Global warming, thermal engines’ efficiency and GHG emissions: The vicious circle of Climate Change

Global warming affects human beings and nature’s ecosystems. Apart from the observed, monitored and measured negative effects on human health and biodiversity, the application of the Laws of Thermodynamics proves that thermal engines can also be affected by having their thermal efficiency reduced due to the decreased value of ΔT (temperature difference between the two heat reservoirs). Considering that the global outcome is kept constant (same power demand and supply), a continuously decreased efficiency results in increased fuel consumption and thus higher CO2 emissions. Since CO2 as GHG favours global warming, a vicious circle is generated. Even though a slight decrease in thermal efficiency seems to be marginal and, thus, ignorable, the vast use of thermal engines in industrial power production and in transportation and the corresponding fossil fuels consumption results in a significant increase in CO2 emissions. The current study examines thermal engines (both for transportation and power generation on board the vessels) and estimates their GHG emissions. The present work, being part of an ongoing vast study on decarbonization, deals with the Carnot and Diesel thermal cycles. Examination of Otto, Dual Combustion, Joule/Brayton, and Rankine cycles will follow. The scenarios are examined to support decisions regarding actions that must be taken to start considering available complementary solutions which provide different levels of technological maturity, cost-effectiveness, and applicability.