1. Model structure

The structure of the Ukraine WESM model is outlined in the sections that follow. Section 1.1 provides an overview of the overall model framework. In contrast, Section 1.2 explains how the OSeMOSYS sets have been configured for the Ukrainian context, including the full range of commodities, technologies, and emissions accounted for. These elements are then combined to form the Reference Energy System (RES), which is introduced in Section 1.3 and subsequently examined in greater detail—sector by sector—in Section 1.4.

1.1 General model structure

The overall model framework is illustrated in the following figure. Primary energy in Ukraine can be either extracted domestically or imported. The country’s energy system is characterised by a diverse resource base: significant nuclear capacity, domestic coal and natural gas, as well as growing contributions from renewables such as wind, solar, hydro, and biomass. Ukraine maintains substantial fossil fuel use, although its dependence on imports, especially natural gas, oil products, and coking coal, remains strategically important due to energy security concerns. Imported fuels and domestically produced energy are distributed across all sectors of the economy. The final energy demand of each sector is translated into energy service requirements within the model, enabling the identification of the cost-optimal technology mix to meet Ukraine’s needs.

1.2 Model configuration - Sets

The “sets” within the Ukraine WESM model define its overall structure, encompassing crucial details such as the model’s temporal and geographical scope. These sets also comprehensively list all the fuels, energy technologies, and types of emissions considered in the analysis.

Region and years

The Ukraine WESM operates as a single-node national model, meaning it treats the entire country as one integrated energy system without explicitly modelling internal energy flows between different regions. Its time horizon spans from 2020 to 2050, with calculations performed in one-year increments. The initial period, specifically 2020 to 2022, is dedicated to model calibration, following the Energy Balance for Ukraine 2020.

Timeslices

Timeslices are how the model represents temporal variations within a single year. The Ukraine WESM employs 72 distinct timeslices, derived from combining 12 seasons (one for each month) and six specific time intervals throughout each day. This detailed temporal resolution allows for a nuanced capture of energy demand and supply fluctuations.

Fuels/Commodities

Fuels in the Ukraine WESM include all commodities represented in the model, whether primary or secondary. Both categories may be sourced domestically or imported. Ukraine possesses significant domestic resources, including coal, natural gas, hydroelectric power, biomass, solar energy, and wind energy, while still relying on imports of oil products and, historically, natural gas to meet its demand. Imported fuels can be used across multiple sectors and include crude oil, petroleum products (such as diesel, gasoline, jet fuel, LPG, kerosene, and heavy fuel oil), as well as natural gas. Locally, renewable-based secondary carriers such as bioethanol, biogas, and biomass-derived heat and power are considered. Electricity is generated from the country’s diverse mix of power plants—dominated by nuclear, hydro, coal, and an increasing share of renewables—and may also be exchanged through cross-border interconnectors with neighbouring European systems. To facilitate model analysis, sector-specific fuel categories are mapped to broader generic fuels via simplified “fuel-technology mix” (FTE) technologies. Finally, as in other OSeMOSYS applications, demands are represented as fuels, each identified by the prefix DEM.

Fuel/commodity	Description
AGRBIO	Agriculture biomass
AGRCOA	Agriculture coal
AGRELC	Agriculture electricity
AGRHET	Agriculture heat
AGRNGS	Agriculture ngs
AGRPPP	Agriculture petroleum products
BID	Biodiesel
BIO	Mining bio
COA	Mining coal
COK	Default commodity
COMBIO	Commercial biomass
COMCOA	Commercial coal
COMCOP	Commercial coal products
COMELC	Commercial electricity
COMHET	Commercial heat
COMLPG	Commercial lpg
COMNGS	Commercial ngs
COP	Coal Products
DEMABIO	Demand agr biomass
DEMACOA	Demand agr coal
DEMAELC	Demand agr electricity
DEMAHEAT	Demand agr heat
DEMANGS	Demand agr ngs
DEMAPPP	Demand agr petroleum products
DEMCBIO	Demand commercial and P serv biomass and waste
DEMCCOA	Demand commercial and P serv coal
DEMCCOP	Demand commercial and P serv coal products
DEMCELC	Demand commercial and P serv electricity
DEMCHET	Demand commercial and P serv heat
DEMCLPG	Demand commercial and P serv lpg
DEMCNGS	Demand commercial and P serv ngs
DEMFTR	Demand freight transport btkm bus
DEMFTRNAV	Demand freight transport btkm navi
DEMFTRRAI	Demand freight transport btkm rail
DEMIMMBIO	Demand industry IMM biomass
DEMIMMCOA	Demand industry IMM coal
DEMIMMCOP	Demand industry IMM coal prod
DEMIMMELC	Demand industry IMM electricity
DEMIMMHHET	Demand industry IMM heat
DEMIMMNGS	Demand industry IMM ngs
DEMIMMPPP	Demand industry IMM petroleum products
DEMIOMBIO	Demand industry IOM biomass
DEMIOMCOA	Demand industry IOM coal
DEMIOMCOP	Demand industry IOM coal prod
DEMIOMELC	Demand industry IOM electricity
DEMIOMHET	Demand industry IOM heat
DEMIOMNGS	Demand industry IOM ngs
DEMIOMPPP	Demand industry IOM petroleum products
DEMIST	Demand iron-steel MTpa
DEMPTR	Demand passenger transport bpkm car bus
DEMPTRNAV	Demand passenger transport bpkm navi
DEMPTRRAI	Demand passenger transport bpkm rail
DEMRC1	Demand - Residential - Cooling demand urban
DEMRC2	Demand - Residential - Cooling demand rural
DEMRK1	Demand - Residential - Cooking urban
DEMRK2	Demand - Residential - Cooking rural
DEMRL1	Demand - Residential - Lighting urban
DEMRL2	Demand - Residential - Lighting rural
DEMRO1	Demand - Residential - heating and hot water urban
DEMRO2	Demand - Residential - heating and hot water rural
ELC001	Electricity before T&D
ELC002	Electricity after T&D
ELCCOA	Electricity coal
ELCNGS	Electricity ngs
ELCSYG	Default commodity
FTPSYG	Syngas for ft plant
FTRBID	Freight transport biodiesel
FTRCOA	Freight transport coal
FTRELC	Freight transport electricity
FTRNGS	Freight transport ngs
FTRPPP	Freight transport petroleum products
H2	H2
H2ELC	Electricity for electrolyzers
HET	Heat
INDBIO	Industry biomass
INDCOA	Industry coal
INDCOK	Industry coking coal
INDCOP	Industry coal pro
INDELC	Industry electricity
INDHET	Industry heat
INDNGS	Industry ngs
INDPPP	Industry petroleum products
IOR	Iron ore
ISTBIO	Biomass iron-steel
ISTCOA	Coal iron-steel
ISTCOK	Coking coal iron-steel
ISTELC	Electricity iron-steel
ISTH2	H2 iron-steel 1E6 Kg
ISTHET	Heat iron-steel
ISTIOR	Iron ore iron-steel
ISTNGS	NGS iron-steel
ISTPPP	Petroleum products iron-steel
ISTSCR	Scrap metal iron-steel
LCFBIO	Biomas for low carbon fuels
LPG	Mining lpg
MTHSYG	Syngas for methanation plant
NGS	Mining ngs
NUC	Default commodity
PPP	Petroleum products
PTRBID	Passenger Transport biodiesel
PTRCOA	Passenger Transport coal
PTRELC	Default commodity
PTRNGS	Passenger Transport ngs
PTRPPP	Passenger Transport petroleum products diesel
RESBIO	Residential bio
RESCOA	Residential coal
RESELC	Residential electricity
RESLPG	Residential lpg
RESNGS	Residential ngs
SCR	Scrap metal
SYG	Syngas

Technologies and modes of operation

All technologies included in the Ukraine WESM are organised within the technologies set. Imported fuels and resources (IMP) and domestic resources (MIN) are characterised by technologies that generate only an output fuel. The power sector is modelled at an individual power plant level (ELC technologies), reflecting the diversity of Ukraine’s generation mix, which includes nuclear, thermal, hydro, and renewable assets. Transmission and distribution (T_D) networks are represented by a single technology to capture system-level losses. Each end-use sector is connected to the energy system through fuel-technology mix (FTE) technologies, one for each fuel available within that sector. These FTEs facilitate the post-processing of model results while also enabling the representation of sector-specific costs and efficiencies that are not directly embedded in the technology definitions. Beyond this, each sector features its own dedicated technologies—identified with sector-specific prefixes—that transform the available fuels into useful energy services (e.g., transport mobility, industrial heat, residential heating, etc.). For the present modelling framework, only one operating mode is assigned per technology.

Technology	Description
ABIO	Agr biomass
ACOA	Agr coal
AELC	Agr electricity
AHET	Agr heat
ANGS	Agr ngs
APPP	Agr petroleum products
CBIO	Com and P sector demand bio
CCOA	Com and P sector demand coal
CCOP	Com and P sector demand coal pr.
CELC	Com and P sector demand electri.
CHET	Com and P sector demand heat
CLPG	Com and P sector demand lpg
CNGS	Com and P sector demand ngs
ELCCECHR	Powert Plant CHP ngs
ELCCOMSOL	Solar PV commercial
ELCIGCC	Integrated Gasification Combined.
ELCNENUCK1	Power Plants Existing - Nuclear Energy - Khmelnitsk 1
ELCNENUCK2	Power Plants Existing - Nuclear Energy - Khmelnitsk 2
ELCNENUCK3	Unit 3 at the Khmelnytska NPP
ELCNENUCK4	Unit 4 at the Khmelnytska NPP
ELCNENUCR1	Power Plants Existing - Nuclear Energy - Rivne 1
ELCNENUCR2	Power Plants Existing - Nuclear Energy - Rivne 2
ELCNENUCR3	Power Plants Existing - Nuclear Energy - Rivne 3
ELCNENUCR4	Power Plants Existing - Nuclear Energy - Rivne 4
ELCNENUCY1	Power Plants Existing - Nuclear Energy - Yuzhnoukrainsk 1
ELCNENUCY2	Power Plants Existing - Nuclear Energy - Yuzhnoukrainsk 2
ELCNENUCY3	Power Plants Existing - Nuclear Energy - Yuzhnoukrainsk 3
ELCNENUCZ1	Power Plants Existing - Nuclear Energy - Zaporizzhya 1
ELCNENUCZ2	Power Plants Existing - Nuclear Energy - Zaporizzhya 2
ELCNENUCZ3	Power Plants Existing - Nuclear Energy - Zaporizzhya 3
ELCNENUCZ4	Power Plants Existing - Nuclear Energy - Zaporizzhya 4
ELCNENUCZ5	Power Plants Existing - Nuclear Energy - Zaporizzhya 5
ELCNENUCZ6	Power Plants Existing - Nuclear Energy - Zaporizzhya 6
ELCNEWNUC	New nuclear power plants
ELCREBIO00	Power Plants Existing00 - Biomass
ELCREGEO00	Geothermal power plants
ELCREHYDPSKY1	Power Plants Existing - Hydro Energy - Pumped storage power - Kyivska 1
ELCREHYDPSDS1	Power Plants Existing - Hydro Energy - Pumped storage power - Dnistrovska 1
ELCREHYDHPSD1	Power Plants Existing - Hydro Energy - Hydro power - Seredniodniprovska 1
ELCREHYDHPKY1	Power Plants Existing - Hydro Energy - Hydro power - Kyivska 1
ELCREHYDHPKR1	Power Plants Existing - Hydro Energy - Hydro power - Kremenchucka 1
ELCREHYDHPKH1	Power Plants Existing - Hydro Energy - Hydro power - Kahovska 1
ELCREHYDHPKA1	Power Plants Existing - Hydro Energy - Hydro power - Kanivska 1
ELCREHYDHPDS1	Power Plants Existing - Hydro Energy - Hydro power - Dnistrovska 1
ELCREHYDHPDP1	Power Plants Existing - Hydro Energy - Hydro power - Dniprovska 1&2
ELCRESOL00	Power Plants Existing00 - Solar e.
ELCRESSOL	Solar PV residential
ELCREWIN00	Power Plants Existing00 - Wind e.
ELCTECHR00	Power Plants Existing00 - Solid F.
ELCTEGAS00	Power Plants Existing00 - Natura.
FTEAGRBIO	Agriculture biomass
FTEAGRCOA	Agriculture coal
FTEAGRELC	Agriculture electricity
FTEAGRHET	Agriculture heat
FTEAGRNGS	Agriculture ngs
FTEAGRPPP	Agriculture petroleum
FTECOMBIO	Com and P Sector bio and residues
FTECOMCOA	Com and P Sector coal
FTECOMCOP	Com and P Sector coal prod
FTECOMELC	Com and P Sector electricity
FTECOMHET	Com and P Sector heat
FTECOMLPG	Com and P Sector lpg
FTECOMNGS	Com and P Sector ngs
FTEELCCOA	Electricity coal
FTEELCNGS	Electricity ngs
FTEELCSYG	Syngas for electricity
FTEFTPSYG	Syngas FT plant
FTEFTRBID	FTR biodiesel
FTEFTRCOA	FTR coal
FTEFTRELC	FTR electricity
FTEFTRNGS	FTR ngs
FTEFTRPPP	FTR petroleum products diesel
FTEH2ELC	Electricity for electrolyzers
FTEINDBIO	Industry biomass
FTEINDCOK	Industry coking coal
FTEINDCOP	Industry coal products
FTEINDELC	Industry electricity
FTEINDHET	Industry heat
FTEINDNGS	Industry ngs
FTEINDPPP	Industry petroleum prod
FTEISTBIO	Bio iron-steel
FTEISTCOA	Coa iron-steel
FTEISTCOK	Coking coal iron-steel
FTEISTELC	Elc iron-steel
FTEISTHET	Heat iron-steel
FTEISTIOR	Iron ore iron-steel
FTEISTNGS	NGS iron-steel
FTEISTPPP	Petroleum prod iron-steel
FTEISTSCR	Metal scrap iron-steel
FTELCFBIO	Low carbon fuels biomass
FTEMTHSYG	Syngas methanation plant
FTEPTRBID	PTR biodiesel
FTEPTRCOA	PTR coal
FTEPTRELC	PTR electricity
FTEPTRNGS	PTR ngs
FTEPTRPPP	PTR petroleum products diesel
FTERESBIO	Residential bio
FTERESCOA	Residential coal
FTERESELC	Residential electricity
FTERESLPG	Residential lpg
FTERESNGS	Residential ngs
FTETINDCOA	Industry coal
FTPLANT	Fischer-Tropsch (FT)
FTRABUBID	FTR truck petroleum biodiesel
FTRABUNGS	FTR truck ngs
FTRABUPPP	FTR truck petroleum products
FTRNAVPPP	FTR navigation petroleum products
FTRRAICOA	FTR rail coal
FTRRAIELC	FTR rail electricity
FTRRAIPPP	FTR rail petroleum products
GSFR	Gasifier
HETREBIO	Heat plants biomass
HETRECOA	Heat plants coal
HETRECOP	Heat plants coal products
HETRENGS	Heat plants ngs
HETREOIL	Heat plants oil
HETREPPP	Heat plants petroleum products
IMMBIO	Ind IMM biomass
IMMCOA	Ind IMM coal
IMMCOP	Ind IMM coal products
IMMELC	Ind IMM electricity
IMMHET	Ind IMM heat
IMMNGS	Ind IMM ngs
IMPCOA	Import coal steam
IMPCOK	Import cooking coal industry
IMPELC	Import Electricity
IMPPP	Ind IMM petroleum products
IOMBIO	Ind IOM biomass
IOMCOA	Ind IOM coal
IOMCOP	Ind IOM coal products
IOMELC	Ind IOM electricity
IOMHET	Ind IOM heat
IOMNGS	Ind IOM ngs
IOMPPP	Ind IOM petroleum products
ISTBFBOF	Blast Furnace-Basic Oxygen Fur.
ISTCCSBF	Blast Furnace-Basic Oxygen Fur.
ISTDRIH2	Direct Reduced Iron H2
ISTDRINGS	Direct Reduced Iron using NGS
ISTEAF	Electric arc furnace
ISTELCH2	Electrolyser
MINBID	Mining Biodiesel
MINBIO	Mining bio
MINCOA	Mining coal
MINCOP	Coal products
MINIOR	Mining iron ore
MINLPG	Mining lpg
MINNGS	Mining ngs
MINNUC	Nuclear fuel
MINPPP	Mining petroleum petroducts
MINSCR	Mining metal scrap
MTHPLANT	Syngas_Methanation Plant
PEMH2	PEM electrolyser
PTRABUBID	PTR buses-auto biodiesel
PTRABUNGS	PTR buses-auto ngs
PTRABUPPP	PTR buses-auto petroleum prod
PTRNAVPPP	PTR navigation petroleum prod
PTRRAICOA	PTR rail coal
PTRRAIELC	PTR rail electricity
PTRRAIPPP	PTR rail petroleum prod
RC1ELC001	Cooling electric urban
RC2ELC001	Cooling electric rural
RK1BIO001	Stove bio urban
RK1COA001	Stove coal urban
RK1ELC001	Stove electricity urban
RK1LPG001	Stove lpg urban
RK1NGS001	Stove ngs urban
RK2BIO001	Stove bio rural
RK2COA001	Stove coal rural
RK2ELC001	Stove electricity rural
RK2LPG001	Stove lpg rural
RK2NGS001	Stove ngs rural
RL1ELC001	Residential - Lighting urban - Ele.
RL2ELC001	Residential - Lighting rural - Elect.
RO1BIO001	Residential-Heating urban - bio
RO1COA001	Residential-Heating urban - Coal
RO1ELC001	Residential-Heating urban - Elect.
RO1HET001	Residential-Heating urban - Heat
RO1NGS001	Residential-Heating urban - NGS
RO1OIP001	Residential-Heating urban - LPG
RO2BIO001	Residential-Heating rural - BIO
RO2COA001	Residential-Heating rural -Coal
RO2ELC001	Residential-Heating rural - ELC
RO2HET001	Residential-Heating rural - Heat
RO2NGS001	Residential-Heating rural - NGS
RO2OIP001	Residential-Heating rural -LPG
T_D	T&D

Emissions

The current version of the Ukraine WESM explicitly tracks only CO₂ emissions. The emissions set includes both a generic CO₂ category applicable across the entire energy system, as well as sector-specific CO₂ entries that allow emissions to be attributed to particular end-use sectors.

Emissions	Description
CO2	Overall carbon dioxide emissions

1.3 Reference energy system

An overview of the complete reference energy system (RES) for Ukraine is shown in the following figure. Beginning on the left, each block represents one or more technologies, depending on whether the associated commodity is domestically produced or imported. The bottom part of the diagram illustrates the power sector (ELC technologies). Each block can correspond to as many as thirty-four individual power plants, since generation in the model is represented at the single-plant level for nuclear power plants and at the global level for other power plants, such as coal and natural gas. Electricity imports are modelled at the transmission stage. At the same time, distribution to the end‑use sectors occurs after both transmission/distribution grids (T_D), with system losses incorporated. Below the uranium production section, other fuels that are consumed directly in end-use sectors are listed, alongside downstream conversion processes such as biomass-to-syngas, which generate secondary fuels. Each end-use sector is represented separately, bounded by the fuel-technology mix (FTE) technologies, and includes its own sector-specific fuels, technologies, and final energy service demands.

1.4 Sectors

Agriculture

The Ukraine WESM features a more detailed representation of agricultural energy use, with distinct demand categories for coal, petroleum products, natural gas, biomass, electricity, and heat. Each fuel type is linked to corresponding technologies that supply the sector, enabling a more comprehensive analysis of Ukraine’s agricultural energy mix and its potential transition pathways.

Commercial sector

In the Ukraine WESM, the commercial and public services sector is modelled with a broader set of fuel demands, reflecting the sector’s diverse energy requirements. These include coal, petroleum products, LPG, natural gas, biomass, electricity, and heat. Each demand category is linked to the relevant technologies, enabling the model to capture Ukraine’s reliance on both fossil fuels and district heating, as well as its growing electricity demand.

Industry

The industrial sector in the Ukraine WESM is represented with more complexity than agriculture or commercial services. It is divided into subsectors, including non-metals and cement (IMM), other manufacturing and processes (IOM), and food processing. Tthe Ukrainian framework considers a broad range of fuels and carriers for industrial activities.

For both IMM and IOM subsectors, demand categories are explicitly defined for coal, coal products, petroleum products, natural gas, biomass, electricity, and heat. This structure reflects the energy‑intensive nature of Ukraine’s industries, particularly steel, cement, and chemicals, which remain major consumers of coal, natural gas, and heat. Meanwhile, food processing and lighter manufacturing are also included, with a stronger emphasis on electricity and heat.

Residential sector

The residential sector is a complex component of the Ukraine WESM, reflecting both its size and its dominant share of final energy consumption. Energy service demands are divided into cooling, cooking, lighting, and heating/hot water, with each category further disaggregated into urban and rural households to capture geographic and socio‑economic differences.

The Ukrainian context is heavily shaped by space heating and hot water demand, given the country’s cold climate and widespread district heating networks. Residential heating can be covered by a broad portfolio of fuels and technologies, including natural gas boilers, coal stoves, biomass burners, electric heaters, and district heating connections. Cooking is also represented by multiple technological variants, spanning gas stoves, electric stoves, LPG stoves, and traditional biomass devices. Lighting relies almost exclusively on electricity in both urban and rural areas. At the same time, cooling demand, although currently small, is met by electricity-based appliances.

Transport

The transport sector in Ukraine, as covered by WESM, encompasses road, rail, and navigation (shipping). Road transport is represented across key modes, including buses, passenger cars, and freight trucks. More minor modes, such as two- and three-wheelers, relevant in other regions, are not explicitly included, given their limited role in Ukraine.

Each road subsector has multiple technology options, reflecting the expanding diversity of Ukraine’s vehicle fleet. These include petroleum products (such as diesel and gasoline), natural gas (CNG/LNG), biodiesel blends, and, in the case of buses and passenger cars. For freight trucks, liquid fuels still dominate. Still, options such as natural gas and biodiesel are also incorporated to account for potential fuel switching.

The railway system is represented by technologies using coal, diesel, and electricity, reflecting the sector’s historical reliance on fossil fuels and its ongoing partial electrification. Passenger rail demand is increasingly electrified, but diesel still plays a role in non‑electrified corridors.

Aviation demand is satisfied exclusively by technologies using jet fuel (kerosene‑based aviation fuel). In contrast, navigation demand (inland and maritime shipping) relies on petroleum products such as heavy fuel oil and diesel.

Iron and Steel

The iron and steel sector in Ukraine’s WESM is explicitly modelled due to its central role in the country’s economy and its significant contribution to energy use and CO₂ emissions. Conventional steelmaking technologies are represented, including the Blast Furnace (BF), Basic Oxygen Furnace (BOF), Open Hearth Furnace (OHF), and Electric Arc Furnace (EAF), which capture the diversity of Ukraine’s current steel production base. In addition to these conventional routes, the model also incorporates low‑carbon steelmaking options. These include the CCS‑equipped Blast Furnace–Basic Oxygen Furnace (CCS BF‑BOF) pathway, which reduces emissions by capturing and storing CO₂; Direct Reduced Iron using Natural Gas (DRI‑NG), a less carbon‑intensive alternative; and Direct Reduced Iron using Hydrogen (DRI‑H₂), coupled with an electrolyser to produce the required hydrogen from water and electricity. By incorporating both traditional and emerging low-carbon routes, the model facilitates the evaluation of transition pathways for Ukraine’s steel industry, taking into account energy demand, opportunities for emission reduction, and technological shifts over time.

Low carbon fuels

The model also incorporates low carbon fuels pathways, which play an important role in decarbonising the transport and power sectors. Syngas (SYG) is produced through gasification processes (GSFR), often using low carbon biomass as feedstock, and can be further converted into synthetic natural gas (SNG) through a methanation process (MTHPLANT). Alternatively, syngas can be directed into a Fischer–Tropsch (FT) plant, which yields FT diesel (FTDSL) as a liquid low carbon fuel, while also capturing and accounting for associated CO₂ emissions. In addition, the system considers the use of hydrogen (H₂) both as a direct input to syngas upgrading and as a complementary pathway to synthetic fuel production. The model also includes the ELCIGCC technology, where syngas is used directly in an integrated gasification combined cycle (IGCC) power plant to generate electricity more efficiently while offering the potential for carbon capture integration. By modelling these conversion routes, the framework captures the potential of advanced low carbon fuels to substitute conventional fossil fuels in Ukraine’s energy mix, supporting deep emission reductions and offering flexibility across multiple demand sectors.