Preprint Article Version 4 Preserved in Portico This version is not peer-reviewed

Sequestering Biomass for Natural, Efficient, and Low-Cost Direct Air Capture of Carbon Dioxide (Version 4)

Version 1 : Received: 3 June 2021 / Approved: 8 June 2021 / Online: 8 June 2021 (11:07:17 CEST)
Version 2 : Received: 14 June 2021 / Approved: 15 June 2021 / Online: 15 June 2021 (11:08:17 CEST)
Version 3 : Received: 22 July 2021 / Approved: 23 July 2021 / Online: 23 July 2021 (09:24:28 CEST)
Version 4 : Received: 28 October 2021 / Approved: 2 November 2021 / Online: 2 November 2021 (10:53:39 CET)

How to cite: Amelse, J.A.; Behrens, P.K. Sequestering Biomass for Natural, Efficient, and Low-Cost Direct Air Capture of Carbon Dioxide (Version 4). Preprints 2021, 2021060212 (doi: 10.20944/preprints202106.0212.v4). Amelse, J.A.; Behrens, P.K. Sequestering Biomass for Natural, Efficient, and Low-Cost Direct Air Capture of Carbon Dioxide (Version 4). Preprints 2021, 2021060212 (doi: 10.20944/preprints202106.0212.v4).

Abstract

Many corporations and governments aspire to become Net Zero Carbon Dioxide by 2030-2050. Achieving this goal requires understanding where energy is produced and consumed, the magnitude of CO2 generation, and the Carbon Cycle. Many prior proposed solutions focus on reducing future CO2 emissions from continued use of fossil fuels. Examination of these technologies exposes their limitations and shows that none offer a complete solution. For example, bioethanol is shown to be both carbon and energy inefficient. Direct Air Capture technologies are needed to reduce CO2 already in the air. The most natural form of Direct Air Capture involves letting nature do the work of creating biomass via photosynthesis. However, it is necessary to break the Carbon Cycle by permanently sequestering that biomass carbon in “landfills” modified to discourage decomposition to CO2 and methane. Tree leaves and biomass grown on-purpose, such as high yield switchgrass, are proposed as good biomass sources for this purpose. Left unsequestered, leaves decompose with a short Carbon Cycle time constant releasing CO2 back to the atmosphere. While in any given year, leaves represent a small fraction of a tree’s above ground biomass, leaves can represent a substantial fraction of the total biomass generated by a tree when integrated over a tree’s lifetime. Understanding the chemistry of the distinct phases landfills undergo is the key to minimizing or eliminating decomposition. First, the compact cross-linked structure of cellulose and keeping water out will make it difficult for initial depolymerization to release sugars. Air ingress should be minimized to minimize Phase I aerobic decomposition. pH manipulation can discourage acid formation during Phase II. Lignocellulose is low in nutrients needed for anaerobic decomposition. Inhibitors can be added if needed. The goal is to move quickly to the dormant phase where decomposition stops. The cost for Carbon Capture and Storage (CCS) for growing and sequestering high yield switchgrass is estimated to be lower than CCS for steam reforming of methane hydrogen plants (SRM) and supercritical or combined cycle coal power plants. Thus, sequestration of biomass is a natural, carbon efficient, and low-cost method of Direct Capture. Biomass sequestration can provide CO2 removal on giga tonnes per year scale and can be implemented in the needed timeframe (2030-2050).

Keywords

Carbon Dioxide; Net Zero; Sequestration; Biomass; Direct Capture; Global Warming; Landfills; Forestry

Subject

EARTH SCIENCES, Atmospheric Science

Comments (1)

Comment 1
Received: 2 November 2021
Commenter: Jeffrey Amelse
Commenter's Conflict of Interests: Author
Comment: This is a minor update.  Methods for reducing CO2 emissions can be placed in two categories:  1) Methods that will reduce fture emissions of CO2 from continued use of fossil fuels; and 2) Methods that can remove CO2 already in the atmosphere.  The second category is needed, because the first category will never be 100% efficient, and thus, CO2 will continue to build in the atmosphere.  Biomass sequestration falls into the second category.  Bioethanol can fall into both categories.  Per the stociiometry of the fermentation of 6 carbon sugars from the hydrolysis of corn starch, 4 carbons go to bioethanol, (which are renewable carbons, and displace emissions from future use of fossil fuels.  However, fermentation converts 2 of the 6 carbons to CO2, which most producers now vent to the atmosphere.  Those 2 carbons can fall into the second category only if CCUS is added to bioethanol plants.  A calculation of the carbon efficienty of bioethanol carbon for the entire corn plant is added.  Carbon efficiency for category 1 is only about 14%, and carbon efficiency for category 2 is only about 7%.  The main advantage of sequetering the carbon in all of the biomass is that carbon efficiency can approach 100% if degredation can be avoided.  Since we are not limited by word count, the abstract has been expanded.
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