Electricity must be provided as it is consumed. Variable renewable generation is available only when the sun shines and the winds blow, so it may or may not be available when it is needed most. As more renewables, especially solar PV, are added to the grid, net load (i.e., the remaining demand that is not met by these renewables) increases in variability and may require dispatchable generation to ramp up and down quickly to fill in any gaps in generation. Electricity storage can be a valuable resource as it can shift electricity from one time period to another as a way to fill in any gaps in generation as well as absorb excess generation that might otherwise be curtailed. A recent OnLocation blog describes policies aimed at expanding the grid electricity storage market in order to address dispatch challenges created by high deployment of new variable renewable generation.
A fine degree of temporal resolution is needed to capture these effects. The REStore model performs an hourly dispatch solving for a minimum-cost dispatch of generating and storage capacity. It provides the NEMS Electricity Market Module with annual storage arbitrage values and storage loading and discharge schedules, as well as variable renewable generation operations and curtailments, if any, in each forecast year. The model measures the marginal arbitrage value that can be achieved by storage capacity additions by solving the linear program twice each model year, once with existing storage capacity and then again with a new increment of storage capacity.
The NEMS model and the REStore submodule are valuable tools used by OnLocation to inform policymakers of the opportunities and challenges of a future with high deployment of variable renewable generation and the role that electricity storage can play in meeting these challenges. REStore might also be applied in novel ways, for example to determine the optimal timing of electric vehicle charging.
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