Biochar as a negative emission technology Cecilia Sundberg

Biochar as a negative emission technology Cecilia Sundberg Associate Professor KTH and SLU

What is biochar? https: //doi. org/10. 3390/agriculture 5030806

Biochar as negative emission CO 2 Heat, power

Carbon dioxide removal with additional benefits: climate, environment, social Increased plant growth • Water and nutrient holding capacity • p. H buffer • Affects soil microbes • Food security • Reduce emissions of methane and nitrous oxide Gitau JK, Mutune J, Sundberg C, Mendum R, Njenga M. 2019. Implications on Livelihoods and the Environment of Uptake of Gasifier Cook Stoves among Kenya’s Rural Households. Applied Sciences. 2019, 9(6) https: //doi. org/10. 3390/app 9061205 • Filter: water, air • Waste management Tisserant, A. and F. Cherubini 2019. Potentials, limitations, co -benefits, and trade-offs of biochar applications to soils for climate change mitigation. Land 8(12)

Variable size of production Many potential uses Azzi, E, Karltun, E, Sundberg C. 2019. Prospective life cycle assessment of large-scale biochar production and use for negative emissions in Stockholm. Environmental Science & Technology 53(14) 84668476. Foto: Elias Azzi Gitau, JK, Sundberg, C, Mendum, R, Mutune, J, Njenga M. 2019. Use of Biochar-Producing Gasifier Cookstove Improves Energy Use Efficiency and Indoor Air Quality in Rural Households, Energies, 12 (22) 4285

As with any biomass technology: Sustainable biomass is a requirement & Biomass is a limited resource Climate system Biomass production Land system Biomass conversion Biochar use Co-product use Energy system

Co-product use is important Heat is a great co-product Azzi, Karltun, Sundberg 2019. Environ Sci Technol 53(14) 8466 -8476

Biochar is rather stable C sequestration, but how stable? h c r a e Res g n i o ong In IPCC National Guidelines since 2019 Helena Söderqvist, 2019. Carbon Stability of Biochar - Methods for assessment and indication. MSc thesis, KTH, Stockholm

Biochar/Biocoal can replace fossil coal. This is also a climate benefit, but not a negative emission Carbon dioxide emissions (Mton/yr) 52 5 -10 0 5 -10 Vägen till en klimatpositiv framtid SOU 2020: 4 2016 Sveriges Radio P 1 Klotet 2 Oct 2019 2045 Vägen till en klimatpositiv framtid SOU 2020: 4

Recommendation • Support biochar for negative emissions, but choose biochar systems that have additional benefits: • • • Waste management Heat production Plant growth Soil greenhouse gas emission reduction Water management Social benefits

cecilia. sundberg@slu. se www. biochar. abe. kth. se