Entropy and the environment

Entropy is simply defined as the property used to determine the amount of heat not available to do work in a system. This energy is dispelled as wasted heat. Entropy in terms of the Second Law of Thermodynamics is constantly increasing. Entropy can never decrease in a system unless the entropy of the surroundings is increased. The increased entropy must always be less than or equal to the original entropy. That is to say ΔSUniverse = ΔSSystem + ΔSSurroundings.
Elaboration
The Second Law of Thermodynamics may help provide explanation for why there have been increases in Earth’s temperatures over the last 250 years, and many professionals are concerned that the entropy increase of the universe is a real threat to the environment. As an engine operates, heat flows from a heat tank of greater temperature to a heat sink of lesser temperature. In between these states, the heat flow is turned into useful energy with the help of heat engines. As these engines operate, however, a great deal of heat is lost to the environment due to inefficiencies. In a Carnot Engine, which is the most efficient theoretical engine, the maximum efficiency is equal to one minus the temperature of the heat sink divided by the temperature of the heat source. This ratio shows that for a greater efficiency to be achieved there needs to be the greatest difference in temperature available. This brings up two important points: optimized heat sinks are at absolute zero, and the longer engines dump heat into an isolated system the less efficient engines will become. Unfortunately for engine efficiency, day to day life never operates in absolute zero. In an average car engine, only 14%-26% of the fuel which is put in is actually used to make the car move forward. This means that 74%-86% is lost heat or used to power accessories. According to the U.S. Department of Energy, 70%-72% of heat produced by burning fuel is heat lost by the engine. The excess heat lost by the engine is then released into the heat sink, which in the case of many modern engines would be the Earth’s atmosphere. As more heat is dumped into the environment, Earth’s atmospheric (or heat sink) temperature will lead to increases in the surface temperature of the Earth. As the surface temperature increases, the oceans will work to disperse the excess heat which will lead to an increase in ocean temperature. As oceans churn and mix, the deeper waters are heated while the shallower waters are cooled, providing more time before there is a dramatic increase in temperature. This, coupled with other environmental factors, is a possible explanation of the recent increase in the rate at which the polar ice caps have been melting. There is much debate over the amount of heat the Earth can absorb before there are noticeable and detrimental effects, or if the Earth can constantly adjust to changing environmental factors in order to support life.
Since the beginning of the Industrial Revolution in 1750, the production and use of engines has greatly increased. Over time, with all these engines producing heat together, the temperature of the heat sink, no matter how large, will begin to rise, because as work is done, the temperature of the heat source and heat sink will always creep toward equilibrium. Once equilibrium is reached, heat flow will no longer occur and work can no longer be generated because the system will have become isothermal. With the entropy of the environment constantly increasing, however, searching for new, more efficient technologies and new non-heat engines has become a priority, or there could be the heat death of the universe.

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