A Novel Long-Duration Hydrogen Storage Concept Without Liquefaction and High Pressure Suitable for Onsite Blending

Abstract

Hydrogen is typically stored as a low-pressure cryogenic liquid or as a high-pressure gas. Both approaches come with technical challenges that complicate the implementation of such systems at the actual power plant scale. Cryogenic liquids can provide high energy and volume densities but require complex storage systems to limit boil-off. That makes such liquid tanks complex, large, and heavy which in turn drives up capital cost. Furthermore, expensive liquefaction equipment is required, too. The liquefaction process is highly energy-intensive, approximately 35% of the fuel energy, hence, reduces the net performance of gas turbine power plants using such hydrogen storage approaches. Conversely, high-pressure gas storage bottles are less complex and can be kept at room temperature. However, they require a thick wall to withstand the high pressure which makes them considerably heavy as well. Furthermore, the energy densities associated with gas storage are dramatically lower than for cryogenic liquids, even at high pressures up to 700 bar. The present study presents and discusses a novel concept for storing hydrogen to be used in gas turbine power plants. Proposed technology enables the storage of hydrogen close to cryogenic density without the need for high pressure or liquefaction and the delivery to the gas turbine asset can be at engine pressure so that no gas compression is required. It is believed that the capacity of the storage system scales easily so that hydrogen can be stored for long durations from daily to monthly cycles which correspond to 10 to 100 hours, respectively. Besides a SWOT analysis, a system will be described that would integrate into the existing OEM infrastructure and allows the blending of hydrogen and natural gas between ratios between 30% and 100%. Specifications will be provided for the storage system and analyzed for a gas turbine power plant with 100 MW.