Expand grid-connected electrolyzer options

[elenya-grant]

Expand grid-connected electrolyzer options to include other use-cases

Currently, in grid-connected cases the electrolyzer assumes that there is a desired hydrogen production and unlimited power, so the electrolyzer returns the power generation profile required to make constant hydrogen ("constant-hydrogen case"). In off-grid cases, the electrolyzer uses a power input signal and outputs hydrogen produced ("variable-power case"). For the constant-hydrogen case, the power profile can only be returned if we set the stack capacity to the overall system capacity (there is no multi-stack control options for this case).

For grid-connected cases, there are other simulation options that may be useful to add. For example, run the electrolyzer with a power generation profile of power bought from the grid. This should be done externally from the electrolyzer, where the power to the electrolyzer is the total grid power minus any ancillary power usage. Another case would be to input a hydrogen demand profile and a grid interconnection limit, where the input power cannot exceed the grid interconnection limit. These changes would require that the electrolyzer toggle between an input hydrogen demand or input power generation be independent of grid-connection.

Similarly, the electrolyzer sizing should be independent of grid-connection. The electrolyzer capacity is sized up to be divisible by the stack capacity - requiring that cluster_size_MW equals electrolzyer_size_mw if the user doesn't want it to be resized. The electrolyzer can be sized to meet a target hydrogen production rate and capacity factor of the power generation system - but could include other considerations such as grid interconnection limit, land area, etc.

This issue arose during the work on greenheart, see the pull request here: #275

Proposed solution

• have either input power or hydrogen demand be input into run_electrolyzer_physics() rather than imbedded in greenheart_config or hopp_results
• add input to specify whether to run a "hydrogen input" case or "power input" case (rather than being assumed from grid-connection)
• future: make sure these capabilities are added into BERT

Alternatives considered

• to run a grid-connected electrolyzer with a constant power input, set greenherat_config["grid_connected"]=False prior to call to run_electrolyzer_physics() and the power bought from the grid would have to be put into hopp_results["combined_hybrid_power_production_hopp"]
• To avoid resizing electrolyzer, set cluster_size_MW equal to electrolyzer_size_MW

Additional context