The storage of natural gas in hydrates has been investigated since it was discovered that they store large quantities of gas. Dtflerent storage methods have been suggested: either keeping hydrate under low temperature or under pressure.
This work presents the results of experiments aimed at improving the quality of the produced hydrate in term of gas content per unit volume of water. We have tested and developed a new water-soluble chemical that promotes methane hydrate formation by reducing the interfacial tension properties of the water. A series of investigations identijied that, depending on the concentration, the effect of hydrate inhibiting agents such as sodium chloride, alcohols and Carbonyl Compounds on gas hydrate formation, can either promote or suppress formation of gas hydrates in systems of water and natural gas.
It was also proven that growth rates of a crystal face depend on how fast the heat is removed from the surface and this depends on the rate of heat transfer at the interface.
The quality and quantity of hydrates were examined for their gas contents in a low temperature PVT apparatus. The total water conversion to hydrate in case of sH and sII hydrates was improved using hydrate promoters discovered during this work The rate of gas content per volume of hydrate was significantly improved from to 196 sm3/sm3 compared with 150–180 sm3/sm3 for pure water hydrate.
The manufacture of natural gas hydrates (NGH), a stable solid comprising natural gas and water, is proposed as an alternative storage and transportation technology for natural gas instead of LNG and pipeline transportation. It is also valid to view this technology as a potential competitor to other energy forms such as LPG, fuel oil and coal. The manufacture of NGH requires only moderate cooling (typically -15 °C) and provides a stable solid when stored in an insulated environment. NHG's are readily decomposed into their hydrocarbon constituents and water at the point of delivery.
Commercialisation of this technology in Western Australia could be undertaken via two principal routes. The first is to directly compete in the small to medium-scale domestic energy market. This market is currently serviced by road and rail transported LPG, fuel oil and increasingly LNG. This market may provide a low cost opportunity to test and commercialise the various NGH technologies. The economics screening study for a road based domestic energy market indicates that the cost of energy from NGH may compete with LPG and diesel delivering energy for a base case scenario at approximately A$6/GJ.
The second route would be via large scale NGH production, competing directly in the global LNG market. This will be reviewed at a later date; some studies supporting this commercialisation route have already been carried out in Scandinavia but are not reviewed in this paper.
The experimental apparatus consists of two equilibrium cells, the main cell is a synthetic sapphire providing 3dimensional visibility, and it has a total volume of 700 ml and is designed to handle pressures up 1500 bar.