October 09 2008 / by Garry Golden
Category: Energy Year: 2018 Rating: 1
Hydrogen fuel cells, which produce electricity, are an evolution to modern day batteries. If we can store hydrogen efficiently as a solid, we can expand the use of energy from intermittent solar and wind power. We can also lower the costs and improve performance of electric vehicles. Two recent research announcements hint that cost effective storage could be much closer to reality.
Nanoscale science & surface area
One of the key enablers of storing hydrogen as a solid is high surface area. How much? Can you imagine holding a gram of material with surface area equal to several football fields for storing hydrogen molecules?
Nanoscale (billionth of a meter) material design means high surface area ratio to volume. We can also tap nanotechnology to create storage materials able to bind and release hydrogen molecules at low pressure and low temperature.
Carbon scaffolding for storage
There are a number of ways to store hydrogen as a solid, and also as a liquid. Earlier we featured a look at metal-organic frameworks or MOFs as a viable long term storage material. Today we’ll look at two other carbon-based hydrogen storage systems.
Carbon is a controversial storage medium since it is ‘sticky’ and can often bind hydrogen too tightly. But mixing (or ‘doping’) carbon with other elements can leverage the benefits of carbon’s high surface area and its Lego-like structural design.
‘Doping corn cobs?’
The Department of Energy has awarded $1.9 million to researchers at the University of Missouri and Midwest Research Institute (MRI)
The Missouri team has found that carbon briquettes (derived from corn cobs) then “doped” (or mixed and layered) with boron, have a unique ability to store natural gas with high capacity at low pressure.
While corn cobs hydrogen storage sounds a bit far fetched, one gram of this carbon material has a surface area comparable to a football field. The boron additive to carbon creates binding energies with H2 molecules that might make this a viable storage medium.
Carbon Graphene Layers
Another carbon based solution was announced last week from researchers in Greece using stacked thin sheets of carbon doped with lithium.
The team has modeled a hydrogen-storage structure using one molecule thin sheets of carbon known as ‘graphene’. These vertical columns of carbon are doped with lithium ions to expand its storage capacity.
The calculations suggest storage up to 41 grams of hydrogen per liter, near to the US Dept of Energy’s target (45 grams of hydrogen per liter) for transportation applications.