A renewable energy is a source of energy renewing itself rather quickly to be regarded as inexhaustible on human scale of time. Renewable energies result from regular or constant natural phenomena caused by the Astre S, mainly the Sun (radiation, cycle of evaporation, photosynthesis, Biocarburant S…).
One attaches to it sometimes wrongly, although without difference practices on the short term,
- the energy caused by the clean rotation of the Earth compared to the system Ground - the Moon (Marée), and
- the heat which one can exploit of the geothermic Gradient resulting from accumulated heat and perhaps also of internal nuclear reactions to the Ground (geothermal energy).
The renewable character of an energy depends on the speed to which the source is regenerated, but also speed to which it is consumed. Thus, the Bois is an renewable energy as long as one cuts down less trees than it does not push any, and than the forest continues to play its vital ecological functions. The behavior of the consumers of energy is thus a factor to be taken into account in this definition.
The concept of renewable energy is often confused with that of clean energy and/or sure. However, even if an energy can be at the same time renewable, clean and sour, all renewable energies are not necessarily clean nor sour: for example, the first refrigerating fluids used (CFC) were gases which, in the event of escape, contributed to the Greenhouse effect and precipitated the destruction the Couche of ozone. One does not know either for the moment how to very manage with long run of the Nuclear waste with high and average activity.
Renewable energies of the type wood, solar, Hydroélectricité… are all resulting from solar energy. Only the Geothermics and the Marée S escape this rule. Except the tidal energy coming from the combined of the Sun and the Moon, all renewable energies and nonrenewable attraction forces thus originate in direct or indirect the natural nuclear energy, coming: either of the sun, (due to the nuclear Fusion of the Hydrogen), or of the Earth, (due to the natural Disintegration of the rocks of the Earth's crust).
The Oil, the Natural gas and the coal are not renewable energies because one will need million years to reconstitute stocks of fossil energy which one currently consumes. In the same way, current nuclear energy, resulting from the atomic fission of Uranium, cannot be regarded as an renewable energy, the reserve of uranium available on Earth being limited. Only the engines with fusion, in project, using Isotopes hydrogen present in the water of the oceans in way quasi unlimited on a human scale), would be means of energy productions not presenting a problem of renewals. Still would be it very polluting because of the quantity of fast neutrons which it generates in the majority of the cases of figure (see however Z machine).
Combustion of wood
The beginning of the use of the Combustible Wood like , or Wood energy, is contemporary control of the Feu. Wood is used as thermal energy source in order to heat and to cook, but also to dehydrate or to smoke the food for better preserving them.
Thereafter, it was discovered that a combustion slow and partial of wood with a tiny oxygen contribution made it possible to produce Charcoal. This last provides more heat than wood and represents a more compact energy source. It is also a purer source of carbon, which makes it useful in the Métallurgie of the Fer for the production of cast iron and Acier. However, the charcoal is not an effective energy source, except recovering the great quantity of energy of wood lost during its manufacture.
The Sylviculture for production of firewood is in competition with the food uses of cultivable surfaces and is consuming virtual Eau.
Recently, a novel method of combustion of wood was developed: the Pellet or granulated wood. The pellet wood is a natural fuel substitute of fuel, intended to supply the boilers of the private individuals and communities. It is produced starting from related sawmill (sawdust, chips, forest plate…).
Many civilizations made use of the force of the water, which represented one of the most important energy sources before the era of the electricity. A known example is that of the water mills, placed along the rivers. Today, although many sites were equipped perfectly, that is not enough any more to compensate for the vertiginous increase in consumption. Nowadays the hydraulic power is used on the level of the stoppings and is used mainly for the electrical production.
In 1961, hydraulics - thus the renewable one - accounted for 51% of the electrical production in France (source: Booklet of reception EDF , 1962).
It was exploited at the origin using windmills equipped with blades in the shape of veil, as those which have can see with the Netherlands or those mentioned in Don Quichotte . These mills made it possible to pump water or to actuate grinding stones to grind the grain. Today, one finds this system in wind S of pumping. Smaller and having more blades than a traditional mill, they turn more quickly. One can find some in particular in the large plains of the the United States.
Another ancestral use of wind energy, much older still than the windmills, is the driving power of the wind, used as of the Antiquité to move on water with Bateau X with veil, as the solar Barque to it testifies to Khéops.
Passive solar energy
The solar energy passivates was for a long time used like energy source in the Architecture. Technologies recently evolved/moved, allowing the realization of passive solar houses completely optimized from a thermal point of view. The performances can more or less approach energy autonomy according to the investment. Certain projects, as to Gennevilliers, aim at building office buildings producing more electricity than they do not consume any.
Geothermal energyThe Greeks and the Romans of antiquity knew already the use of the geothermal energy, as the towns testify some of water, " Aquae Sextiae" , of the Consul Sextius (Aix-en-Provence, Aix-the-Baths, Aachen,…), but also the provençaux well which they built to air-condition their dwellings. Heat-Acute, water spouting out with 81° makes it possible to heat with few expenses some buildings.
Energy of the plants
See also: Biomass (energy)
It is about solar energy stored in organic form thanks to the Photosynthèse. This energy is exploited by Combustion. This energy is regarded as renewable if it is admitted that the burned quantities do not exceed the produced quantities. One can in particular quote the Bois and the Biocarburant S.
See also: Solar energy
thermal Solar energy, production of heat, by energy transformation contained in the solar, very profitable radiation for the heating in the sunny areas.
- thermodynamic Solar energy or Heliothermodynamique or Thermosolaire, production of vapor starting from the heat of the sun by concentration, then conversion of the vapor into electricity,
- Energy photo voltaic, electrical production starting from the light, in particular using Solar panels.
- Solar energy passivates, use direct of the light for the heating.
- solar, also named Veil photovoile , for the space zones step too far away from the sun.
Energy of water
See also: Hydraulic power
- Energy of the waves: use the power of the movement of the Vague S,
- tidal Énergie: exit of the movement of water created by the Tide S (variations of the sea level, currents of tide),
- Energy hydrolienne: The Hydrolienne S use the currents submarines,
- marethermic Énergie: produced by exploiting the difference of Temperature between surface waters and deep water of the Ocean S,
- osmotic Energy: The ionic diffusion caused by the fresh water arrival in salt water of the sea is energy source.
Energy of the wind
See also: Wind energy
It can be used in two manners: in a direct and indirect way.
- Mechanical Conservation of energy : the wind is used to advance a vehicle (Sailing ship or Sand yacht), to pump water (mills of Majorque, wind S of pumping to water the cattle) or to make turn the grinding stone of a Moulin.
- Transformation into electrical energy: the wind is coupled with a electric Générateur to manufacture a D.C. current or alternate, the generator is connected to an electrical communication or it functions in an autonomous way with an auxiliary generator (for example a Generator) and/or a park of battery S or another device of Stockage of energy.
Energy interns Earth
See also: Geothermal energy
The principle consists in extracting the geothermal energy contained in the ground to use it in the form of Chauffage or to transform it into electricity. Most of the heat of the Earth is produced by the natural Radioactivité rocks which constitute the earth's crust: it is the nuclear energy produced by the disintegration of the Uranium, the Thorium and the Potassium.
Compared to other renewable energies, geothermics has the advantage of not depending on the atmospheric conditions (sun, rain, wind). The geothermal fields have one lifespan of several tens of years.
Particular case of hydrogen
See also: hydrogen Economy
Hydrogen is not an energy source, but a vector of energy. This paragraph on hydrogen thus does not have in theory its place in this article. It is all the same interesting to speak about it here, because it could in the future replace the vectors of energy produced starting from oil (gasoline, Kérosène, diesel, etc).
Vector of energy: reserve of energy, allowing to store this energy (and to transport it if possible) for a future use.
Many research is currently made to develop the combustible battery, which makes it possible to create electrical energy starting from chemical energy stored in chemical compounds, of which hydrogen. On the other hand, that résoud not the problem of the provisioning, since the manufacture of this hydrogen requires by construction exactly as much energy than it will release some.
See also: Combustible battery
Within the framework of this article on renewable energies, it should be specified that the production of hydrogen requires energy. For example: electrical energy to electrolyze water out of hydrogen and oxygen.
If electrical energy is provided by power stations to fossile fuels, nuclear power or not renewable, the combustible battery is not an renewable energy.
On the other hand, if the electrical production is renewable (hydroelectricity, voltaic photograph,…), the combustible battery provides an renewable energy, the solar layer and the Cycle of water being renewable. Hydrogen is a vector of transport and storage of energy.
Several projects are being studied concerning the storage of energy in the form of hydrogen. An example of project of this type is the Projet Pure (in the islands the Shetland), or with the wind mills are associated with an electrolyser to produce hydrogen continuously and in a completely clean way.
See also: not-renewable Energy
The not-renewable independent sources of energies are the fossile fuels (coal, Pétrole, Natural gas…) or nuclear (Uranium, Plutonium) and are resulting from layers which will end up being dried up in the more or less long term. The expiry depends mainly on the rate/rhythm of consumption, and also of technological advances and scientists.
However, according to the experts of nuclear industry, an optimal use of the residues of nuclear industry would make it possible to re-use worn fuels, to reduce ultimate waste, and to multiply the resource Uranium by a factor approximately 50. The industrial feasibility of such a multiplication of the nuclear resources was proven by the French engine Phoenix, which was not still continued industrially in France because the uranium resources larger than being envisaged still leave us a century. In Japan, Russia, the USA and South Korea this industrial development is the subject of intense research on the closing of the cycle, with the nuclear reactors of generation IV whose additional mission aims at the total combustion of uranium and thorium.
Moreover, if one manages one day to control the nuclear Fusion for the energy production, it will be about an eternal energy, of duration higher than that of the Sun because the " combustibles" (the Isotopes of hydrogen) are present in unlimited quantity, on a human scale, in the water of the oceans. The " propreté" future fusion reactors nuclear power would be perfect if one succeeded in amalgamating stable isotopes (Hydrogen ordinary and natural Lithium7), which is for the moment out of our range. For the moment one approaches the industrial divergence of reaction of fusion (ITER) less difficult, unfortunately releasing a fast neutron which is melted in cores of atoms of structure, making them a little radioactive, but much less than fission.
Renewable energies associate advantages on the level environmental, social, economic, like geopolitical.
Advantages on the environmental level
renewable energy has of another layer only its fundamental source, the Sun which still has some for 5 billion years: thus the wind, the biomass are without layer thus eternal for us. They have rather limits of exploitation (random power, weak density of energy, large surfaces of collection) affecting their economic profitability (only within the narrow framework of a setting in competition with traditional sources) but as soon as they are storable (wood, biomass) they become true reliable sources.
- Their impact out of gas with greenhouse effect is of null principle (cycle of vegetable CO2) provided that their exploitation of mass does not let escape from small quantities of by-products as the methane which is 28 times more opaque at the infra-red radiations than CO2.
- the Déchet S produced by a system of production of renewable energy are primarily waste of dismantling of the generating stations at the end of the lifetime. The thermo plants with coal deposit in more ashes of this last - a problem to demolish itself of 100.000 tons per annum and large section, those with gas in as much as any industrial facility at the end of the lifetime. The nuclear power, also but in current exploitation generates only waste of very low volume (53 tonnes/an in France against 3 to 4 million tons of ashes in Germany) very radioactive, which led this last industry to insulate them and protect well before all other industries. Their major hiding was studied to guarantee in the long run that they will turn over to the biosphere only once " éteints".
- In way " cachée" , certain renewable energies emit however Gaz with greenhouse effect, in particular during the production of the energy devices of exploitation (solar panels, wind mills, etc). These emissions are much lower than those of the fossil energies, with the proviso of not having to temporarily compensate for the lack of not-storable renewable energy (sun, wind) by carbonaceous energies (for example to feed an electrical communication).
Advantages over the social plan
the impacts in the event of serious accident are more easily controllable than those of nuclear or oil industry, except notable for the hydroelectric stoppings: the accidents related to hydroelectric made more deaths than those related to nuclear according to Jancovici.
- the exploited resources are local, thus allowing a Local development territories: cohesion of the territory, developing country, employment not délocalisables.
- waste is not very dangerous.
Advantages over the economic plan
There is a Valeur carbon for this type of energy.
- the Démantèlement of the systems of production of renewable energy is easy, fast and inexpensive.
- waste is inexpensive.
Advantages in Geopolitical term and of safety
Renewable energies can contribute to peace by decreasing the dependence with oil, and by improving the Energy independence, renewable energies are a security source in the economic domains, social and environmental, especially when a range of sources complementary to energy is exploited (for example the wind one functions better when there is no sun and the solar one produces often more when there is no wind).
Selon a recent study (2007) ordered by the German Department of the Environment, compared to the large energy power stations thermal (of which nuclear) and Hydroelectric which centralizes the energy production, clean energies, sure, renewable when they are decentralized are of many interests in term of civil Sécurité energy, interior, military and , as regards terrorist risk, just as for climatic safety , the Développement, the Investissement S and the Financial markets.
Constraints and limits
Today, one often compares the term of renewable energy to that of clean energy. In a strict sense, the definition is different: an clean energy does not produce a pollutant, or it produces pollutants which disappear quickly. Consequently, an renewable energy is not necessarily clean, and conversely. One can quote the case of the biomass. Energy resulting from the combustion of the biomass is clean provided that consumption is not excessive and makes it possible the flora to reabsorb all released carbon dioxide.
Renewable energies will not be enough to limit climate warmingClean energies and renewable are sometimes presented as a solution to the problem of the Climate warming. It would be necessary for that to be able sufficiently to develop renewable energies to be able to decrease the consumption absolute (and nonrelative) of fossil energies. However the energy production of origin renewable is limited by its output, its storage, the surface or the infrastructures necessary. Expressed differently, the development of renewable energies is necessary but, according to the experts, will not be enough to avoid an important reduction in consumption of energy: in spite of the renewable ones, changes of our lifestyles are necessary.
The production of renewable energy, resting on the exploitation of natural phenomena, requires certain geographical conditions, such as for example the presence of a sufficiently powerful wind to allow the wind use of S. Certains country or certain areas can consequently be underprivileged.
A difficulty inherent in renewable energies is their diffuse nature and their irregularity (except for the geothermal energy, which is however accessible only where the earth's crust is thin, like the hot sources and the Geyser S). Since the energy sources renewable provide an energy of a relatively low intensity distributed on large surfaces, new kinds of “power stations” are necessary to convert them into sources usable. For better including/understanding the “low intensity on large surfaces”, it should be noted that to produce 1 000 kWh of electricity per annum (yearly consumption per capita in the Western countries), the owner of a dwelling in cloudy Europe must install 8m ² solar panels (by supposing a average Energy efficiency of 12,5%).
A significant development of renewable energies will have effects on the landscapes and the medium, with substantial differences of ecological or landscape impact according to the installation concerned and according to whether the medium is already artificialized or that projected installation still aims at a space (relatively) wild. The impacts landscape and visual are to some extent Subjectif S. , like the solar roofs. One enters then on a field that wisdom orders to prevent, according to the maxim that " tastes and colors, pas" is not discussed; ; The experiment proving nevertheless that time, and him only, rule this type of polemics: with the practice, one will be accustomed to the wind mills as one could be accustomed to the pylons with high voltage, and before them to the thousands of windmills (technological florets of another time) which strewed the European landscapes. From a technical, financial and esthetic point of view, it is useful and important to integrate to the maximum the technical elements of production of renewable energy in the systems which fill traditionally of other functions. For example, the solar collectors can integrate large surfaces which are in any event implemented: roofs, frontages and even windows of the buildings, fences and barriers, anti-noise wall, etc -->
The construction of the large installations (solar power station type) always has an impact on the landscape. One often quotes large the wind S, and more rarely the solar roofs. This is why efforts are made to try to integrate these installations in the landscape (to paint the wind mills in green in their low part and pale blue in their upper part for example). A decentralized production can also decrease the need for pylons and Lignes with high voltage. The Medium Average networks can be buried.
Risk S for the fauna
The construction of a hydroelectric Barrage has heavy consequences: flood of whole valleys, profound change of the local ecosystem. Moreover, the hydroelectric stoppings make obstacle with the migration of fish, which represents a problem for the rivers of the North-West of North America, where the populations of Saumon S were reduced in an important way.
One also showed the wind S to represent a danger to the birds (although a wind mill kills 0 to 3 birds per annum whereas a kilometer of line with high voltage in keep silent several tens per annum, there are 100.000 km in France of them). In fact, it would seem that the largest risk is for the bats, which one regularly finds corpses on the wind sites, including protected spaces. For the moment, the causes of these collisions with the wind mills are not yet well identified. Some thought that the movements of blades interfered with the ultrasounds, but this assumption was not checked yet.
Solar energy and its derivatives (wind, falls of water, etc) are not available to the request, it is thus necessary to compensate, while having a sufficient storage, near the consumer, of the producer, or through a network of exchange (similar to the old network of distribution ).
Examples of a direct use of renewable energy are the solar furnaces, the geothermic heat pumps, and the mechanical windmills. Examples of an indirect use, passing by other forms of energy, are the production of electricity by wind S or photovoltaic cells, or the production of Carburant S such as the ethanol resulting from the biomass (See Biocarburant).
The renewable energy utilization, which can often be produced “on the spot”, decreases the calls to the delivery systems of electricity. An average household laying out of a photovoltaic system Solar with storage of energy, and Solar panels of the good size, needs to resort to external sources of electricity only a few hours per week. By generalizing this example, the partisans of renewable energy think that delivery systems of electricity (Lignes VHV, transformers,…) should be less important and easier to control.
In the strongly industrialized countries, the majority of the consumers and energy producers are connected to an electrical communication which can ensure of the exchanges of an end the other of a country or between country. A strongly inter-connected network on continental scale would allow, condition of being suitably dimensioned and managed, to reduce the risks of production and consumption, thanks to the multiplication of the sources of production available and with the covering of time beaches of use different. The problem of the intermittency of the wind would become thus less critical (see Débat on wind energy). The diversification of the sources could also authorize interesting complementarities.
Economic constraints and organisational
implementation the concrete must yield with the constraints of the markets. The logic of the Investment trust is not always a logic of investment.
the Economic agents concerned are dispersed. It is necessary to gather them and imagine adapted conditions of organization: contracts of die, contracts territorial,… Any remainder to be made for the definition of the industrial Die S.
The placement of a die of renewable energy requires to make an economic assessment. The installation of the licenses of emission of Gaz to greenhouse effect (see Stock Exchange of carbon) returns these Filière S profitable.
Discounted economic profitabilities are very strong: one awaits rates of 12% what is exceptional.
However, one does not know exactly which will be the profitabilities compared according to the technical processes employed. The industrial Filière S were not implemented yet at large scales. It is necessary to imagine integrated Filières. One starts to have experience feedbacks, but it can always occur of the unexpected difficulties.
Today, renewable energies account for 13,5% of the total intake of energy entered in the world and 18% of the worldwide production of electricity. The biomass and waste ensure the essence of this production (10,6%). that “the champions of the wind one that are Germany and Denmark obtained, respectively, 0,1% and 1,3% of their total energy by this means in 1999 (source IEA). In Denmark, which probably has one of the strongest rates of wind energy in the world, the consumption of energy increased, over the decade 1990, of… 1,3% per annum on average (source IEA). Ten years of efforts in the wind one just were used for " absorber" one year of rise of consumption of energy, and for this reason, it was necessary to put machines of them! ”
The Spain began the production of wind energy recently, but as of 2002 caught up with the the United States to become the country with the second highest level for the capacity installed of wind energy.
The Austria, the Greece and the Germany are at the head in the field of the solar production of heat. The Spain should soon know a boom thanks to widening with the whole of its territory of the Solar Ordonnance of Barcelona (obligation to install a Solar-fired heater on all new construction of collective dwelling or during restorations). Successes of these countries are partly based on their geographical advantages, although it is worth the sorrow to note that Germany does not have particularly good wind or sun resources (much worse for example than the England, where the policies had much less success). Other factors thus played a big role in its engagement in the development of renewable energies.
The France produces 6% of its energy starting from renewable sources, 4% coming from the biomass (primarily Bois energy) and 2% of hydraulics. The wind one, on the other hand, is still developed very little in spite of annual growth rates close to 100%. In the same way France counts among the European poor pupils as regards solar surface installed per capita. However assistance systems should be able to improve the situation:
- For the private individual, of the assistances of 50% of the cost of the material is proposed for the installation of apparatus using renewable energies (solar-fired heater, heating wood,…) by the system of the tax credit. Moreover, the majority of the District councils, like some general advices and Municipalités offer subsidies. List assistances available
- to support the renewable electrical production of origin, it is the principle of the tariff of purchase which was retained: each renewable kWh electric is bought at a fixed price in advance and over one limited duration. This system ensures the investors a visibility necessary for emergence of new technologies. The revision with the rise of these tariffs on July 10th, 2006 makes the professionals optimistic on the development of renewable electricity, in particular of the photovoltaic one. Tariffs of purchase of renewable electricity in France
In France, one traditionally charges the delay taken in the development of renewable energies (like the wind one or the solar photovoltaic one) to the stress laid to nuclear energy and hydraulics, but should not be neglected the social brakes: still today, the real estate schemes individual or collective, private or public, leave only one completely marginal place to the systems of collecting of solar energy (what directs housing stock for the next decades).
Renewable energies in Europe
- Europa.eu and Agence European for the Environment, Copyright EEA, Copenhagen, (2006)
- For 2004, the data result from the BMU (Bundesministerium für Umwelt, the German Department of the Environment). They relate to only the European Union of the 25.
Renewable electricity in the worldClassification of the countries in the electric production of renewable energy in 2000 (this classification illustrates the quantity of produced energy, not the share of renewable energy in national consumption):
Professional organizations and Associations
- Agency of the environment and the control of energy (ADEME)
- Trade union of renewable energies
- renewable energies Group, environment and solidarity (MANAGE)
- Caisse of the deposits
- Energy-Cities, the association of European local authorities for a durable local energy policy
- Observatory of renewable energies (France)
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