Digestate to biochar Added value or added risk?

Transcription

1 Digestate to biochar Added value or added risk? Jan Mumme (ATB Potsdam) Digestate use & treatment Swedish-German Workshop 5th September 2013, Malmo/Höör, Sweden

2 Project APECS Overview Aim: Combined production of biogas and biochar Approach: Experimental Partners: ATB and Technical University Berlin Team: 4 Postdoc 5 PhD researchers Time: 09/ /2014 Funding: PtJ/BMBF Bioenergy2021 (junior research teams)

3 The biochar idea, from the soil perspective Biomass Biomass Biomass Pyr Soil Stable C Stable C Stable C Today - natural C stabilisation (humification) - stable C is a significant factor for soil fertility Future scenario - less return of biomass to soil - increased mineralization -> decrease of stable C pool -> loss of soil fertility -> less biomass yield Biochar scenario - addition of stable C to soils -> increase of stable C pool -> higher soil fertility -> higher biomass yield -> C sequestration

4 The biochar idea, from the biogas perspective Lignocellulosic biomass Biogas Lignocellulosic biomass Treatment Biogas Low biogas yield Biomass treatment -> increased biogas yield Lignocellulosic biomass Carb onisa tion Biogas Char Soil Lignocellulosic biomass Carb onisa tion Biogas 4 Char Market Digestate to Biochar to Soil -> increased biomass yield -> higher biogas yield per hectare Digestate to Biochar to Market -> additional economic yield

5 Biochar the Technology, Pyrolysis Traditional earth kiln Lehmann 2009 Simple technology, high energy losses and high GHG emissions

6 Biochar the Technology, Pyrolysis State of the art Quelle: J f. Terroirwein u. Biodivers. Continuous process with heat recovery, use or treatment of by-products (pyrolysis gas, condensate) Screw reactor (Pyreg GmbH) works only with dry biomass

7 Biochar the Technology, hydrothermal carbonization (HTC) SmartCarbon AG HTC pressure vessel reactor (batch operation) Suncoal Industry GmbH HTC pressure vessel reactor (conti. operation) Stadtwerke Halle GmbH (Artec reactor) HTC pressure pipe reactor (conti. operation) works with wet biomass no long-term full size experiences yet biochar intended for fuel use (yet)

8 Biochar Pyrolysis vs. HTC Factor Pyrolysis HTC Temperature C C Pressure 0-1 bar bar Time min min Water status dry process wet process Biomass dry only wet and dry Char yield (%TS) 40-70% 60-90% Mainapplications Charcoal,biocharfor soil amendment Alternate solid fuel Maturity proven pilot/demonstration

9 Biochar lab at ATB 1-L-HTC reactor 18 L HTC reactor rotary kiln

10 Char properties 190 C 230 C 270 C -> HTC suitable for converting digestate into biochar -> Digestateyields hydrogen-rich chars (highly energetic MJ/kg) Mumme et al

11 Field trials with HTC char from maize silage Plot 1.5 x 3.3m = 5 m² Variations Fresh char and refined char 1% and 2% (final soil carbon) Char application 06/2011 Crop rotation Sorghum 06/11-10/11 Rye 10/11 05/12 Maize 05/12 10/12 Wheat 11/12 08/

12 Field trials Sorghum [deciton/ha, TS] -> fresh char inhibits crop growth Mumme et al (in prep.)

13 Organic contaminants, FTICR-MS (aromatics) Maize char (lab) Digestate char (lab) Maize char (pilot scale) Noah et al. unpublished

14 Organic contaminants, Temperature impact (GC-MS) Relative peak area Helmis, M. (Master thesis at ATB & Beuth-Hochschule) Relative Rel. Peakfläche peak area Toluol Methyl-/ Dimethyl-/ 2- Cyclopenten-1-on Methyl-/ Dimethyl-/ Benzofuran Phenol 190 C 230 C 250 C 270 C Huge variety of toxicants Strong influence by HTC temperature Post-treatment necessary!

15 Fermentation of HTC chars under mesophilic temperatures, three weeks

16 Field trials, 1. crop in rotation Sorghum [deciton/ha, TS] -> fermentation reduced negative effects on crop growth

17 Energy efficiency of Biogas and HTC char from straw Net efficiency 54% Estimated auxiliary power: for biogas production 25% (HHV of biogas) and dry HTC char 10% (HHV Char) Funke et al /3 of the energy stays in digestate Energy yield can be doubled by HTC (energetic use of char)

18 Conclusions Digestate to Biochar HTC is very feasible, yields high energetic chars energy yield can be doubled (energetic use of biogas plus biochar) But: various organic toxicants (not relevant for energetic use) Digestate to Biochar to Soil Needs post-treatment (remove toxicants, add nutrients) Fermentation (Biogas) is very suitable (also for HTC waste water), yields enough biogas to fuel the HTC Next steps Gathering long-term experience on HTC (pilot scale) and soil impact of HTC char Establishing the legal basis for production, trade and use of biochar Bringing in the stakeholders and create a strategy for commercializing biochar

19 Biochar stakeholder meeting COST ACTION TD1107 Biochar as option for sustainable resource management Breaking ground 1 st Stakeholder Meeting 23 October (2 to 6 PM), Velence Spa & Conference Center Hungary, 2481 Velence, Tó Street 4-6 up to 40 participants can be reimbursed by EU COST

20 Thank you!