Cause to get fired up for 'clean coal' lobby

A study finds it is possible to collect and store carbon emissions from the plentiful, relatively cheap, but highly polluting fuel.

Smoke billows from chimneys at the Ningdong Coal Base in Yinchuan, China.

Scientists have said they could ease a key doubt that clouds "clean coal" - the dream of harnessing a fuel that is as cheap and plentiful as it is environmentally dangerous. China, India and other countries have increased their burning of coal this decade to power their growth and reduce their dependence on expensive imported oil. By doing so, they have also cranked up emissions of carbon dioxide (CO2), the heat-trapping by-product of this dirty, low-energy fuel.

The UAE is also turning to the coal option to meet surging demand for electricity. Although there are plans to build a nuclear power plant, it may be 10 years before the infrastructure is completed. Authorities in Ras al Khaimah announced last month they would build a coal-fired power plant in the next two years, while the Dubai Electricity and Water Authority (DEWA) said in January that it would invite bids from private companies to set up a coal-fired power station. It is also considering building a power plant that would burn hydrogen derived from coal.

The RAK Investment Authority said its project would be environmentally friendly, although it did not specify whether the plant would use clean coal technology, while DEWA has said the carbon emissions from its plant would be stored underground. Globally, a powerful lobby has emerged, sustained by the coal industry itself, to argue that with financial help and innovation, "clean coal" is on the horizon.

The term refers to a basket of technologies, the biggest of which is carbon capture and storage, or CCS. Under CCS, power stations would burn coal but siphon off the CO2 at source before pumping the unwanted gas into deep chambers underground, such as disused gas or oil fields. The CO2 would be stored there indefinitely rather than be disgorged into the atmosphere to add to the greenhouse effect. CCS has surged up the agenda in the past few years as the United States, Australia and other big coal producers struggle to address their greenhouse-gas emissions yet also keep using their biggest sources of indigenous energy.

But ecologists and geologists have sounded a loud word of caution: what are the guarantees that these chambers are leakproof? A breach would surrender the man-made CO2 to the air, amplifying global warming. In a study published yesterday in the journal Nature, a British team give a qualified "yes" to that question. So far, attempts to investigate the leak issue have been limited to computer simulation and a few small-scale pilot studies in the North Sea and the United States, which have only been going on for a few years.

The British scientists have taken a different tack. They pored over chemical signatures from gas fields in North America, China and Europe that are rich in natural CO2. "We looked at nine CO2 fields, ranging from 10,000 years to about 42 million years old, and they have all stored CO2 for this length of time without obvious leakage signs," said Stuart Gilfillan, of the Scottish Centre for Carbon Storage at the University of Edinburgh.

"Basically, if you store it in the right location, the CO2 should be contained on that sort of time scale." What traps the CO2 is, quite simply, underground water, Dr Gilfillan and colleagues believe. They looked at the ratio between isotopes of carbon dioxide and isotopes of a group of so-called noble gases, including helium. These signatures indicate that highly soluble CO2 dissolves in the groundwater - just like sparkling mineral water - and does not leak to the surface, Dr Gilfillan said.

The team believe that a small amount - 18 per cent or less - of the CO2 reacts with minerals in the rock to form a new carbonate shell in the chamber. This is the other theoretical way by which CO2 can be sequestrated. Dr Gilfillan said the outcome of the study is good news for "clean coal" but not an automatic green light for it. Any potential storage site had to be thoroughly prospected to see it was geologically sound and ensure that its groundwater did not leak to the surface, he said.

"If you're talking about an old gas field or an old oil field and you've got no evidence of [gas] leakage up to the surface or oily water coming up, then that would be a strong candidate for storage." Another shadow hanging over CCS is the cost of stripping out the CO2 and pumping it to the nearest suitable underground chamber. Critics say the price could be higher than switching to a mix of solar, wind, fuel cells and other renewables that would resolve the problems of fossil fuels once and for all.

* Agence France-Presse, with additional reporting by The National