With global oil prices soaring and continued concerns over the security of gas supplies, the need to exploit alternative sources of fossil fuels has never been greater.
The US Geological Survey estimates that the amount of organic carbon stored as frozen natural gas under the Earth’s surface is greater than the world’s oil, coal and non-frozen, free gas reserves combined. Large reserves are thought to exist under the oceans off the coasts of
Like conventional natural gas, the methane held within these reserves was formed as a by-product by microbes feasting on organic matter trapped in sediment. In cold, high-pressure environments, water molecules form open solid lattices that trap methane molecules without chemical bonding — methane hydrates. It is thought that around 55 million years ago some event caused vast quantities of gas to be released from these structures, causing abrupt global warming.
Methane from hydrates is more environmentally friendly than normal natural gas as it produces less carbon dioxide when burned. However, accidental creation of a large uncontrollable leak could be catastrophic. Identifying and extracting methane from hydrates for commercial use thus presents an enormous technical challenge that has swallowed millions of research dollars in countries including
Methane hydrate is the most abundant natural form of clathrate, a unique class of chemical substance in which molecules of one material (in this case, water) form an open solid lattice that encloses, without chemical bonding, appropriately-sized molecules of another material (in this case, methane).
The US National Energy Technology Laboratory’s National Methane Hydrate Programme, initiated in 1997, aims to develop technologies to allow the commercial production of gas from methane hydrates by 2015.
Last month researchers led by chemist Dr Devinder Mahajan of the Advanced Fuels Group at the
But in the same month the
‘The official position is that, with high energy prices, industry will pick up the shortfall,’ said Edith Allison, exploration programme manager at NETL’s Office of Natural Gas and Petroleum Technology.
Now, another country is poised to join the quest. Though the
Partnered with Dublin-based oil and gas firm Providence Resources and
The hydrates off
If water or steam is pumped into the well the hydrate can be warmed, a technology used by scientists from the
In December 2003 the £12.5m project produced a five-day flow of natural gas from frozen deposits after pumping hot water into the ice to raise the temperature and banging it with drills to create fractures that lowered the pressure.
‘This process is messy and uses a lot of energy,’ warned Mac Aodha. He believes the most efficient method would be one based on technology used to extract oil tar whereby a small burner is dropped into the well. This burns a small amount of gas from the hydrate as it dissociates. The level of burning can be determined by controlling the oxygen supply. ‘This way, about 10 per cent of the gas is burned, but the other 90 per cent is recovered,’ Mac Aodha said.
Another technology involves the use of specific frequency microwaves that target and heat the hydrate. ‘This method is more efficient as it allows you to heat only the hydrate rather than the surrounding rock,’ said Mac Aodha.
‘In north America, gas hydrate development will have to be competitive with the large conventional natural gas accumulations that are often spatially near, or underlying, the gas hydrate accumulations, none of which have transportation to market currently,’ said Kirk Osadetz, manager of the Gas Hydrates Fuel of the Future programme at Geological Survey of Canada in Calgary. ‘Where issues of supply security override economic competitiveness, such as in
Compared with international methane hydrate extraction attempts,