Wednesday, January 7, 2009

The Hidden Dangers of Carbon Dioxide Sequestration

In an effort to stave-off global warming due to the excessive carbon dioxide by-product of coal-fired power plants, is carbon dioxide capture and sequestration really a sensible environmental solution?

By: Ringo Bones

The relative abundance and cheapness of coal means we’ll be using this fossil fuel for a few centuries more given our current use for electric power generation. But they do have one serious drawback: excessive carbon dioxide output. Given that carbon dioxide is the primary greenhouse gas generated by our industrial processes – namely electricity production. Science has recently devised a scheme to allow us to generate cheap electricity from burning coal while “supposedly” avoiding the harmful consequences of the global warming effects of greenhouse gases such as carbon dioxide via carbon dioxide capture and sequestration.

The concept is by no means an ideal solution even though most coal-fired power plants built after the year 2000 are already doing it, but is carbon dioxide capture and sequestration – usually shortened in the mainstream press as “carbon capture and sequestration”. Especially when injecting the gas underground or deep into the ocean floor for long-term storage (hopefully forever) really good for our environment?
Though global warming is primarily caused by excessive carbon dioxide being dumped into our atmosphere as a by-product of our current industrial activity. The gas can only do harm when it is in our atmosphere. Devise a method to capture it from the flue gases of the coal-fired power plant’s chimney and store it somewhere away from our atmosphere is one brilliant solution to minimize our contribution to global warming. Power loss aside, is carbon dioxide capture and sequestration absolutely safe for our environment?

A reminder of what can possibly go wrong in carbon capture and sequestration schemes is the Lake Nyos tragedy that occurred in Cameroon back in August 21, 1986. A Limnic eruption of the crater-lake of Lake Nyos resulted in the sudden release of a large cloud of carbon dioxide gas. The incident caused the suffocation of 1,700 people inhabiting on several nearby villages’ downhill from the lake and also resulted in the death of 3,500 head of cattle and other livestock. Though not completely unprecedented, it was the first known large-scale asphyxiation caused by a natural event.

Even though the capture of the carbon dioxide gas by-product from the coal-fired power plant’s flue gases via amine-based separation solvent is a proven technology. Regenerating the solvent for the next cycle after extracting the carbon dioxide gas and its transport and storage into a supposedly safe long-term storage area requires energy. The solvent separation and regeneration part usually from the coal-fired power plant itself, so it is an energy intensive process resulting in the generation of extra amounts of carbon dioxide gas.

Then there’s the problem of where to store the sequestered carbon dioxide. The site selected for long-term storage should be geologically stable or there will be a repeat of the Lake Nyos incident to those people living downwind and downhill from the storage facility – given that carbon dioxide is 1.5 times denser than air. Plus detectors that trigger alarm bells when carbon dioxide gas levels in the atmosphere rises to lethal levels are not exactly cheap – nor are they commonly available.
Given our future energy demands are likely to increase, using carbon capture and sequestration to offset the carbon dioxide being thrown into our atmosphere by the new coal-fired power plants is an exercise in futility. Geologically stable sites for long-term carbon dioxide storage are not exactly dime a dozen and the increasing output of carbon dioxide by coal-fired power plants are only going to increase in the future if the coal lobbyists get their way.

For our long-term future, carbon dioxide capture and sequestration from coal-fired power plants should only be seen as a stop gap measure. Before we can develop energy sources and electricity generation schemes that doesn’t generate excessive amounts of greenhouse gases like carbon dioxide that will surely exacerbate the effects of global warming.