Tuesday, November 07, 2006

What is Geosequestration? (Draft)

"Clean" coal a con job to cover up dangerous greenhouse emissions

Coal, dubbed the "dirtiest of fossil fuels," emits 80 per cent more carbon per unit of energy than gas and 29 per cent more than oil. Technologies to deal with the carbon dioxide coming from coal are unproven and, according to international scientists, unecenomical and not environmentally sustainable.

Greens MP and mining spokesperson Lee Rhiannon urges government to reject the notion of ‘clean’ coal, and ensure that the State Plan includes a transition from coal-based energy to renewables, energy efficiency and gas...

"There is no such thing as ‘clean’ coal. This term was coined by the coal industry's PR machine to divert public understanding from the fact that coal is the worst of the fossil fuels causing climate change. This spin will not get us out of climate change. Coal is the dirtiest of fossil fuels, emitting 80 per cent more carbon per unit of energy than gas and 29 per cent more than oil."

She urges the rapid development of renewable industries, particularly in traditional coal mining areas. "It is vital for the future" she said, the government should not allow future energy planning to be captured by the coal industry on the basis that coal can be ‘clean’.

Technologies such as Carbon Capture and Storage (CCS) to deal with the carbon dioxide coming from coal are unproven and, according to international scientists, at least 50 years away from being economically and environmentally viable at a widespread level.

CCS could triple the price of coal for electricity, making it much more expensive than renewable energy. Storage sites would have to be maintained and monitored for 100,000 years, plus unquantified liability issues of leaking C02.

She said "Coal companies should not be allowed to continue to make mega profits at the expense of jobs and the environment. For years coal companies have received direct and indirect subsidises from successive Labor and Coalition governments. Now is the time to put that support behind a plan for a transition program to clean efficient energy".

Carbon Leakage and Geosequestration

Scientists conclude that human activities are contributing to climate change by adding large amounts of greenhouse pollution to the atmosphere. Use of coal, oil and gas (fossil fuels) are the main source of this pollution. Every time we drive a car, use electricity from coal-fired power plants, or heat our homes with oil or natural gas, we release carbon dioxide and greenhouse pollutants into the air.

Atmospheric levels of the main greenhouse pollutants are currently higher than at any point in the last 420,000 and possibly 20 million years. [SOURCE]

Within this context governments in Australia and overseas have been discussing “geosequestration” – the controversial plan to capture and dispose of greenhouse pollution underground – as a technology to reduce greenhouse gas emissions.

Of paramount importance for geosequestration is the issue of whether greenhouse pollution disposed of underground is permanently stored. Clearly, if sequestered greenhouse pollution in the form of carbon dioxide (CO2) leaks back into the atmosphere, then geosequestration will have failed as a technology to reduce greenhouse pollution. Depending on the quantity of CO2 stored, the rate of leakage and the level of stabilisation of CO2 in the atmosphere, the implications of leakage for the global climate system could be catastrophic. In addition, if the leakage is rapid, it can asphyxiate humans and animal life in the vicinity.

The greater the reliance on geosequestration to prevent dangerous climate change, the greater the impact will be if leakage does occur.

Leakage is Likely to Occur
Studies show that some leakage is likely, because geological formations are not completely stable, or they could be disturbed by, for example, earthquakes, or because the injection points could become unstable over time.

To be effective, any underground storage of CO2 must not be able to leak out at a rate that would exceed levels that would contribute to dangerous levels of climate change. But how small is small enough? That depends on the amount that is stored and to a lesser extent, the level at which we seek to stablise greenhouse gases in the atmosphere. The latter is generally defined as a certain level of carbon dioxide in the atmosphere measured in parts per million volume (ppm). Environment groups consider that atmospheric levels of carbon dioxide should be stablised at 450ppm to avoid dangerous levels of climate change.

What Level of Leakage is Acceptable?
The safest rate of leakage is zero and that should be the goal for every geosequestration site. Researchers vary greatly in their assumptions and conclusions regarding a likely level of leakage. It seems that some leakage is likely and there will be a need to set standards and regulations for acceptable rates of leakage and the monitoring and verification regimes to ensure compliance.

Leakage must not compromise the ability of future generations to avoid dangerous climate change.

By the end of the 22nd century the entire ‘carbon budget’ of future generations
would be consumed by leakage from geosequestration sites. This would mean that future generations could not avoid dangerous climate change, even if they reduced their own greenhouse gas emissions to zero.


The assumption of exclusive reliance on storage may be an extreme one, however the example illustrates that emphasis on energy efficiency and increased reliance on renewable energy must be priority areas for greenhouse gas mitigation. The higher the expected leakage rate and the larger the uncertainty, the less attractive geosequestration is compared to other mitigation alternatives such as shifting to renewable energy sources, and improved efficiency in production and consumption of energy.

SOURCE: Climate Action Network Australia

LINKS: Greenpeace Article


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