Storage of hydrogen is one of the more complex and costly parts of the hydrogen generation/supply chain. The nature of hydrogen means that it seeps into steel and causes degradation of the material (embrittlement) but also being such a small molecule can escape from it's container much more easily than other gases. To add to that, in its natural state is is not very dense so to be space efficient needs a variety of solutions such as compression or alternative storage methodologies (metal hydrides, ammonia, methanol, etc) to get it into an efficient form for storage.
Compression of the gas and storing at pressure is one of the most developed methodologies, today. Ongoing research continues to see higher and higher storage pressures. Where steel tanks were once most commonly used with pressures up to around 170 bar (car tyres are inflated to 2-3 bar), technology has brought carbon fibre hydrogen tanks into the market (used in passenger vehicles) that can store hydrogen at a pressure of up to 1,000bar. While this type of pressure will allow more gas to be stored in the same size vessel, the full carbon fibre vessels themselves are expensive. For mass storage, a vessel that can store at high pressure without the high cost of carbon fibre becomes an ideal solution.
To provide clarity in what type of tank is being used, construction methods have been given a 'Type' designation. Type I tanks are made of solid steel. Type III tanks are made of a composite material with an aluminium liner to hold the gas, while a Type IV tank is also a composite shell with a plastic liner. Composite can be glass fibre, a hybrid glass/carbon fibre or 100% carbon fibre. Carbon fibre is stronger and lighter than other composites meaning you can pack more storage vessels into a space, but you are trading off cost with space and volume.
Umoe Advanced Composites design and manufacture a Type IV tank that is essentially constructed using a plastic inner liner and resin cured glass fibre on the outside. The fibre and resin provide the strength for high pressure, without the high cost of carbon fibre. Their technology overall provides a good balance between high storage capacity and cost of construction. Individual tanks are typically installed within shipping containers, providing a robust, transportable and safe storage vessel for large volumes of hydrogen.
The construction materials of Umoe's storage bring numerous advantages to a storage solution:
The strength of glass & resin allows storage pressures of up to 425bar currently, which when packaged in a set of 18 tubes within a 40' shipping container, can transport in excess of 900kgs of hydrogen. Research work continues to further increase these numbers.
While still heavy, relative weights compared to traditional Type 1 storage make these 40' containers transportable within Australian road regulations.
With glass being a poor conductor of heat, stored hydrogen is better protected from environmental heat variations, and more importantly very well protected from any risk of flames reaching the tubes (European testing has confirmed the tubes can withstand 9x the benchmark of standard heat tests, from ordinary tanks).
Vessel walls are a mesh of fibre and resin, which when set provide an incredibly strong shell that is almost impossible to penetrate.
Vessels are typically housed in shipping containers, providing a further level of protection against damage to the capability of the tubes.
Skai Energies has worked with Australian authorities to approve the vessels for use in Australia, and can support the supply and configuration for any specific need in a hydrogen solution. Whether it be for static storage, or needs to be zoned for a mobility solution, please contact us to discuss the various options available.