Fossil fuel reversibility

Industrialization and the burning of fossil fuels reverses this process. Instead of being absorbed out of the air, carbon is extracted from the ground and sent into the atmosphere. 

All natural energy forms that do not derive from the combustion of fossil fuels. Reversible potential... 

Since the late 1960s, and more especially since 1973, when OPEC policies reversed fossil fuel pricing patterns that had virtually eliminated it as a major component of the Canadian energy economy, coal has not only regained substantial footholds in industrial fuel markets, but also attracted increasingly serious attention as a key resource from which, in future, more diverse energy demands could be met. 

Stabilising the atmospheric C02 by carbonisation is just a reverse operation to restore the coal and other fossil fuels which had been formed underground from plant remains over geologic years, and which have been mined and burned by the mankind for these few hundred years. 

The calculated values of exergy ratios for various primary and secondary sources are shown in Table 1. It 1s to be noted that all the fossil fuel sources are inherently of very high quality. The value of aE greater than unity for coal stems from the fact that a reversible oxidation of carbon at ambient temperature has a negative TQ S and results in production of more work than the enthalpy of combustion, with an associated absorption of heat from the environment. In spite of these high values of < r, when fossil fuels are combusted, say for electrical generation, the maximum temperature is limited not by thermodynamic considerations but by materials constraints. The effective < under this limitation is restricted to values below 0.65. t... 

The thermal efficiency of this cycle is that of a Carnot engine, given by (5.8). As a reversible cycle, it could serve as a standard of comparison for actui steam power plants. However, severe practical difficulties attend the operatk of equipment intended to carry out steps 2 3 and 4 1. Turbines that take i saturated steam produce an exhaust with high liquid content, which causes sevel erosion problems, t Even more difficult is the design of a pump that takes in mixture of liquid and vapor (point 4) and discharges a saturated liquid (poll 1). For these reasons, an alternative model cycle is taken as the standard, at lei for fossil-fuel-buming power plants. It is called the Rankine cycle, and diSei from the cycle of Fig. 8.2 in two major respects. First, the heating step 1 2 ... 

The burning of fossil fuels has reversed this natural trend and currently transfers around 5x10 kg C per year into the atmosphere as C02. Parts of the cycle outside human control may be... 

The structural molecules of the skeletons and shells of invertebrates, which function as physical defenses against predation, are important in marine environments, where they produce carbonate and silicate rocks. Deposition in anaerobic environments has also been the basis for the formation of the extensive deposits of gas and oil that now fuel modern industrial societies. Removal of carbon from the biosphere by organisms to produce carbonate rocks, coal, oil, and hydrocarbon gases has been responsible for the presence of oxygen in the atmosphere of the Earth. Reversal of this process by human consumption of fossil fuels has already produced a detectable increase in atmospheric carbon dioxide. 

In effect, the reactions in Eqns 7.3 and 7.4 bring about the reverse ofEqns 7.1 and 7.2. Another anthropogenic gas, nitric oxide (NO), scavenges ozone in a similar way (to form nitrogen dioxide, N02) and is produced by the dissociation of N20, which can be generated from fossil fuel combustion and from the decomposition... 

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