Direct Coupling of Marine Renewable Electric Power with Subsea Electrolytic Hydrogen Production

Abstract:

AIMS & OBJECTIVES The research is focused on operational principles and materials compatibility of scalable subsea prototype laboratory electrolyzers that are powered by marine renewable energy. A first objective of the work is to demonstrate that GTA electrolyzers, constructed primarily from marine-grade engineered polymeric materials and exclude platinum group electrodes, possess performance features that rival metal-intensive electrolyzers. A second objective is to demonstrate that native hydrogen purity produced by the electrolyzers is sufficient for virtually all hydrogen-consuming industrial manufacturing operations wherein the hydrogen is currently obtained from steam methane reforming of natural gas.

RESULTS AND SIGNIFICANCE The analytical report showed a native hydrogen purity of 99.65%, a value that is sufficient for virtually all industrial processes and manufacturing markets. The data also indicate that additional standard purification steps will upgrade the hydrogen to fuel cell grade standards. The significance of the work is: First, GTA electrolyzers contain no moving parts and are constructed from relatively inexpensive and robust commodity materials that exclude platinum group metals. Second, native GTA hydrogen purity is sufficient for most of the industrial applications that use the ten million metric tons of hydrogen produced annually in the United States from fossil feedstocks, primarily natural gas. Third, the emerging markets for high-purity fuel cell grade hydrogen for electric utility grid balancing and hydrogen fuel cell cars and trucks, currently on sale in Japan, Europe, California, and elsewhere can be achieved with GTA electrolyzers plus standard chemical engineering unit operations. Fourth, hydrogen gas pipelines need not compete for onshore access to the electric grid. Fifth, important parameters for large-scale production of renewable hydrogen are safety, purity, pressure, CAPEX, OPEX and system efficiency. Subsea hydrogen production powered by offshore wind and marine hydrokinetic devices are the most advantageous renewable power sources for optimizing the parameters because deep-water hydrostatic pressure can be leveraged for equipment cooling and producing high pressure hydrogen at the sea floor without mechanical compressors or high strength materials.