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Water requirements of bio-fuel expansion

Water requirements of bio-fuel expansion. R. Schaldach, J. Alcamo, M. Flörke, D. Lapola Center for Environmental Systems Research University of Kassel, Germany. Environmental Impacts of bio-fuels. Impacts on land and water:. Large areas of land are needed

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Water requirements of bio-fuel expansion

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  1. Water requirements of bio-fuel expansion R. Schaldach, J. Alcamo, M. Flörke, D. Lapola Center for Environmental Systems Research University of Kassel, Germany

  2. Environmental Impacts of bio-fuels Impacts on land and water: • Large areas of land are needed • (e.g. a 10% substitution of petrol and diesel fuel is • estimated to require 43% and 38% of current cropland • area in the United States and Europe, respectively • (Righelato & Spracklen 2007). • Replacement of food crops? • (e.g. increasing food prices) • Invasion of pristine natural lands? • (deforestation, e.g. in Brazil?) • Increased pressure on water resources by irrigation water use

  3. Outline • 2 studies to quantify crop irrigation water requirements • Focus on field crops for 1st generation bio-fuelsand the transport sector • India, impact assessments: How much water is additionally needed for irrigation of sugarcane for ethanol production • Europe, resource planning tool: Which amount of bio-energy can be yielded under different boundary conditions Jatropha Rapeseed Sugar-cane Maize India USA, EU India, Brazil EU

  4. Methods for modeling bio-fuel crops • LandSHIFT = global simulation of land-use dynamics (5 arc-minutes raster) • LPJmL = estimates of crop yields and water requirements (30 arc-minutes raster) • WaterGAP= simulation of water use and water stress (River basins)

  5. The LandSHIFT model

  6. Simulation of land-use change Gg Productdemand Production (t+1) Macro level time Socio-economy and production data Resourceallocation Intermediate level Micro level Yields (t) Slope Land use (t) + 30‘ gridBasins 5‘ grid Land use (t+1) Suitability analysis

  7. Simulation of vegetation processes The LPJmL Model (Sitch et al., 2003; Bodeau et al., 2007) Lund-Potsdam-Jena dynamic global vegetation model with managed lands

  8. Irrigation water requirements Crop water requirements (ETc) = Crop evapotranspiration Irrigation water requirement = Crop water requirement – eff. precipitation

  9. Modeling approach How is irrigation demand calculated in LPJmL? If ω< 0.7, then water is provided Emax :Maximum traspiration rate (=5-7 mm/d) Epot: equilibrium evapotranspiration [f (lat, T, sunshine hours) based on Prescott equation] wr : plant root weighted soil moisture Αm : empirical constant (=1.4) gpotΦ:nonwater stressed potential canopy conductance [f (photosynthesis)] gm : empirical constant (= 5.0)

  10. Case Study 1: India Question: Irrigation water requirements of additional bio-fuel crops in 2030 1. Goal: Substitution of fossil fuel in transport by ethanol (Singh 2006) • Production of 483 PJ energy equivalent • 10% of transport fuel in 2030 2. Definition of energy pathway: Specification of energy crop or crop mix • Ethanol from sugarcane: energy content 21.3 MJ l-1 • Additional 264 Mt of sugarcane production (290 Mt in 2000) 3. Simulation and analysis of pathway (2000 – 2030) • Computation of land use for base scenario (MEA Order from Strength) • Population: increase from 1.032 billion to 1.54 billion • GDP: increase from 463$ to 1200$ • Strong increase of crop production and productivity • Computation of land use with additional sugarcane demand for ethanol • Computation of irrigation water requirements of bio-fuels

  11. Land use change 2000 - 2050

  12. Irrigation water requirements Sugar cane area for ethanol: ~30.000 km² (36% of total sugar cane area) Total IWR = 33.1 km³ Ethanol IWR = 11.9 km² Furrow irrigation (efficiency 31-62%) 19.2 - 38.4 km² irrigation water demand mm

  13. Case study 2: Europe Which amount of energy can be yielded under different boundary conditions? maize Crop choice Total IWR 5.5 t Min. crop yield Indicators IWR / EnergyArea / Energy Area Crop production Global map* Irrigation area 500, 700, 900 mm Total energyproduction Crop IWR *Siebert et al. (2005)

  14. Irrigated area for bio-energy IRW < 500 mm IRW < 900 mm 11.547 km² IRW < 700 mm 127.233 km² 72.100 km² Total irrigated area 367.057 km²

  15. Calculation of indicators 500 mm IWR / Energy = 0.087 km³ / PJ Area / Energy = 201 km² / PJ 700 mm IWR / Energy = 0.116 km³ / PJ Area / Energy = 197 km² / PJ 900 mm IWR / Energy = 0.133 km³ / PJ Area / Energy = 200 km² / PJ Assumptions: Ethanol yield: 1t maize = 396 l ethanol Energy content: 1l ethanol = 21.3 MJ EU target biofuels: 1453 PJ (34,6 Mtoe, 1 toe = 42 GJ)

  16. Summary and conclusion • Available land and water resources are limiting factors for cultivation of bio-energy crops • Model based assessment of irrigation water requirements for India and Europe • Tools to support the development of options for efficient use of these resources • Further study enhancements: • Consistent scenario building • Inclusion of climate change impacts on yields and IWR • Simulation of expansion of irrigated areas • Competition with other water-use sectors

  17. Results • 500mm • 11547 km² • 6823 kt == 57,55 PJ Area / PJ = 201 km² /PJ • 4,99 km³ IWR / PJ = 0.087 km³ / PJ • 700mm • 72100 km² • 43357 kt == 365,7 PJ Area / PJ = 197 km² / PJ • 42,6 km³ IWR / PJ = 0.116 km³ / PJ • 900 mm • 127233 km² • 75320 kt == 635,3 PJ Area / PJ = 200 km² / PJ • 84,8 km² IWR / PJ = 0.133 km³ / PJ

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