v2.4

• Time-sliced fuels: Added an option to designate fuels as time-sliced or non time-sliced (via FUEL.timesliced: use 1 for a time-sliced fuel and 0 for a non time-sliced fuel). This determines whether NEMO simulates the production, consumption, and trade of a fuel in time slices or at the annual level only. Prior to NEMO 2.4, the production, consumption, and trade of all fuels was simulated in time slices. Designating fuels as non time-sliced can significantly improve the performance of complex models because it simplifies the underlying optimization problem. In many models, using non time-sliced fuels doesn't materially change the optimization results. The new FUEL.timesliced column has a default value of 1, so NEMO's original behavior of simulating fuels in time slices has been retained.

• Technology groups: Implemented a new dimension in NEMO, technology groups. These are arbitrary groups of technologies that can be used in certain constraints. Technologies are mapped to technology groups in the new TTGroup parameter.

• Technology subsidies: Added support for modeling technology subsidies, which function like a discount on technology capital costs. A new parameter, TechnologySubsidy, defines the maximum permissible subsidy amount per unit of new (endogenously built) technology capacity. Total subsidies disbursed are tracked in two decision variables, vsubsidybytechnology (total subsidies for a technology in a region and year) and vsubsidybyregion (sum of vsubsidybytechnology across technologies). You can limit the total subsidies disbursed at the technology, technology group, or region level (with the MaxSubsidyPerTechnology, MaxSubsidyPerTechnologyGroup, and MaxSubsidyPerRegion parameters, respectively). If NEMO elects to apply a subsidy to new technology capacity, this reduces the capacity's capital investment and financing cost. These variables and downstream variables that depend on them, such as salvage value and total discounted cost, are net of subsidies.

• Maximum production share: Added MaxShareProduction, a parameter that specifies a technology's maximum share of production of a fuel in a given region and year (excluding production from storage).

• Capacity constraints by region group and technology group: Provided eight new parameters that allow you to set technology capacity deployment limits by region group or technology group: TotalAnnualMaxCapacityRG (maximum exogenous + endogenous capacity for a technology in a region group), TotalAnnualMaxCapacityTG (maximum exogenous + endogenous capacity for a technology group in a region), TotalAnnualMaxCapacityInvestmentRG (maximum addition of endogenous capacity for a technology in a region group), TotalAnnualMaxCapacityInvestmentTG (maximum addition of endogenous capacity for a technology group in a region), TotalAnnualMinCapacityRG (minimum exogenous + endogenous capacity for a technology in a region group), TotalAnnualMinCapacityTG (minimum exogenous + endogenous capacity for a technology group in a region), TotalAnnualMinCapacityInvestmentRG (minimum addition of endogenous capacity for a technology in a region group), and TotalAnnualMinCapacityInvestmentTG (minimum addition of endogenous capacity for a technology group in a region).

• Data validation function: Introduced a function, data_validation, that performs data validation checks in a scenario database. NEMO runs this function when a scenario is calculated. If any checks fail, the function returns an error and warning messages describing the problem. You can use the function yourself to check data without calculating a scenario. Right now, the function includes only a few checks, but more will likely be added in the future.

• OSeMOSYS to NEMO converter: Added a function for converting OSeMOSYS models to NEMO - convert_osemosys. The function takes as an input an OSeMOSYS model's data (in either SQLite or CSV format, as produced by OSeMOSYS tools for energy work (otoole)) and returns a NEMO scenario database for the model. Many thanks to Iain Morrow for this enhancement!

• Minimum and maximum capacity additions for transmission lines: Provided parameters to specify minimum and maximum endogenous capacity additions for transmission lines (TransmissionAnnualMinCapacityInvestment and TransmissionAnnualMaxCapacityInvestment). Both of these parameters are indexed by line and year. If you calculate selected years only, TransmissionAnnualMaxCapacityInvestment is scaled up to account for non-modeled years. These parameters do not apply to lines with exogenously specified construction years.