Safety Issues
There are a number of safety issues relating to an envisioned new generation of coal fired power stations with CCS. Coal fired power generation is already intrinsically unsafe. Mine and coal transport accidents outnumber deaths and injuries in any competing technology, ash releases remain substantial (despite the advent of bag houses and precipitators). Acids, mercury and other compounds released from flue gasses cause substantial environmental and health damage. The US National Council on Radiation Protection and Measurements (NCRP) estimates the average radioactivity of coal is 17,100 millicuries/4,000,000 short tons resulting in a radiation dose to the population from a 1000 MW coal fired plant of 490 person-rem/year; a hundred times more than from a comparable nuclear plant.
The use of ammonia or amides to flush CO2 from flue gasses (if used) poses additional safety and environmental concerns. Ammonia is a mildly toxic gas (and liquid) and can cause lung damage and death in humans exposed to concentrations above 400 parts per million. It is highly soluble in water and extremely toxic to aquatic animals (and hence environmentally damaging) if accidentally released; or if traces remain in the CO2 stream. Ammonia and amide plants also consume relatively high levels of electricity. Alternatives such as membrane technology may solve some of these issues in future.
Adding very large volume movements of CO2 to this list may be the final ‘show stopper’ for environmental scale CCS. CO2 is a relatively non-toxic gas, compared to ammonia, but at around 10% by volume in air it is lethal to humans (anything over 4% is considered very dangerous[8], it is normally under 0.04% in air). The last large natural release of CO2 was at Lake Nyos in Cameroon in1986. It killed nearly 2,000 people and all the animals, birds and insects too. It is heavier than air and fills depressions. Depending on concentrations, internal combustion engines may stop, compromising any rescue attempts. Moving large volumes about the countryside poses significant risks to people and animals.
If CCS is fully implemented for the power industry alone, in just 20 years 1.3 billion tonnes of CO2 will underlie many hundreds of thousands of square kilometres of NSW, in an as yet unabsorbed state.
Theory has it that in about 10,000 years it will have been fully integrated with the rocks into which it is pumped. It might then be safe, unless there is ever an igneous intrusion or meteor impact in the area. But if in the meantime just some of the sequestered CO2 escaped somehow, due to a borehole malfunction, miscalculation of capacity or an earthquake, Chernobyl (57 direct deaths and 4,000 potentially injured by future cancers) could look like a picnic; and a fraction of a square kilometre of nuclear waste storage, a trivial problem for posterity.