Working under pressure

A system for taking samples under pressure from deep within the sea bed could shed vital light on the formation of methane and methane hydrates, a potentially abundant source of energy.

If the bacteria that create the gas can be identified, researchers believe they could increase oil well yields and also discover how long hydrates take to form, revealing whether the energy source is sustainable.

Researchers at Cardiff University’s Manufacturing Engineering Centre have built a high-pressure isolation system so that bacteria can be taken from sediments and cultured at pressures of up to 1,000 atmospheres.

The research, led by Prof John Parkes of the School of Earth, Ocean and Planetary Sciences is part of a e1m (£670,000) EU project, HYACINTH, aimed at recovering gas hydrates and live bacteria under high pressure, then transporting them to the lab for study.

The bacteria break down organic ocean sediments, releasing methane gas which is then converted to methane hydrates by high pressures and low temperatures. This super-concentrated methane ice contains more reserves of hydrocarbons than all known stores of conventional fossil fuels. However, hydrates melt during recovery and many bacteria within the sediments cannot survive at normal atmospheric pressure, making it impossible to study how the methane hydrates are formed.

The high-pressure facility contains a cutting chamber where samples can be taken in sterile and anaerobic or oxygen-less conditions. Allowing any air into the chamber would kill the bacteria.

The device is made from titanium and stainless steel alloys and has sapphire windows that can withstand great internal pressures. Mini cameras allow researchers to view the samples as well as operate electronically-controlled devices to manipulate the chamber’s contents.

‘We need to understand the role of the bacteria in making methane,’ said Parkes. If they are very active and make methane quickly, it would allow us to take hydrates from a site then go back at a later date by which time more hydrates would have formed. If we can inject and control a methanogenic (methane forming) bacteria into hydrocarbon reserves we may be able to get extra gas from them. But first we need to find the right organism.’

The chamber could also throw light on the mystery behind the Bermuda Triangle. One theory is that methane is released from hydrates beneath the ocean when the seabed becomes periodically unstable. The explosive mixture of air and methane above the ocean could cause ships and planes to be destroyed.