Waste of energy

Waste of energy

Many processes for transforming thermal energy into mechanical energy (usable) have emerged in the various fields of human activity:

-for transport: the reciprocating piston engine largely predominates (with all possible variations in the arrangement of the piston and even the movement of the piston), the industrial application of rotary engines remains anecdotal (although Mazda has won the Mans in 1992 thanks to a Wankel engine)

- for the production of electricity: steam turbine (or gas turbine) whose steam is heated by boilers.

-for aviation: the gas turbine playing on the compression and expansion of the combustion gases in order to create a thrust.

All these systems for transforming thermal energy into mechanical energy, with very distinct technologies that have existed for several decades have, with some exceptions, a maximum efficiency (on fuel consumption) of around 35% ...

It is legitimate to wonder about the low efficiency of these systems, based on old thermodynamic principles. These systems really “waste” 2/3 of the thermal energy consumed. That is to say that out of 100 francs of fuel consumed in your vehicle, 70 francs are wasted in thermal losses (heat).

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efficiency of a heat engine

Efficiency diagram of a reciprocating engine currently used in automobiles. Ps: the efficiency of a Diesel engine is slightly higher, hence lower consumption on Diesel engines.

Exhaustible resources

In the face of dwindling oil resources, such a waste of energy is no longer acceptable, in fact: oil production seems to reach its maximum during the mid-1990s (as shown in the following document). Certain other studies place this peak in the middle of the decade 2000-2010.

Despite this, it must be understood that the rise in prices has not yet been felt because the price of oil depends more on political and economic notions than on its real cost of extraction. ($ 2 to $ 4 a barrel from Saudi Arabia).

It should be noted that the daily consumption of humanity would amount, in 2002, to approximately 75 million barrels. This figure is to be compared to the loss resulting from the fires of Saddam Hussein's oil wells in 1991: more than 66 million barrels over 6 months. And it had been considered an ecological and economic disaster by all the media in the world ...

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hubert curve of production and discovery of oil resources

Oil production curve and annual discoveries (Source: World Energy Committee)

In addition, a large part of the Western economy (except, perhaps, the United States having built up more than 2 years of reserve and having significant resources) is dependent on OPEC countries (Organization of Exporting Countries of Oil). Such dependence is very dangerous (see the oil crises of 1973 and 1979). But on the other hand, this dependence allows an economic hegemony of industrialized and consumer countries, all subject to a homogeneous price of energy. On the other hand, the current taxation of petroleum makes the emergence of developing countries very difficult. In this sense, if oil is a source of local conflict (in producing countries… 80% of current conflicts in the world are of oil origin), its energy monopoly is the guarantor of world peace.

It will also be noted that electricity, the 2nd energy of the XXth century, is produced at 60% thanks to fossil fuels (and in the USA currently still at 80%).

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Experts estimate that there are about 50 years of oil reserves left (in absolute terms, given the evolution of consumption and new discoveries) ... But we must not confuse reserves and exploitable resources, although the rate extraction rate, thanks to new petroleum technology, is increasingly higher.

It is time for humanity to save fossil fuels and for manufacturers and competent organizations to quickly take technological and behavioral measures to rationalize. For too long companies have neglected the environmental cost and energy savings under the pretext of a favorable short-term cost.

It is time to apply what the grandes écoles know how to teach us so well: to have a global and long-term vision of investments.

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