Low-cost additive turns concrete slabs into super-fast energy storage
newatlas.com
newatlas.com
> But the great thing here is that this energy storage device doesn't need to be small; concrete tends to get used in bulk. An average American 2,000-sq-ft (185.8-m2) home built on a reasonably standard five-inch-thick (13-cm) concrete slab uses about 31 cubic yards (~24 m3) of concrete. Add more if you've got a driveway or a concreted garage, and significantly more again if the house is built using concrete walls or columns.
> The MIT team says a 1,589-cu-ft (45 m3) block of nanocarbon black-doped concrete will store around 10 kWh of electricity – enough to cover around a third of the power consumption of the average American home, or to reduce your grid energy bill close to zero in conjunction with a decent-sized solar rooftop array. What's more, it would add little to no cost.
> The team has tested these concrete supercaps at small scale, cutting out pairs of electrodes to create tiny 1-volt supercapacitors about the size of button-cell batteries, and using three of them to light up a 3-volt LED. Now, it's working on blocks the size of car batteries, and targeting a 1,589-cu-ft, 10-kWh version for a larger-scale demonstration.
"Carbon–cement supercapacitors as a scalable bulk energy storage solution" (2023) https://www.pnas.org/doi/10.1073/pnas.2304318120
> This process takes advantage of the way that water and cement react together; the water forms a branching network of channels in the concrete as it starts to harden, and the carbon black naturally migrates into those channels. These channels exhibit a fractal-like structure, larger branches splitting off into smaller and smaller ones – and that creates carbon electrodes with an extremely large surface area, running throughout the concrete.
>> Here's a discussion about the lower costs of hemp supercapacitors as compared with graphene super capacitors: https://news.ycombinator.com/item?id=16814022
FWIU, Heat-treated hemp bast fiber is comparable to graphene electrodes, and at least was far less costly because bast fiber is otherwise a waste output (and graphene at least was hazardous to produce and doesn't have a natural dendritic branch structure).
"Hemp Carbon Makes Supercapacitors Superfast" (2013) https://www.asme.org/engineering-topics/articles/energy/hemp... :
> Hemp fiber waste was pressure-cooked (hydrothermal synthesis) at 180 °C for 24 hours. The resulting carbonized material was treated with potassium hydroxide and then heated to temperatures as high as 800 °C, resulting in the formation of uniquely structured nanosheets. Testing of this material revealed that it discharged 49 kW of power per kg of material—nearly triple what standard commercial electrodes supply, 17 kW/kg.
Pretty much all concrete used in building a house — especially the slab or basement — will get wet so that renders this idea moot for storing power for a home.