Introduction
Aside from a discount in CO₂ emissions by 90% the IPCC calls for “Carbon Dioxide Removal” (CDR) that pulls giant quantities of CO₂ out of the ambiance. One promising method is spreading high-quality floor rocks onto agricultural lands. The rock dissolves and reacts with water and CO₂ and generates carbonates which retailer the CO₂ away from the ambient air for a very long time (see our video for particulars). That is known as “Enhanced Rock Weathering” (ERW) as a result of we pace up a pure weathering course of by grinding the rock and inserting it in a positive place to extend the response pace.
The trustworthy reality although is: We nonetheless know solely little concerning the chemical processes involving carbon that truly happen within the soil as soon as rock mud has been amended. Most significantly we shouldn’t have a dependable method of measuring the precise assortment of CO₂ over time: How a lot CO₂ is being captured after x years? We at Undertaking Carbdown have been engaged on this for 3 years now.
As announced in November 2022 we constructed our new greenhouse experiment in January 2023 that can assist us perceive the processes of ERW in soils utilizing over 300 pot experiments which are monitored with quite a few MRV (monitoring, reporting and verification) approaches for the following 24-36 months.
On this article we’re going to describe our reasoning for the experiment design and doc the precise constructing course of. We hope this may allow different groups to construct on our work and to create related experiments the place ideally the outcomes stay considerably comparable. Please tell us for those who construct upon our work: info@carbon-drawdown.de
Why A Greenhouse Experiment?
The precise doing for ERW, i.e. throwing rocks on fields, is a reasonably simple course of, solely the required pace of scale-up is an precise problem (we’d like a doubling each 2 years till 2050!).
However scaling requires a very good MRV and the MRV of ERW is really hard as a result of the heterogeneity and “signal noise” of nature and agriculture on croplands along with some advanced issues happening within the soil itself (see the Cartion Park Model) simply hides the weathering alerts. What makes issues worse is the truth that the noticed processes are gradual and a few outcomes may even take years to indicate up.
Aside from being the muse for the certification and the economics of ERW, a dependable measurement technique that doesn’t require years to get significant information can be required to measure completely different variations so we are able to shortly iterate by way of all accessible choices for rock, soil, remedy charge, location, crop, and many others. and optimize the weathering.
With this in thoughts we consider there are three main obstacles that must be overcome earlier than ERW can develop into a significant participant for CDR sooner or later:
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How a lot how briskly?
For certification and for optimization we’d like one and even a number of, converging strategies to measure how a lot CO₂ is definitely faraway from the ambiance and by which time. -
How will we examine strategies?
Up to now scientific groups have performed discipline and lab experiments of their nation with their soils, their rocks, and their measurement strategies. So information from completely different groups was laborious to check. We want a standard set of samples and information factors to have the ability to examine the strategies and discover out in the event that they converge. -
The place is the (public) information?
The required scale of progress will inevitably make it essential to largely work with pc fashions to calculate/estimate the weathering for certifications as a result of we simply can’t take x samples from many 1000’s fields and take a look at them within the lab 2-4 occasions a yr. Digital sensors may finally assist decrease the uncertainties. However there may be barely any information accessible to coach and take a look at pc fashions.
With our experiment idea we wish to work on all these three obstacles.
Prime Directive: Pace First!
We don’t have time. We merely can’t look ahead to weathering information to “grow” on fields in open nature at nature’s pace (years, and little or no progress within the winter, if any!). By transferring our experiments right into a greenhouse with a managed setting (heat & moist for 12 months a yr) we wish to compress time. For our experiment we determined that we are going to flip all accessible knobs up to 11 (=to the max) that can doubtlessly pace up the reactions – even when this implies we’re transferring away from the state of affairs in open fields for now.
A few of these knobs are:
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temperature (we keep a minimal temperature of 18°-20° C for twenty-four hours on 12 months per yr as a result of 10° C much less would already cut back response speeds by an element of 10, see Pogge von Strandmann et.al. 2022),
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Irrigation with 100% rain water (cisterne) as an alternative of faucet water (decrease TA, no ion modifications over time, most faucet water has no fixed chemical combination) with excessive irrigation charges (we use 2000 mm/a and 8000 mm/a),
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perennial vegetation (which create CO₂ within the soil 12 months per yr, we use a grass by the scientific identify of “lolium perenne”),
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collection of soils that promise excessive soil CO₂ values and excessive drainage potential,
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and a collection of quick weathering rocks/dusts (e.g. Dunite and metal slag).
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(Because of an absence of adequate energy strains we couldn’t work with progress lamps, although.)
The purpose is to create the quickest and strongest weathering sign that we are able to (whereas nonetheless having flowers/bio exercise in our pots – we even added worms) and use this to search out/develop an precise measurement technique. As quickly as this has been discovered we are able to transfer again to nature.
Second Directive: Preserve price and labor per pot low!
Once we began to plan this experiment we shortly realized that we might want to arrange tons of of pots/lysimeters. This meant that we couldn’t use our two earlier lysimeters ideas (base prices €150 of the 2021 model and €70 per pot for the 2022 model) for price and for house/logistics causes. So we got here up with a brand new lysimeter design that prices lower than €6 per pot and incorporates 10 liters of soil.
