A Vertical Axis Wind Turbine design from the 1920s and 1930s by F.M. Darrieus, a French wind turbine designer.
Search the Web for DarrieusThe number of consecutive days the stand-alone system will meet a defined load without solar energy input. This term is related to system availability.
Search the Web for Days Of StorageAgreement in which a certain amount of foreign debt is canceled in exchange for local currency investments that will improve natural resource management or protect certain areas in the debtor country from harmful development.
Search the Web for Debt-for-nature SwapPerennial plants whose leaves die all at once (and usually fall) at the end of each growing season, to be replaced by new leaves at the next growing season. Most deciduous plants are broad-leaved, though a few, such as Larix laricina (Tamarack), have needles. Plants whose leaves live year-round are evergreen.
Search the Web for DeciduousThe release of a substance (usually a gas when referring to the subject of climate change) into the atmosphere.
Search the Web for DecomposerA 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.
Search the Web for Deep Cycle BatteryThe number of consecutive days the stand-alone system will meet a defined load without solar energy input. This term is related to system availability.
Search the Web for Deep DischargeAbility of materials to break down, by bacterial (biodegradable) or ultraviolet (photodegradable) action.
Search the Web for DegradabilityRemoval of nitrate and nitrate product from water to produce a quality that answeres common water standards.
Search the Web for DenitrificationThe tendency of a population's growth rate to depend on its size, with an increase in population density corresponding to a decrease in growth. This self-regulating dynamic helps prevent extinction.
Search the Web for Density DependenceThe conversion of salt or brackish water into usable fresh water. Distillation is the most common commercial method; heat from the Sun or conventional fuels vaporizes brine, the vapor condensing into fresh water on cooling. Reverse osmosis and electrodialysis both remove salt from water by the use of semipermeable membranes; these processes are more suitable for brackish water. Pure water crystals may also be separated from brine by freezing.
The biggest problem holding back the wider adoption of desalination techniques is that of how to meet the high energy costs of all such processes. Only where energy is relatively cheap and water particularly scarce is desalination economic, and even then complex energy conservation procedures must be built into the plant.
Search the Web for DesalinationThe 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.
Search the Web for DesertificationThe month having the combination of insolation and load that requires the maximum energy from the photovoltaic array.
Search the Web for Design MonthAnimals and plants that consume detritus (decomposing organic material), and in doing so contribute to decomposition and the recycling of nutrients.
Search the Web for DetritivoreA pesticide used on citrus fruits.
Search the Web for DicofolA condition in trees or woody plants in which peripheral parts are killed, either by parasites or due to conditions such as acid rain.
Search the Web for DiebackSunlight falling directly upon a collector. Opposite of diffuse insolation.
Search the Web for Direct InsolationWater that flows from the ground surface directly into streams, rivers, and lakes.
Search the Web for Direct Run-offAir pollutants dropped by prevailing winds.
Search the Web for Dirty FalloutDispatchability is the ability of a power plant to be turned on quickly to a desired level of output. Wind power plants are not dispatchable.
Search the Web for DispatchabilityA Dispersion Trench is a method by which effluent after processing is distributed back into the environment in a way which reduces environmental impact. They often positioned so that the effluent is distributed by a grid of trench pipes into the soil directly; the aim being that the effluent never gets to the surface.
DERs. A variety of small, modular power-generating technologies that can be combined with energy management and storage systems and used to improve the operation of the electricity delivery system, whether or not those technologies are connected to an electricity grid.
Search the Web for Distributed Energy ResourcesThe difference between maximum and minimum temperature over a period of 24 hours.
Search the Web for Diurnal Temperature RangeA unit used to measure the abundance of ozone in the atmosphere; one Dobson unit is the equivalent of 2.69 x 1016 molecules of ozone/cm2.
Search the Web for Dobson UnitA traditional window style with two glass-holding frames that slide past each other vertically.
Search the Web for Double-hung WindowsDowncycling is the recycling of a material into a material of lesser quality. For example, when plastics are recycled they are turned into a lower grade quality plastic.
Search the Web for DowncyclingThe 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.
Search the Web for DownwellingThis is the total surface area, upstream of a point on a stream, where the water from rain, snowmelt, or irrigation not absorbed into the ground flows over the ground surface, back into streams, to finally reach that point.
Search the Web for Drainage AreaThe practice of spraying water directly on the base of plants so that less water is needed to make them grow.
Search the Web for Drip IrrigationEmissions of sulphur and nitrogen oxides that, in the absence of water in the atmosphere (i.e., rain), settle to the ground as particulate matter.
Search the Web for Dry DepositionA type of farming practiced in semi-arid or dry grassland areas without irrigation using such approaches as fallowing, maintaining a finely broken surface, and growing drought-tolerant crops.
Search the Web for Dry FarmingA crumbling and drying of wood that is caused by a fungus; turns wood into powder.
Search the Web for Dry Rot(water management) Accumulation of salts in soils, soil water and ground water; may be natural or induced by land clearing
Search the Web for Dryland SalinityDryland systems are ecosystems characterised by a lack of water. They include cultivated lands, scrublands, shrublands, grasslands, savannas, semi-deserts and true deserts.
Search the Web for Dryland SystemsA device to which wind generator power flows when the system batteries are too full to accept more power, usually an electric heating element. This diversion is performed by a Shunt Regulator, and allows a Load to be kept on the Alternator or Generator.
Search the Web for Dump LoadAcidic bodies of water that contain many plants but few fish, due to the presence of great amounts of organic matter.
Search the Web for Dystrophic Lakes