Pyrogenic carbon capture and storage

Abstract

The growth of biomass is considered the most efficient method currently available to extract carbon dioxide from the atmosphere. However, biomass carbon is easily degraded by microorganisms releasing it in the form of greenhouse gases back to the atmosphere. If biomass is pyrolyzed, the organic carbon is converted into solid (biochar), liquid (bio‐oil), and gaseous (permanent pyrogas) carbonaceous products. During the last decade, biochar has been discussed as a promising option to improve soil fertility and sequester carbon, although the carbon efficiency of the thermal conversion of biomass into biochar is in the range of 30%–50% only. So far, the liquid and gaseous pyrolysis products were mainly considered for combustion, though they can equally be processed into recalcitrant forms suitable for carbon sequestration. In this review, we show that pyrolytic carbon capture and storage (PyCCS) can aspire for carbon sequestration efficiencies of >70%, which is shown to be an important threshold to allow PyCCS to become a relevant negative emission technology. Prolonged residence times of pyrogenic carbon can be generated (a) within the terrestrial biosphere including the agricultural use of biochar; (b) within advanced bio‐based materials as long as they are not oxidized (biochar, bio‐oil); and (c) within suitable geological deposits (bio‐oil and CO2 from permanent pyrogas oxidation). While pathway (c) would need major carbon taxes or similar governmental incentives to become a realistic option, pathways (a) and (b) create added economic value and could at least partly be implemented without other financial incentives. Pyrolysis technology is already well established, biochar sequestration and bio‐oil sequestration in soils, respectively biomaterials, do not present ecological hazards, and global scale‐up appears feasible within a time frame of 10–30 years. Thus, PyCCS could evolve into a decisive tool for global carbon governance, serving climate change mitigation and the sustainable development goals simultaneously.

Strategies for mitigation of climate change: a review

“…This would be the case as long as the biochar is technically matched with the type of crop, soil and growing conditions related to the specific cropping system. Besides soil, Schmidt et al introduced other carbon sink applications for biochar which include construction materials, wastewater treatment and electronics, as long as the product does not thermally degrade or oxidize throughout its life cycle (Schmidt et al 2019). Furthermore, it has been argued in the literature that marginal and degraded lands can potentially be utilized for dedicated plantations, relieving pressure on land that can be used for other purposes.…”

Feedstock choice, pyrolysis temperature and type influence biochar characteristics: a comprehensive meta-data analysis review

“…Greater pyrolysis temperatures tend to create relatively stable, aromatic C compounds and silicate-carbon complexes that are usually regarded as recalcitrant to microbial oxidation (Guo and Chen 2014). When placed in soils, recalcitrant C could last hundreds to thousands of years, and as such, biochar land application may play a role in climate mitigation (Schmidt et al 2019;Werner et al 2018;Woolf et al 2018;Bolan et al 2012).…”

Biochar as multi-purpose sustainable technology: experiences from projects in Tanzania

“…So far, the substantial efforts of biochar proponents to make biochar an officially recognised mitigation technology by connecting it to the clean development mechanism (CDM) have been unsuccessful (Biochar International 2018;Maraseni et al 2010). However, Schmidt et al (2018) argue that biochar is likely to gain importance in climate policy contexts in the coming years, and Smith (2016) argues for its inclusion in integrated assessment models because of its advantages over other NETs.…”