About 10 percent of EU CO2 emissions could be offset by more productive use of biomass and plant residues through pyrolysis. This is the conclusion of Prof. Bruno Glaser from the University of Halle and author of the article “Biochar use: a productive alternative to carbon storage”. Biochar produced from pyrolyzed (carbonised) biomass and plant residues can be used as soil improver and as a source for other carbon applications such as construction or animal feed.
11 gigatons of carbon dioxide (CO2) per year
Greenhouse gases such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are the basis of man-made air pollution. Man’s main contribution to the global greenhouse effect is the emission of unimaginably high amounts of CO2 into the atmosphere. This corresponds to about 11 gigatons of carbon © per year, a mind-boggling amount. 80% of this is caused by exhaust gases from fossil fuels (power generation, transport and cement and steel production) and about 20% is released by agriculture (deforestation, conversion of grassland into arable land, etc.). Due to rising population growth, greenhouse gas emissions will continue to rise. In addition, the potential of natural CO2 storage in the oceans, for example, is expected to decrease with rising temperatures, which contributes to the greenhouse effect. Therefore, sustainable solutions for the removal (sequestration) of atmospheric CO2 are needed for the global environment. According to Glaser, Europe could offset 10% of its annual carbon emissions if only part of its annual organic waste (grain residues, forest residues, garden and green waste; about 500 megatons) were converted into biochar (about 140 megatons).
Current options for long-term carbon storage
Carbon capture and storage (sequestration) only makes sense if it removes CO2 from the atmosphere in the long term – at least hundreds of years, preferably sending dew. The agricultural techniques currently available (no tillage, desertification) will contribute little to carbon sequestration into the soil. According to Glaser, the conversion of agricultural land into grassland (grazing land) would also only aggravate the current problem due to the enormous energy loss incurred by the conversion of plants into animal feed. All previous options for C‑sequestration are therefore dealt with, including:
- Carbon Capture and Storage (CCS): Large-scale carbon sequestration at power plants and permanent storage in underground deposits.
- Carbon Capture and Use (CCU): CO2 capture, in particular from combustion gases, and use in other chemical processes.
- Separation and storage of solid carbon in (polluted) ocean sediments
- Use of carbon as an adsorbent (activated carbon) and subsequent removal of carbon in fallow land (landfills, abandoned mines, deserts, etc.)
Economic benefit thanks to stable CO2-binding
Conventional technologies for climate change mitigation such as biofuels and CCS are “closed loop”, i.e. they only bind emitted CO2. Therefore, these techniques cannot reduce the actual or future CO2 content of the atmosphere. Since they are not 100 percent efficient, Glaser says they will further increase the atmospheric carbon dioxide content. Biochar, on the other hand, is resistant to biochemical degradation thanks to its molecular stability. Capturing CO2 in a stable and solid form such as biochar and using it to improve ecosystem services or in building materials can actively reduce atmospheric CO2 concentrations while generating economic added value. This added value results from the possibility of carbon-negative food production (more carbon is bound than released), greater plant productivity, savings in the purchase of mineral fertilizers, an increase in corporate brand value through demonstrably sustainable production processes and an income stream from the acquisition of CO2 certificates traded on the voluntary carbon market.
Biochar as a building material
However, not only agriculture benefits from the added value generated by biochar. Plant charcoal can also be used as a modern building material in other industrial areas such as in the construction industry. Carbon fibres are state-of-the-art materials with properties such as low weight, high strength and chemical stability. Carbon composites can replace steel and other metals, although they have different properties. Carbon fibres are already being used in tensile-resistant building materials to reinforce concrete for special applications and actively protect the climate.