Research network on electrochemical energy storage,
Research center on batteries and supercapacitors

Must we talk of energy or energies?

Must we talk of energy or energies?

First of all, one must not mistake “form of energy” for “source of energy”.  We have listed the main forms of energy (chemical, electric, nuclear,), but each of these forms can be carried or conveyed by very numerous vectors of different natures.  Thus, a lump of sugar, oil, kerosene, wood, natural gas, coal, peat… are sources of chemical energy


Let’s note that the very large majority of available energy sources on earth are of solar origin,

  •  SOLAR THERMAL and PHOTOVOLTAIC energy, of course,
  • BIOMASS is the result of the photosynthesis process that transforms the solar radiations energy into chemical energy,
  • Wind (wind energy), resulting from the movement of volumes of air of various temperatures, therefore differently exposed to the solar radiation,
  •  HYDROELECTRIC energy, resulting from the storage of evaporated water in altitude.  The water is exposed to the sun and therefore evaporates.
  • WAVES, which origin is the wind,
  • THERMAL ENERGY from the oceans, consists in capturing the radiative energy that the sun provides the oceans
  •  OCEAN CURRENTS, resulting from the differences in density and temperature between the water masses from the ocean.

Only the tidal energy sources (gravitational mechanical energy), geothermal (nuclear decomposition of unstable nucleus in the earth crust) and of course nuclear energy used in uranium fission reactors, are not of solar origin.

Some of these sources are said to be renewable and others non renewable.

Non renewable energies

They have various origins and their stock is limited by the size of the planet and by the rate of the present human energy consumption.  These resources can be found in the soil and can be fossil (mainly coal, gas and oil), i.e. they come from the decomposition of organic matters from the earth or the sea, or fissile (uranium).

Non renewable energies are energies that will eventually die out one day because these resources on earth are in finite quantities, and also because their use has not been and still is not mastered.  They have been exploitable and exploited by Man for hundred years but at such a rate that Man has nearly used in 200 years the entire resources that our planet gathered in millions of years.

Renewable energies

Everything around us is ENERGY … There again, there are various sources of energy called ‘renewable energies’ which are also called «clean energy or green energy».  These energies i.e. solar, wind, geothermal, biomass, etc. with low CO2 footprint, are also described as clean energies as well as being unlimited.  Among these resources that, besides tidal energy or geothermal energy, are all dependent on the solar activity, one must stress that we get from the sun 10000 times the energy that the planet needs.  More precisely, every 90 minutes of solar energy on earth corresponds to the amount of energy Man consumes every year. To face up  today’s  major environmental challenge we MUST, as researchers facilitate the use of renewable energies.  Such energies need to be captured and stored at a large scale to  meet the peoples’ needs in energy consumption while preserving our Planet.  Today’s real issue is to efficiently and inexpensively convert and store these renewable energies