Abstract.

Though the problem of urban pollution continues to grow unabated, the demand for transportation fuels remains high. As a result, interest in the development of alternative fuels for vehicles is on the increase in Canada and elsewhere. In recent years, natural gas has emerged as an important clean-energy alternative, largely because:

  • it is the cleanest-burning of the fossil fuels

  • it is efficient

  • it is available on a massive scale.

However, the need for high pressure (3200 psig) and heavy storage cylinders is an impediment to the widespread use of natural gas as a common vehicular fuel.

Adsorption storage of natural gas (ANG) is a promising alternative which has been investigated by many research organizations. Our group is actively working in this area. The natural gas adsorption technology currently under development uses KOH-treated activated carbon, whose adsorption capacity can be as high as 14–172 litres of natural gas per litre of storage. Furthermore, it has the potential to save 50% of refuelling station costs, 50% of operational costs and will permit a decrease in storage pressure to 500 psig from 3200 psig.

I NT R O DUCTI ON Though the problem of urban pollution continues to grow unabated, the demand for transportation fuels remains high. As a result, interest in the development of alternative fuels for vehicles is on the increase in Canada and elsewhere. In recent years, natural gas has emerged as an important cleanenergy alternative.

Natural gas is an abundant and economical resource. Systems for its distribution and storage are already in place, and technology that permits the use of natural gas as a fuel for motor vehicles is proven and available at a very competitive cost.

However, because of its low energy content under normal conditions, it is necessary to compress the natural gas (CNG) in high pressure cylinders in order to assure the vehicle a respectable range of operation.

Normal storage pressures are between 16.5 MPa (2400 psig) and 20.7 MPa (3000 psig).

Seeking ways to decrease these pressures while maintaining a reasonable vehicular range, Gaz Mé- tropolitain Inc and le 'Groupe de recherche sur les diélectriques de l'université du Québec à Trois-Rivières', and CANMET are actively engaged in the development of adsorption storage methods. The advantage that absorbed natural gas (ANG) has over compressed natural gas (CNG) is that it permits storage of gas at pressures several times lower than those required by conventional compression.

Low-pressure storage offers significant economic and logistic advantages. Primary among them is a

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