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What is Biomass Carbon Removal and Storage?
Biomass Carbon Removal and Storage (BiCRS—pronounced ‘bikers’) is a set of carbon removal technologies that remove carbon dioxide by either halting or slowing the decomposition of organic material—known as biomass.
For example, over the course of its life, a plant will capture and store carbon dioxide from the atmosphere via photosynthesis. When the plant dies, the process of decomposition releases this carbon dioxide back into the atmosphere. BiCRS halts or slows the decomposition of the plant. This prevents carbon from returning to the atmosphere, enabling it to be permanently stored.
How does Biomass Carbon Removal and Storage work?
BiCRS typically involves either converting biomass into materials that decompose more slowly—through processes like pyrolysis—or storing it in environments where decomposition is naturally slowed.
Pyrolysis
One of the primary BiCRS methods involves stopping the decomposition of biomass and capturing carbon dioxide for storage by pyrolysis. Pyrolysis involves heating biomass in the absence of oxygen at or above 500°C. Due to the lack of oxygen, the biomass does not combust and instead converts into biochar—a charcoal-like material—and combustible synthetic gas. Elements of this synthetic gas—known as the condensable fraction—can also be condensed into a stable liquid called bio-oil.
Once the pyrolysis process is complete, the carbon-rich biochar and bio-oil must be stored. Typically, biochar is spread onto fields where it acts as a fertilizer and decomposes far slower than unpyrolysed biomass. Under the right conditions, biochar can durably store carbon dioxide for upwards of 1,000 years.
Bio-oil is typically stored deep underground in geological formations—such as depleted oil and gas reservoirs. Once underground, the carbon dioxide within the bio-oil is safely stored for thousands of years, almost as if running fossil fuel extraction in reverse.
Biomass burial
Alternatively, rather than making the biomass hard to decompose, another BiCRS approach is to store the biomass in places where decomposition takes place very slowly. This can include storing biomass deep in the ocean, in landfill sites, geological formations, or in “dry tombs”: underground stores with low moisture, high acidity, and high salinity.
What types of biomass can be used for Biomass Carbon Removal and Storage?
While in theory any source of biomass could be used for BiCRS, waste biomass is the most common. Using waste materials prevents the release of additional carbon dioxide from the production of purpose-grown biomass. Typical sources of waste biomass used in BiCRS include corn and rice husks, sawdust, waste materials from forestry and papermaking, as well as human and animal waste.
What are the advantages of Biomass Carbon Removal and Storage?
Proven scale and deployment
Relative to other carbon dioxide removal technologies, BiCRS has already been proven to work at scale and is being readily deployed. It is the most scaled method of carbon dioxide removal in use today. The majority of high-durability carbon removal credits issued to date have been delivered by producing biochar.
Durable storage
BiCRS technologies can effectively store carbon dioxide for upwards of 1,000 years. For example, when stored in geological formations—like depleted oil and gas reservoirs—bio-oil can sequester carbon dioxide for thousands of years.
Additionally, while it was previously believed that biochar could store carbon dioxide for no more than hundreds of years, new research has found that—if properly managed—carbon dioxide can remain durably stored in biochar for more than 1,000 years.
Improvements in agriculture and forestry
Biochar can have significant additional benefits when spread on agricultural land. Biochar can improve nutrient retention, water holding capacity and drainage, soil acidity and also can increase the amount of nutrients in the soil.
This both incentivizes farmers to spread biochar on their fields and can result in healthier and higher-yield crops. Additionally, the use of waste materials from forestry can help to reduce the risk of wildfires, by removing potential sources of fuel from the forest floor.
How much does Biomass Carbon Removal and Storage cost?
BiCRS today has a large range of costs, from relatively inexpensive for biochar to moderately expensive for other applications. Prices typically range between $100-$300 per tonne for biochar and $475-$600 per tonne for bio-oil. The cost typically depends on the availability of waste biomass and method of processing.
