BY MARK WAKEHAM & KIRSTEN BLAIR
DARWIN — Natural gas is currently being depicted as a clean source of energy, which will help to wean the industrialised world away from its dependence on oil and coal and play a key role in Australia's response to global warming.
But make no mistake, despite the assertion of Northern Territory chief minister Denis Burke on June 9 that "We need to move from fossil fuels to gas", natural gas is indeed a fossil fuel. It is formed from the breakdown of prehistoric plant matter buried deep beneath the surface of the earth and consists mostly of methane, with varying quantities of carbon dioxide, both of which are core greenhouse gases.
Darwin-based development of the Timor Sea gas fields, along with the associated proposed liquid natural gas (LNG) and methanol projects, will therefore lead to a huge increase in the NT's greenhouse gas emissions.
There are currently four major gas-based developments proposed for the Darwin region: two LNG plants and two methanol production plants.
The LNG plants are proposed by Phillips Oil and Woodside. Phillips wants to locate their plant at Wickham Point (on Middle Arm) in Darwin Harbour. The company has completed an environmental impact statement (EIS) which details some predicted levels of emissions likely to result from their plant. Woodside is in the process of preparing its EIS for a site at Gunn Point.
Recent statements from the NT government indicate that it would prefer for all gas-based development to be located on Middle Arm, but irrespective of the location, these projects all have major greenhouse implications.
The Northern Territory Environment Centre has major concerns about both the greenhouse implications and the on-site environmental impacts of industrial expansion.
The proposed Wickham Point LNG plant will produce a high level of greenhouse gas. Total emissions are estimated at 1.8 mega-tonnes per year, or 0.3% of Australia's 1994 emissions.
The natural gas that will be fed down the proposed pipeline from the Bayu-Undan field in the Timor Sea already contains 6% carbon dioxide. As a point of comparison this is twice the carbon dioxide content of the gas which supplies Woodside's North-West Shelf LNG plant in Western Australia.
However, over half of the 1.8 mega-tonnes of carbon dioxide to be emitted every year will be produced during the process of combustion from the use of gas-powered turbines and heaters. Methane, a greenhouse gas at least 25 times more potent than carbon dioxide, will also be emitted from flaring.
Phillips Oil argues in its response to submissions on the draft EIS that whilst the plant will emit large quantities of carbon dioxide, these would only represent a 0.0045% increase in global emissions.
It then offers the spurious argument that 40% of the emissions "occur naturally" in the gas supplied to the plant, rather than through the process of combustion. Of course, no emissions would occur at all if the gas were left in its natural state — under the sea.
Moreover, the company asserts, there will be a net decrease in global emissions if the LNG product is used in preference to oil and coal for electricity generation.
There are some plans to use the gas to replace dirtier power sources. The proposed Darwin to Moomba gas pipeline may see some of the Timor gas replace coal-fired power in southern Australia.
The Nabalco bauxite mine at Gove (currently the single biggest polluter in the NT, with greenhouse emissions larger than for the whole of Darwin) also has plans to utilise the gas and change from oil-based power generation.
But it is likely that most of the LNG will be exported to meet the US economy's insatiable energy demand with no accompanying decrease in oil and coal use, especially if President George W Bush follows through with his current energy plan.
Phillips has signed a letter of intent with El Paso Global LNG for the supply of up to 4.8 million tonnes per annum of LNG starting in 2005. El Paso will sell the LNG to customers on the west coasts of the US and Mexico.
When producing LNG, carbon dioxide and other impurities need to be removed.
Some of this can be done in the field before the gas comes to shore and avoid the release of some greenhouse gases. The carbon dioxide can be "reinjected" into spaces beneath the sea floor and effectively trapped there. This method can provide a cost saving in some cases as the size of the shore-bound pipeline can be reduced if the carbon dioxide is removed beforehand.
Phillips argues that the percentage of carbon dioxide in the Timor Sea gas is not significant enough to warrant removal before it is piped onshore. The company has also stated that no suitable structures for re-injection were found in the vicinity of the potential platform sites.
Carbon dioxide will therefore be removed at the Phillips plant and released through a chimney. Removal of the carbon dioxide from the gas turbine emissions at the Darwin end is technically feasible but not considered an economical option by the company "as no suitable market or disposal options are available".
It appears that Phillips intends to take little more than a few grudging half-measures in response to some very real greenhouse concerns.
What we are looking at here is a massive increase in Australia's greenhouse gas contribution. The Timor Sea contains something like 600 billion cubic metres of natural gas reserves (or 22 trillion cubic feet) as well as 1.05 billion barrels of oil, condensate and LPG.
Extracting even a small proportion of this will make it more difficult to meet Australia's already generous Kyoto Protocol emissions target of 8% above 1990 levels by 2010.
It is true that natural gas has a lower greenhouse gas emission rate than oil and coal due to its lower carbon content (around half that of coal and two-thirds of oil).
The gas industry has successfully communicated this fact to our politicians and gas is recognised as a "transition fuel", an energy source to be used in place of coal and oil while renewable energy systems are established.
However, this fact is irrelevant in cases where the gas is planned to supply new markets, not replace coal and oil. NSW electricity company Pacific Power made a similar point last year when it argued that natural gas was not the answer to meeting Australia's greenhouse commitments.
Gas would be unlikely to replace existing coal-fired plants in an industry characterised by high capital costs and long life assets. Increased gas use would therefore only mean that emissions would increase at a slower rate, rather than achieve outright reductions. Instead we should be trying to substantially decrease emissions from all fossil fuels and encourage the switch to renewables.
[Abridged from Environment NT.]