New Metal-Organic Framework fuel tanks could revolutionize the future for natural gas driven vehicles and supply chains

Courtesy: science.tamu.edu

Courtesy: science.tamu.edu

Although much has been said about reducing transportation costs in supply chains and lowering CO2 emissions through the use of natural gas trucks for transporting goods, implementation has been slow.

The slowness of the take-up of natural gas trucks is due to several factors, including:

  • The high cost of natural gas trucks as opposed to diesel trucks
  • The lack of natural gas dispensing service stations across the US
  • Minimal ROI because of a reduction in current fuel surcharge revenues

Part of the problem for supply chains is the high cost of natural gas powered trucks and the difficulty of storing natural gas on board vehicles, whether the natural gas is in compressed format (CNG), or liquefied format (LNG) which must be kept cold.

The good news is that this that could be about to change.

The Metal-Organic Framework (MOF) fuel tank

Researchers at the University of California, Berkeley, have successfully developed a new flexible, porous material – something they call a metal-organic framework (MOF) that can be used for storing gas and that solves the existing difficulties.

The MOF collapses as methane is extracted to fuel the engine. It also expands when the methane is pumped back in under moderate pressure; the sort of pressure that can be supplied by the types of ordinary compressors that people sometimes have in their homes.

Refuelling your car at home with natural gas

The research that led to the idea of the flexible MOF-based fuel tank, which was carried out in conjunction with the National Institute of Standards and Technology and the Ford Motor Company (among others) means that consumers will potentially be able to fill up their cars’ fuel tanks at home from a bigger storage tanks without the need for having to stop at roadside filling stations.

Whereas currently, vehicles operating on compressed natural gas require the gas to be put into the fuel tank at 3600 psi, the new flexible MOF-based fuel tank can be loaded with methane (the main constituent of natural gas) at only between 500 to 900 psi.

Vehicles fuelled with LNG operate at lower pressures but need significantly better insulation systems in order to keep the natural gas at -162°C so that it stays in its liquid state.

The new research carried out relates to something called Adsorbed Natural Gas (ANG) whereby the challenges involved coming up with a material that adsorbed gas at a pressure of 35 atmospheres which relates to approximately 500 psi.

However this material must also then release all the gas prior to the pressure reaching five to six atmospheres, which is the minimum pressure that enables a car engine to operate.

The problem in the past has been that too much gas remained in the fuel tank and could not be used.

Small fuel tanks and better mileage consumption is the target

Prof Geoffrey Long of UC Berkeley says that the development of the new flexible MOF’s is a significant advance in terms of both storage capacity and temperature management. What it boils down to is that we can have smaller fuel tanks and/or obtain more miles from existing sized fuel tanks.

However, while the research has resulted in a positive advance, there still remains more work to be done before we will see a significant increase in the number of natural gas fuelled cars and lorries on our roads, and realize a benefit to supply chains in general.

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