Hydrogen storage using depleted uranium
S. Himmelstein | January 02, 2023A U.K. consortium has been awarded £7.7 million (U.S.$9.3 million) from the Net Zero Innovation Portfolio (NZIP) of the U.K. Government’s Department for Business, Energy & Industrial Strategy (BEIS) to develop a hydrogen storage demonstrator, in which hydrogen is absorbed on a depleted uranium bed, which can then release the hydrogen when needed for use.
The Hydrogen in Depleted Uranium Storage (HyDUS) project partners, which include the University of Bristol, EDF UK, the U.K. Atomic Energy Authority and Urenco, will demonstrate the chemical storage of hydrogen at ambient conditions by chemically bonding the hydrogen to depleted uranium 238 to form
heavy-metal hydride compounds.
In the HyDUS system, the hydrogen is in a stable but reversible metal hydride form. The technology focuses aimed on longer-term energy storage and the enhancement of energy storage density. The depleted uranium material is available from recycling and has been used in other applications such as counterbalance weights on aircraft.
According to Tom Scott, professor at the University of Bristol School of Physics, “The hydride compounds that we’re using can chemically store hydrogen at ambient pressure and temperature but remarkably they do this at twice the density of liquid hydrogen. The material can also quickly give-up the stored hydrogen simply by heating it, which makes it a wonderfully reversible hydrogen storage technology.”
Urenco will contribute depleted uranium, a by-product of the uranium enrichment process, to the project, which is expected to deliver a modular demonstrator system within the next two years. The HyDUS units will first be installed at nuclear sites to enhance the profitability of nuclear power plants. The technology could be more widespread in the future and be deployed to support transport and heavy industries such as aluminum and steel smelting
It would be nice if some metrics were given,, such as lb of hydrogen storage per lb of depleted uranium,, temperature differential requirement,, availability of depleted uranium...
In reply to #1
The announcement says the hydride is UH3, which means 3 grams of hydrogen per 238 grams of uranium. This sounds like a very low ratio but the relative densities of the two elements needs to be considered. For uranium it is 19.1g/cm3 and for liquid hydrogen it is 0.071g/cm3.
The announcement mentions hydrogen storage at quantities double the amount in the liquid form, so the effective density of the hydrogen in the hydride is closer to 0.14g/cm3. This is a similar amount of storage compared to hydrides of aluminum and a few other metals which have been investigated as methods for storing hydrogen in motor vehicles since the 1980's.
To effectively allow the reversible chemical reaction in fairly short time periods, the uranium metal would have to be in a finely divided form, which would reduce its density somewhat.
Worldwide, the amount of depleted uranium created from the weapons and atomic energy industries is much greater than 1x106 kg. Therefore I would doubt that its supply as a chemical is a significant problem. It is "routinely" used in munitions as well as counter weights and armor, so the technology to convert it from uranium fluoride or uranium oxide is in regular use.
I see two significant problems or dangers:
--JMM