(681d) Market-Integrated Optimization of Wind-Battery-Hydrogen Hybrids for Peaking Capacity Via Storage

As greater amounts of renewable energy are deployed to support a decarbonized electricity grid and electrification of various industries advance, challenges around demand and resource uncertainty, changing and increasingly volatile market signals, and requirements for reliability and affordability may be addressed from multiple directions, including storage, distributed energy resources, transmission, market changes, and integration of renewable hybrid energy with other generation sources as part of Integrated Energy Systems (IES). IESs combine multiple power generators and storage technologies in order to provide more services and demand-responsiveness than the individual technologies alone; this provides the potential for more value and less risk via resource diversification, complementary overbuild, and revenue-stacking, but requires more sophisticated forecasting, controls, and market participation strategies. As the value add of IESs is dependent on how it is dispatched by the market, grid interactions should play an important role in the design phase but instead are usually treated as exogenous inputs.

In this study, the goal is to hybridize and retrofit "existing" wind and natural gas (NG)-burning combined cycle combustion turbine (CCCT) plants for operation on a publicly available representative grid system (the Reliability Test System - Grid Modernization Lab Consortium (RTS-GMLC)) to study the impacts and implications of replacing NG peak generation capacity with wind, battery, PEM electrolysis, hydrogen tanks and hydrogen turbines. The Design Integration and Synthesis Platform to Advance Tightly Coupled Hybrid Energy Systems (DISPATCHES) is developed to integrate the grid-interactive optimal control and market participation strategies with the IES design phase in two primary ways: simultaneous optimization of plant design/operation and market dispatch via surrogate models of production cost models (PCM); and co-simulation of the IES operating and bidding within the PCM in a "double loop" framework.

The wind-battery-hydrogen IES is designed to meet the dispatch of a pair of RTS-GMLC wind and CCCT plants and then simulated within the PCM Prescient with different bidding strategies in order to compare performance across scenarios. The conceptual design phase combines design and operation optimization to maximize net present value. Design decision variables include the capacities of the battery, PEM, hydrogen tank and turbines to most cost-effectively meet the given dispatch, while the operating variables include how to split the wind power among battery, PEM, and the grid, the battery power profile, and the inlet and outlet flows of the hydrogen tank.

Using three market participant bid strategies co-simulated with Prescient, the revenue and dispatch are compared with the CAPEX for hybridization and retrofitting. In the first scenario, the IES bid is the sum of the original wind and CCCT bids, a baseline where there is no change to the PCM decisions, provided the IES can meet its market promises. This demonstrates how wind generation that would have otherwise been curtailed during off-peak months can be utilized for making the hydrogen to be burned during the peak months. In the second scenario, the IES bid is modified to a break-even cost given an expected energy output and uses the assumption that the change in the bid does not affect the grid dispatch. We compare the change in revenue and dispatch, and the challenges of assuming an expected energy output from historical or a-priori knowledge. In the final scenario, the IES bid is optimized using the market surrogate model to find the best bid while representing how the grid dispatch will respond. This shows the importance of modeling grid-interaction, but also identifies challenges for long-term economic dispatch for hydrogen storage. We look at the price and cost implications of wind-battery-hydrogen IESs using curtailed wind for hydrogen storage to displace NG peaking capacity on the RTS-GMLC, and present a workflow that can be extended to study IES design, control and market participation in the modernizing, decarbonizing grid.