Biochar
Grill, chill, and remove carbon
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Nerd rating: 4 (1 to 10 scale on the technical density of the post)
Notes: Thanks, @JosiahHunt11 of pacificbiochar.com, for sending me some helpful resources on Twitter
Biochar
Soil carbon management, and the litany of practices associated with it, is a way to introduce more carbon into the soil and/or keep the carbon present in the soil for a more extended period of time. Most farmers and/or land maintenance professionals already practice some form of soil management, whether knowingly or not. They include:
Planting cover crops
Leaving leftover plant biomass to natural decay
Actively selecting plant species or varietals that have a greater root mass
Using no-till or low-till practices
Double-cropping
These practices are sometimes referred to as “carbon farming” or “regenerative agriculture.”
Biochar sometimes referred to as charcoal or black carbon (although not to be confused with carbon black), is a carbon-rich material produced from biomass pyrolysis (thermal decomposition) in an oxygen-deprived environment. This type of sequestration is sometimes called pyrogenic carbon capture and storage, or bio-energy carbon capture and storage, with the latter being more commonly used.
The general thesis behind how biochar can mitigate climate change and sequester carbon revolves around photosynthesis. Plants take in carbon dioxide through their metabolic processes (photosynthesis) and thus sequester that carbon in their biomass. That biomass is harvested and then pyrolyzed.
The biomass pyrolyzation process of creating biochar
"The thermal treatment of biomass at 350 °C–900 °C in an oxygen-deficient atmosphere. Three main carbonaceous products are generated during this process, which can be stored subsequently in different ways to produce [negative emissions]: a solid biochar as soil amendment, a pyrolytic liquid (bio-oil) pumped into depleted fossil oil repositories, and permanent-pyrogas (dominated by the combustible gases CO, H2 and CH4) that may be transferred as CO2 to geological storages after combustion.”
Notice the creation of bio-oil; Charm Industrial makes and pumps into the subsurface.
Deliberate biochar creation has a long history. Humans have been taking advantage of this soil additive for a long time, documented at least 150 years in the western world, and evidence of its use for centuries longer in Africa and Asia.
Alongside its long history of use, biochar has a unique property that some other removal technologies do not: straightforward co-benefits. In a meta-analysis of 26 studies, it was found that.
In 26 meta-analyses published since 2016, encompassing more than 1500 scientific publications, the application of biochar delivered mean positive effects for all investigated parameters regarding performance and environmental impact of land cultivation. No negative agronomic or environmental effects were consistently demonstrated for any of the parameters evaluated. Even if there is a certain tendency in scientific publication practice to publish rather significant and positive results (publication bias), the number of studies and the selection criteria used here nevertheless stands for a robust data basis.
Biochar can affect many different parameters: plant productivity, stimulation of root growth and photosynthetic performance, microbial biomass and enzymatic activity of nitrogen fixation, plant-available soil water and bulk density, soil organic matter increase, reducing heavy metal uptake, and so on.
As this same paper points out, the type, mixing, and application of biochar is not a one-size-fits-all situation, and this should be factored into the analysis1
Type of biochar (biomass feedstock, pyrolysis conditions, particle size) and possible post-pyrolysis treatment (biological treatments such as lactic fermentation or composting, chemical treatments such as acidification, etc.).
Mode of mixing biochar and fertilizer (separate application, mixing biochar with liquid fertilizer, mixing biochar with a solid, chemical formulation of the blended fertilizer, etc.)
Optimal application method (homogeneous spreading, strip application, injection, micronized biochar particles via drip irrigation, etc.).
Next week’s post will dig more deeply into the pros and cons of biochar as a soil conditioner and as a removal tool.
Current Market and Potential
Although biochar is a relatively mature technology (compared to other removal methods), the market is still reasonably small. Although I found the numbers to vary pretty wildly based on what group I was looking at, the current US market is somewhere around $125M while the global market is around $1.3B. This is slated to increase over the coming years and, depending on who’s numbers you trust, could grow by over $1.47B by 2026 or $3.238B by 2026.
Alongside the dedicated revenue streams associated with soil management, several organizations have begun to offer carbon offsets through biochar. This provides another revenue stream for biochar producers and necessarily increases their market potential.
The potential for biochar as a climate change mitigation tool is substantial, although mixed in magnitudes. Current variations in contributions of carbon sequestration lie between 1 to 35 GT CO2 per year. Still, due to uncertainties in the availability of biomass for pyrolysis and the yet to be demonstrated scale of projects, it could be anywhere from 0.3-2 GT CO2 per year.
Takeaways
Biochar has numerous co-benefits that set it apart from other removal technologies. This, coupled with the ability to scale relative to other technologies, make it an attractive option for carbon removals. However, some doubts remain on the durability of these removals.
Next week I’ll dive into a more detailed analysis of biochars’ advantages and some of the challenges through the lens of removals.
Next week: Biochar: Pros and Cons
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https://onlinelibrary.wiley.com/doi/full/10.1111/gcbb.12889
Sir:
I am on the board of the U.S. Biochar Initiative and author of <i>The Biochar Solution: Carbon Farming and Climate Change</i> (2009) and <i>BURN: Using Fire to Ignite a New Carbon Economy to End the Climate Crisis</i> (2018). In a collaborative spirit let me offer a few corrections to errors in your post.
“Biochar sometimes referred to as charcoal”
Biochar is never referred to as charcoal. Charcoal has little quality control, is burned, and returns its carbon to the atmosphere. It is often tainted with additives unsuited to farming and gardening.
“This type of sequestration is sometimes called pyrogenic carbon capture and storage, or bio-energy carbon capture and storage, with the latter being more commonly used.”
The two processes are distinct. BECCS may or may not produce biochar but produces energy as heat and/or electricity. PyCSS produces biochar and bio-oils and may or may not capture heat or co-generate electricity.
"The thermal treatment of biomass at 350 °C–900 °C in an oxygen-deficient atmosphere.”
Below 450°C you will not get torrified biomass not biochar. Temperature matters because that is what releases elemental bonds and changes carbon's molecular form to create the ring and chain structures that do not readily degrade. At 350°C the product you create will not withhold carbon from biological cycling as it remains in a labile form. Above 450° - 600°C (depending on other variables) it may be withheld from the carbon cycle for hundreds to thousands of years. There are documented examples of hundred-million-year-old biochars.
“Three main carbonaceous products are generated during this process, which can be stored subsequently in different ways to produce [negative emissions]: a solid biochar as soil amendment, a pyrolytic liquid (bio-oil) pumped into depleted fossil oil repositories, and permanent-pyrogas (dominated by the combustible gases CO, H2 and CH4) that may be transferred as CO2 to geological storages after combustion.”
You need to separate each product from its potential uses. All have multiple applications, which affect durability, price, and other values. Biochar strengthens concrete 30%, for instance, and reduces the requirement for sand. It is also valuable in electronics, dyes, batteries, water filtration, mold-control and much more. Soil application may be its lowest value proposition. Likewise it would be a great waste to pump bio-oil or volatile gases into geological storage when those can form industrial cascades as bioplastics, composites, polymers, chemicals and epoxies, and also have soil chemistry applications.
“Deliberate biochar creation has a long history. Humans have been taking advantage of this soil additive for a long time, documented at least 150 years in the western world, and evidence of its use for centuries longer in Africa and Asia."
Anthropogenic dark earths widely found in South America have been dated back 8000 years. There is no continent except Antarctica where ancient, biochar-infused soils have not been discovered.
Durability is a function of kiln temperature; pyrolysis dwell time; and end application—in other words, it is susceptible to quality control, and that is coming to be regulated by the drawdown credit marketplace and ESG demands by buyers.
“The potential for biochar as a climate change mitigation tool is substantial, although mixed in magnitudes. Current variations in contributions of carbon sequestration lie between 1 to 35 GT CO2 per year. Still, due to uncertainties in the availability of biomass for pyrolysis and the yet to be demonstrated scale of projects, it could be anywhere from 0.3-2 GT CO2 per year.”
When all the potential uses for biochar at a profit are taken into account (ignoring carbon offset subsidies), its limiting factor is only the availability of photosynthetic-origin feedstocks. As Kathleen Draper and I describe in detail in <i>BURN,</i> if you factor in future marine algae farming and kelp forestry wastes, municipal sewage and rubbish, wildfire mitigation, and step-harvested agroforestry, the potential for <i>annual</i> sequestration for biochar is likely to be well above 50 GT CO2.
Thank you for your consideration of this important topic.
Albert Bates
Global Village Institute for Appropriate Technology
givx.org