Data were primarily collected from the reports and websites of international organizations, including the Latin America Energy Organisation (OLADE), the International Renewable Energy Agency (IRENA), the International Energy Agency (IEA), and the Intergovernmental Panel on Climate Change (IPCC). Data were also collected from the South America Model Base (SAMBA) . The data sources used are detailed in this section.
2.1 Electricity Supply System Data
Data on Uruguay's existing on-grid power generation capacity, presented in Table 1, were extracted from the PLEXOS World dataset [3,4,5] using scripts from OSeMOSYS global model generator . PLEXOS World provides estimated capacities and commissioning dates by power plant, based on the World Resources Institute Global Power Plant database .These data were used to estimate installed capacity in future years based on the operational life data in Table 2. Data on Uruguay's off-grid renewable energy capacity were sourced from yearly capacity statistics produced by IRENA . Cost, efficiency and operational life data in Table 2 were primarily collected from the SAMBA dataset , which provides estimates for these parameters by technology in South America. Where estimates were not available in SAMBA, costs were extrapolated from reports by IRENA for diesel electricity generation, medium hydropower, and off-grid solar PV [8,9]. The costs of renewable energy technologies are expected to fall in the future. In order to calculate estimated cost reductions in the region, technology-specific cost reduction trends from a very recent IRENA report focussing on Africa  were applied to the regional current cost estimates used from SAMBA [7,8,9]. For offshore wind, the cost reduction trend was instead taken from a technology-specific IRENA report on the future of wind  since it is not featured in . The resulting cost projections are presented in Table 3 and Figure 2. It is assumed that costs fall linearly between data points and those costs remain constant beyond 2040 when the IRENA forecasts end (except for offshore wind, where the IRENA forecast continues to 2050). Fixed costs for renewable energy technologies in each year were estimated by calculating a certain percentage (ranging from 1-4% depending on the technology) of the capital cost in that year, as done by IRENA .
Country-specific capacity factors for solar PV, onshore wind and hydropower were sourced from Renewables Ninja and the PLEXOS-World 2015 Model Dataset [3,10,11]. These sources provide hourly capacity factors for 2015 for solar PV and wind, and 15-year average monthly capacity factors for hydropower, the average values of which are presented in Table 2. Country-specific capacity factors for offshore wind were estimated based on an NREL source that gives estimates of the potential wind power capacity by capacity factor range in each country , from which a capacity-weighted average was calculated. The capacity factor data were also used to estimate capacity factors for 8 time slices used in the OSeMOSYS model (see detail in Annex 1). Capacity factors for other technologies were sourced from SAMBA , which provides estimated capacity factors for South America. The capital costs, operational lives, and efficiencies of power transmission and distribution were also taken from SAMBA , which provides future projections. Techno-economic data for refineries were sourced from the IEA Energy Technology Systems Analysis Programme (ETSAP) , which provides generic estimates of costs and performance parameters, while the refinery options modelled are based on the methods used in The Electricity Model Base for Africa (TEMBA) .
2.2 Fuel Data
Fuel price projections for crude oil were taken from a 2020 US EIA oil price forecast , based on which projections for LFO and HFO were estimated by increasing the price by 1/3 for LFO and reducing the price by 20% for HFO, as done in TEMBA . The natural gas price forecast was taken from SAMBA, which provides country-specific forecasts to 2063 . The domestic biomass price was estimated based on a report on international biomass markets  that includes cost estimates for biomass production in Brazil. This cost was increased by 10% to estimate a price for imported biomass, reflecting the cost of importation.
2.3 Emissions Factors and Domestic Reserves
Emissions factors were collected from the IPCC Emission Factor Database , which provides carbon emissions factors by fuel. The domestic solar and wind resources were collected from NREL datasets, which provide estimates of potential yearly generation by country [12,18]. Other renewable energy potentials were sourced from a regional report by OLADE  and the World Small Hydropower Development Report , which provide estimated potentials by country. The large and medium hydropower potential was estimated by subtracting the small hydropower potential  from the estimated overall hydropower potential . Estimated domestic coal and oil reserves were sourced from the SAMBA dataset , while natural gas reserves were sourced from the 2019 BP Statistical Review , which provide estimates of reserves by country.
2.4 Electricity Demand Data
The final electricity demand projection for Uruguay is based on the Current Policy Scenario of the OLADE Energy Outlook 2019 , which provides regional aggregated demand projections to 2040.These regional cost projections were divided by country using historical consumption data from the IEA , and extended to 2050 by extrapolating the growth trend to 2050.