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FASOM

FASOM. Hamburg July 1-3, 2008. Topics. FASOM Basics FASOM Equations Analyzing FASOM Modifying FASOM. I FASOM Basics. Model Scope. Natural Resources Agriculture Forestry Processing Food, Fibre, Timber, Energy Markets. Purpose and Objectives.

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FASOM

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  1. FASOM Hamburg July 1-3, 2008

  2. Topics • FASOM Basics • FASOM Equations • Analyzing FASOM • Modifying FASOM

  3. I FASOM Basics

  4. Model Scope • Natural Resources • Agriculture • Forestry • Processing • Food, Fibre, Timber, Energy Markets

  5. Purpose and Objectives To study and advice policy makers about the agricultural and forestry sector response to • Policies • Environmental change • Technical change • Socioeconomic change

  6. Policy Scope • Climate and other environmental policies • Research subsidies • Agricultural policies • Trade policies Simultaneous assessment

  7. Structural Changes • Policies • Environmental change • Technical change • Socioeconomic change (population, preferences)

  8. Methodology • Partial Equilibrium • Bottom Up • Constrained Welfare Maximization • Dynamic Optimization • Integrated Assessment • Mathematical programming • GAMS

  9. Model Structure Limits Limits Resources Land Use Technologies Products Markets Inputs Demand Functions, Trade Processing Technologies Environmental Impacts Supply Functions Limits

  10. FASOM = Large Linear Programs

  11. Programming Declare and Assign • Indexes • Exogenous data • Endogenous data • Equations (endogenous/exogenous) Run Programs and Display Results

  12. Regions Periods Altitudes Species Resources Cohorts Farm sizes Farm types Technologies Products Substances Major Indexes (Sets)(decl_basicsets.gms)

  13. Sets • Identify scope • Efficient but dangerous and difficult • Super sets, Sub sets, Tuples • decl_basicsets.gms • 2_activesets.gms • calc_tuples.gms

  14. Exogenous Data • Resource endowments • Technologies (Inputs,Outputs, Costs) • Demand functions • Environmental Impacts • Policies

  15. Exogenous Data • Parameters (Tables, Scalars) • decl_parameters.gms • Data_*.gms

  16. Data Subdirectories • EPIC • FINDUS • FADN + others • OSKAR • FAO • BIODIV

  17. Endogenous Data • Land use decisions (control variables), Impacts (state variables), Shadow prices of constraints • Positive and Free Variables • (Integer Variabales) • 4_eufasom_model.gms

  18. Equations • Understanding them is • to understand FASOM

  19. Equations • Objective Function • Resource Restrictions • Technological Restrictions • Environmental Accounts • Others

  20. Major ParametersFOREST_DATA (PERIOD,REGION,SOILTYPE,SOILSTATE,SPECIES,FARM,AGE,ALLTECH,ALLITEM)PEREN_DATA (PERIOD,REGION,SOILTYPE,SOILSTATE,SPECIES,FARM,AGE,ALLTECH,ALLITEM)CROP_DATA (PERIOD,REGION,SOILTYPE,SOILSTATE,SPECIES,FARM,ALLTECH,ALLITEM)ECO_DATA (PERIOD,REGION,SOILTYPE,SOILSTATE,ALLTECH,ALLITEM)LIVE_DATA (PERIOD,REGION,ANIMAL,ALLTECH,ALLITEM)FEED_DATA (PERIOD,REGION,PRODUCT,ALLTECH,ALLITEM)PROCESS_DATA (PERIOD,REGION,ALLTECH,ALLITEM)PRODUCT_DATA (PERIOD,REGION,PRODUCT,ALLITEM)MARKET_DATA (PERIOD,REGION,ALLITEM,SDTYPE,SDITEM)TRADE_DATA (PERIOD,REGION,REGION,PRODUCT,ALLITEM)RESOURCE_DATA (PERIOD,REGION,ALLRESOURCE,SDITEM)STOCK_DATA (PERIOD,REGION,PRODUCT,ALLITEM)LUC_DATA (PERIOD,REGION,SOILTYPE,SPECIES,ALLCHANGE,ALLITEM)

  21. Major VariablesRESOURCE_VAR (PERIOD,REGION,RESOURCE) FOREST_VAR (PERIOD,REGION,SOILTYPE,SOILSTATE,SPECIES,OWNER,AGE,FORTECH) PEREN_VAR (PERIOD,REGION,SOILTYPE,SOILSTATE,SPECIES,FARM,AGE,CROPTECH) CROP_VAR (PERIOD,REGION,SOILTYPE,SOILSTATE,SPECIES,FARM,CROPTECH) LIVE_VAR (PERIOD,REGION,ANIMAL,LIVETECH) FEED_VAR (PERIOD,REGION,ANIMAL,PRODUCT,FEEDTECH)ECO_VAR (PERIOD,REGION,SOILTYPE,SOILSTATE,ECOTECH) PROCESS_VAR (PERIOD,REGION,PROCTECH) LUC_VAR (PERIOD,REGION,SOILTYPE,SPECIES,CHANGE) DEMAND_VAR (PERIOD,REGION,PRODUCT) SUPPLY_VAR (PERIOD,REGION,PRODUCT) TRADE_VAR (PERIOD,REGION,REGION,PRODUCT)

  22. Major EquationsOBJECTIVE_EQU RESOURCEBAL_EQU (PERIOD,REGION,RESOURCE) RESOURCEMAX_EQU (PERIOD,REGION,RESOURCE) SOILSTATE_EQU (PERIOD,REGION,SOILTYPE,SOILSTATE) FORINVENT_EQU (PERIOD,REGION,SOILTYPE,SOILSTATE,SPECIES,OWNER,AGE,FORTECH) LUC_EQU (PERIOD,REGION,SOILTYPE,SPECIES,CHANGE) LUCLIMIT_EQU (PERIOD,REGION,SOILTYPE,SPECIES,CHANGE) STOCK_EQU (PERIOD,REGION,STOCK)EMIT_EQU (PERIOD,REGION,SUBSTANCE)PRODUCTBAL_EQU (PERIOD,REGION,PRODUCT) MINFEED_EQU (PERIOD,REGION,ANIMAL,NUTRIENT) MAXFEED_EQU (PERIOD,REGION,ANIMAL,NUTRIENT)

  23. Managing the Model Scope • 2_active_sets.gms • index elements on/off • decl_scope.gms • components on/off

  24. FASOM File Structure • Main directory (full access) • Data subdirectories (restricted access) • Agriculture (FADN) • Crop environmental impacts (EPIC) • Bioenergy (ENFA) • Nature Reserves (HABITAT) • Forest Stands (OSKAR) • Forest Industry (FINDUS) • FAOSTAT • Dynamics

  25. FASOM File Naming (Main Dir) • Data files (data_*.gms) • Declaration files (decl_*.gms) • Input calculation files (calc_*.gms) • Program files (#_*.gms) • GAMSCHK files (*.gck), Solver option files (*.opt) • Report files (rep_*.gms) • Special program files (z#_*.gms) * = description # = 1,2,...,k

  26. FASOM Sub Directories • Store original data files in provider format • Convert data to FASOM format (names, resolution, unit consistency) • Automated programs, slow, infrequent use • Protect main FASOM directory from information floods • Confidentiality (FADN), IPR

  27. FASOM Execution • 1_load_data.gms (primary data files) • 2_active_sets.gms (determine model size) • 3_precompute.gms (calculation files) • 4_eufasom_model.gms (equations) • 5_base_report.gms (base solution report) • 6_scenario.gms (repeated solves) • 7_results.gms (scenario differences)

  28. Save / Restart When using GAMSIDE, each program segment must restart from previous one and save for the next • 1_load_data.gms (save .\t\a1) • 2_active_sets.gms (restart .\t\a1 save .\t\a2) • 3_precompute.gms (restart .\t\a2 save .\t\a3) • 4_eufasom_model.gms (restart .\t\a3 save .\t\a4) • 5_base_report.gms (restart .\t\a3 save .\t\a4) • ...

  29. * Indexes $include decl_basicsets.gms $include decl_foresttuple.gms $offlisting * Load Data $include data_crop2000.gms $include data_faowood.gms $include data_faocrop.gms $include data_faoworldcrop2002.gms $include data_oatsprice.gms $include data_feed.gms $include data_land.gms $include data_cropsupply.gms $include data_averagecropemission.gms $include data_euepic.gms $include data_euluc.gms $include data_uscrops.gms $include data_peat.gms $include data_forprocess.gms $include data_forproduct.gms $include data_formarket.gms $include data_treelog.gms $include data_rotlength.gms $include data_forestrent.gms $include data_forest_set.gms $include data_forest_nor.gms $include data_forest_lrg.gms $include data_forest_sml.gms 1_load_data.gms

  30. 2_active_sets.gms • Define active set elements • Region • Period • Product • Cohort • Can limit model scope to 1 Region, 1 Period, 1 Product

  31. 3_precompute.gms • Assumptions and Definitions (Discounting) • Deal with Data Gaps • Calculations (Data, Tuples) • Checks • Calibrations (Zero Marginal Profits!) • Experiments • Check whether statements can be moved to subdirectory

  32. 4_eufasom_model.gms • Variable declarations • Equation declarations • On/off switches for some equations • FASOM equations (see part II) • First solve statement • 4_eufasom_model.gck

  33. 5_base_report.gms • Declaration of report indexes and parameters • Display of FASOM base solution • Current period (?=? observation) • Future periods (?=? econometric forecast)

  34. 6_scenario_loop.gms • Define scenarios • Number (Set) • Assumptions (Parameters) • Declare report • Loop over scenario set • Restore all parameters to original values • Implement scenario assumptions • Solve • Save solution

  35. 7_scenario_report.gms • Display scenario results • Comparison between base line solution and scenario solution

  36. 8_scenario_graphs.gms • Display scenario results graphically • Need gnupltxy installed

  37. II FASOM Equations 4_eufasom_model.gms

  38. Understanding FASOM Equations • GAMS code (indexed equation block) • DISPLAYCR output (individual equations) • Display equation components

  39. Condition(al)s • Restrict cases (very important, many indexes) • Use GAMSCHK to check PRODUCTBAL_EQU(REGION,PERIOD,PRODUCT) $ PRODUCT_TUPLE(REGION,PERIOD,PRODUCT).. • calc_tuples.gms

  40. Constrained Optimization Max z = f(X) ... objective function s.t. G(X) <= 0 ... constraints

  41. FASOM = Large Linear Programs

  42. Objective Function(Normative Economics) Maximize + Area underneath demand curves - Area underneath supply curves - Costs ± Subsidies / Taxes from policies Maximum equilibrates markets!

  43. Alternative Objective Function To get „technical potentials“ from land use for alternative objective u, simply use Maximize u s.t. all constraints Examples: u = Carbon Sequestration, Wheat production, Mire area

  44. Is FASOM linear? • Input prices increase with increasing input use (scarcity of resources) • Output prices decrease with increasing output supply (saturation of demand) • Hence, FASOM has non-linear objective function but is solved as Linear Program using linear approximations

  45. Linear Approximation? • For well behaved functions: yes • Concave benefit / convex cost functions • Decreasing marginal utilities • Increasing marginal costs • For ill behaved: no, need integer variables • Fixed cost (Investment) • Minimum habitat requirements (Biodiversity)

  46. Linear Approximation in FASOM • Use step variables (xi) ... with i steps • Convexity Restriction Sum(i, xi) = 1 • Identity Restriction Sum(i, aixi) = x DEMAND_VAR(REGION,PERIOD,PRODUCT) DEMAND_STEP(REGION,PERIOD,PRODUCT,STEP) DEMAND_CONVEXITY(REGION,PERIOD,PRODUCT) DEMAND_IDENTITY(REGION,PERIOD,PRODUCT) How many steps?

  47. Correct Convex Combination? Model will automatically choose closest neighbor points

  48. Constraints

  49. PRODUCTBAL_EQU • Very important • Multi-input, Multi-output • Negative coefficients - Inputs • Positive coefficients - Outputs

  50. RESOURCEBAL_EQU • Sum resource uses over all technologies, species, farm structures into an accounting variable RESOURCE_VAR(REGION,PERIOD,RESOURCE)

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