While renewable energy fuel has always had no cost, in the past the cost of the energy conversion technology was prohibitive. Today, due to improved efficiency in the technology and substantial increases in manufacturing volume the cost to generate electricity from the renewables and the cost to store this electricity in lithium-ion batteries for four hours has made these technologies more than competitive with traditional sources. As higher renewable energy penetrations occur the variability and intermittent nature of solar photovoltaic (PV) electricity can cause steep ramping of conventional power plants, so longer term energy storage (days, weeks, instead of hours) will be needed to increase the reliability of grid operation. In Florida cloud cover of a PV field can cause rapid fluctuations of PV output requiring a fast response to smooth out the PV electric power output. A polymer electrolyte membrane (PEM) electrolyzer can serve as a utility controllable load that can be available at all times and the produced hydrogen can be sold or converted back into electricity directly through a PEM fuel cell. To study the integration of renewable solar with hydrogen for increasing grid reliability, a multi-software power control method and a transient thermal electrochemical PEM electrolyzer model has been developed.

One-dimensional ("through-plane") and two-dimensional ("through-plane" and "in-plane") un-steady state models using gPROMS 2.1.1. were developed. The model considers mass, energy, momentum and current balance equations. The thermal energy balance considers the heat transfer through the backing layer, the flowfield plates and the gas and liquid flows. Kinetic parameters used in the model were determined using parameter estimation of single cell steady state polarization curves [1]. The single cell unsteady state models were extended to a stack model by adding cells in series and parallel. Real-time PV data taken from a 8.9 MW_AC solar farm from Orlando Utilities Commission’s Stanton Energy Center was scaled up to 75 MW_AC to design the electrolyzer that would be sized with the typical utility PV installation in Florida. The 75 MW PV data was smoothed using a power control strategy developed in MATLAB. The developed multi-software power control method and the electrochemical dynamic stack model shows the effectiveness of an electrolyzer in smoothing the PV signal to increase the grid stability and flexibility. Results are presented of different size electrolyzers to minimize short term cloud cover spikes in power while maximizing hydrogen production and the effectiveness of the electrolyzer.

[1] Vincenzo Liso, Giorgio Savoia, Samuel Simon Araya, Giovanni Cinti and Søren Knudsen Kær, “Modelling and Experimental Analysis of a Polymer Electrolyte Membrane Water Electrolysis Cell at Different Operating Temperatures”, Energies, 11 (2018) 3272. doi:10.3390/en11123273