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NPP Modelling for Biomass Energy Estimations of South Africa Markus Niklaus, Markus Tum, Kurt Günther. AARSE 2010 Addis Ababa. Outline. Energy yield from Biomass Production Modelling vegetative Carbon exchange with BETHY/DLR Converting Carbon uptake to Energy Yield Potential
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NPP Modelling for Biomass Energy Estimations of South AfricaMarkus Niklaus, Markus Tum, Kurt Günther AARSE 2010 Addis Ababa
Outline • Energy yield from Biomass Production • Modelling vegetative Carbon exchange with BETHY/DLR • Converting Carbon uptake to Energy Yield Potential • The Energy Yield Potential of South Africa
Energy from Biomass Biogas – Anaerobic digestion Bioethanol Biomass burning – Straw and wood pellets
Dynamical modelling of vegetative carbon balance Waterbudget Heat-transfer Radiation Transpiration Precipitation CO2- Exchange Evaporation Photosynthesis Soil water Roots, water uptake Soil Heatflux
C Scheme of Dynamic Vegetation Model BETHY/DLR BETHY/DLR Land Cover, GLC2000 (1 km) Photosynhetic Reactions Fraction of Cover, MODIS (1 km) Precipitation ECMWF (0.5°) Wind Speed, ECMWF (0.5°) Temperature, ECMWF (0.5°) PAR, ECMWF (0.5°) Input Data LAI, CYCLOPES (1 km) … Gross- and Net- Primary-Productivity Maintanance Respiration NPP = GPP - MR
Input Data: Leaf Area Index (LAI) • Definition:LAI = Leaf area of canopy / ground projection area of canopy [m²/m²] Time series of interpolated 10-day composites Tree Cover Spatial resolution: 1 km
2001 200 0 Results: Model Output for South Africa Gross- and Net Primary Productivity (GPP/NPP) National NPP-Sum for the year 2001 ~ 130 MtC
– Tuber Forage plant Roots Grain Water content Non-C-Elements Straw The way from NPP to Straw-Biomass NPP
Converting Straw Potential to Energy Yield Total yield for 2003 from straw: 312 PJ Net Calorific Factor: 18.1 MJ/kg
Potentials Tree compartiments Leaves, Blossom, Fruit Crown Logging remains: Brushwood Solid volume (≥ 7 cm) Whole Tree Full tree Logging remains: Solid volume Solid Volume from Crown Brushwood (≥ 7 cm) Stem- wood Roots Source: DBFZ
Aboveground Biomass (increment) AGB = NPP / ConF / (1 + R) AGB = Aboveground Biomass NPP = Net-Primary-Productivity ConF = Conversion factor (0,45-0,55) R = Ratio of Aboveground and Belowground Biomass - Coniferous: 0,239 - Broadleaved: 0,268 Solid Volume (increment) SV = AGB * Frac SV = Solid Volume AGB = Aboveground Biomass Frac = Fraction of solid volume from Aboveground Biomass (0,64 – 0,72) Converting NPP to Solid Volume NPP
From NPP to Energy Yield (woods) Total yield for 2003 from wood: 149 PJ Net Calorific Factor: 19.7 MJ/kg
Conclusion • Using a vegetation model (BETHY/DLR) with remote sensing data as input annual NPP of South Africa can be calculated with 1 km resolution • With specific conversion factors the energy yield potential of South Africa can be estimated (total 2003 from agriculture and forestry: 461 PJ) • The comparison with statistics (energy supply 2003 from renewables and waste: 546 PJ) shows a good fit to the results • For higher accuracy more detailed information of specific conversion factors would be necessary
Thank you for your attention! markus.niklaus@dlr.de