Railroads both purchased and sold scrap metal in the 19th century, and the steel and automobile industries purchased scrap in the early 20th century. Many secondary goods were collected, processed and sold by peddlers who scoured dumps and city streets for discarded machinery, pots, pans, and other sources of metal. By World War I, thousands of such peddlers roamed the streets of American cities, beverage bottles were recycled with a refundable deposit at some drink manufacturers in Great Britain and Ireland around 1800, notably Schweppes. New chemical industries created in the late 19th century both invented new materials (e. g. Bakelite and promised to transform valueless into valuable materials, new and better paths are opened to reach the goals desired. Recycling was a highlight throughout World War II, during the war, financial constraints and significant material shortages due to war efforts made it necessary for countries to reuse goods and recycle materials
4.
Renewable energy
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Renewable energy is energy that is collected from renewable resources, which are naturally replenished on a human timescale, such as sunlight, wind, rain, tides, waves, and geothermal heat. Renewable energy often provides energy in four important areas, electricity generation, air and water heating/cooling, transportation, based on REN21s 2016 report, renewables contributed 19. 2% to humans global energy consumption and 23. 7% to their generation of electricity in 2014 and 2015, respectively. This energy consumption is divided as 8. 9% coming from biomass,4. 2% as heat energy,3. 9% hydro electricity and 2. 2% is electricity from wind, solar, geothermal. Worldwide investments in renewable technologies amounted to more than US$286 billion in 2015, with countries like China, globally, there are an estimated 7.7 million jobs associated with the renewable energy industries, with solar photovoltaics being the largest renewable employer. As of 2015 worldwide, more than half of all new electricity capacity installed was renewable, Renewable energy resources exist over wide geographical areas, in contrast to other energy sources, which are concentrated in a limited number of countries. Rapid deployment of energy and energy efficiency is resulting in significant energy security, climate change mitigation. In international public opinion there is strong support for promoting renewable sources such as solar power. At the national level, at least 30 nations around the already have renewable energy contributing more than 20 percent of energy supply. National renewable energy markets are projected to continue to grow strongly in the coming decade, for example, in Denmark the government decided to switch the total energy supply to 100% renewable energy by 2050. While many renewable energy projects are large-scale, renewable technologies are also suited to rural and remote areas and developing countries, United Nations Secretary-General Ban Ki-moon has said that renewable energy has the ability to lift the poorest nations to new levels of prosperity. Renewable energy systems are becoming more efficient and cheaper. Their share of energy consumption is increasing. Growth in consumption of coal and oil could end by 2020 due to increased uptake of renewables, in its various forms, it derives directly from the sun, or from heat generated deep within the earth. Included in the definition is electricity and heat generated from solar, wind, ocean, hydropower, biomass, geothermal resources, rapid deployment of renewable energy and energy efficiency, and technological diversification of energy sources, would result in significant energy security and economic benefits. New government spending, regulation and policies helped the industry weather the financial crisis better than many other sectors. As of 2011, small solar PV systems provide electricity to a few million households, United Nations Secretary-General Ban Ki-moon has said that renewable energy has the ability to lift the poorest nations to new levels of prosperity. At the national level, at least 30 nations around the already have renewable energy contributing more than 20% of energy supply. Some countries have much higher long-term policy targets of up to 100% renewables, outside Europe, a diverse group of 20 or more other countries target renewable energy shares in the 2020–2030 time frame that range from 10% to 50%
5.
Wind power
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Wind power is the use of air flow through wind turbines to mechanically power generators for electric power. The net effects on the environment are far less problematic than those of power sources. Wind farms consist of individual wind turbines which are connected to the electric power transmission network. Onshore wind is a source of electric power, competitive with or in many places cheaper than coal or gas plants. Offshore wind is steadier and stronger than on land, and offshore farms have less visual impact, small onshore wind farms can feed some energy into the grid or provide electric power to isolated off-grid locations. Wind power gives variable power which is consistent from year to year. It is therefore used in conjunction with other power sources to give a reliable supply. As the proportion of power in a region increases, a need to upgrade the grid. In addition, weather forecasting permits the power network to be readied for the predictable variations in production that occur. As of 2015, Denmark generates 40% of its power from wind. In 2014 global wind power capacity expanded 16% to 369,553 MW, yearly wind energy production is also growing rapidly and has reached around 4% of worldwide electric power usage,11. 4% in the EU. Wind power has been used as long as humans have put sails into the wind, for more than two millennia wind-powered machines have ground grain and pumped water. Wind power was available and not confined to the banks of fast-flowing streams, or later. Wind-powered pumps drained the polders of the Netherlands, and in regions such as the American mid-west or the Australian outback, wind pumps provided water for live stock. The first windmill used for the production of power was built in Scotland in July 1887 by Prof James Blyth of Andersons College. Blyth offered the surplus power to the people of Marykirk for lighting the main street, however. The Brush wind turbine had a rotor 17 metres in diameter and was mounted on an 18 metres tower, although large by todays standards, the machine was only rated at 12 kW. The connected dynamo was used either to charge a bank of batteries or to operate up to 100 incandescent light bulbs, with the development of electric power, wind power found new applications in lighting buildings remote from centrally-generated power
6.
Solar power
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Solar power is the conversion of energy from sunlight into electricity, either directly using photovoltaics, or indirectly using concentrated solar power. 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 into an electric current using the photovoltaic effect. Most solar installations would be in China and India, Solar PV is rapidly becoming an inexpensive, low-carbon technology to harness renewable energy from the Sun. The current largest photovoltaic power station in the world is the 850 MW Longyangxia Dam Solar Park, in Qinghai, commercial concentrated solar power plants were first developed in the 1980s. The 392 MW Ivanpah installation is the largest concentrating solar power plant in the world, long distance transmission allows remote renewable energy resources to displace fossil fuel consumption. Solar power plants use one of two technologies, Photovoltaic systems use solar panels, either on rooftops or in ground-mounted solar farms, concentrated solar power plants use solar thermal energy to make steam, that is thereafter converted into electricity by a turbine. A solar cell, or photovoltaic cell, is a device that converts light into electric current using the photovoltaic effect, the first solar cell was constructed by Charles Fritts in the 1880s. The German industrialist Ernst Werner von Siemens was among those who recognized the importance of this discovery, following the work of Russell Ohl in the 1940s, researchers Gerald Pearson, Calvin Fuller and Daryl Chapin created the silicon solar cell in 1954. These early solar cells cost 286 USD/watt and reached efficiencies of 4. 5–6%, the array of a photovoltaic power system, or PV system, produces direct current power which fluctuates with the sunlights intensity. For practical use this usually requires conversion to certain desired voltages or alternating current, multiple solar cells are connected inside modules. Modules are wired together to form arrays, then tied to an inverter, which produces power at the voltage, and for AC. Many residential PV systems are connected to the grid wherever available, in these grid-connected PV systems, use of energy storage is optional. In certain applications such as satellites, lighthouses, or in developing countries, batteries or additional power generators are often added as back-ups, such stand-alone power systems permit operations at night and at other times of limited sunlight. Concentrated solar power, also called concentrated solar thermal, uses lenses or mirrors, contrary to photovoltaics – which converts light directly into electricity – CSP uses the heat of the suns radiation to generate electricity from conventional steam-driven turbines. A wide range of concentrating technologies exists, among the best known are the trough, the compact linear Fresnel reflector, the Stirling dish. Various techniques are used to track the sun and focus light, in all of these systems a working fluid is heated by the concentrated sunlight, and is then used for power generation or energy storage. Thermal storage efficiently allows up to 24-hour electricity generation, a parabolic trough consists of a linear parabolic reflector that concentrates light onto a receiver positioned along the reflectors focal line. The receiver is a tube positioned right above the middle of the mirror and is filled with a working fluid
7.
Biomass
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Biomass is an industry term for getting energy by burning wood, and other organic matter. It has become popular among power stations, which switch from coal to biomass to comply with the law. Biomass most often refers to plants or plant-based materials that are not used for food or feed, 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. Conversion of biomass to biofuel can be achieved by different methods which are classified into, thermal, chemical. Historically, humans have harnessed biomass-derived energy since the time people began burning wood to make fire. Even today, biomass is the source of fuel for domestic use in many developing countries. Biomass is all biologically-produced matter based in carbon, hydrogen and oxygen, the estimated biomass production in the world is 104.9 petagrams of carbon per year, about half in the ocean and half on land. Wood remains the largest biomass energy source today, examples include forest residues, yard clippings, wood chips, wood energy is derived by using lignocellulosic biomass as fuel. Harvested wood may be used directly as a fuel or collected from waste streams to be processed into pellet fuel or other forms of fuels. The largest source of energy from wood is pulping liquor or black liquor, in the second sense, biomass includes plant or animal matter that can be converted into fibers or other industrial chemicals, including biofuels. Based on the source of biomass, biofuels are classified broadly into two major categories, first-generation biofuels are derived from sources such as sugarcane and corn starch. Sugars present in this biomass are fermented to produce bioethanol, a fuel which can be used directly in a fuel cell to produce electricity or serve as an additive to gasoline. However, utilizing food-based resources for production only aggravates the food shortage problem. Second-generation biofuels, on the hand, utilize non-food-based biomass sources such as agriculture. These biofuels mostly consist of lignocellulosic biomass, which is not edible and is a waste for many industries. Despite being the alternative, economical production of second-generation biofuel is not yet achieved due to technological issues. These issues arise due to chemical inertness and structural rigidity of lignocellulosic biomass. Plant energy is produced by crops grown for use as fuel that offer high biomass output per hectare with low input energy
8.
Hydropower
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Hydropower or water power is power derived from the energy of falling water or fast running water, which may be harnessed for useful purposes. A trompe, which compressed air from falling water, is sometimes used to power other machinery at a distance. In the late 19th century, hydropower became a source for generating electricity, cragside in Northumberland was the first house powered by hydroelectricity in 1878 and the first commercial hydroelectric power plant was built at Niagara Falls in 1879. In 1881, street lamps in the city of Niagara Falls were powered by hydropower, since the early 20th century, the term has been used almost exclusively in conjunction with the modern development of hydroelectric power. In China and the rest of the Far East, hydraulically operated pot wheel pumps raised water into crop or irrigation canals, the power of a wave of water released from a tank was used for extraction of metal ores in a method known as hushing. The method was first used at the Dolaucothi Gold Mines in Wales from 75 AD onwards, hushing was also widely used in Britain in the Medieval and later periods to extract lead and tin ores. It later evolved into hydraulic mining when used during the California Gold Rush and these include an endless belt with jugs attached, a cow-powered shadoof, and a reciprocating device with hinged valves. In 1753, French engineer Bernard Forest de Bélidor published Architecture Hydraulique which described vertical-, the growing demand for the Industrial Revolution would drive development as well. At the beginning of the Industrial Revolution in Britain, water was the source of power for new inventions such as Richard Arkwrights water frame. In the 1830s, at the peak in US canal-building, hydropower provided the energy to transport barge traffic up. Technological advances had moved the water wheel into an enclosed turbine or water motor. Francis, while working as engineer of Lowells Locks and Canals company. He applied scientific principles and testing methods to the problem of turbine design and his mathematical and graphical calculation methods allowed confident design of high efficiency turbines to exactly match a sites specific flow conditions. The Francis reaction turbine is still in use today. Hydraulic power networks used pipes to carrying pressurized water and transmit power from the source to end users. The power source was normally a head of water, which could also be assisted by a pump and these were extensive in Victorian cities in the United Kingdom. A hydraulic power network was developed in Geneva, Switzerland. The world-famous Jet dEau was originally designed as the relief valve for the network
9.
Sustainable transport
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Components for evaluating sustainability include the particular vehicles used for road, water or air transport, the source of energy, and the infrastructure used to accommodate the transport. Another component for evaluation is pipelines for transporting liquid or gas materials, Transport operations and logistics as well as transit-oriented development are also involved in evaluation. Transportation sustainability is largely being measured by transportation system effectiveness and efficiency as well as the environmental, the entire life cycle of transport systems is subject to sustainability measurement and optimization. Sustainable transport systems make a contribution to the environmental, social. The advantages of increased mobility need to be weighed against the environmental, social, Transport systems have significant impacts on the environment, accounting for between 20% and 25% of world energy consumption and carbon dioxide emissions. The majority of the emissions, almost 97%, came from burning of fossil fuels. Greenhouse gas emissions from transport are increasing at a faster rate than any other energy using sector, road transport is also a major contributor to local air pollution and smog. The United Nations Environment Programme estimates that each year 2.4 million premature deaths from air pollution could be avoided. The social costs of transport include road crashes, air pollution, physical inactivity, time taken away from the family while commuting, many of these negative impacts fall disproportionately on those social groups who are also least likely to own and drive cars. Traffic congestion imposes economic costs by wasting time and by slowing the delivery of goods. Traditional transport planning aims to improve mobility, especially for vehicles, communities which are successfully improving the sustainability of their transport networks are doing so as part of a wider programme of creating more vibrant, livable, sustainable cities. There are many definitions of the transport, and of the related terms sustainable transportation. Is Affordable, operates fairly and efficiently, offers a choice of transport mode, Sustainability extends beyond just the operating efficiency and emissions. A Life-cycle assessment involves production, use and post-use considerations, a cradle-to-cradle design is more important than a focus on a single factor such as energy efficiency. Most of the tools and concepts of sustainable transport were developed before the phrase was coined, walking, the first mode of transport, is also the most sustainable. Public transport dates back at least as far as the invention of the bus by Blaise Pascal in 1662. The first passenger tram began operation in 1807 and the first passenger service in 1825. Pedal bicycles date from the 1860s and these were the only personal transport choices available to most people in Western countries prior to World War II, and remain the only options for most people in the developing world
10.
Electric motor
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An electric motor is an electrical machine that converts electrical energy into mechanical energy. The reverse of this is the conversion of energy into electrical energy and is done by an electric generator. In normal motoring mode, most electric motors operate through the interaction between an electric motors magnetic field and winding currents to generate force within the motor, small motors may be found in electric watches. General-purpose motors with highly standardized dimensions and characteristics provide convenient mechanical power for industrial use, the largest of electric motors are used for ship propulsion, pipeline compression and pumped-storage applications with ratings reaching 100 megawatts. Electric motors may be classified by electric power source type, internal construction, application, type of motion output, perhaps the first electric motors were simple electrostatic devices created by the Scottish monk Andrew Gordon in the 1740s. The theoretical principle behind production of force by the interactions of an electric current. The conversion of energy into mechanical energy by electromagnetic means was demonstrated by the British scientist Michael Faraday in 1821. A free-hanging wire was dipped into a pool of mercury, on which a permanent magnet was placed, when a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a close circular magnetic field around the wire. This motor is often demonstrated in experiments, brine substituting for toxic mercury. Though Barlows wheel was a refinement to this Faraday demonstration. In 1827, Hungarian physicist Ányos Jedlik started experimenting with electromagnetic coils, after Jedlik solved the technical problems of the continuous rotation with the invention of the commutator, he called his early devices electromagnetic self-rotors. Although they were used only for instructional purposes, in 1828 Jedlik demonstrated the first device to contain the three components of practical DC motors, the stator, rotor and commutator. The device employed no permanent magnets, as the fields of both the stationary and revolving components were produced solely by the currents flowing through their windings. His motor set a record which was improved only four years later in September 1838 by Jacobi himself. His second motor was powerful enough to drive a boat with 14 people across a wide river and it was not until 1839/40 that other developers worldwide managed to build motors of similar and later also of higher performance. The first commutator DC electric motor capable of turning machinery was invented by the British scientist William Sturgeon in 1832, following Sturgeons work, a commutator-type direct-current electric motor made with the intention of commercial use was built by the American inventor Thomas Davenport, which he patented in 1837. The motors ran at up to 600 revolutions per minute, and powered machine tools, due to the high cost of primary battery power, the motors were commercially unsuccessful and Davenport went bankrupt. Several inventors followed Sturgeon in the development of DC motors but all encountered the same battery power cost issues, no electricity distribution had been developed at the time
11.
Lighting
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Lighting or illumination is the deliberate use of light to achieve a practical or aesthetic effect. Lighting includes the use of artificial light sources like lamps and light fixtures, as well as natural illumination by capturing daylight. Daylighting is sometimes used as the source of light during daytime in buildings. This can save energy in place of using lighting, which represents a major component of energy consumption in buildings. Proper lighting can enhance performance, improve the appearance of an area. Indoor lighting is accomplished using light fixtures, and is a key part of interior design. Lighting can also be a component of landscape projects. With the discovery of fire, the earliest form of lighting used to illuminate an area were campfires or torches. As early as 400,000 BCE, fire was kindled in the caves of Peking Man, prehistoric people used primitive oil lamps to illuminate surroundings. These lamps were made from naturally occurring materials such as rocks, shells, horns and stones, were filled with grease, lamps typically used animal or vegetable fats as fuel. Hundreds of these lamps have been found in the Lascaux caves in modern-day France, oily animals were also used as lamps after being threaded with a wick. Fireflies have been used as lighting sources, candles and glass and pottery lamps were also invented. Chandeliers were a form of light fixture. A major reduction in the cost of lighting occurred with the discovery of whale oil, in 1849, Dr. Abraham Gesner, a Canadian geologist, devised a method where kerosene could be distilled from petroleum. Earlier coal-gas methods had been used for lighting since the 1820s, gesners kerosene was cheap, easy to produce, could be burned in existing lamps, and did not produce an offensive odor as did most whale oil. It could be stored indefinitely unlike whale oil, which would eventually spoil, the American petroleum boom began in the 1850s. By the end of the decade there were 30 kerosene plants operating in the United States, the cheaper, more efficient fuel began to drive whale oil out of the market. John D. Rockefeller was most responsible for the success of kerosene
12.
Greywater
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Greywater or sullage is all wastewater generated in households or office buildings from streams without fecal contamination, i. e. all streams except for the wastewater from toilets. Sources of greywater include, e. g. sinks, showers, baths, the use of non-toxic and low-sodium soap and personal care products is recommended to protect vegetation when reusing greywater for irrigation purposes. Greywater, by definition, does not include the discharge of toilets or highly fecally contaminated wastewater, when greywater is mixed with toilet wastewater, it is called sewage or blackwater and should be treated in sewage treatment plants or onsite sewage facility, which often is a septic system. When it is separate, it may open up interesting decentralized treatment. The separate treatment of greywater falls under the concept of source separation which is one principle commonly applied in ecological sanitation approaches, the main advantage of keeping greywater separate from toilet wastewater is that the pathogen load is much reduced and the greywater is therefore easier to treat and reuse. Treated greywater has many uses, for example toilet flushing or irrigation, in households with conventional flush toilets, greywater makes up about 65% of the total wastewater produced by that household. In may be a source of water for reuse, because there is a close relationship between the production of greywater and the potential demand for toilet flushing water. Greywater usually contains traces of excreta and is therefore not free of pathogens. The excreta comes from washing a persons anal area in the bath and shower, the quality of greywater can deteriorate rapidly during storage because it is often warm, contains some nutrients and organic matter as well as pathogens. Stored greywater also leads to odour nuisances for the same reason, most greywater is easier to treat and recycle than blackwater, because of lower levels of contaminants. If collected using a separate plumbing system from blackwater, domestic greywater can be recycled directly within the home, garden or company, if stored, it must be used within a very short time or it will begin to putrefy due to the organic solids in the water. Recycled greywater of this kind is never safe to drink, but a number of treatment steps can be used to water for washing or flushing toilets. Mechanical systems In constructed wetlands, the plants use contaminants of greywater, such as food particles, as nutrients in their growth. However, salt and soap residues can be toxic to microbial and plant life alike, but can be absorbed and degraded through constructed wetlands and aquatic plants such as sedges, rushes, and grasses. Demand on conventional water supplies and pressure on sewage treatment systems is reduced by the use of greywater, re-using greywater also reduces the volume of sewage effluent entering watercourses which can be ecologically beneficial. In times of drought, especially in areas, greywater use in gardens or toilet systems helps to achieve some of the goals of ecologically sustainable development. S. Greywater use for irrigation appears to be a safe practice, a 2015 epidemiological study found no additional burden of disease among graywater users irrigating arid regions. The safety of reuse of greywater as potable water has also been studied, a few organic micropollutants including benzene were found in greywater in significant concentrations but most pollutants were in very low concentrations
