Definitions - g


The process by which an organic material, such as biomass, is converted into synthetic gas, a mixture of hydrogen gas and carbon monoxide. The synthetic gas can then be used to produce various synthetic fuel constituents.

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Gassing Current

The portion of charge current that goes into electrolytical production of hydrogen and oxygen from the electrolytic liquid. This current increases with increasing voltage and temperature.

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General Circulation Model

A global, three-dimensional computer model of the climate system; GCM's are highly complex and they represent the effects of such factors as reflective and absorptive properties of atmospheric water vapor, greenhouse gas concentrations, clouds, annual and daily solar heating, ocean temperatures and ice boundaries. The most recent GCM's include global representations of the atmosphere, oceans, and land surface.

They are often used to model the effects of human induced climate change into the future; but the accuracy of the models are highly dependent upon:

  • The accuracy of the initial starting conditions;
  • The accuracy of how the climatic processes are modeled, and;
  • The accuracy of the assumptions made in the model construction.
Like all modeling systems that attempt to predict the future the further they attempt to 'look' into the future the more inaccurate they become with respect to reality.

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Genetically Modified Organism

Genetically Modified Organisms (GMOs) are organisms whose genetic materials have been altered using genetic engineering.

There are concerns that GMOs contribute to environmental concerns such as increased cancer risk, allergens, toxins, and contamination.

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GeoExchange System

A geoexchange system is an electrically powered heating and cooling system for interior spaces. This system utilizes the earth (or a pond or lake) is both a heat source and a heat sink. Components of the system include a heat pump, a hydronic pump, a ground heat exchanger and a distribution subsystem. Most geoexchange systems utilize air ducting for the distribution system and polyethylene piping in the earth for the heat exchanger.

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Pertaining to those processes that affect the form or shape of the surface of the earth.

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The soils, sediments, and rock layers of the Earth's crust, both continental and beneath the ocean floors.

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Geostrophic Wind

A theoretical horizontal wind blowing in a straight path, parallel to the isobars or contours, at a constant speed. The geostrophic wind results when the Coriolis force exactly balances the horizontal pressure gradient force.

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A variety of fabrics made from recycled materials used in soil containment and stabilization.

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Geothermal Energy

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Geothermal Heat Pump

A Geothermal heat pump is the pump system used in a ground heat transfer system to heat a property using the latent heat in the earth.

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Ghost Acres

Land used to grow feed for animals being reared for meat and dairy production. Ghost acres are often in poorer countries, used to grow feed for cattle in richer nations, and so are not seen by consumers in rich countries, hence the term.

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Goddard Institute of Space Studies – a US NASA unit.

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A multi-year surplus accumulation of snowfall in excess of snowmelt on land and resulting in a very large mass of ice.

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Glass Recycling

Glass bottles and jars can be recycled endlessly. Which means that unlike some other recycled products, a recycled bottle can be recycled into another glass bottle, and another, and so on forever.

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Glazing Factor

The ratio of interior illuminance at a given point on a given plane to the exterior illuminance under overcast sky conditions.

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Global Carbon Budget

The balance of the exchanges (incomes and losses) of carbon between the carbon reservoirs or between one specific loop (e.g., atmosphere biosphere) of the carbon cycle. An examination of the carbon budget of a pool or reservoir can provide information about whether the pool or reservoir is functioning as a source or sink for CO2.

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Global Radiation Balance

A balance, which implies that globally the amount of incoming solar radiation must on average be equal to the sum of outgoing reflected solar radiation and outgoing infrared radiation emitted by the climate system.

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Global Surface Temperature

The average of the sea temperature in the first few meters of the oceans and the temperature 1.5 m above ground on land surfaces.

Note: This is very subjective, the method of calculation and extrapolation to synthesis temperature for regions where there is scant direct temperature measurement (such as at the Poles), varies a lot.

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Global Warming

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Global Warming Potential

The GWP is the ratio of the warming caused by a substance to the warming caused by a similar mass of carbon dioxide. Thus, the GWP of CO2 is defined to be 1.0 . CFC-12 has a GWP of 8,500, while CFC-11 has a GWP of 5,000.

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A polyethylene or polyvinyl chloride bag-like enclosure affixed around an asbestos-containing source (most often thermal system insulation) permitting the material to be removed while minimizing release of airborne fibers to the surrounding atmosphere.

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See definition of e-waste.

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Gluten Free

Gluten Free refers to food or a diet which has a greatly reduced amount of Gluten in it. It may indeed be totally gluten free but it practice this is usually very hard to achieve as gluten is found in so many off the shelf foods and ingredients - often not directly referred to in the labeling.

The exact level at which gluten is harmless is uncertain and controversial. A recent systematic review tentatively concluded that consumption of less than 10 mg of gluten per day is unlikely to cause histological abnormalities, although it noted that few reliable studies had been done.

Also exactly what the label gluten-free actually means on food varies markedly by country.

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Gluten Free Diet

A Gluten Free Diet is a diet which has had all gluten removed from it.

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Gluten Intolerance

Gluten Intolerance (or Gluten Sensitivity) is a spectrum of disorders, including coeliac disease and wheat allergy, in which gluten has an adverse effect on the body. It can be defined as a non-allergic and non-autoimmune condition in which the consumption of gluten can lead to symptoms similar to those observed in Coeliac Disease or wheat allergy (other conditions which fall under the gluten-related disorders spectrum).

Research as to the exact mechanism in play is still ongoing and how it fits in with other food disorders.

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Going Green

Going green refers to action that can be taken to consciously curb harmful effects on the environment through consumer habits, behavior, and lifestyle.

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Government Solar Rebates

A government solar rebate is where the government provides a payment or rebate against the cost of installing a solar power system.

This is either in the form of a direct payment or carbon credit multipliers (where the number of carbon credits the system has is multiplied).

Usually you don't get to deal with the rebate directly, the system installer will take care of the paperwork for you and your installation cost will be discounted by the amount of the rebate.

There is some debate over whether the rebate mechanism has 'distorted' the market and made solar seem overly competitive when compared to other methods of generating power.

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Granular Activated Carbon Treatment

filtering system often used in small water systems and individual homes to remove organics. Also used by municipal water treatment plantsd. GAC can be highly effective in lowering elevated levels of radon in water.

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Gray Water

Domestic wastewater composed of wash water from kitchen,
bathroom, and laundry sinks, tubs, and washers.

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Green Advertising

Green Advertising is either the advertising of a green product or service, or the act of advertising itself is green (such as reverse graffiti or green graffiti).

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Green Architecture

Green Architecture refers to the process of designing a building to have a reduced environmental impact either by reusing existing materials or using new materials in a lower impact way. Green architecture also focuses on reducing the ongoing energy consumption of the building.

Note: This does not mean than an existing building cannot be made more Green, rather it encompasses making sensible use of what is preexisting in a way that is more Green. Often reusing a building than completely removing it can have a dramatic positive impact on reducing environmental impact over the longer term.

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Green Building

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Green Christmas

A green Christmas is where the celebration of Christmas is done in such a way that the presents & gifts, the party, the dinner, food and venue are all chosen to minimize environmental impact.

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Green Clothing

This is clothing and other accessories that are designed to use organic and recycled materials, less packaging and more energy-efficient manufacturing.

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Green Collar Worker

A green-collar worker is a worker who is employed in the environmental sectors of the economy, or in the agricultural sector. Environmental green-collar workers satisfy the demand for green development. Generally, they implement environmentally conscious design, policy, and technology to improve conservation and sustainability. Formal environmental regulations as well as informal social expectations are pushing many firms to seek professionals with expertise with environmental, energy efficiency, and clean renewable energy issues. They often seek to make their output more sustainable, and thus more favorable to public opinion, governmental regulation, and the Earth's ecology.

Wikipedia Entry

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Green Fatigue

Describes becoming tired with some of the constant messages of corporate green credentials and tales of impending global doom.

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Green Finance

Green Finance is money that is provided to fund Green Projects and is often supplied by a dedicated Green Fund or business. The idea being that the money is put to good use on Green causes and any profit made is then further spent on other Green Projects.

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Green Graffiti

Green Graffiti is an environmentally friendly form of outdoor art (or advertising), idea being to leave the place where the art occurs greener than prior to the art. How this greening is achieved is usually by one of three means:

  • Painting with a bio sourced natural paint equivalent (like moss, for a recipe see here and examples here) such that the living form is the art or advertising message, or,
  • Planting into a structure or wall so that the planting forms the art or advertising message, or,
  • Cleaning a surface in such a way as to leave the art or advertising message as required by the act of careful cleaning alone (also referred to specifically as reverse graffiti).

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Green Graffiti Removal

Green Graffiti Removal refers to the usage of green methods of removing graffiti; e.g. no nasty chemicals or processes are used that could damage the environment.

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Green House

A 'green house' used to just refer to a building with lots of glass designed to trap heat for the purpose of growing plants. Nowadays it also refers to a home that has been specially designed to follow 'green' design principals by reducing energy consumption and damage to the environment.

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Green Investment

Carbon Pollution refers to the human produce Co2 that is meant to be harming the environment.

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Green Manure

In agriculture, a green manure is a type of cover crop grown primarily to add nutrients and organic matter to the soil. Typically, a green manure crop is grown for a specific period, and then plowed under and incorporated into the soil.

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Green Marketing

If a business practices some form of sustainability or takes conscious action to limit its environmental impact (by reducing waste and limiting the consumption of resources for example) then that business is in a position to employ green marketing.

Green marketing is communicating environmental credentials to business partners, clients and consumers within a marketing context. In this way a conscious consumer or business is more likely to have their awareness of that business raised.

Of course green marketing has to be truth based or it turns into a form of green washing if things are exaggerated or untrue. In some cases this exaggeration can be illegal!

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Green Pesticides

Green pesticides, also called ecological pesticides, are pesticides derived from organic sources which are considered environmentally friendly and causing less harm to human and animal health, and to habitats and the ecosystem.

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Green Procurement
Green procurement is probably better described as sustainable procurement. This means that suppliers must tick all the boxes on environmental issues, such as: reduced packaging, less pollutants, energy efficiency, water conservation, etc. But there is more, suppliers also need to treat their workers fairly, offer a safe workplace and purchase their own inputs in a similarly sustainable fashion.

For example, Hewlett-Packard adopted the Electronics Industry Code of Conduct in 2004, and has now signed up 557 of its biggest suppliers. The code covers a wide range of issues including: the environment, ethics, how workers are treated and safe working conditions.

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Green Roof

A green roof is a conventional roof covered with a layer of vegetation, also known as “living roofs”. Green roofs serve several purposes for a building, such as absorbing rainwater, providing insulation, creating a wildlife habitat and helping to lower urban air temperatures and combat the urban heat island effect. There are two types of green roofs: intensive roofs, which are thicker and can support a wider variety of plants but heavy and require ongoing maintenance, and extensive roofs, which are covered in a light layer of vegetation and are lighter than an intensive green roof.

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Green Search

A Green Search refers to the act of using the internet to find environmental or green related information and facts. This is often performed on 'green search engines' that are dedicated to the task and focused on indexing solely green and environmentally related sites (as the EcoWho search engine does).

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Green Technology

Green Technology is Technology which is either itself considered green by its design or its intended purpose.

Technology that is Green in of itself has been designed to not pollute the environment during its manufacturer or final decommissioning, Technology that is Green by purpose is technology which is used to implement a service or process which in of itself is considered Green.

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Green Washing

Green washing is a superficial nod to the environment that marketers and businesses that historically were not interested in sustainable concerns, are doing in order to improve their public relation standings with the consumer or public. 

Businesses have recognized that a significant percentage of consumers are concerned about the environment in some form and green washing allows companies to appeal to these consumers whilst doing very little indeed to help the environment. Watch out for 'bolt on' certifications, far future pledges and vague commitments dependent on or in partnership on others to deliver.

This is analogous to brain washing. Do not be fooled by dishonest companies employing green washing techniques.

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GreenGuard certification for a product indicates it has been tested to ensure chemical and particle emissions meet acceptable standards. It uses performance-based standards to define goods such as building materials, interior furnishings, furniture, cleaning and maintenance products, electronic equipment and personal care products with low chemical and particle emissions for use indoors.

The standards establish certification procedures including test methods, allowable emissions levels, product sample collection and handling, testing type and frequency, and program application processes and acceptance.

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Greenhouse Gas

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Grey Water System

A grey water system is a water processing system that uses slightly dirty water (as from a shower or basin) to allow it to then be reused for irrigation purposes. 

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Grid Connected

Grid connected refers to a solar panel electrical system which is connected to the mains power grid, so any excess power it generates can be fed back into the mains power grid. The owner of the solar panel system can often earn 'credits' for feeding in such power.

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Grid-tie Inverters

This refers to devices used to change DC Power into AC Power. Grid tie Inverters are different from regular Inverters in that they are designed to 'feed-into' the existing electric supply to your building.

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Grime Writing

An alternative phrase for Green Graffiti.

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Ground Source Heat Pump

These heat pumps are underground coils to transfer heat from the ground to the inside of a building.

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Ground Water

The supply of fresh water found beneath the Earth's surface, usually in aquifers, which supply wells and springs. Because ground water is a major source of drinking water, there is growing concern over contamination from leaching agricultural or industrial pollutants or leaking underground storage tanks.

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Ground-Water Discharge

Ground water entering near coastal waters which has been contaminated by landfill leachate, deep well injection of hazardous wastes, septic tanks, etc.

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Guerrilla Gardening

Guerrilla gardening describes the unauthorized cultivation of plants or crops on vacant public or private land. The aim being to improve the often neglected, barren or overgrown spaces. Often its also done as a form of political or social statement.

The act of guerrilla gardening is either often done overnight to avoid unwanted attention; or it is done in plain sight to get community involvement.

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Gulf Stream

A current of warm ocean water that flows from the Gulf of Mexico to the coasts of Europe, providing heat that keeps Europe warmer in winter than regions of North America at the same latitude.

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Click on a letter to see all the terms and definitions that begin with that letter.

A free Android app containing all these definitions is now available, called the Green Dictionary. Click here to see the entry on the Android market; or click here if on an Android phone.