Uniform dispatch and storage of Green Hydrogen from wind energy in Patagonia Argentina. Cost impact

SCHMIDHALTER, IGNACIO; DIEGO, OLIVA; FUENTES MORA, MAUREN; MUSSATI, SERGIO F.; MUSSATI, MIGUEL C.; AGUIRRE, PIO A.

Congreso; WCCE11 11th World Congress of Chemical Engineering; 2023

Green hydrogen is gaining wide acceptance in several countries in the world as an answer to a clean energy future. The focus of this study is to analyze uniform dispatch constraints and consequently the need for hydrogen storage. As it is known hydrogen storage is cost intensive because of the investment and energy consumption. Hence, the Levelized Cost Of Hydrogen (LCOH) production accounting for the whole system, wind farm, electrolyzer plant, and storage units, is addressed. In this study, three different scenarios according to different dispatch constraints and considering H2 storage as compressed gas at 170 bar are investigated. A representative year is divided into several time-slots with equal lengths (number of days) and is modeled in hourly basis. A same amount of hydrogen must be dispatched for all the slots. The scenarios differ on the length of the time-slots. In the first scenario, the length of the time-slot is 1 day. This means that every day of the year the same amount of hydrogen calculated as the ratio of the total yearly production to the number of days must be dispatched. No constraints on the hourly H2 production or dispatch within the slot are imposed. In the second scenario, the length of the time-slot is 7 days implying that a same amount of H2 must be dispatched each week of the year. Similarly to the previous scenario, no constraints on the hourly production or dispatch within the slot are imposed. Finally, 14 days is assumed for the length of the time-slot in the third scenario.For all of the scenarios, the minimum LCOH is obtained from the optimal combination of power peak of wind farm, power peak of electrolyzer plant and storage capacity. A model is implemented in EXCEL in order to determine the optimal system size for hydrogen production at minimum value of the LCOH including storage. It is shown that storage precludes the hydrogen annual production to reach the maximum value obtained when no storage is considered. In order to optimize the size of the entire process, the trade-offs among the hydrogen production (which depends on the length of the time-slot), storage capacity, seasonal changes in the wind resource should be taken into account. Hydrogen production is sacrificed in order to reduce the need for large Storage Capacity. Seasonal changes in the resource are the main reason for these behaviors. The optimization approach involves several heuristics rules that decide at each hour the amount of hydrogen the system produce. Hourly productions are constrained by different mathematical conditions, which are derived from mass balances. Several suitable sites for hydrogen production with wind energy in South of Argentina are considered. A ranked list of the minimum values of LCOH computed for all scenarios and sites with H2 storage is presented and the optimal behaviors of the subsystems (electrolyzer plant, wind farm and H2 storage unit) are discussed in depth.