Hydrogen Intermediate Storage and Compression: A Deeper Insight

Published by firstgreen on

In the journey of transitioning to a sustainable energy landscape, hydrogen is emerging as a promising alternative energy carrier. But for the efficient production of products like liquid hydrogen, ammonia, methanol, and e-fuels, there exists a crucial step: intermediate hydrogen storage. In this article, we will delve into the nuances of hydrogen intermediate storage, its significance, and the vital role of compression.

Why Intermediate Hydrogen Storage?

With the rapid advancement in electrolysis techniques, there is a disparity in the production dynamics between electrolysis and downstream conversion processes, like hydrogen liquefaction and synthesis. These downstream processes are more restrictive, operating only within specific load ranges. Thus, to ensure a consistent hydrogen supply for continuous operations, there’s a need for a buffer – the hydrogen intermediate storage system. This system provides a steady flow of hydrogen, bridging the gaps when electrolytic production isn’t active.

Traditional Storage Options

Traditionally, over ground steel tanks have been the storage of choice, holding several tons of gaseous hydrogen at pressures reaching 100 bar. However, this method comes with a hefty price tag, exceeding 500 EUR/kg of hydrogen storage capacity. For those looking at more cost-effective bulk storage, underground salt caverns are an attractive option. They boast investment costs below 10 EUR/kg of storage capacity. But, these caverns come with their own set of challenges – the requirement of specific geological formations and extended planning and construction timelines of up to a decade.

Underground Pipe Storage: A Potential Game-Changer

In this study, we delve into another promising option – underground pipe storage. A technique already popular for natural gas storage, its principles mirror those of side-by-side pipelines. While still untested for hydrogen storage due to previously limited demands, underground pipe storage, operated at pressures up to 100 bar, presents a viable option. Expected investment costs lie between 250 EUR/kg and 500 EUR/kg.

Storage volumeOptimization Variable
Max. pressure80bar
Min. pressure10bar
CAPEX2,100 EUR/m³ / 330 EUR/kggross
OPEX1% of CAPEX/yr
Technical and Economic Parameters for Underground Pipe Storage:

The Role of Compression

Given the disparity in the storage pressure and production pressure of hydrogen, compression is pivotal. Compressors are needed to elevate the hydrogen’s pressure from its electrolytic production value of 30 bar to a storage-ready 80 bar. For a production capacity of 19.3 tons of H2/hour, a setup with five compressors operating concurrently ensures redundancy and efficiency.

Total rated mass flow19.3tons/h
Input pressure30bar
Output pressure80bar
Number of stages2
Specific Power Consumption0.4kWh/kg
OPEX4% of CAPEX/yr
Key Parameters for Hydrogen Compression

Wrapping Up

Intermediate hydrogen storage is a linchpin for ensuring the seamless production of green energy products. As the hydrogen economy grows, exploring viable and efficient storage options, coupled with effective compression techniques, will remain at the forefront of sustainable energy discussions.