A controversial theory, supported by the IPCC, UN and most scientific organisations, both governmental and NGOs, concerning the cumulative impact of human activities which is causing a significant change to the composition of the atmospheric gases, with the consequence of changes to the global climate stability.
The policy of ScienceLibrary.info is to present the facts, and let the scientific evidence dispel the myths which have taken hold in the public arena. These myths are:
A useful distinction between energy sources is whether the source is potentially a very long-term contender for a stable, ever available and non-destructive energy source. Finite resources which will inevitably be depleted at any level of use are termed non-renewable. In truth, all of the energy sources we consider non-renewable will eventually be renewed, and all renewable sources are destined to run out at some point. However, the timescales under which these happen are far beyond expectations of human civilisation survival times. It would take tens of millions of years to replace the oil we have consumed more than half of. And the solar radiation we exploit in photovoltaic cells will be available for billions of years to come.
Since the beginning of the Industrial Revolution in the latter half of the eighteenth century, fossil fuels have been the primary energy source for industry and domestic use alike. These are the derivatives of organic material (containing carbon) laid down over tens or even hundreds of millions of years. These derivatives take the form of aolids, liquids, and gas. The gas is methane, the liquids various polymers of petroleum, and the solid fuel is coal. Diamond and graphite are also carbon compounds derived from dead organic matter, but are not sources of energy (although diamond would burn!).
Uranium is one of the few energy sources that does not derive its energy ultimately from the sun, but rather was formed, and gained its radioactive nature, in the supernova which formed our solar system. It has been decaying ever since, and its decay product ratio provides a useful marker for ageing the Earth and the solar system.
Often considered to be so plentiful and used in such relatively small quantities, uranium is not generally viewed as being non-renewable. But in reality it is, and excessive reliance on it would eventually deplete it as a resource. However, the reason for its decline in favour is not fears of depletion but rather safety and cost issues.
Greenhouse gases (GHGs) include a number of gases which cause infrared radiation to be trapped near the Earth's surface rather than be reradiated back into space. A major GHG is CO2 - not because of its potency as a GHG, but for the volume of it produced by man.
The eco-efficiency of a fuel in terms of its greenhouse potential is measured in the mass of CO2 generated per MJ of energy obtained. Notice that mass if used rather than volume. Why do you think that is? Answer
|Fuel Type||World electrical power generation (%)||CO2 emission per unit energy (g MJ-1)|
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1792 - 1871
John Herschel is the son of William Herschel, and the nephew of Caroline Herschel, two famous astronomers. He continued his father's work, publishing enhanced catalogues of astronomical objects, but was also prolific in many other fields of science and technology, notably as a pioneer of photography.
E pur si muove (And yet it moves)
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