Electrolyzer Plant

Electrolyzer Plant#

The hydrogen electrolyzer modules use the electrolyzer package developed by the National Renewable Energy Laboratory to predict hydrogen output of hydrogen electrolyzer plants. This repo contains models for PEM and Alkaline electrolyzer cell types.

To create a hydrogen electrolyzer plant, set component_type = ElectrolyzerPlant in the input dictionary (.yaml file).

Inputs#

Required Parameters#

The parameters listed below are required unless otherwise specified as Optional.

  • general: General simulation parameters.

  • initial_conditions: Initial conditions for the simulation including:

    • power_available_kw: Initial power available to the electrolyzer [kW]

  • electrolyzer: Electrolyzer plant specific parameters including:

    • initialize: boolean. Whether to initialize the electrolyzer.

    • initial_power_kW: Initial power input to the electrolyzer [kW].

    • supervisor:

      • system_rating_MW: Total system rating in MW.

      • n_stacks: Number of electrolyzer stacks in the plant.

    • stack: Electrolyzer stack parameters including:

      • cell_type: Type of electrolyzer cell (e.g., PEM, Alkaline).

      • max_current: Maximum current of the stack [A].

      • temperature: Stack operating temperature [degC].

      • n_cells: Number of cells per stack.

      • min_power: Minimum power for electrolyzer operation [kW].

      • stack_rating_kW: Stack rated power [kW].

      • include_degradation_penalty: Optional Whether to include degradation penalty.

      • hydrogen_degradation_penalty: Optional boolean, whether degradation is applied to hydrogen (True) or power (False)

    • cell_params: Electrolyzer cell parameters including:

      • cell_area: Area of individual cells in the stack [cm^2].

      • turndown_ratio: Minimum turndown ratio for stack operation [between 0 and 1].

      • max current_density: Maximum current density [A/cm^2].

      • p_anode: Anode operating pressure [bar].

      • p_cathode: Cathode operating pressure [bar].

      • alpha_a: anode charge transfer coefficient.

      • alpha_c: cathode charge transfer coefficient.

      • i_0_a: anode exchange current density [A/cm^2].

      • i_0_c: cathode exchange current density [A/cm^2].

      • e_m: membrane thickness [cm].

      • R_ohmic_elec: electrolyte resistance [A*cm^2].

      • f_1: Faradaic coefficient [mA^2/cm^4].

      • f_2: Faradaic coefficient [mA^2/cm^4].

    • degradation: Electrolyzer degradation parameters including:

      • eol_eff_percent_loss: End of life efficiency percent loss [%].

      • PEM_params or ALK_params: Degradation parameters specific to PEM or Alkaline cells:

        • rate_steady: Rate of voltage degradation under steady operation alone

        • rate_fatigue: Rate of voltage degradation under variable operation alone

        • rate_onoff: Rate of voltage degradation per on/off cycle

    • controller: Electrolyzer control parameters including:

      • control_type: Controller type for electrolyzer plant operation.

    • costs: Optional Cost parameters for the electrolyzer plant including:

      • plant_params:

        • plant_life: integer, Plant life in years

        • pem_location: Location of the PEM electrolyzer. Options are [onshore, offshore, in-turbine]

        • grid_connected: boolean, Whether the plant is connected to the grid or not

      • feedstock: Parameters related to the feedstock including:

        • water_feedstock_cost: Cost of water per kg of water

        • water_per_kgH2: Amount of water required per kg of hydrogen produced

      • opex: Operational expenditure parameters including:

        • var_OM: Variable operation and maintenance cost per kW

        • fixed_OM: Fixed operation and maintenance cost per kW-year

      • stack_replacement: Parameters related to stack replacement costs including:

        • d_eol: End of life cell voltage value [V]

        • stack_replacement_percent: Stack replacement cost as a percentage of CapEx [0,1]

      • capex: Capital expenditure parameters including:

        • capex_learning_rate: Capital expenditure learning rate.

        • ref_cost_bop: Reference cost of balance of plant per kW.

        • ref_size_bop: Reference size of balance of plant in kW.

        • ref_cost_pem: Reference cost of PEM electrolyzer stack per kW.

        • ref_size_pem: Reference size of PEM electrolyzer stack in kW.

      • finances: Financial parameters including:

        • discount_rate: Discount rate for financial calculations [%].

        • install_factor: Installation factor for capital expenditure [0,1].

  • log_channels: List of output channels to log (see Logging Configuration below)

Outputs#

Logging Configuration

The log_channels parameter controls which outputs are written to the HDF5 output file. This is a list of channel names. The power channel is always logged, even if not explicitly specified.

Available Channels#

Scalar Channels:

  • H2_output: Total hydrogen produced during the last timestep

  • H2_mfr: Mass flow rate of the hydrogen production in kg/s

  • power: Power that the electrolyzer plant used to create hydrogen (kW). This follows the convention that power consumed is negative power.

  • Power_input_kw: Power allocated to the electrolyzer plant to use (kW)

  • stacks_on: Total number of stacks producing hydrogen

Array Channels:

  • stacks_waiting: Boolean list of the stacks that are waiting to start producing hydrogen (True for stacks waiting, False for stacks not waiting)

Example:

ele:
  component_type: ElectrolyzerPlant
  log_channels:
    - power
    - H2_output
    - H2_mfr
  initial_conditions:
    - power_available_kw: 3000
  electrolyzer:
  # ... other parameters

If log_channels is not specified, only power will be logged.

References#

  1. Z. Tully, G. Starke, K. Johnson and J. King, “An Investigation of Heuristic Control Strategies for Multi-Electrolyzer Wind-Hydrogen Systems Considering Degradation,” 2023 IEEE Conference on Control Technology and Applications (CCTA), Bridgetown, Barbados, 2023, pp. 817-822, doi: 10.1109/CCTA54093.2023.10252187.

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