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Model structure
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AIM/Technology is a bottom-up energy system model, where energy supply and demand, as well as their associated emissions, are estimated based on the operating conditions of several energy technologies determined through linear programming to minimize total energy system cost, including the annualized initial cost of technologies and operating costs, subject to exogenous energy service demand.
The energy efficiency and cost parameters of each technology, energy service demands, and technological constraints such as primary energy resources are provided to the model as exogenous parameters.
Final energy demand, primary and secondary energy supply, greenhouse gas emissions and sequestration, energy system costs, and carbon prices are calculated as output variables from the model.
A schematic overview of AIM/Technology is provided below.

.. figure:: inc_file/AIMTechnology-Overview.png
    :alt: model-overview

    Schematic overview of AIM/Technology

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Sector and technology representations
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AIM/Technology models energy technologies in various energy sectors with a detailed sub-sector classification, as summarized below.
The energy demand sectors include the industry, buildings and transport sectors, which are disaggregated in terms of industrial product types, building energy services and transport modes.
The energy supply sectors include primary energy production from fossil fuel extraction and biomass supply, as well as secondary energy transformation to obtain electricity, heat and hydrogen.
In each sector, specific energy technologies are modeled.
Some energy sectors are disaggregated into multiple energy service types and transport modes.
The other industry sector covers several energy services, including heat demand for boilers and furnaces, power for electronics, and other services.
The residential and commercial sectors are disaggregated based on energy service, including space heating and cooling, water heating, cooking, lighting and other appliances.
The transport sector includes various transport modes, namely road and rail transport, maritime navigation and aviation. The international transport sector includes both maritime navigation and aviation.

.. list-table:: Sector classifications and codes
    :header-rows: 0
    :widths: 1,5

    * - STL
      - Steel
    * - IYC
      - Cement
    * - OIN
      - Other industries
    * - RSD
      - Residential
    * - SER
      - Commercial
    * - PSS
      - Passenger transport
    * - FRG
      - Freight transport
    * - BNK
      - International transport
    * - AFF
      - Agriculture
    * - ODM
      - Other energy demand sector
    * - ELE
      - Electricity
    * - HET
      - Heat
    * - H_H
      - Hydrogen production
    * - COL
      - Coal extraction and supply
    * - OIL
      - Oil extraction and supply
    * - GAS
      - Gas extraction and supply
    * - CRN
      - Biomass supply
    * - NEN
      - Non-energy use
    * - CCS
      - Carbon capture and underground storage

.. list-table:: Mitigation options included in AIM/Technology
    :header-rows: 1

    * - Sector
      - Mitigation options
    * - Industry
      - Advanced coke oven, COG recovery, COG latent heat recovery, Coke dry quenching, Advanced sintering furnace, Blast furnace with CCS, BFG recovery, Dry TRT, BOG recovery, BOG latent heat recovery, Scrap pre-heater, Advanced electric furnace, Hydrogen DRI, Continuous casting, Vertical Mill, Advanced cement kiln with CCS, Tube Mill, Advanced boiler, Biomass boiler, Electric boiler, Industrial heat pump, Hydrogen boiler, Advanced furnace, Biomass furnace, Electric furnace, Hydrogen furnace, Advanced power electronics, Inverter use.
    * - Buildings
      - High-efficiency air conditioner, Biomass stove for space heating, High-efficiency water heater, Electric water heater, Heat pump water heater, Solar thermal water heater, Biomass water heater, Fuel cell water heater, High-efficient cooking device, Electric cooking equipment, Biomass cooking equipment, LED lamp, High-efficiency electric appliances, Energy-efficient building envelope.
    * - Transport
      - Fuel economy improvement for ICE, HEV, PHEV, BEV, FCEV; Energy efficiency in rail, navigation and aviation; Biofuel use, synthetic liquid fuel use, and ammonia use for navigation.
    * - Energy supply and other
      - IGCC w/CCS, IGCC w/o CCS, IGFC w/CCS, IGFC w/o CCS, gas CC w/CCS, CC w/o CCS, Fuel cell gas CC w/ and w/o CCS, Nuclear power, Onshore wind power, Offshore wind power, Solar PV, Geothermal power, Biomass w/ and w/o CCS, Hydropower, Pumped hydro storage, Battery storage, Hydrogen generation through electrolysis, Biomass to hydrogen w/ and w/o CCS, Fossil fuel to hydrogen w/ and w/o CCS, Synthetic hydrocarbon production, Direct air capture (DAC).

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Region classification
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AIM/Technology includes 33 regions, while AIM/Enduse included 32 regions [#akashi2014]_; African regions are classified into XNF, ZAF and XAF for mapping to the 17 regions of AIM/Hub [#fujimori2017]_. Region codes are summarized below.

.. figure:: inc_file/map_world.png
    :alt: map-world

    Region classification in AIM/Technology

.. list-table:: Summary of region classifications and codes
    :header-rows: 0

    * - JPN
      - Japan
    * - CHN
      - China
    * - IND
      - India
    * - IDN
      - Indonesia
    * - KOR
      - Korea
    * - THA
      - Thailand
    * - MYS
      - Malaysia
    * - VNM
      - Vietnam
    * - XSE
      - Other Southeast Asia
    * - XSA
      - Other South Asia
    * - XEA
      - Other East Asia
    * - XCS
      - Other Central Asia
    * - AUS
      - Australia
    * - NZL
      - New Zealand
    * - XOC
      - Other Oceania
    * - XE15
      - EU-15 (incl. UK)
    * - XE10
      - EU-10
    * - XE3
      - EU-3
    * - XEWI
      - Other Western Europe
    * - XEEI
      - Other Eastern Europe
    * - XENI
      - Other Europe
    * - TUR
      - Turkey
    * - RUS
      - Russian Federation
    * - USA
      - United States
    * - CAN
      - Canada
    * - MEX
      - Mexico
    * - ARG
      - Argentina
    * - BRA
      - Brazil
    * - XLM
      - Other Latin America
    * - XME
      - Middle East
    * - ZAF
      - South Africa
    * - XNF
      - South Africa
    * - XAF
      - Other Africa

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Model dynamics
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AIM/Technology performs recursive dynamic simulation with a one-year step.
The existing stock of technologies and their vintage information is calculated based on the previous year’s stock vintage information and newly installed capacity in the simulation year, which is endogenously determined.
Energy supply constraints for depletable resources are calculated based on the cumulative consumption of those energy resources.
These characteristics of the model dynamics mean that the simulation in each year is performed with a myopic perspective on topics such as energy and emission price changes and new technology development.

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References
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.. [#akashi2014] Akashi, O., Hanaoka, T., Masui, T., Kainuma, M. (2014). Halving global GHG emissions by 2050 without depending on nuclear and CCS. Climatic Change, 123(3), 611-622. https://doi.org/10.1007/s10584-013-0942-x
.. [#fujimori2017] Fujimori, S., Hasegawa, T., Masui, T., Takahashi, K., Herran, D. S., Dai, H., Hijioka, Y., Kainuma, M. (2017). SSP3: AIM implementation of Shared Socioeconomic Pathways. Global Environmental Change, 42, 268-283. https://doi.org/10.1016/j.gloenvcha.2016.06.009