Bubbles Domes Geothermal Urban (1981) Meaux 77100 (France)
What is Geothermal Energy ?
The further down in the crust, more rock and groundwater are hot. Various geothermal techniques used to recover this heat, according to the different temperatures. But the heat reservoir is not inexhaustible ...
the average increase in temperature all 100 m deep.
geothermal, geo Greek (Earth) and thermos (the heat) is a word that refers to both the science that studies the internal thermal phenomena of the Earth, and technology that seeks to exploit. By extension, geothermal energy also means sometimes geothermal energy from the Earth energy is converted into heat.
To capture geothermal energy, a fluid is circulated into the depths of the Earth. This fluid may be that of a sheet of natural captive hot water, or the injected water under pressure to fracture a hot rock and waterproof. In both cases, the fluid is heated and rises loaded with calories (thermal energy). These calories are used directly or converted partially into electricity.
Geothermal energy is locally exploited for heating or hot water have for millennia, for example in China, in ancient Rome and in the Mediterranean basin.
The temperature of the hot water geo increases with depth, depending on the thermal gradient of each region (average increase of temperature as a function of depth). The gradient has an average global value 3 it's for 100 m deep.
He then ranges between:
1 it's for 100 meters and 10 it's for 100 meters, depending on the physical and geological conditions of the region.
The different types of geothermal
Geothermal techniques differ depending on the temperature of the geothermal water, which also defines the use that is made of these waters :
– between 20 ° C 90 °C, heat and geothermal water are used for geothermal heating. This is the low geothermal energy .
– between 90 ° C 160 °C, water is used at the liquid surface of. It transfers its heat to another fluid, which vaporizes at low temperatures and actuates a turbine for electricity generation. This is the average geothermal energy.
– Beyond 160 °C, this water is then in vapor form when it reaches the ground surface. It turns turbines whose movement also generates electricity.
This is the high geothermal energy.
Boundaries so defined temperature ranges are indicative, and uses may vary depending on economic conditions of places considered.
The availability of geothermal resources
This heat is variable depending on the zone. In the globe, the mean heat flow is low (it is the energy available to an area and time period). This flow amounts to 0,06 watts per square meter per year, is 3 500 times less than the solar flux received in a year by the same soil surface ! Therefore the heat resources of certain areas may provide significant amounts of energy priority in seeking to exploit. These "geothermal reservoirs" are available in all sedimentary basins in the world but the high geothermal energy lies mainly near volcanoes. In these areas, the heat flow can reach 1 watt/m²/an.
Geothermal reservoirs tend to run out in as and their exploitation, some faster than others. Their replacement capacity based on :
internal heat sources in the Earth's crust (essentially radioactivity and residual heat) .
energy input from outside of the reservoir (solar heat) for uses very low temperature by means of heat pumps (PAC). Ensuring these global conditions is all the more crucial for GSHP the basement is also cooled by external factors : in winter, for example, less heat is collected there.
the groundwater flow that allows them to warm in contact with heat sources remote reservoir, before returning thereof. So, to be able to operate a sustainably tank, we must ensure the gradual replenishment of its resources calorific. This involves capping the amounts of heat removed and the time limitation of the operation of the site.
In addition, the availability of geothermal energy is limited geographically. The heat transport over long distances in fact generates significant heat loss. This results in difficulty in matching places of production and consumption locations to cover the energy needs.
Networks of Heat and Electricity Generation for City..
The City of Meaux, which was engaged in the development of geothermal energy from 1982, now has geothermal district heating together the largest in France.
Thanks to the presence of 2 thermal power plants and 8 well, located in the district Beauval / Collinet (3 doublets) and the Hospital District (1 doublet), geothermal feeds a long district heating network 43 km of which heat is from the Dogger, groundwater basin Parisian.
So, 15 000 housing are powered (75 % the heat produced), a total of 21 000 dwellings in the City. The hospital, municipal buildings and many school groups also benefit from the geothermal heating. exploitation, managed by the Joint Association for Geothermal Meaux, the subject of a public service contract awarded to Energie Meaux (Coriance group).
An amendment to the public service delegation, concluded in November 2011, provided significant work : Rehabilitation of existing geothermal wells for reinjection operation,
drilling 3 new production wells (2 and in Beauval 1 to the hospital), the establishment of a heat pump on the network Beauval.
Meaux is one of 10 % Urban heat networks Cheapest in France.
Between 1998 and 2012, increased geothermal heating prices was lower than inflation (22,1% against 25,09%) and much lower than the increase in prices of other energy sources such as oil (383,8 %) or gas (114,8 %). Eventually, there is a reduction in CO2 emissions 11 700 t./an, equivalent to the annual emissions 9 800 Car. Brought wide Meaux, this would be equivalent to reducing 40 % traffic of its inhabitants.
In 2013, Meaux incurred upgrades its geothermal heating network that will soon be completed.
More than 20 million of investments and invested to strengthen the capacity of geothermal generation in the city.
The geothermal heat network of Meaux being modernized:
Work is almost completed. With 26 million invested in modernization and
the extension of geothermal Meldois network, the site is quiet for thirty years !
The Domes of Geothermal Site Meaux (77)