Mathematical Formulation
Objective function
The objective function equation of the planning mode is the sum of all the regional costs in addition to the inter-regional tranmission link costs discounted to the reference year. While, in the operational mode, the objective function is just the sum of the fixed and variable costs with their related taxes within the modeled year.
Planning mode
Total Objective Function
Regional Objective Function
Trades Objective Function
Operation mode
Total Objective Function
Regional Objective Function
Trades Objective Function
Equations
costs
calculating the components of the objective function including the investment, fixed and variable operation and maintenance and decommissioning costs followed by the related taxes considered for each unit of investment or fixed cost of the technologies. Carbon taxes are also included to be applied for the carbon-intensive technologies. Alongside the related costs of technologies, some revenues are considered in the objective function with a negative sign. These revenues are including the salvage values on some of the investments where the operational lifetime of the technology lasts longer than the end of the modelling time horizon and subsidies that are applied to some technologies based on the national policies. The Hypatia model considers the economic life time of the technologies in the investment cost calculation. Therefore, each required investment in a specific year “y” is divided into a stream of annuities during several years (from “y+1” to “y+ELIFE”) which is determined by the technology-specific economic lifetime, depreciation rate and time value of money.
Note
In Hypatia, the inter-regional links are modeled as technologies. Therefore all the below equations for calculating the objective function cost components and intermediate variables except the taxes and subsidies have been correspondingly written in the source code for the transmission links.
Investment Cost
The cost required for the new installed capacity of the technologies.
Investment Salvage Value
The revenues calculated at the end of the time horizon for the unused period of the investments whose technical liftime exceeds the modelling horizon.
Fixed Cost
The fixed annual operation and maintenance cost based on the total installed capacity of each technology.
Taxes & Subsidies
Taxes and incentives calculated based on the total investment and fixed cost of each technology.
Decommissioning Cost
Cost of dismantling the new capacities installed in the vintage years of the modelling horizon.
Variable Cost
Annual variable operation and maintenance costs including the cost of consumed fuels.
Carbon Tax
The taxed dedicated to the amount of CO2 emitted by each technology.
Capacity
Accumulated New Installed Capacity
Total Installed Capacity
Decomissioned Capacity
Calculates the annual decommissioning capacities based on the previously installed new capacities in the vintage years of the horizon.
Emission
Calculates the annual CO2 emission based on the annual production of each technology
and the exogenous specific emission given by the user per unit of output activity.
Constraints
Energy balance
Guarantees the balance between the supply and demand sides of the energy system.
Note
All the technologies within Hypatia have one input carrier or/and one output carrier except for the conversion-plus technologies whose the production and use of each input and output carrier must be calculated from the following equations based on the given input and output carrier ratios given by the user:
Trade balance
Ensures that the amounts of imports and exports among any pair of
regions are completely balanced.
Resource & Technology Availability
Ensures that the production of each technology does not exceed its
available activity based both the technology capacity factor and resource capacity factor.
Capacity
Maximum & Minimum Regional Total Capacity
Maximum and minimum allowed annual total installed capacity for each
technology in each region based on the defined scenario.
Maximum & Minimum Regional New Capacity
Maximum and minimum allowed annual new installed capacity for each technology in each region
based on the defined scenario.
Maximum & Minimum Overall Total Capacity
Maximum and minimum allowed annual aggregated total installed capacity for each technology over all the regions
based on the defined scenario.
Maximum & Minimum Overall New Capacity
Maximum and minimum allowed annual aggregated new installed capacity for each technology over all the regions
based on the defined scenario.
Activity
Maximum & Minimum Regional Production
Maximum and minimum allowed production of each technology in each region
based on the defined scenario.
Maximum & Minimum Overall Production
Maximum and minimum aggregated production of each technology over all the regions
based on the defined scenario.
Output to Input Activity Ratio
Ensures the relationship between the production and consumption of each technology based on the given efficiency (output/input activity ratio)
CO2 Equivalent Emissions
Regional Emission cap
Ensures that the annual amount of CO2 emisstion emitted in each region does not exceed the given maximum allowed annual carbon emissions.
Overall Emission cap
Ensures that the aggregated annual amount of CO2 emitted over all the regions does not exceed the maixmum allowed annual values by the user.