Sustainable Technology


Sustainable Energy sources are energy sources which are not expected to be depleted in a timeframe relevant to the human race, and which therefore contribute to the sustainability of all species. This concept is termed sustainability. An additional criterion for strict sustainability, useful for short- and medium-term decisions is social and political sustainability of an energy technology. Sustainable energy sources are most often regarded as including all renewable sources, such as solar power, wind power, wave power, geothermal power, tidal power, and others.



Solar power is the conversion of sunlight into electricity, either directly using photovoltaics (PV), or indirectly using concentrated solar power(CSP). Concentrated solar power systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. Photovoltaics convert light into an electric current using thephotovoltaic effect.



Passive solar technologies convert sunlight into usable heat, cause air-movement for ventilation or cooling, or store heat for future use, without the assistance of other energy sources. Technologies that use a significant amount of conventional energy to power pumps or fans are classified as active solar technologies. Some passive systems use a very small amount of conventional energy to control dampers, shutters, night insulation, and other devices that enhance solar energy collection, storage, and use.



Solar heating systems are generally composed of solar thermal collectors, a fluid system to move the heat from the collector to its point of usage, and a reservoir or tank for heat storage and subsequent use. The systems may be used to heat domestic hot water, swimming pool water, or for space heating. The heat can also be used for industrial applications or as an energy input for other uses such as cooling equipment. In many climates, a solar heating system can provide a very high percentage (50 to 75%) of domestic hot water energy. In many northern European countries, combined hot water and space heating systems (solar combisystems) are used to provide 15 to 25% of home heating energy



Geothermal energy is thermal energy generated and stored in the Earth. Thermal energy is the energy that determines the temperature of matter. The geothermal energy of the Earth’s crust originates from the original formation of the planet and from radioactive decay of materials (in currently uncertain[1] but possibly roughly equal proportions). The geothermal gradient, which is the difference in temperature between the core of the planet and its surface, drives a continuous conduction of thermal energy in the form of heat from the core to the surface.



Air flow through wind turbines or sails can produce significant mechanical power. Windmills are used for their mechanical power, windpumps for water pumping, and sails to propel ships, but the most frequent current use is to turn a generator for electrical power. Wind power, as an alternative to burning 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 far less problematic than those of nonrenewable power sources.



Hydropower or water power  is power derived from the energy of falling water or fast running water, which may be harnessed for useful purposes. Since ancient times, hydropower from many kinds of watermills has been used as a renewable energy source for irrigation and the operation of various mechanical devices, such as gristmills, sawmills, textile mills, trip hammers, dock cranes, domestic lifts, and ore mills. A trompe, which produces compressed air from falling water, is sometimes used to power other machinery at a distance.



Tidal power, also called tidal energy, is a form of hydropower that converts the energy obtained from tides into useful forms of power, mainly electricity.



An LED lamp is a light-emitting diode (LED) product that is assembled into a lamp (or light bulb) for use in lighting fixtures. LED lamps have a lifespan and electrical efficiency that is several times better than incandescent lamps, and significantly better than most fluorescent lamps, with some chips able to emit more than 100 lumens per watt.

Low voltage appliances can save you lots of money if you are considering a renewable energy system. Low voltage DC (Direct Current) powered equipment normally uses less power than the same type of appliance running from mains (240v) electricity. What’s more, if an appliance can take a low voltage supply, it saves the use of an inverter to change the power from DC to AC (mains), which will save you both money and energy.



Getting out of a pool and standing in a breeze will help you feel cool, even on a hot day. This is the principle behind evaporative cooling. Evaporative coolers, often called “swamp coolers”, are cooling systems that use only water and a blower to circulate air. In the system, warm, dry air is pulled through a water-soaked pad. As the water evaporates, a cooling effect on the surrounding air occurs. Evaporative coolers use only a fraction of the energy of traditional air conditioning systems. Unfortunately, except for in very dry climates, they may increase humidity to a level that makes occupants uncomfortable. Two-stage evaporative coolers do not produce humidity levels as high as that produced by traditional single-stage evaporative coolers. In the first stage of a two-stage cooler, warm air is pre-cooled indirectly without adding humidity (by passing inside a heat exchanger that is cooled by evaporation on the outside). In the direct stage, the precooled air passes through a water-soaked pad and picks up humidity as it cools. Because the air supply to the second stage evaporator is pre-cooled, less humidity is added to the air (because cooler air can’t hold as much moisture as warmer air). The result, according to the manufacturer, is cool air with a relative humidity between 50 and 70 percent, depending on the climate, compared to a traditional system that produces about 80 percent relative humidity air. An advanced two-stage evaporative cooler uses 100 percent outdoor air and a variable speed blower to circulate cool air. Two-stage evaporative coolers can reduce energy consumption by 60 to 75 percent over conventional air conditioning systems, according to the American Society of Heating and Engineers (ASHRAE). Yet this relative improvement depends on location and application. Evaporative coolers work best in very dry climates and are not suitable for much of the East Coast, Midwest, and Coastal U.S.



Greywater and Blackwater Recycling – Greywater, sometimes spelled graywater, grey water or gray water and also known as sullage, is non-industrial wastewater generated from domestic processes such as washing dishes, laundry and bathing. Greywater comprises 50-80% of residential wastewater. Greywater is distinct from blackwater in the amount and composition of its chemical and biological contaminants (from feces or toxic chemicals). Greywater gets its name from its cloudy appearance and from its status as being neither fresh (white water from groundwater or potable water), nor heavily polluted (blackwater). According to this definition wastewater containing significant food residues or high concentrations of toxic chemicals from household cleaners etc. may be considered “dark grey” or blackwater. In recent years concerns over dwindling reserves of groundwater and overloaded or costly sewage treatment plants has generated much interest in the reuse or recycling of greywater, both domestically and for use in commercial irrigation. However, concerns over potential health and environmental risks means that many jurisdictions demand such intensive treatment systems for legal reuse of greywater that the commercial cost is higher than for fresh water. Despite these obstacles, greywater is often reused for irrigation, illegally or not, in older rural construction, simple construction old and new, often consisting of nothing more than a “drain out back” (pipe pointed down the nearest hill). In droughtzones or areas hit by hose pipe bans (irrigation restrictions) greywater can be harvested informally by manual bucketing. In the third world, reuse of greywater is often unregulated and is common. At present, the recycling of greywater is poorly understood compared with elimination.
Blackwater (waste) is a relatively recent term used to describe water containing fecal matter and urine. It is also known as brown water, foul water, or sewage. It is distinct from greywater or sullage, the residues of washing processes.
Blackwater is heavily polluted and difficult to treat because of the high concentrations of mostly organic pollution. The term is commonly used on recreational vehicles where separate tanks collect blackwater and greywater wastes.



A Composting Toilet is any system that converts human waste into a organic compost and usable soil, through the natural breakdown of organic matter into its essential minerals. Aerobic microbes do this in the presence of moisture and air, by oxidizing the carbon in the organic material to carbon dioxide gas, and converting hydrogen atoms to water vapour. “Self-contained” composting toilets complete the composting “in-situ,”, while “central unit” ones flush waste to a remote composting unit below the toilet. Vacuum flush systems can flush horizontally or up. Composting toilets can be installed anywhere, such as a cabin, cottage, bunkie, yurt, RV, pool cabana, boat, shed, barn, or home. Some composting toilets use electricity, and some electrical systems use fans to exhaust air and increase microbial activity. Others require the user to simply rotate a drum within the composting toilet to allow for an aerobic breakdown of waste.
Some composting toilets have a large compartment below the toilet. Others are little larger than a traditional toilet. All composting toilets eventually need some end-product removal. A full size composting toilet does not need to have solids removed for several decades if the active tank volume is at least three times the yearly addition. This is because the waste dramatically decreases in volume — after around 5 years only 1-2% of the original volume remains. It is then a mineralized soil which will not decompose any further. Other smaller systems may need to remove solids several times a year. A related device, though only by its stand-alone use and not for its sustainability, is the incinerating toilet, which uses natural gas or propane to reduce the waste material to ash in a process similar to a self cleaning oven. However, these systems are quite expensive to run and emit a foul odour. Composting toilets reduce the volume of humanure and other organic materials on site over months or years through predominantly mesophilic composting and yield a fertilizer that is, after the legally required period, able to be used in horticultural or agricultural applications. Composting toilets are also becoming more common as an accepted alternative in homes, where the odor-free operation of a properly functioning unit appeals more to some houseowners than conventional toilets, with their consumption of large quantities of clean water



Rainwater harvesting is the collection and storage of rain from roofs or from a surface catchment for future use. The water is generally stored in rainwater tanks (cisterns) or directed into mechanisms which recharge groundwater. This is appropriate in many parts of the world, such as western Britain, China, Brazil, Thailand, Sri Lanka, Germany, Australia and India, where there is enough rain for collection and conventional water resources either do not exist or are at risk of being over-used to supply a large population. Rainwater harvesting can provide lifeline water for human consumption, reduce water bills and the need to build reservoirs which may require the use of valuable land.


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