Concrete Energy Storage Calculations

• 1 cubic meter of concrete weighs 2400 kg
• MGH - energy if taken up to 100 meters with a crane
• Common cranes are 80m max and 20ton capacity - [1]
• Take 30 meters tall and 2.5 ton capacity (practical village scale). Can double up as an observatory or sky diner on top.
• Take 2.5 ton weights - about a cubic meter
• One 2.5 ton weight raised 30 meters - takes MGH=2500*10*30=750,000 joules=750k watt-seconds
• 750kWs=20 kW minutes = 0.3 kWhr. 3 weights of a cubic meter give 1 kWhr. But at $300 concrete cost off the shelf. So mix your own concrete - and do 1/5 the cost for concrete. 1kWhr for $60 in concrete cost - simple DIY if $10 bag of 100 lb cement - $20 makes 1 ton of concrete if no aggregate cost. Absolute minimum - $50/weight if aggregate is free - just cement cost.
• Not bad. But concrete cost itself is $150/kWhr - which kills it right there. Aim for $30/kWhr by lower cost cement mix in bulk.
• Take 30 such blocks - about 30 meters tall - one column - and energy in there is 30*2500*10*15 - with 15 average height raise.
• That is 4.5 kWhr
• To make this practical - would need many such towers. Geometry, stabilization, handling are the keys - how to achieve a sound design?
• In principle sounds like a great idea, if the automation and CV AI can help
• For much smaller scale - say 10 meters tall and blocks of 2 tons - take 100 blocks -
• $100/cu yd of concrete - bioconcrete or burned limestone could be a trick here.
• Take 100 yards of concrete mix - $10,000
• Tower - $10k in materials
• $20k cost total
• 100 blocks * 2500*10*5=12.5 MJ = 3.5 kWhr * 80% efficiency = 2.8Kwhr
• 2.8kWhr for $20k? 10 meter tall Doesn't make sense.
• But 120' = 10kWhr - is better.
• Check out this crane for 140' tall, 30 ton capacity - $25k - [2]
• Basic cost -

Bulk Cement

• $75/ton - [3] min order of 100 tons
• 1000 kg for $75 vs $10 for 50 kg - 1/3 the cost. So go from $50 to $17/ cubic meter weight
• 100' height - 30 meters - 100 of these weights - cost - $1700. Then recycled steel beams - 33kWhr storage. At $1700 concrete, and $1700 for tower - $100/kwhr

Conclusion

• Regeneratively grown biomass turned to charcoal is 3kWhr/gallon - so $1/kWhr of useful energy. That is the easiest carbon-neutral storage option, followed by Saturated Water and Hydrogen Storage.