Guest essay by Eric Worrall
The BBC reports a new highly porous metal organic sponge can hold large volumes of hydrogen at low pressure. But there are still a few issues to solve, like where to get all the hydrogen.
Climate change: ‘Bath sponge’ breakthrough could boost cleaner cars
By Matt McGrath
18 April 2020
A new material developed, by scientists could give a significant boost to a new generation of hydrogen-powered cars.
However, hydrogen vehicles suffer from some drawbacks.
The gas is extremely light – In normal atmospheric pressure, to carry 1kg of hydrogen which might power your car for over 100km, you’d need a tank capable of holding around 11,000 litres.
To get around this problem, the gas is stored at high pressure, around 700 bar, so cars can carry 4-5kg of the gas and travel up to 500km before refilling.
Now researchers believe they have developed an alternative method that would allow the storage of high volumes of hydrogen under much lower pressure.
The product, with the glamorous name of NU-1501, has been built from organic molecules and metal ions which self-assemble to form highly crystalline, porous frameworks.
“It’s like a bath sponge but with very ordered cavities,” said Prof Omar Farha, from Northwestern University in the US who led the research.
“With a sponge, if you spill water and you wipe it, in order to reuse the sponge, you squeeze it.
“With this material we use the same thing – we use pressure to store and release these gas molecules.”
…Read more: https://www.bbc.com/news/science-environment-52328786
The abstract of the study;
Balancing volumetric and gravimetric uptake in highly porous materials for clean energy
Zhijie Chen1,*, Penghao Li1,*, Ryther Anderson2,*, Xingjie Wang1, Xuan Zhang1, Lee Robison1, Louis R. Redfern1, Shinya Moribe1,3, Timur Islamoglu1, Diego A. Gómez-Gualdrón2, Taner Yildirim4, J. Fraser Stoddart1,5,6, Omar K. Farha1,7,†
A huge challenge facing scientists is the development of adsorbent materials that exhibit ultrahigh porosity but maintain balance between gravimetric and volumetric surface areas for the onboard storage of hydrogen and methane gas—alternatives to conventional fossil fuels. Here we report the simulation-motivated synthesis of ultraporous metal–organic frameworks (MOFs) based on metal trinuclear clusters, namely, NU-1501-M (M = Al or Fe). Relative to other ultraporous MOFs, NU-1501-Al exhibits concurrently a high gravimetric Brunauer−Emmett−Teller (BET) area of 7310 m2 g−1 and a volumetric BET area of 2060 m2cm−3 while satisfying the four BET consistency criteria. The high porosity and surface area of this MOF yielded impressive gravimetric and volumetric storage performances for hydrogen and methane: NU-1501-Al surpasses the gravimetric methane storage U.S. Department of Energy target (0.5 g g−1) with an uptake of 0.66 g g−1 [262 cm3 (standard temperature and pressure, STP) cm−3] at 100 bar/270 K and a 5- to 100-bar working capacity of 0.60 g g−1 [238 cm3 (STP) cm−3] at 270 K; it also shows one of the best deliverable hydrogen capacities (14.0 weight %, 46.2 g liter−1) under a combined temperature and pressure swing (77 K/100 bar → 160 K/5 bar).Read more: https://science.sciencemag.org/content/368/6488/297
I don’t see the hydrogen economy happening, just because someone invented a new storage material.
Hydrogen has huge problems. For starters, there is no economically viable path to producing affordable hydrogen from renewables.
The dominant industrial process for producing hydrogen is steam reforming, which requires vast quantities of fossil fuel. Feedstock, usually methane, is heated with steam at such an extreme pressure the water actually combines with the methane; the carbon in the methane grabs the oxygen from the water, producing hydrogen and carbon monoxide. The process is strongly endothermic, so even more fossil fuel is required to heat the reaction chamber.
Renewables can’t even beat this absurdly wasteful process.
There are lots of academics like Australia’s Chief Scientist, who are all excited about the imaginary hydrogen economy of the future, but none of them can explain exactly how to build an economically viable hydrogen economy. Their plan seems to be to throw vast sums of government money at the problem and wait for the magic to happen.
A variation on the theme is to use steam reforming, but sequester the carbon monoxide and carbon dioxide produced by the reaction. The idea is to strip the carbon out of the fossil fuel before it reaches the end user. Although this process is cheaper than absurd ideas involving renewables, it would still dramatically increase the cost of energy, compared to simply burning the unprocessed natural gas directly.
There is also a zero carbon nuclear powered hydrogen production process, but greens mostly like to pretend nuclear power doesn’t exist.
Even if the renewable production cost problems are solved, hydrogen is a terrible gas to keep in confined spaces. Large quantities of hydrogen would be far more hazardous in a home environment than natural gas, heating oil or gasoline. If hydrogen use becomes widespread, it seems likely a lot of people would be injured or killed in hydrogen storage accidents.