Life

The first law of thermodynamics is best described as the conservation of mass and energy.   As chemical reactions and energy movements occur within a closed system the total amount of matter within the system is constant as is the total energy within the system.   The mass may change from liquid to vapor, solid to liquid, or change from fuel to carbon dioxide and water.   Energy can move from potential energy stored in chemical bonds or water in a reservoir to electricity or heat.   Yet the total of each remains constant.
The second law of thermodynamics states that entropy in a process environment is always positive.   Though a process may have negative entropy, the environment in which the process operates will experience an increase in entropy greater than the reduction of entropy of the process itself.   This means that there is a “tax” every time a process is employed.   The process of moving, changing, or using energy is no exception.   This can be thought of in terms of the efficiency of processes.   In an internal combustion engine only about one third of the energy from the fuel is actually utilized in the power band (development of horsepower and torque).   The rest of the energy from the fuel is dissipated as heat through the engine cooling jacket and the exhaust.
A barrel of oil therefore cannot be reconstituted with the energy released by burning the oil.   In other words, it requires a greater amount of energy to put the oil back together than it released when being burned.   An analogy to this is the burning of a piece of wood.   A new tree can use the water and carbon dioxide produced by burning the piece of wood to make a new log of the same mass and potential energy but it will require more energy from the sun than the original piece of wood produced through combustion.