Energy economics and environment protection are important issues in a modern society that aspires to aim at sustainable development. The evaluation of environmental and operational efficiency would be an important first step towards sustainable development. Renewable energies, especially hydroelectricity, geothermal, solar and wind, are playing an increasingly important role in the energy sector. Therefore, oil & gas companies are progressively transforming into energy companies following an energy transition policy. This raises the question whether the renewable energies promote the environmental and operational efficiency of petroleum companies. First, this paper examines two types of efficiency measures – operational and environmental – for 45 US oil & gas companies during the period 2000–2018 using on the true fixed effect (TFE) model. Second, this research aims to study the effect of renewable energies on both types of efficiency. The results reveal that the overall average operational efficiency (desirable output) of the US oil & gas companies is 76% for a period of 19 years, while the overall average level of CO2 emissions efficiency (undesirable output) of the oil & gas companies is 79%. The results highlight that US oil & gas companies have begun to transition to low CO2 emission in recent years. Furthermore, the renewable energies and biomass energies contribute to destroying the operational efficiency and to promote the environmental efficiency of oil & gas companies.