-SOLAR POWER-

Solar power is the generation of electricity from sunlight. This can be direct as with photovoltaics (PV), or indirect as with concentrating solar power (CSP), where the sun's energy is focused to boil water which is then used to provide power. The solar power gained from photovoltaics can be used to eliminate the need for purchased electricity (usually electricity gained from burning fossil fuels) or, if energy gained from photovoltaics exceeds the home's requirements, the extra electricity can be sold back to the home's supplier of energy, typically for credit.^[1] The largest solar power plants, like the 354 MW SEGS, are concentrating solar thermal plants, but recently multi-megawatt photovoltaic plants have been built. Completed in 2008, the 46 MW Moura photovoltaic power station in Portugal and the 40 MW Waldpolenz Solar Park in Germany are characteristic of the trend toward larger photovoltaic power stations. Much larger ones are proposed, such as the 550 MW Topaz Solar Farm, and the 600 MW Rancho Cielo Solar Farm. Solar power is a predictably intermittent energy source, meaning that whilst solar power is not available at all times, we can predict with a very good degree of accuracy when it will and will not be available. Some technologies, such as solar thermal concentrators have an element of thermal storage, such as molten salts. These store spare solar energy in the form of heat which is made available overnight or during periods that solar power is not available to produce electricity.

Solar power is the conversion of sunlight to electricity. Sunlight can be converted directly into electricity using photovoltaics (PV), or indirectly with concentrating solar power (CSP), which normally focuses the sun's energy to boil water which is then used to provide power, and technologies such as the Stirling engine dishes which use a Stirling cycle engine to power a generator. Photovoltaics were initially used to power small and medium-sized applications, from the calculator powered by a single solar cell to off-grid homes powered by a photovoltaic array.

Solar power plants can face high installation costs, although this has been decreasing due to the learning curve.^[2][3] Developing countries have started to build solar power plants, replacing other sources of energy generation.^[4][5][6]

Since solar radiation is intermittent, solar power generation is usually combined either with storage or other energy sources to provide continuous power, although for small distributed producer/consumers, net metering makes this transparent to the consumer. On a slightly larger scale, in Germany, a combined power plant has been demonstrated, using a mix of wind, biomass, hydro-, and solar power generation, resulting in 100% renewable energy.^[7]

A legend claims that Archimedes used polished shields to concentrate sunlight on the invading Roman fleet and repel them from Syracuse.^[8] Auguste Mouchout used a parabolic trough to produce steam for the first solar steam engine in 1866.^[9]

Concentrating Solar Power (CSP) systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. The concentrated heat is then used as a heat source for a conventional power plant. A wide range of concentrating technologies exists; the most developed are the parabolic trough, the concentrating linear fresnel reflector, the Stirling dish and the solar power tower. 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.^[10]

A parabolic trough consists of a linear parabolic reflector that concentrates light onto a receiver positioned along the reflector's focal line. The receiver is a tube positioned right above the middle of the parabolic mirror and is filled with a working fluid. The reflector is made to follow the Sun during the daylight hours by tracking along a single axis. Parabolic trough systems provide the best land-use factor of any solar technology.^[11] The SEGS plants in California and Acciona's Nevada Solar One near Boulder City, Nevada are representatives of this technology.^[12][13] The Suntrof-Mulk parabolic trough, developed by Melvin Prueitt, uses a technique inspired by Archimedes' principle to rotate the mirrors.^[14]

Concentrating linear fresnel reflectors are CSP-plants which use many thin mirror strips instead of parabolic mirrors to concentrate sunlight onto two tubes with working fluid. This has the advantage that flat mirrors can be used which are much cheaper than parabolic mirrors, and that more reflectors can be placed in the same amount of space, allowing more of the available sunlight to be used. Concentrating linear fresnel reflectors can be used in either large or more compact plants.^[15][16]

A Stirling solar dish, or dish engine system, consists of a stand-alone parabolic reflector that concentrates light onto a receiver positioned at the reflector's focal point. The reflector tracks the Sun along two axes. Parabolic dish systems give the highest efficiency among CSP technologies.^[17] The 50 kW Big Dish in Canberra, Australia is an example of this technology.^[12] The Stirling solar dish combines a parabolic concentrating dish with a Stirling heat engine which normally drives an electric generator. The advantages of Stirling solar over photovoltaic cells are higher efficiency of converting sunlight into electricity and longer lifetime. A solar power tower uses an array of tracking reflectors (heliostats) to concentrate light on a central receiver atop a tower. Power towers are more cost effective, offer higher efficiency and better energy storage capability among CSP technologies.^[12] The Solar Two in Barstow, California and the Planta Solar 10 in Sanlucar la Mayor, Spain are representatives of this technology.^[12][18]

A solar bowl is a spherical dish mirror that is fixed in place. The receiver follows the line focus created by the dish (as opposed to a point focus with tracking parabolic mirrors).

-WIND POWER-

Wind power is the conversion of wind energy into a useful form of energy, such as electricity, using wind turbines. At the end of 2008, worldwide nameplate capacity of wind-powered generators was 121.2 gigawatts (GW).^[1] In 2008, wind power produced about 1.5% of worldwide electricity usage;^[1][2] and is growing rapidly, having doubled in the three years between 2005 and 2008. Several countries have achieved relatively high levels of wind power penetration, such as 19% of stationary electricity production in Denmark, 11% in Spain and Portugal, and 7% in Germany and the Republic of Ireland in 2008. As of May 2009, eighty countries around the world are using wind power on a commercial basis.^[2]

Large-scale wind farms are connected to the electric power transmission network; smaller facilities are used to provide electricity to isolated locations. Utility companies increasingly buy back surplus electricity produced by small domestic turbines. Wind energy as a power source is attractive as an alternative to fossil fuels, because it is plentiful, renewable, widely distributed, clean, and produces no greenhouse gas emissions. However, the construction of wind farms is not universally welcomed because of their visual impact and other effects on the environment.

Wind power is non-dispatchable, meaning that for economic operation, all of the available output must be taken when it is available. Other resources, such as hydropower, and standard load management techniques must be used to match supply with demand. The intermittency of wind seldom creates problems when using wind power to supply a low proportion of total demand. Where wind is to be used for a moderate fraction of demand such as 40%, additional costs for compensation of intermittency are considered to be modest.^[3][4]

Humans have been using wind power for at least 5,500 years to propel sailboats and sailing ships, and architects have used wind-driven natural ventilation in buildings since similarly ancient times. Windmills have been used for irrigation pumping and for milling grain since the 7th century AD.

In the United States, the development of the "water-pumping windmill" was the major factor in allowing the farming and ranching of vast areas otherwise devoid of readily accessible water. Windpumps contributed to the expansion of rail transport systems throughout the world, by pumping water from water wells for the steam locomotives.^[5] The multi-bladed wind turbine atop a lattice tower made of wood or steel was, for many years, a fixture of the landscape throughout rural America. When fitted with generators and battery banks, small wind machines provided electricity to isolated farms.

In July 1887, a Scottish academic, Professor James Blyth, undertook wind power experiments that culminated in a UK patent in 1891.^[6] In the United States, Charles F. Brush produced electricity using a wind powered machine, starting in the winter of 1887-1888, which powered his home and laboratory until about 1900. In the 1890s, the Danish scientist and inventor Poul la Cour constructed wind turbines to generate electricity, which was then used to produce hydrogen.^[6] These were the first of what was to become the modern form of wind turbine.

Small wind turbines for lighting of isolated rural buildings were widespread in the first part of the 20th century. Larger units intended for connection to a distribution network were tried at several locations including Yalta in 1931 and in Vermont in 1941.

The Earth is unevenly heated by the sun, such that the poles receive less energy from the sun than the equator; along with this, dry land heats up (and cools down) more quickly than the seas do. The differential heating drives a global atmospheric convection system reaching from the Earth's surface to the stratosphere which acts as a virtual ceiling. Most of the energy stored in these wind movements can be found at high altitudes where continuous wind speeds of over 160 km/h (99 mph) occur. Eventually, the wind energy is converted through friction into diffuse heat throughout the Earth's surface and the atmosphere.

The total amount of economically extractable power available from the wind is considerably more than present human power use from all sources.^[7] An estimated 72 TW of wind power on the Earth potentially can be commercially viable,^[8] compared to about 15 TW average global power consumption from all sources in 2005. Not all the energy of the wind flowing past a given point can be recovered (see Betz' law).

In a wind farm, individual turbines are interconnected with a medium voltage (usually 34.5 kV) power collection system and communications network. At a substation, this medium-voltage electrical current is increased in voltage with a transformer for connection to the high voltage electric power transmission system.

The surplus power produced by domestic microgenerators can, in some jurisdictions, be fed back into the network and sold back to the utility company, producing a retail credit for the consumer to offset their energy costs.^[11][12]

- WATER ENERGY-

WaterEnergy is a reseller for water treatment and energy conservation solutions. Whether you operate a commercial laundry, hotel, restaurant or tourist resort, farm or animal processing plant, hospital, correctional facility, industrial factory or water treatment system, you can rely on Water Energy to provide the latest technology solutions to help you save money on water treatment and purification.

Our leading-edge ozone treatment systems for commercial laundry facilities can help you save thousands of dollars by completely eliminating the need for hot water. Proven at leading resorts and hospitals, Water Energy ozone solutions not only save you money in energy costs, they often qualify for very favorable tax credits. Let us know your requirements and we can specify the right system for you.

Water Energy also specializes in organic bacteria solutions. The ideal solution for petroleum refineries, industrial operations, farms and animal processing plants, Water Energy bacteria can treat organic and inorganic waste quickly and efficiently, saving our customers thousands of dollars per month compared to conventional filtration systems.

Be sure to sign up for our free Water Energy Report and keep up with the latest solutions for water treatment and purification.

Large scale hydroelectric power has been used worldwide for a long time to generate huge amounts of power from water stored behind massive dams. Small scale hydropower has been used for hundreds of years for manufacturing, including milling grain, sawing logs and manufacturing cloth. However, it can also be used without a dam to generate electricity for home scale remote power systems. These so-called micro-hydro installations can be a very good complement to a solar power system, as they produce electricity 24 hours a day.

Waterwheels--It's important to differentiate between water wheels and water turbines. A water wheel is more akin the antique version we are all familiar with--a massive wooden wheel that slowly turns as the creek pours down over it. Water wheels spin slowly, but with lots of torque. They are also surprisingly efficient! One very good place to go for waterwheel information, kits and photos is The Waterwheel Factory.

Turbines--All of the commercial micro hydro generators available today use a small turbine connected to an electrical generator or alternator. Water is collected in an intake pipe upstream, travels down to the turbine in plastic pipe, and is forced through one or more nozzles by its own gravity pressure. No dam is needed; systems without a dam are called "run of river" systems. Power is generated by a generator or alternator directly connected to the turbine wheel (no gears or pulleys needed). All of the factors below must be calculated correctly for your micro-hydro equipment to make power most efficiently. All commercial micro-hydro setups are custom-made by the manufacturer for your specific application. For proper operation, you must supply the manufacturer with specific data about your site, most importantly the vertical drop in feet (called "head"), the amount of water flow available during different seasons in gallons per minute, and the length of pipeline required to get a sufficient head.

• In general, for a water turbine you need at least 3 feet of fall and at least 20 gallons per minute of flow. If you have more fall (head), less water is required. You can calculate potential head with a water level, a contractor's level and stadia rod, or with just a string level attached to a measuring stick. The more fall and flow that you have, the more potential power you can generate. You can measure flow by building a weir in the creek and measuring how fast it will fill up a 5 gallon bucket.
• Your pipeline must be of a big enough diameter to minimize friction loss in the pipe. Your micro-hydro supplier can give you specific information regarding this.
• Nozzle size and turbine wheel type are all interrelated to your total head and flow. Again, your hydro supplier will customize these for your specific application. Often, different size nozzles are designed to be switched in and out as stream conditions change throughout the year.
• There are two main types of turbines, impulse and reaction. With impulse turbines, a jet of water is created by the nozzle and squirted onto the wheel. Reaction turbines are more akin to propellor that spins INSIDE the pipe, generating power.
• The 3 primary impulse turbine wheel types are Pelton, Turgo, and Cross-flow. Pelton wheels are used in low flow, high head conditions, and Cross-flow wheels are for high flow, low head installations. Turgo wheels are somewhere in the middle. Francis and propellor turbines are the most common reaction type; the Francis design is very similar to the innards of a centrifugal pump. A Kaplan turbine is also similar to this design.
• Home built reaction turbines have been built using centrifugal pumps running in reverse (generating power with moving water instead of using power to move the water). We hope to have more information about experimenting with this soon. You can buy a book about from ITDG books, they also have a book about using induction motors as generators for micro hydro power.

WaterEnergy is a reseller for water treatment and energy conservation solutions. Whether you operate a commercial laundry, hotel, restaurant or tourist resort, farm or animal processing plant, hospital, correctional facility, industrial factory or water treatment system, you can rely on Water Energy to provide the latest technology solutions to help you save money on water treatment and purification.

Our leading-edge ozone treatment systems for commercial laundry facilities can help you save thousands of dollars by completely eliminating the need for hot water. Proven at leading resorts and hospitals, Water Energy ozone solutions not only save you money in energy costs, they often qualify for very favorable tax credits. Let us know your requirements and we can specify the right system for you.

Water Energy also specializes in organic bacteria solutions. The ideal solution for petroleum refineries, industrial operations, farms and animal processing plants, Water Energy bacteria can treat organic and inorganic waste quickly and efficiently, saving our customers thousands of dollars per month compared to conventional filtration systems.

Be sure to sign up for our free Water Energy Report and keep up with the latest solutions for water treatment and purification.

Large scale hydroelectric power has been used worldwide for a long time to generate huge amounts of power from water stored behind massive dams. Small scale hydropower has been used for hundreds of years for manufacturing, including milling grain, sawing logs and manufacturing cloth. However, it can also be used without a dam to generate electricity for home scale remote power systems. These so-called micro-hydro installations can be a very good complement to a solar power system, as they produce electricity 24 hours a day.

Waterwheels--It's important to differentiate between water wheels and water turbines. A water wheel is more akin the antique version we are all familiar with--a massive wooden wheel that slowly turns as the creek pours down over it. Water wheels spin slowly, but with lots of torque. They are also surprisingly efficient! One very good place to go for waterwheel information, kits and photos is The Waterwheel Factory.

Turbines--All of the commercial micro hydro generators available today use a small turbine connected to an electrical generator or alternator. Water is collected in an intake pipe upstream, travels down to the turbine in plastic pipe, and is forced through one or more nozzles by its own gravity pressure. No dam is needed; systems without a dam are called "run of river" systems. Power is generated by a generator or alternator directly connected to the turbine wheel (no gears or pulleys needed). All of the factors below must be calculated correctly for your micro-hydro equipment to make power most efficiently. All commercial micro-hydro setups are custom-made by the manufacturer for your specific application. For proper operation, you must supply the manufacturer with specific data about your site, most importantly the vertical drop in feet (called "head"), the amount of water flow available during different seasons in gallons per minute, and the length of pipeline required to get a sufficient head.

• In general, for a water turbine you need at least 3 feet of fall and at least 20 gallons per minute of flow. If you have more fall (head), less water is required. You can calculate potential head with a water level, a contractor's level and stadia rod, or with just a string level attached to a measuring stick. The more fall and flow that you have, the more potential power you can generate. You can measure flow by building a weir in the creek and measuring how fast it will fill up a 5 gallon bucket.
• Your pipeline must be of a big enough diameter to minimize friction loss in the pipe. Your micro-hydro supplier can give you specific information regarding this.
• Nozzle size and turbine wheel type are all interrelated to your total head and flow. Again, your hydro supplier will customize these for your specific application. Often, different size nozzles are designed to be switched in and out as stream conditions change throughout the year.
• There are two main types of turbines, impulse and reaction. With impulse turbines, a jet of water is created by the nozzle and squirted onto the wheel. Reaction turbines are more akin to propellor that spins INSIDE the pipe, generating power.
• The 3 primary impulse turbine wheel types are Pelton, Turgo, and Cross-flow. Pelton wheels are used in low flow, high head conditions, and Cross-flow wheels are for high flow, low head installations. Turgo wheels are somewhere in the middle. Francis and propellor turbines are the most common reaction type; the Francis design is very similar to the innards of a centrifugal pump. A Kaplan turbine is also similar to this design.
• Home built reaction turbines have been built using centrifugal pumps running in reverse (generating power with moving water instead of using power to move the water). We hope to have more information about experimenting with this soon. You can buy a book about from ITDG books, they also have a book about using induction motors as generators for micro hydro power.

-BIOFUEL-

Biofuels � liquid fuels derived from plant materials � are entering the market, driven by factors such as oil price spikes and the need for increased energy security.

Bioethanol is an alcohol made by fermenting the sugar components of plant materials and it is made mostly from sugar and starch crops. With advanced technology being developed, cellulosic biomass, such as trees and grasses, are also used as feedstocks for ethanol production. Ethanol can be used as a fuel for vehicles in its pure form, but it is usually used as a gasoline additive to increase octane and improve vehicle emissions. Bioethanol is widely used in the USA and Brazil.

Biodiesel is made from vegetable oils, animal fats or recycled greases. Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as a diesel additive to reduce levels of particulates, carbon monoxide, and hydrocarbons from diesel-powered vehicles. Biodiesel is produced from oils or fats using transesterification and is the most common biofuel in Europe.

Biofuels provided 1.8% of the world�s transport fuel in 2008. Investment into biofuels production capacity exceeded $4 billion worldwide in 2007 and is growing.^[1]

-GEOTHERMAL POWER-

Geothermal power (from the Greek roots geo, meaning earth, and thermos, meaning heat) is power extracted from heat stored in the earth. This geothermal energy originates from the original formation of the planet, from radioactive decay of minerals, and from solar energy absorbed at the surface. It has been used for bathing since paleolithic times and for space heating since ancient roman times, but is now better known for generating electricity. Worldwide, geothermal plants have the capacity to generate about 10 gigawatts of electricity as of 2007, and in practice supply 0.3% of global electricity demand. An additional 28 gigawatts of direct geothermal heating capacity is installed for district heating, space heating, spas, industrial processes, desalination and agricultural applications.

Geothermal power is cost effective, reliable, sustainable, and environmentally friendly, but has historically been limited to areas near tectonic plate boundaries. Recent technological advances have dramatically expanded the range and size of viable resources, especially for applications such as home heating, opening a potential for widespread exploitation. Geothermal wells release greenhouse gases trapped deep within the earth, but these emissions are much lower per energy unit than those of conventional fossil fuels. As a result, geothermal power has the potential to help mitigate global warming if widely deployed in place of fossil fuels.

The Earth's geothermal resources are theoretically more than adequate to supply humanity's energy needs, but only a very small fraction of it may be profitably exploited. Drilling and exploration for deep resources costs tens of millions of dollars, and success is not guaranteed. Forecasts for the future penetration of geothermal power depend on assumptions about technology growth, the price of energy, subsidies, and interest rates.

Approximately 70 countries made direct use of a total of 270 petajoules (PJ) of geothermal heating in 2004. More than half of this energy was used for space heating, and another third for heated pools. The remainder supported industrial and agricultural applications. The global installed capacity was 28 GW but capacity factors tend to be low (30% on average) since heat is mostly needed in the winter. The above figures are dominated by 88 PJ of space heating extracted by an estimated 1.3 million geothermal heat pumps with a total capacity of 15 GW.^[2] Heat pumps are the fastest-growing means of exploiting geothermal energy, with a global annual growth rate of 30% in energy production.^[6] Most of these new heat pumps are being installed for home heating.

Direct heating in all its forms is far more efficient than electricity generation and places less demanding temperature requirements on the heat resource. Heat may come from co-generation with a geothermal electrical plant or from smaller wells or heat exchangers buried in shallow ground. As a result, geothermal heating is economic over a much greater geographical range than geothermal electricity. Where natural hot springs are available, the heated water can be piped directly into radiators. If the ground is hot but dry, earth tubes or downhole heat exchangers can collect the heat. But even in areas where the ground is colder than room temperature, heat can still be extracted with a geothermal heat pump more cost-effectively and cleanly than it can be produced by conventional furnaces.^[7] These devices draw on much shallower and colder resources than traditional geothermal techniques, and they frequently combine a variety of other functions, including air conditioning, seasonal energy storage, solar energy collection, and electric heating. Geothermal heat pumps can be used for space heating essentially anywhere in the world.

Geothermal heat supports many applications. District heating applications use networks of piped hot water to heat buildings in whole communities. In Reykjav?k, Iceland, spent water from the district heating system is piped below the pavement and sidewalks to melt snow. ^[8] Geothermal desalination has been demonstrated.