2.2 Sunlight, gravitational potential, decay of radioactive isotopes, and rotation of the Earth are the major sources of energy driving physical processes on Earth. Sunlight is a source external to Earth, while radioactive isotopes and gravitational potential, with the exception of tidal energy, are internal.

The first law of thermodynamics states that the energy of the universe is constant. The change in the internal energy of a system is the sum of the heat transferred and the work done. The heat flow is equal to the change in the internal energy of the system plus the PV work done.

geothermal

The Earth has two basic sources of energy – that reaching the Earth from the Sun (Solar Energy) and that reaching the surface of the Earth the Earth itself (Internal or Geothermal Energy). Solar Energy – reaches the Earth in the form of radiant energy, and makes up 99.987% of the energy received by the Earth.

The pressure of continuing population growth is a major reason for the need for supplemental external energy. The additional population needs to be fed, housed, and clothed. The additional people also needs jobs, and in today’s world, these jobs require external energy inputs.

The Sun is the major external source of energy. Two primary sources of internal energy are the decay of radioactive isotopes and the gravitational energy from Earth’s original formation.

External geological agents and processes affect the Earth’s surface. They are powered by solar energy. External processes shape the relief created by internal processes. External agents carry out this process: water, ice, wind, atmosphere and human beings.

External Energy is energy exchanged with the fluid existing between point 1 and point 2 and its surroundings….External Energy

• Microbial Fuel Cell.
• Nanoparticles.
• Energy Supply.
• Sustainable Development.
• Biomass.
• Hydrogen.
• Energy Source.
• Microbial Electrolysis Cell.