Embodied Energy of Stabilized CEB
Embodied Energy of Stabilized CEB
Rasmus:
In terms of bricks, I know you are heavily invested in CEBs, and that's fine. I was just struck by the elegance of that Vertical Shaft Brick Kiln and the very modest amount of energy needed, at around 100 grams of coal per brick.
Marcin:
I'm not heavily invested. If you can show a product with better embodied energy qualities on a lifetime scale, I'm all for it:)
What size of brick?
If we press CEBs to waterproof, the energy consumption is about 13 grams per brick in fuel, or more like 20 grams coal equivalent. This is our embodied energy of brick pressing with our machine. Tractor handling is not included, just as I am assuming materials handling is not included in the embodied energy of the vertical shaft brick kiln.
This source [1] says it takes 1 kg of coal for 10 kg of lime. Each of our bricks is 15 lb and takes 375 grams of lime at 5% stabilization, or 38 grams of coal equivalent. Each wall section (4 feet) has 200 block - so a house with 48 wall sections (like a Seed Eco-Home has 38g*200*48=364 kg coal. With 24 MJ/kg, we have about 9 GJ per house.
So I am getting about about 50 grams of coal for our stabilized block. If you are considering standard bricks - then CEBs are about 8x less embodied energy for stabilized block compared to burned bricks - as our block is about 4x the size of a standard brick.
8x is an important number - can it be verified in the literature?
Embodied Energy of Non-Stabilized CEB
Above, 13 grams of fuel per block was mentioned. Is that correct?
We know we can burn 2 gal of fuel (tractor + CEB press) per hour at 6 block per minute. 5.7 kg of gasoline f0r 360 block. This is 16 grams of gasoline per block.
We can likely 2-3x better than this with an optimized hydraulic design, which includes a 2 stage pump.
Let's say the above number is just about correct.
Then we have about 4 GJ for a CEB house made with unstabilized block.
