school energy&environment

Limits of methane hydrates

The exploitation of such quantities of natural gas is not possible today: present day technologies are not yet able to collect the hydrates so as to extract the gas, without losing it in the environment.
The first problem that has to be solved is that of finding the deposits. The research for methane hydrates utilizes geophysical methods that make use of the particular property of layers rich in hydrates to reflect seismic waves. Appropriate systems (usually compressed air ‘cannons’, for investigation in the sea) provoke the propagation of seismic waves that, passing through the rocks beneath the sea floor, are reflected at particular levels (the so-called Bottom Simulating Reflectors). This phenomenon occurs also for levels rich in hydrates: the so-called ‘seismic profiles’ are thus obtained and are real ‘ultrasound scans’ of the rocks that make up the sea floor. Italy is in the forefront in this type of research that is carried out by the Istituto Nazionale di Oceanografia e Geofisica Sperimentale (National Institute for Oceanography and Experimental Geophysics) with the research ship, OGS-Explora.
The second problem is that not much is known about these compounds: currently studies continue both for scientific research purposes and for commercial reasons. The GEOMAR Institute of Kiel, one of the major institutes of marine research, has created a laboratory in which the temperature and pressure conditions required for the conservation of methane hydrates have been recreated: in this way they can be studied in a laboratory at controlled conditions. Other research institutes, like the Brookhaven National Laboratory (USA), are carrying out experiments regarding the creation of these substances in a laboratory.
As far as commercial research is concerned, in March 2005, an expedition set out, financed by the American Energy Department and by the oil company, Chevron-Texaco. During the 35 days spent in the Gulf of Mexico, hydrate samples, collected with the additional aid of mini submarines at a depth of 1,300 m, were studied. Laboratory tests will enable us to understand in what way the methane trapped in ice can be released, recovering the maximum amount possible without losing it in the environment: extractive technologies, in fact, will have to consider the separation and collection of the gas directly in the sediments.