TITLE:
Environment Temperature Fluctuations as a Source of Energy Generation
AUTHORS:
Ryszard Petela
KEYWORDS:
Environment Temperature Fluctuation, Radiation as Working Medium, Carnot Efficiency, Exergy Efficiency
JOURNAL NAME:
Energy and Power Engineering,
Vol.18 No.7,
July
7,
2026
ABSTRACT: This article examines the potential of environmenttemperature variability as a source of usable energy for free. For example, on the Moon, the diurnal temperature swing reaches 300 K (approximately 100 K to 400 K), enabling a heat engine to operate with a Carnot efficiency of about 75%. On Earth, the most favorable conditions occur in the Taklamakan Desert, where a diurnal variation of 35 K (from roughly 255 K to 290 K) corresponds to a Carnot efficiency of 12.1%. The analysis employs the classical Carnot efficiency for systems with two heat reservoirs of constant temperature and introduces the concept of exergy efficiency for configurations in which only one reservoir maintains a constant temperature. Opportunities for practical implementation are discussed for selected locations on Earth and within the Solar System. Both substance working fluids and radiation working media are considered. For context, the study also compares these results with the exergy efficiency of natural solid fuels, which can exceed 100%.