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Commodities

Some nodes can act as a source or a sink of commodities instead of forcing a balance between inputs and outputs. To make that happen, commodities must have a price and be connected to those nodes that serve (or buy) that particular commodity at the given price. In other words, commodity is separate from node so that the user can use the same commodity properties for multiple nodes. Commodities can also have a co2_content. The commodity and its nodes are connected by establishing a new entity between the commodity and each of its nodes (e.g. coal--coal_market).

  • price - [CUR/MWh or other unit] Price of the commodity. Constant, period or time.
  • co2_content - [tCO2/MWh] Constant.
  • price_method - How the commodity price enters the LP. price (default) treats price as the marginal cost of every traded MWh. price_ladder_annual / price_ladder_cumulative activate a stepped supply curve authored via the parameters below; the engine then represents commodity trade as a sum of tier variables, one per ladder step.
  • price_ladder_annual - Stepped supply curve for price_method = price_ladder_annual. 2d map of (tier, period) → price/volume entries. Each tier's quantity is a per-year amount; a solve covering less than a full year (a short solve, or one roll of a rolling solve) is only allowed its own share of that year's quantity, in proportion to the hours it covers. In a stochastic solve the forecast branches of a period use that period's ladder.
  • price_ladder_cumulative - Stepped supply curve for price_method = price_ladder_cumulative. 2d map with rolling cumulative breakpoints.
  • Ladder tiers (both ladders): a tier label is a name, kept as written (1, 01 and a are three different tiers); the model buys the tiers by price, whatever their labels or order. Every tier needs a price (a tier without one is an error). A tier without a quantity is unlimited.
  • unitsize - [MWh] Numeric scaling for the v_trade variable (analogous to virtual_unitsize on units). Used with the price-ladder methods to keep tier-step variables well scaled; default 1.0.

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