STEP cement: Solar Thermal Electrochemical Production of CaO without CO2 emission

Abstract

New molten salt chemistry allows solar thermal energy to drive calcium oxide production without any carbon dioxide emission. This is accomplished in a one pot synthesis, and at lower projected cost than the existing cement industry process, which after power production, is the largest contributor to anthropogenic greenhouse gas emissions.

Sustainable Electrochemical Synthesis of Large Grain- or Catalyst-Sized Iron

“…The electrolysis potential is measured as the voltage between the anode and the cathode at constant current. We have previously reported on STEP cathode or oxygen anode potentials in a variety of molten carbonates [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] During electrolysis, the iron product accumulates at the cathode, which is subsequently removed and cooled. Details of STEP electrolysis are provided in references [5][6][7][8].…”

“…Fundamental, electrochemical, and impurity effects on STEP iron have been investigated [8], and the general effects of alkali earth and hydroxide on STEP processes in molten carbonates have been reported [14][15][16][17][18][19][20]. The fundamental increase in solar electrolysis efficiency with the use of solar thermal has been analyzed for CO 2 and H 2 O splitting theoretically [10][11][12] and experimentally [13][14][15] and the fundamental endogenic decrease in electrochemical potential with the increasing temperature demonstrated for a number of STEP processes [10][11][12][13][14][15][16][17][18][19][20]. The requisite solar thermal heating for any given process will depend on the current density, which controls the overpotential and the net difference between the thermoneutral potential and the applied electrolysis potential.…”

“…The general solar thermal electrochemical process (STEP) of sunlight to decrease (endogenic) electrolysis potentials leads to high solar energy conversion efficiencies [6][7][8][9][10][11]. A variety of other STEP electrolyses have been demonstrated to decrease CO 2 including the production of cement, ammonia, fuels, and carbon for the direct removal of atmospheric or smokestack carbon dioxide [10][11][12][13][14][15][16][17][18][19][20]. Fundamental, electrochemical, and impurity effects on STEP iron have been investigated [8], and the general effects of alkali earth and hydroxide on STEP processes in molten carbonates have been reported [14][15][16][17][18][19][20].…”

“…A variety of other STEP electrolyses have been demonstrated to decrease CO 2 including the production of cement, ammonia, fuels, and carbon for the direct removal of atmospheric or smokestack carbon dioxide [10][11][12][13][14][15][16][17][18][19][20]. Fundamental, electrochemical, and impurity effects on STEP iron have been investigated [8], and the general effects of alkali earth and hydroxide on STEP processes in molten carbonates have been reported [14][15][16][17][18][19][20]. The fundamental increase in solar electrolysis efficiency with the use of solar thermal has been analyzed for CO 2 and H 2 O splitting theoretically [10][11][12] and experimentally [13][14][15] and the fundamental endogenic decrease in electrochemical potential with the increasing temperature demonstrated for a number of STEP processes [10][11][12][13][14][15][16][17][18][19][20].…”

Towards a Computational Model for Heat Transfer in Electrolytic Cells

“…At the George Washington University, discovery of new molten salt chemistry has resulted in the use of electrolysis for calcium oxide (CaO) production from limestone (CaCO 3 ), without the generation of carbon dioxide that is normally released in regular processes [1]. The underlying reaction requires a certain temperature threshold to be maintained, which motivates us to study the thermal energy movement in the system.…”