michael beyer wrote:i'm specifically interested in the lime life cycle
technically the hemp could be carbon neutral or negative (as hempcrete absorbs carbon over time) if it is acquired locally with machines run on biomass or something (dreaming 😂🌈)
and if local, then there's little to no packaging or transportation costs
but the lime i'm wondering about — certainly the mining will be intensive but how much so? and also the processing of limestone to like is intensive but how much so exactly?
can hempcrete ever become a more sustainable form of building than using local wood?
Phil Stevens wrote:The carbon dioxide absorbed by lime as it turns back into calcium carbonate (limestone) will only ultimately equal the amount emitted when the source material was fired to produce quicklime. So the LCA is net neutral on this factor.
Phil Stevens wrote:Michael - assuming the transport and processing component is minimal, if you use a carbon-neutral energy source to calcine the lime then hempcrete would indeed have a net negative footprint. Running a lime kiln requires a lot of heat, so that will either come from renewable electricity, biomass, or possibly a solar furnace. There's a potential industry for sunny places with limestone at hand...solar limeworks.
Phil Stevens wrote:Is 3500 C hot enough for you?
Calcining lime requires 825 C, and I think you could achieve that pretty easily with mirrors and a well-insulated refractory vessel. Is there BB potential here?
Phil Stevens wrote:Pickaxe, shovel and wheelbarrow! Although we can also make explosives from bird droppings if you're keen to experiment....