Oil shale is a fine-grained sedimentary rock containing significant amounts of kerogen (a solid mixture of organic chemical compounds), from which liquid hydrocarbons can be extracted. The name oil shale has been described as a promotional misnomer, since the rock is not necessarily a shale and its kerogen is not crude oil; it requires more processing than crude oil, which affects its economic viability as a crude oil substitute.[1][2] Deposits of oil shale are located around the world, including major deposits in the United States. Global deposits are estimated as equivalent to 2.8 trillion to 3.3 trillion barrels (450×109 to 520×109 m3) of recoverable oil.[2][3][4][5]
The chemical process of pyrolysis can convert the kerogen in oil shale into synthetic crude oil. When oil shale is heated to a sufficiently high temperature a vapor is driven off which can be distilled (retorted) to yield a petroleum-like shale oil—a form of non-conventional oil—and combustible shale gas (shale gas can also refer to gas occurring naturally in shales). Oil shale can also be burnt directly as a low-grade fuel for power generation and heating purposes and can be used as a raw material in the chemical and construction materials industries.[6][2]
Oil shale has gained attention as an energy resource as the price of conventional sources of petroleum has risen and as a way for some areas to secure independence from external suppliers of energy.[7][8] The oil shale industry is well-established in Estonia, China, and Brazil, and the United States is taking steps in that direction. At the same time oil shale mining and processing involves a number of environmental issues, such as land use, waste disposal, water use and waste water management, and air pollution.[9][10] The industry has foundered in Australia due to opposition on these grounds.
Geolog
Oil shale consists of organic-rich sedimentary rock: it belongs to the group of sapropel fuels.[11] It is differentiated from bitumen-impregnated rocks (tar sands and petroleum reservoir rocks), humic coals and carbonaceous shale. While tar sands have been created by biodegradation of oil, the kerogen in oil shales has not yet been naturally transformed into petroleum by heat and pressure.[2][12][13] Coal contains a higher percentage of organic matter than oil shale. In commercial grades of oil shale the ratio of organic matter to mineral matter is about 0.75:5 to 1.5:5. At the same time, the organic matter in oil shale has an atomic ratio of hydrogen to carbon approximately the same as for crude oil and four to five times higher than for coals.[2][11]
Oil shale does not have a definite geological definition nor a specific chemical formula. Oil shales vary considerably in their mineral content, chemical composition, age, type of kerogen, and depositional history.[14] The organic components of oil shale derive from a variety of organisms, such as the remains of algae, spores, pollen, plant cuticles and corky fragments of herbaceous and woody plants, and cellular debris from other aquatic and land plants.[2][15] Some deposits contain significant fossils; Germany's Messel Pit is a Unesco World Heritage Site. The mineral matter in oil shale includes various fine-grained silicates and carbonates.[11][6]
Geologists can classify oil shales on the basis of their composition as carbonate-rich shales, siliceous shales, or cannel shales.[16] Another classification, assigning kerogen types, is based on the hydrogen, carbon, and oxygen content of oil shales' original organic matter. This classification is known as the van Krevelen diagram.[14] The most used classification of oil shales was developed between 1987 and 1991 by Adrian C. Hutton of the University of Wollongong, adapting petrographic terms from coal terminology. According to this classification, oil shales are designated as terrestrial, lacustrine (lake-bottom-deposited), or marine (ocean bottom-deposited), based on the environment where the initial biomass was deposited. [6][17] Hutton's classification scheme has proven useful in estimating the yield and composition of the extracted oil.[2]
From : http://en.wikipedia.org/wiki/Oil_shale
Oil shale
plato
Plato (Greek: Πλάτων, Plátōn, "wide, broad-browed"[1]) (428/427 BC[a] – 348/347 BC), was a Classical Greek philosopher, who together with his teacher, Socrates, and his student, Aristotle, helped to lay the philosophical foundations of Western culture.[2] Plato was also a mathematician, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the western world. Plato was originally a student of Socrates, and was as much influenced by his thinking as by what he saw as his teacher's unjust death.
Plato's sophistication as a writer and thinker can be witnessed by reading his Socratic dialogues. Some of the dialogues, letters, and other works that are ascribed to him are considered spurious.[3] Interestingly, although there is little question that Plato lectured at the Academy that he founded, the pedagogical function of his dialogues, if any, is not known with certainty. The dialogues have since Plato's time been used to teach a range of subjects, mostly including philosophy, logic, rhetoric, mathematics, and other subjects about which he wrote.
Biography
[edit] Early life
[edit] Birth and family
The exact birthdate of Plato is unknown. Based on ancient sources, most modern scholars estimate that he was born in Athens or Aegina[b] between 429 and 423 BC[a] His father was Ariston. According to a disputed tradition, reported by Diogenes Laertius, Ariston traced his descent from the king of Athens, Codrus, and the king of Messenia, Melanthus.[4] Plato's mother was Perictione, whose family boasted of a relationship with the famous Athenian lawmaker and lyric poet Solon.[5] Perictione was sister of Charmides and niece of Critias, both prominent figures of the Thirty Tyrants, the brief oligarchic regime, which followed on the collapse of Athens at the end of the Peloponnesian war (404-403 b.c.e.).[6] Besides Plato himself, Ariston and Perictione had three other children; these were two sons, Adeimantus and Glaucon, and a daughter Potone, the mother of Speusippus (the nephew and successor of Plato as head of his philosophical Academy).[6] According to the Republic, Adeimantus and Glaucon were older than Plato.[7] Nevertheless, in his Memorabilia, Xenophon presents Glaucon as younger than Plato.[8]
According to certain reports of ancient writers, Plato' s mother became pregnant through a virginal conception: Ariston tried to force his attentions on Perictione, but failed of his purpose; then the ancient Greek god Apollo appeared to him in a vision, and, as a result of it, Ariston left Perictione unmolested.[9] Another legend related that, while he was sleeping as an infant, bees had settled on the lips of Plato; an augury of the sweetness of style in which he would discourse philosophy.[10]
Ariston appears to have died in Plato's childhood, although the precise dating of his death is difficult.[11] Perictione then married Pyrilampes, her mother's brother,[12] who had served many times as an ambassador to the Persian court and was a friend of Pericles, the leader of the democratic faction in Athens.[13] Pyrilampes had a son from a previous marriage, Demus, who was famous for his beauty.[14] Perictione gave birth to Pyrilampes' second son, Antiphon, the half-brother of Plato, who appears in Parmenides.[15]
In contrast to his reticence about himself, Plato used to introduce his distinguished relatives into his dialogues, or to mention them with some precision: Charmides has one named after him; Critias speaks in both Charmides and Protagoras; Adeimantus and Glaucon take prominent parts in the Republic.[16] From these and other references one can reconstruct his family tree, and this suggests a considerable amount of family pride. According to Burnet, "the opening scene of the Charmides is a glorification of the whole [family] connection ... Plato's dialogues are not only a memorial to Socrates, but also the happier days of his own family".[17]
[edit] Name
According to Diogenes Laertius, the philosopher was named Aristocles after his grandfather, but his wrestling coach, Ariston of Argos, dubbed him "Platon", meaning "broad" on account of his robust figure.[18] According to the sources mentioned by Diogenes (all dating from the Alexandrian period), Plato derived his name from the breadth (platutês) of his eloquence, or else because he was very wide (platus) across the forehead.[19] In the 21st century some scholars disputed Diogenes, and argued that the legend about his name being Aristocles originated in the Hellenistic age.[c]
[edit] Education
Apuleius informs us that Speusippus praised Plato's quickness of mind and modesty as a boy, and the "first fruits of his youth infused with hard work and love of study".[20] Plato must have been instructed in grammar, music, and gymnastics by the most distinguished teachers of his time.[21] Dicaearchus went so far as to say that Plato wrestled at the Isthmian games.[22] Plato had also attended courses of philosophy; before meeting Socrates, he first became acquainted with Cratylus (a disciple of Heraclitus, a prominent pre-Socratic Greek philosopher) and the Heraclitean doctrines.[23]
from : http://en.wikipedia.org/wiki/Plato
