Solar Concrete

• Embodied energy of concrete - 5.6 MJ/kg. Note that pure cement is only 1 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 kW 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 block per day.
• 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.