Fossile

Résumé

thumb|Squelette de baleine Miocène fossilisé in situ dans le désert d'Ica, Pérou. vignette|Fossile de Lethe corbieri, papillon de l'Oligocène de Provence, France. vignette|Ammonite fossilisée. vignette|Poisson (Coelodus costai) fossilisé exposé au musée d'histoire naturelle de Milan. vignette|Libellule () fossilisée. Un fossile (dérivé du substantif du verbe latin fodere : fossile, littéralement « qui est fouillé ») est la trace plus ou moins minéralisée d'un ancien organisme vivant ou de son activité passée, ou bien son simple moulage, conservés dans une roche sédimentaire. Il peut s'agir de restes plus ou moins bien conservés de l'organisme lui-même (ossements, dents, feuilles, mycélium, biofilms) ou d'empreintes laissées par ce dernier (empreintes de pas, de peaux ou de téguments), moulages externes naturels (ambre, par exemple), terriers, stromatolithes, coprolithes). Les fossiles et les processus de fossilisation sont principalement étudiés dans le cadre de la paléontologie, mais

Source officielle

https://fr.wikipedia.org/wiki/Fossile

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Publications associées (18)

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Concepts associés (206)

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Cours associés (17)

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Séances de cours associées (28)

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Analysis and comparison of hydrogen routes for automotive use

Peter Loveday

The goal of this project would be to analyze and compare systematically the different existing and emerging processes producing hydrogen from fossil and renewable resources. As the perspective would be the replacement of fossil fuels with hydrogen in the transportation sector, the comparison of the different processes will essentially be based on the environmental impacts.

2009

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Heating, electricity and transportation are the three components of urban systems final energy consumption. Geothermal energy and biomass are two promising renewable energy resources that can be used for the production of heat, electricity and biofuels, thus allowing a reduction of fossil fuel consumption and of the associated greenhouse gas emissions. The goal of this paper is to assess the potential for the integration of geothermal energy combined with biomass in the energy system of a city, taking into account the consumption of fossil and renewable resources, costs and environmental impact. Several process options are available for both resources. For geothermal energy, deep aquifers and EGS (Enhanced Geothermal Systems) are considered, for both separate production of heat and electricity, and cogeneration. For biomass, besides the option of direct combustion, conversion to biofuels by a set of alternative processes (pyrolysis and gasification) is included in this study. The use of pinch analysis and optimization allows the evaluation of possible hybrid energy conversion systems integrating geothermal with biomass. The European city of Lausanne (Switzerland) is used as an example case study. The heat demand of the city is partially satisfied by a district heating network. The complete urban energy system is modeled in order to account for the potential competition and synergies between different energy carriers and technologies for the same end-uses. A set of “ad hoc” scenarios is developed with the goal of assessing the interest of geothermal and biomass within the long-term strategic energy planning of the city.

2015

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Diformylxylose as a new polar aprotic solvent produced from renewable biomass

Graham Reid Dick, Anastasiia Komarova, Jeremy Luterbacher

Lignin is a promising candidate for the replacement of fossil-based materials, due to its natural abundance and aromatic structure. This same structure poses major challenges to lignin's exploitation for material development. The harsh conditions generally needed for its isolation make it susceptible to uncontrollable side reactions that limit its further upgrading and/or functionalization. Here, by using aldehyde-assisted fractionation (AAF), we have extracted lignin while avoiding condensation reactions and, at the same time, introduced new functional groups on the lignin in a single step. By using a multifunctional aldehyde such as terephthalic aldehyde (TALD), we used acetal functionalization to prevent the dehydration and condensation of lignin's β-O-4 linkage and introduced an aldehyde on the lignin backbone. By tuning the amount of TALD during the extraction process, we were also able to precisely control the degree of chemical functionalization. We then exploited the reactivity of the newly functionalized biopolymer to increase phenolation reactions yields in both acid and basic environment, in order to provide better lignins for incorporation in phenol formaldehyde resins. These TALD-lignins were more reactive than Kraft lignin or mild organosolv lignin extracted in an acid solution of 80% ethanol in water, which could facilitate their use for developing more sustainable resins and materials.

2021

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