Techno-economic comparison of energy storage integration with hydro, tidal and other variable renewable generation
Energy Storage: Increased deployment of variable renewable generation (VRG) assets and lower costs of grid-scale battery energy storage system (BESS) have led to increased deployment of hybrid generation and storage systems. The technology required to enable such integration is common across VRG resources such as run-of-river (ROR) hydropower, solar, tidal, and wind. Yet, the generation profiles (notably variability) and the uncertainty in forecasting differ considerably. Most of the attention in industry currently is on hybridizing wind and solar, but the financial performance from hybridizing ROR hydropower and tidal is yet to be explored. This is driven by the fact that ROR hydropower and tidal energy are much less variable and more predictable over the typical 24-hour period relative to wind and solar. The objective of this work is to conduct side-by-side financial value comparison of integrating BESS with ROR hydropower, wind, solar, and tidal generation resources. The analysis considered two U.S. independent system operators (ISO) – the California ISO (CAISO), and the Pennsylvania – New Jersey – Maryland (PJM) interconnection and investigated one highly volatile locational marginal price (LMP) node from each market. Electrically co-located ROR hydropower, solar, and wind generation profiles are selected for the respective LMP nodes while tidal generation profiles are selected in proximity of the markets from the publicly available tidal current database. ROR hydropower forecast has been obtained by leveraging historical volumetric flow forecast from National Oceanic and Atmospheric Administration (NOAA), while numerical weather prediction model, coupled with an analog ensemble technique has been used for solar and wind generation forecast. Tidal current periodicity has been leveraged in Fourier analysis to obtain tidal generation forecast. Each one-year actual and forecast generation profile is normalized by their respective maximum actual generation and BESS of same capacity and duration is integrated to ensure fair comparison across these four VRG + BESS hybrids. The normalized generation profiles, BESS, and LMP information are fed into the Revenue, Operation, and Device Optimization (RODeO) model to assess the above mentioned seven financial metrics. From the analysis for the selected LMP nodes, it is observed that ROR hydropower + BESS and tidal + BESS illustrate financial performance comparable to solar + BESS, and wind + BESS. Specifically, higher value in energy arbitrage is observed due to the periodicity in tidal generation and consistency in ROR hydropower generation. Also, the variability in ROR hydropower plays role in increasing post charging VRG only revenue. In terms of the impact from forecast, however, tidal generation stood out on severity as the forecast lacked exogenous information.