Le stockage d'énergie, condition de déploiement des énergies renouvelables / Energy storage as a prerequisite for renewable energy sources deployment

An extensive use of renewable energy sources requires finding an appropriate solution for energy storage. Renewable energy sources, such as wind and solar, are intermittent, and therefore some kind of back-up is needed for meeting the demand.  It can be provided by a gas-fired combibed cycle power-plant, but for increasing the penetration of renewable energy sources, while reducing the use of fossil fuels, some kind of energy storage system is needed. Large capacity storage is provided by pumped hydro-storage systems, but they are limited by the number of appropriate natural sites and the large size of the installations. In such a case, the storage location is generally located far from the production site. Therefore, large electricity transport costs are involved, together with resulting energy losses.  Such systems are clearly not appropriate for short duration intermittencies.  Other storage systems , such as batteries or flywheels,  are then required. Energy storage is quite costly. As practised now, it can represent 50 to 150 €/ MWh. These figures do not include the cost of electricity transportation. It is therefore a priority to develop new more cost-efficient energy storage systems. It is especially important to develop systems which could be cost-effective while being displayed near the production site. Liquid phase chemical systems, compressed air storage systems are potential candidates, but no option can  be considered as wholly satisfactory and energy storage remains until now the main hurdle to overcome for developing renewable energy sources.  

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Un recours très étendu aux énergies renouvelables implique de résoudre un problème particulièrement critique qui est celui du stockage d'énergie. En effet les énergies renouvelables, éolien et solaire sont intermittentes. Le vent peut s’arrêter et souffle à des vitesses très variables. Le rayonnement reçu du soleil est aussi très variable et s'annule la nuit. L’intermittence des systèmes de production d’électricité utilisant une énergie renouvelable (solaire, éolien), peut être compensée en modulant la puissance d’une centrale thermique opérant en back-up (telle qu’une centrale au gaz à cycle combiné). Pour augmenter le niveau de pénétration des énergies renouvelables, il faudra dans l’avenir recourir à des systèmes de stockage d’énergie de grande capacité. 

Pearltree pour préparer l'avenir / for preparing the future

Internet links for "Future at stake"

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Liens internet pour "L'avenir en question"

Pétrole contre nourriture? Oil against food?

Biomass is already ensuring roughly 10% of the primary energy supply in the world, i.e. 1 G toe from 11 Gtoe. Wood is the main contributor. A large proportion of this biomass is used nder poor conditions and contributes to deforestation. Human food represents the equivalent of 600 Mtoe, and clearly the energy demand might threaten a proper access to food if biomass is extensively used for energy production. Biomass used for firing boilers can be provided to a large extend by waste (waste from wood constructions, biogas from organic waste). This is not the case with biofuels, which are produced from sugar extracted from sugar plants or derived from starch crops. From 419 Millions tons of cereals produced in 2009 in United States, 119 Millions have been transformeinto ethanol for producing biofuels. This production of biofuels competes then directly with food needs.  For this reason, R&D work is aiming at the production from biomass fraction which cannot be used for food, such as lignocellulosic biomass. Attemps are made also fopr prodicing biofuels from microalgae in bioreactors. These different options are costly and it is still difficult to know if they might be developed at a large scale and when.  

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C’est dans le domaine de l’énergie que la demande pourrait être potentiellement la plus importante. De toutes les énergies renouvelables, la biomasse est celle qui est la plus facilement substituable aux énergies fossiles. En effet l’énergie issue de la biomasse est utilisée sous forme de combustibles solides, liquides ou gazeux, qui peuvent remplacer dans certaines conditions des combustibles fossiles tels que le charbon, le pétrole ou le gaz naturel.

Une chimie verte ? / A green chemistry?

Biomass is becoming more and more attractive as a raw material for the production of a wide array of materials and products. Some of these applications have been known for a long time, such as the production of cotton fibers for the textile industry or the transformation of lignin into paper pulp. New applications are now growing very fast, for materials (fibers for composite materials) and products. A growing share of the oil used for chemistry might be displaced by biomass in the years to come and biorefineries might replace, at least partly, oil refineries.

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Les usages alimentaires de la biomasse ne sont pas les seuls. La biomasse est utilisée aussi pour la production de fibres, de produits chimiques et pour la production d’énergie.  Dans tous ces domaines, les applications tendent à se multiplier, notamment pour remplacer le pétrole comme matière première, entraînant des risques de conflit avec les usages alimentaires.

Energie, matières premières et environnement / Energy, raw materials and environment

Energie, matières premières et environnement / Energy, raw materials and environment

Publiez sur Calaméo ou explorez la bibliothèque.

Presentation based upon the book "The future at stake"

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Présentation à partir des thèmes discutés dans l'ouvrage "L'avenir en question"

De la prédation à la symbiose / From predation to symbiosis

 Man has behaved as a predator from the origin. Hunting and gathering was the way of collecting food in prehistoric time. The Neolithic revolution introduced agriculture and farming, enabling the human population to grow up to the present level. Presently, this level is so high, that human activities represent a threat for the environment. The economic system remains based upon predation, which consists in picking up from the environment the resources which are needed and rejecting waste. Thus, it becomes necessary to develop a new way of operating the economy, which is no more based on predation but symbiosis. As opposed to parasitis, symbiosis makes the coexistence between different species mutually beneficial. Man can bring to the nature his intelligence and help the environment to improve its resilence, but it requires a new way in handling natural resources, such as a systematic recycling of raw materials in order to reach a near zero waste situation, in order to create the conditions of a "sustainable evolution".

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L’être humain pour survivre a été depuis l’origine des temps un prédateur, puisant sur les ressources que lui offrait son environnement. Les chasseurs cueilleurs de la préhistoire se contentaient de prélever autour d’eux les aliments dont ils avaient besoin. La révolution du néolithique, en introduisant l’agriculture, l’élevage et l’industrie a profondément transformé les conditions de vie de l’espèce humaine, en modifiant à son profit le milieu naturel, de façon à disposer de ressources alimentaires de plus en plus importantes. C’est cette transformation qui a permis l’explosion démographique de la population humaine. Elle a également permis à la plus grande partie de la population d’être libérée du souci de trouver de la nourriture et de pouvoir se consacrer à d’autres activités. 

Le développement durable, un concept hybride pour une période de transition / Sustainable Development, a hybrid concept for a transition period

The concept of « sustainable development » has been proposed in 1987 by Gro Harlem Bruntland, was then Prime Minister of Norway, as an attempt to conciliate economic development and environment preservation. This concept has encountered a great success. It has been used both by communities and enterprises. It has helped to alleviate somewhat the policy based on short-term demand and to take into account broader views. 

At the same time the concept of "sustainable development" as conceived until now presents also limitations. It can be interpreted as consisting to operate mean adjustments, when radical changes seem required. The notion of "development" is by itself ambiguous, as it remains close to the notion of "growth", bringing the question whether or not illimited growth is possible and what lind of growth might remain sustainable. Therefore, it can be considered as a "hybrid" concept, which can help us to organize the transition from the "growth" system of the pasr, bringing us to the "sustainable evolution" of the future.

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   Le concept de « développement durable »[1] fut proposé en 1987 par Gro Harlem Bruntland, qui était alors Premier Ministre de Norvège, comme une tentative de concilier les notions de développement économique et de préservation de l’environnement. Le développement durable était présenté comme une politique se situant à l’intersection des préoccupations économiques, sociales et environnementales. Selon la définition devenue célèbre de Gro Harlem Bruntland, le développement durable consiste à « satisfaire les besoins actuels, sans compromettre la capacité des générations futures à satisfaire les leurs ».