Wednesday, April 20, 2016

Wind turbine installation

Wind power refers to the kinetic energy stored in wind, and it's extraction using wind turbines. This article deals mainly with the intricacies of large scale deployment of wind turbines to generate electricity.

See wind turbine for more on individual turbines.
Wind Turbine
Wind Turbine
As a general rule, wind generators are practical where the average wind speed is greater than 20 km/h (5.5 m/s). Obviously, meteorology plays an important part in determining possible locations for wind parks, though it has great accuracy limitations.

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How Does Wave Energy Work?

Wave power is a method of electrical generation, where energy from waves moving in water is transferred into an electrical current; the electricity thus produced is coined asrenewable energy.
Wave power generation is not a widely employed technology with only a few experimental sites in existence. Wave power has however an advantage in comparition with many other renewable energy sources, because of it's stability in production. Where for instance the amount of wind power being produced relies heavily on how strong winds there are locally, which fluctuates heavily from day to day and from season to season, the amount of wave power being produced wouldn't fluctuate so heavily, since the amount energy stored in waves are more constant, and not so heavily dependent on the local weather conditions.
Wave power
The problems sketched is one of the heaviest barriers in making an entire area dependent on renewable energy, for instance in a country like Denmark where approximately 20 % of the power being produced originates from wind farms, when the wind is strong, however over 100 % of the consumption of the danish energy grid is being produced by wind farms, and the surplus is being sold to other nearby countries, such as Sweden and Germany at a low price (since these countries also has a high production of wind and river energy at times with wind in Denmark), when there is no wind, Denmark has to buy power from it's neighbouring countries at a much higher price. These conditions makes wind power less profitable, and many experts are of the opinion that Denmark has reached it's maximal percentage of wind power being generated, unless some sort of storage of energy is being used. Wave power could, when fully developed be another key for expanding the amount of renewable energy being produced, because of its much more stable production.
Wave power
Wave power
Many different system designs are currently being developed.
In one system, floating blocks are driven by wave action to push or pull a generator lying in the water. Water pushing through tubes will push a turbine which drives the generator.
With another method, wave action compresses air in a tunnel which drives the vanes of the generator. The bigger the difference between wave top and wave valley, the more power potential there is.
In yet another design, the overtopping of the waves are being led to a reservoir, the water, being pulled downwards through a tube by gravity, drives a generator.
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Water turbine - Types of Turbine

Water Turbine
Water Turbine
Water turbine - Types of Turbine
Water is very heavy and its flow energetic. The Power available in flowing water is described by;
where:
 Power( Joules/sec or Watts)
 turbine efficiency
 density of water (Kg/meter3)
 accelaration of gravity (9.8 meters/sec2)
 head (meters, this is the height at which still, unimpeded water starts falling from)
 flow rate (meters3/sec)
Theory of operation
Water turbines are divided into two groups; reaction turbines and impulse turbines.
Impulse turbines change the direction of flow of the water, leaving the exit flow with diminished energy. The water's energy is converted to kinetic energy by a nozzle prior to hitting the turbine blades. No pressure change occurs at the turbine blades and the turbine doesn't require a housing for operation. Impulse turbines are more often used in high head applications.
Reaction turbines are acted on by water changing pressure as it moves through the turbine. The turbine must be cased to contain the water pressure (or fully submerged in the water flow). Reaction turbines are more often used in low head applications.
Turbine designs often combine both these concepts.
The critical speed of a water turbine is the speed at which water flows through the turbine without resistance and no energy is extracted from the water flow. The operating speed is always less than the critical speed.
Some water turbines are designed to reverse flow and turn into a pump. They can fill a high reservoir during off-peak electrical hours and revert to a turbine for power generation during peak electrical demand.

Types of turbines
Reaction turbines:
Francis
Propeller
Kaplan
Tyson
Water Wheel
Impulse turbines:
Pelton
Turgo
Banki(Crossflow)
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Tuesday, April 19, 2016

Solar water heating

Using the sun to heat water
A collector is placed on or forms the roof of a building, or on a wall facing the sun, or may be free-standing. The working fluid is either pumped or driven by convection through it. Active control or simple physics ensures it only moves when a net gain in heat will occur.

The collector can be a simple glass topped box with copper pipes in it, or a set of metal tubes surrounded by a evacuated (near vacuum) glass cylinder. A parabolic mirror can also be added to concentrate the sun's light on the tube.

A simple water heating system would pump cold water out to a collector to be heated, the heated water flows back to a collection tank. This type of collector can provide enough hot water for a family, for very little or no monthly cost.
Solar water heating
Solar water heating
Heat is stored in a hot water tank. The volume of this tank will be larger with solar heating systems in order to allow for bad weather, and because the optimum final temperature for the absorber is lower than a typical immersion or combustion heater.

The working fluid for the absorber may be the hot water from the tank, but more usually at least in pumped systems will be a separate loop of fluid contining anti-freeze and a corrosion inhibitor which delivers heat to the tank through a heat exchanger - a coil of copper tubing within the tank.
If a central heating system is also present and heats water then either the solar heat will be concentrated in a pre-heating tank that feeds into the tank heated by the central heating, or the solar heat exchanger will be lower in the tank than the hotter one.

The water from the collector can reach very high temperatures in good sunshine, or if the pump fails. Designs should allow for relief of pressure.

The collector can be a simple glass topped box with copper pipes in it, or a set of metal tubes surrounded by a evacuated (near vacuum) glass cylinder. A parabolic mirror can also be added to concentrate the sun's light on the tube. A simple water heating system would pump cold water out to a collector to be heated, the heated water flows back to a collection tank. There are even ways to do this without a pump, using natural convection. This type of collector can easily provide enough hot water for a family, for very little or no monthly cost. Temperature regulators are required to mix the hot water from the tank with cold water because at peek times the water from the collector can reach very high temperatures. Using some of the more advanced collectors, it is possible to get much higher temperatures (well above the boiling point of water) therefor a medium with a boiling point over the operating temperature is required, and many are available. This heated fluid would, by way of a heat exchanger, heat water.
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What is sea level rise?

Sea level rise, a phenomena sometimes held to be caused by global warming and thus evidence supporting the Global Warming Theory.

Rising atmosphere temperature theoretically is causing the ice caps to melt and the oceans to expand (heat does cause ice to melt and water to expand). On the other hand, heat also causes water to evaporate, so it is not known what effect global warming will have on sea level.

Some researchers believe that rising average sea levels are proof of the global warming theory and that likely further global warming will cause additional sea level rise, possibly wiping out shore-based communities.

Other researchers believe that rising average sea levels are unrelated to global warming and that any global warming thot occurs will likely result in lower average sea levels.
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Renewable energy

Renewable energy is any type of energy generation that isn't dependent on a limited resource like fossil fuels. Renewable energy may be used directly, such as solar ovens, geothermal heat pumps, or windmills. Other forms of renewable energy sources generate electricity, such as solar power cells, wind generators, tidal waves and hydroelectricpower. Still other forms generate fuels, such as vegetable oils generated from biomass.

Most renewable energy can trace their root to solar energy, perhaps with the exception of geothermal and tidal wave power. For example, wind is caused by the density difference of the air when the sun heats various parts of the earth unevenly. Hydroelectric power can be ultimately traced to the sun too. When the sun evaporates water in the ocean, the vapor forms clouds which later falls on mountains as rain which runs through turbines to generate electrity. The transformation goes from solar energy to potential energy to kinetic energy to electric energy.

Most renewable energy sources have no emissions, with the exception of biomass fuels. Even for biomass, however, the generation of new plantlife consumes the same elements from the atmosphere that it emits when burned.

Iceland is a world leader in renewable energy due to its abundant hydro and geothermal energy sources. Over 99% of the country's electricity is from renewable sources and most of its urban household heating is geothermal. Israel is also notably as much of its household hot water is heated by solar means. These countries' successes are at least partly based on their geographical advantages.

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Photovoltaic energy systems definition

Photovoltaics is the direct conversion of radiant energy such as sunlight into electricity through quantum mechanical processes. Photovoltaics is also known as 'solar electric power' or 'solar power', though the latter term fails to adequately distinguish photovoltaics from other technologies that make use of solar energy, such as solar hot water, or solar thermal electricity generation.
The photovoltaic effect - the process by which sunlight is converted to electricity - was first noted by Edmund Becquerel in 1839.
The principle component of a photovoltaic system is the photovoltaic cell, or solar cell. Commercial solar cells are typically made from silicon, though other materials such as gallium arsenide, and even more exotic combinations are also used, particularly in high efficiency laboratory devices, or cells meant for satellite and space applications, where capital cost is small compared to the cost of sending material into orbit. The common feature of the materials that can be used to make a solar cell is that they are semiconductors.
Semiconductors can have a high electrical resistance, but be put into a lower resistance mode when under the correct conditions. Another way of describing this is that there are not many free electrons in a semiconductor, but a small amount of energy can release the electrons from the atoms they are bonded to.
Photovoltaic energy
Photovoltaic energy

Photovoltaics research institutes
There are many research institutions and departments at universities around the world who are active in the field of photovoltaic. Countries which are particularly active in the field of photovoltaics are Germany, Japan, Australia, China, and the USA.
Some universities and institutes which have a photovoltaics research department.
Centre for Photovoltaic Engineering at The University of New South Wales
Institut fĂŒr Solare Energiesysteme ISE at the Fraunhofer Institute
Centre for Sustainable Energy Systems at the Australian National University
National Renewable Energy Laboratory NREL
Advanced Energy Systems at Helsinki University of Technology
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What is passive solar energy and heating system?

Passive solar is a term referring to those technologies that can be employed to convert natural sunlight into usable heat, to cause air-movement for ventilation or cooling, or to store the heat for future use, without the use of electrical or mechanical equipment. Technologies that use pumps or fans are classified as active solar technologies.

Passive solar technologies used domestically include the use of direct solar gain, solar space heating, those solar hot water systems based on the thermosiphon, thermal mass, the Trombe wall, solar cookers, the solar chimney, and earth sheltering. More widely, they include technologies such as the solar furnace and solar forge.

Passive solar systems require no additional energy to operate and therefore have zero operating costs, have low maintenance costs, and emit no greenhouse gasses in operation. For these reasons, passive solar technologies (together with energy conservation measures) should be considered before active solar technologies.

For the use of passive solar technologies in buildings, see passive solar building design.
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Oil Tankers

Oil Tankers are ships of varying sizes designed for the bulk carriage of crude oil and various refined spirits. The largest are up to 650,000 tonnes.

The current custom is for crude oil to be transported to near its point of use where it is refined as required.

At various times, there have been accidents that have led to serious and catastrophic pollution. Another concern has been the pollution caused by careless cleaning of ships' tanks.

During World War II, the transport of oil and its products was a critical strategic activity, since shortages had a paralysing impact on mechanised nations. The destruction and defence of these ships was, therefore, a prime concern.
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Liquefied natural gas (LNG)

Liquefied natural gas (LNG). Natural gas can be cooled until it becomes liquid and stored in tanks. This reduces the volume about 600 times. For transportation between locations where other means of transportation (such as pipelines) is uneconomic, natural gas can be transported as LNG by ship.

The infrastructure needed for LNG transportation consists of a liquification terminal, where the gas is cooled, LNG-ships for transportation and a regasification terminal at the destination, where it will be reheated and turned into gas. The regasification terminals are usually connected with a distribution network of pipelines.
Liquefied natural gas
LNG
The costs of LNG treatment and transportation have fallen in recent years, making LNG a more competitive means of distribution. Several receiving terminals exist both in Europe and in the United States, allowing gas import from other continents such as Africa.

The risk of freighting gas as LNG are not clear, some claim that since the gas is cooled rather than compressed, the gas would vaporize and burn slowly, and not explode. There has been no serious accident involving LNG since long distance transportation started in the 1960s.
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Monday, April 18, 2016

Ground-coupled heat exchanger

Earth cooling tubes utilize the earth's near constant subterranean temperature to warm or cool air for residential, farm or industrial uses. It is often a viable and economical alternative to conventional heating, cooling or heat pump systems since there are no compressors, chemicals or burners and only require a blower to move the air.

Most systems are usually four inch to eighteen inch diameter, smooth-walled, rigid or semi-rigid plastic or metal pipes, buried six to ten feet underground where the temperature is typically 50-70 degrees year round (in the northern hemisphere). There are basically three configurations, a closed loop design, an open 'fresh air' system or a combination.

With the closed loop system, air from inside the home or structure is blown through a U-shaped loop(s) of typically one hundred to five hundred feet of tube(s) where it is moderated to near earth temperature before returning to be distributed via ductwork throughout the home or structure. Larger diameter tubes need less total length.

The open system draws outside air from a screened intake in the yard through, typically, a hundred or more feet of straight tube into the home. The closed loop system is usually more effective than the open system since it cools and recools the same air.

A combination system can be crafted with unidirectional check valve dampers to allow either closed or open operation depending on the season and/or fresh air ventilation requirements. Such a combo design, even in closed loop mode, could draw a quantity of fresh air when an air pressure drop is created in the house by a fireplace chimney draft or attic fan.

Earth cooling tubes are, by their subterranean nature, usually located to penetrate the wall of a house's basement where they interconnect with a standard system of ventilation ductwork for distribution of the air throughout the home. As such, they may be better suited for new construction than for retrofit into an existing home, especially if there is a limited outside yard space to work with.

The efficiency of earth cooling tubes can vary widely depending on tube depth, climate, soil type, soil moisture content and ground level sun or shade. Generally sandy, dry soil with little or no ground level shade will yield the poorest benefit while dense clay or damp loam with considerable shade should perform well. Careful siting and making provision for adequate soil moisture, perhaps via landscape drainage or soaker hoses could be advisable. Damp soil absorbs and dissipates the warmth drawn off the tubes better than dry soil.
Ground-coupled heat exchanger
Ground-coupled heat exchanger
One drawback often cited to earth cooling tubes is the possibility of condensation buildup in the tubes and subsequent mold growth. A properly designed system that maintains a constant downward slope from the (upper) warm air intake end to the(lower) cool air outlet end should provide adequate drainage of condensation that can be handled by a floor drain, much like a conventional home air conditioning system. Also, it is important not to use corrugated or ribbed tubing as this would create traps where moisture would assuredly accumulate.

While some possibility of mold growth might still be possible, smooth round tubes should be much easier to clean than conventional rectangular metal ductwork found in the average home or office where mold growth is, of course, a common and accepted problem.

In the context of today's diminishing fossil fuel reserves, increasing electrical costs, air polution and changing climate, properly designed earth cooling tubes present an intriguing alternative for our heating and ventilation needs. Like solar heating, earth cooling tubes let us design and build in harmony with nature to achieve comfortable, clean, cost-effective and renewable homes for the future.
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Greenhouse Gas

A greenhouse gas is one which contributes to the greenhouse effect. Greenhouse gases are the most commonly considered factors in global warming.

Water vapor is the primary greenhouse gas, accounting for most of the greenhouse effect. In public policy discussions, however, water vapor is generally disregarded.

Other greenhouse gases include carbon dioxide, methane, nitrous oxide and chlorinated fluorocarbons (CFCs) such as freon. Carbon dioxide is the subject of a proposed global warming treaty (see Kyoto Protocol).

Since the beginning of the Industrial Revolution, the concentrations of many of the greenhouse gases have increased. Carbon dioxide is up 30%, methane over 50%, nitrous oxide 15%. Scientists agree that the increased concentration of greenhouse gases is caused by human activity, primarily the burning of fossil fuels.

As the concentrations of greenhouse gases in the atmosphere increases, some scientists believe, the temperature will increase, leading to harmful global warming. Other scientists believe that the global warming seen since the late 19th century is a natural recovery from the Little Ice Age.
See: global warming controversy, environmental agreements

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What is the Greenhouse Effect?

The greenhouse effect is one of the things that make life on Earth possible. The light from the Sun passes through the atmosphere and reaches the earth's surface where much of it is absorbed, thereby warming the surface. Some of the infrared radiation is reflected upwards again. The greenhouse gases in the atmosphere then reflects some of this radiation back to the surface again, thus utilizing some more of the energy from it.

The greenhouse effect is necessary for life on Earth, but recent years have seen it develop into global warming. Temperatures are increasing, causing disturbances to ecosystems.
Greenhouse Effect
Greenhouse Effect
The term greenhouse effect originally came from gardening. A greenhouse is built of glass roofs and windows to keep plants warm. Sunlight passes through the glass and warms up the plants and objects inside the greenhouse. The heat is radiated back as infrared in longer wavelengths. The longer wavelength outgoing infrared cannot penetrate glass as well as the shorter wavelength incoming radiation. In a sense, a greenhouse let more of the solar energy coming in than going out. The temperature inside the greenhouse builds up over time. The greenhouse effect refers to the heat trapping characteristics of a greenhouse.

Despite the higher visibility when associated with the global warming concern, the greenhouse effect can be observed in almost any enclosure with glass windows. One very common example is a passenger car in a hot summer day. The greenhouse effect can bring the temperature in a car up to as high as 180° F within a short time. In the US, a small number of children and a larger number of pets are killed by the greenhouse effect each year when careless parents and owners leave them in cars for a long period of time.
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How a Gas Turbine Works?

A gas turbine is a turbine that uses some form of gasseous fuel.

Generally speaking, the fuel is stored in liquid form for convenience. It is mixed with compressed air and burned, which greatly increases the "potential volume" of the air (ie, it wants to get much larger). From there it is directed out an expanding nozzle, flowing past the turbine on the way.
Gas Turbine
Gas Turbine

The most common form of gas turbine in the jet engine. Jet engines typically use the power extracted from the turbine to drive the compressor and fuel systems.

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Fuel oil

Fuel oil is a fraction obtained from petroleum distillation. Fuel oil is the heaviest commercial fuel that can be obtained from crude oil; it is heavier than gasoline and gas oil, its boiling temperature ranging from 370 to 600 ÂșC. It is made of long hydrocarbon chains (from 20 to 70 carbon atoms), particularly alkanes, cycloalkanes and aromatics. As a fuel, it is mainly used for ship propulsion. Fuel oil is classified into six classes, according to its boiling temperature, composition and purpose. The lightest is fuel oil no. 1, the heaviest fuel oil no. 6.
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Fossil-fuel power station

Synonyms: Steam electric power plant (US); thermal power power plant (asia) or power station (UK). A fossil fuel power plant (FFPP) is an energy conversion center designed on a large scale for continuous operation. Just as a battery converts relatively small amounts of chemical energy into electricity for temporary or intermittent use, the FFPP converts the sun's energy stored in [fossil fuels]] such as coal, oil, or natural gas successively into thermal energy, mechanical energy, and finally electric energy for continuous use and distribution across a wide geographic area. Each FFPP is a highly complex, custom designed system, costing over $1000/kw, or $500 million for a 500MWe unit. Multiple generating units may be built at a single site for more efficient use of land, resources, and labor. The operational descriptions below are typical and will vary from one plant to the next.
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Filling station

A gas station or gasoline station is a place that sells gasoline and diesel fuel. In the United Kingdom and Ireland they are known as Petrol Stations where they sell petrol anddiesel fuel.

Gas stations were known to offer free oil company road maps as a strategy to build brand loyalty. However, the oil companies discontinued distributing free maps in the 1970s. Nowadays, the stations sell maps produced by Rand McNally and the AAA (American Automobile Association) and CAA (Canadian Automobile Association).

Gas stations sell gasoline by the US gallon in the United States and by the litre (US: liter) in Canada, Mexico, and most parts of the world.

There are generally two types of gas stations: premium and discount brands.
Gas stations with premium brands are often international brands that include Esso, Exxon, Chevron, Mobil, Shell, Sinclair, and Texaco. They accept credit cards and often have much higher prices. The stations are numerous in locations and much more modern with brighter lighting and are cleaner. For ease and convenience, these stations have pay-at-the-pump facilities.

Discount brands are often smaller regional chains or independent stations. Most purchase wholesale gasoline from suppliers. In some cases, discount brands typically accept cash only. Many discount stations have a few locations and, in some cases, appear outdated (i.e., non-digital pumps) and rundown. An exception is the discount brand Arco (part of BP), which has a combination of modern and dilapidated stations. Lower price gas stations are also found at some co-ops, supermarkets (Albertsons, Kroger, and Vons), convenience stores (7-Eleven), mass merchandise stores (Wal-Mart)and membership warehouse stores (Costco). A membership at some stations (e.g., the supermarkets and membership warehouses) is required to receive the discounted price.

A gas station that also offers such services as oil change and mechanical repairs to automobiles is called a service station. Until the 1970s the vast majority of gas stations were service stations; now only a minority are.

In the UK, a 'service station' refers to much larger facilities, usually attached to motorways or major trunk routes, which provide food outlets, large parking areas, and often other services, such as hotels, arcade games, and shops in addition to 24-hour fuel supplies and a higher standard of restrooms. Fuel is typically more expensive from these outlets due to their premium location. UK service stations do not usually repair automobiles. In parts of the U.S. this arrangement occurs on tollroads and is called an oasis. In the US, the TravelCenters of America is one the largest full-service chains.

Some gas stations have a smaller fast food outlet inside such as a McDonald's, Jack in the Box, Pizza Hut, or Taco Bell. They are usually express versions with limited seating.

Many stations are self-service. However, in some American states like Oregon and countries like Mexico, gas stations are exclusively mini-service or full-service.
British petrol pumps differ from US and Canadian gas pumps. The latter involves turning on the pump first by lifting a lever and then selecting the proper octane by pushing a button. In most cases, British visitors to Canada or the United States would likely have some difficulty using the gas pumps at stations.

Some gas stations are equipped with car washes. They are sometimes free of charge with a certain amount of gas purchase (usually 8 US gallons or more). This promotion is usually advertised near the gasoline price boards.

Many gas stations have air compressors with tire guages and water machines. Some machines are free of charge whereas some may charge a small fee to use (usually 25 cents to $1). In many states of the US, free air must be provided for paying customers as required by law. In most cases, a token provided by the attendant is used in lieu of coins.

Gas stations also provide squeegees, towels, and restrooms for customer use. But a large number of discount gas stations do not provide these amenities. The cleanliness and standards of gas station restrooms vary and a restroom in a fast food restaurant would be a better choice.

In the United States, many gas stations are also convenience stores that sell food, beverages, cigarettes, motor oil, and sometimes auto parts, among other things. Prices tend to be higher at these convenience stores when compared to a supermarket or mass merchandiser.
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What is Biomass?

In industrial contexts, biomass refers to living and recently living biological material, usually plant matter grown for use as biofuel. It excludes organic material which has beentransformed by geological processes into substances such as coal or petroleum. It is usually measured by dry weight.
Most plant matter that can be processed into various industrial material:
biofuel (including biodiesel, methanol fuel, and ethanol fuel)
building materials
biodegradable plastics and paper (using cellulose fibers)
In industry, biomass is grown from several plants, including switchgrass, hemp, corn, and sugarcane.
Biomass is a growing industry as interest in sustainable fuel is growing.
Biomass
Biomass

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Types of Biofuels

Classes of Biofuels

Solid biofuels
Wood — see Wood heat
Liquid biofuels
Bioalcohols — see alcohol as a fuel.
Ethanol (not produced from petroleum) - A significant amount of ethanol produced from sugar cane is being used as automotive fuel in Brazil. Ethanol produced fromcorn is being used as a gasoline additive (oxygenator) in the United States.
Methanol - Currently, methanol is produced from natural gas. It is possible, but not economically viable at anywhere near current price levels, to produce methanol from biomass (biomethanol).
Straight vegetable oil (SVO) - used in modified diesel engines.
Waste vegetable oil (WVO)
Biodiesel - obtained from animal fats and vegetable oil (vegoils), using transesterification. Properly processed biodiesel is satisfactory for use in diesel cars.
Biofuel
Biofuel
Energy obtained from biomass, this is, from renewable sources, not like petrol and fossil fuels.
There is two main classes :
Ethanol and methanol natural alcohols: you cannot use a 100 % bioalcohol in your gasoline petrol car.
Significant amounts of ethanol (produced from sugar beets) are used as automotive fuel in Brazil.
Significant amounts of ethanol (produced from corn) are used as a gasoline additive (oxygenator) in the United States.

Currently, methanol is produced from natural gas. It is possible, but not economical at anywhere near current price levels, to produce methanol from biomass.
Biodiesel: you can use a 100 % biodiesel in your nowadays diesel petrol car. Biodiesel is obtained from animal fats and vegetable oil (vegoils).
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