Solar Concrete

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Concept

Use PV to make cement from limestone. PV heats limestone, emits CO2 and produces cement. Cement is used in construction, and it absorbs C02 to make rock-hard structure. Overall process is carbon neutral, and thus solves the issue of vast CO2 emissions from industry standard cement production. OSE calls for distributed production as such, to be deployed in resilient communities worldwide at low cost.

Numbers

  • Embodied energy of cement - 5.6 MJ/kg. Note that concrete blocks are about 1.5 MJ/kG
  • 1 MJ = 0.3 kWhr (1 kWhr = 3.6 MJ)
  • Thus, a 10 kW solar panel array, affordable by any University Solar Concrete Project - pr donated for conscience - has 60kW hrs of energy per day
  • Concrete block is only 10-15% cement
  • 1 kWhr gets us .6 kg of cement
  • 60 kWhr gets us 36 kg of cement!
  • 8x8x16" cinder blocks [1] are 30 lb or 15 kg
  • Concrete block - [2]
  • 1:3:6 cement for concrete blocks - [3]
  • We can make 36 kg of cement per day with a 10 kW array, or 360 kg of block - or 24 cinder block per day. Or 72 full sized CEB Blocks.
    • Standard concrete blocks are $1.40 each - [4]
    • The value of electricity for 60kWhr is $6. The value of cement is $9 or 50% more. Value of block is $34 or 600% more.
  • The key here is using excess electricity from inexpensive PV, which otherwise may be left unused.
  • Negotiating power sales to the grid can be attractive pending ability to disconnect from grid if company terms are not favorable, so there is a strong case for the negotiating power of small producers. But this depends on the ability of producers to have storage, for night time use, if disconnected from the grid.
  • $25*300= $7500 - a good value per year for an experimental club in school which stockpiles cement or special use block such as pervious pavement blocks.
  • Notes - calculations above are for portland cement, so lime cement should be 30-40% less energy intensive?