Clean coal is a term you're likely to hear a lot more of in the near future. To some it is what it says; a real solution to environmental issues related to coal use, to others it's an oxymoron; i.e. coal can never be clean.
Clean coal is created through a variety of processes including:
Washing
Removes some impurities from the fossil fuel, which helps it to burn more efficiently.
Gasification
Instead of the coal being burned, it reacts with oxygen and steam to create "syngas" that is primarily composed of hydrogen which can then be burned in a gas turbine.
Flue scrubbing
A solution of limestone and water is sprayed in the flue which reacts with sulphur dioxide (SO2) to creat gypsum; which can then be used for construction purposes.
low NOx burners
These minimize the nitrogen oxide (NOx) gas being created by restricting the amount of oxygen in the chamber where coal is burned
Flue filters and precipitators
An electrical field charges particles that are then deposited on collection plates or fabric filters can also be used to remove particles.
What about the carbon dioxide emissions?
For the clean coal industry, one of the big challenges is dealing with carbon dioxide emissions and most favor carbon sequestration.
The sequestration aspect of carbon dioxide, a major contributor to global warming, is still very much untested on a large scale and the long term ramifications unknown. Various sequestration methods are being considered and trialed. These include ocean sequestration whereby carbon dioxide is injected deep into the sea. This raises concerns with some environmentalists, particularly given that our oceans are already saturated in CO2 to a point some are becoming acidic.
Another method is geological sequestration where the carbon dioxide is pumped into underground chambers such as old oil reservoirs and aquifers. Will it stay where it's pumped? The Lake Nyos disaster that killed around 1,700 people and 3,500 livestock suggests perhaps not.
Then there's the challenges of liquifying and transporting the carbon dioxide to the sequestration sites. More energy, more complications.
It's great to see serious moves to make coal "cleaner" - but it will never be clean in my opinion and shouldn't be touted as such. It gives people a somewhat false impression and may encourage excessive consumption.
Aside from the impacts from the actual use of the fossil fuel, there's also the terrible environmental damage wrought by coal mining - the release of methane during the mining process, interference with groundwater, dust thrown into the atmosphere and the destruction of what was once fertile land. No matter how clean coal is made, those issues are unlikely to change.
Mildred, PA coal sludge (Photo credit: Jared Dowhower)
Surface coal mining in Wyoming
The issue of coal is huge; it's as important as oil; perhaps even more so. Around 39% of electricity is generated from coal fired power stations and approximately 70% of global steel production depends on coal. It's one of the world's most abundant fossil fuel resources and relatively easy to mine. We like things easy. We like energy sources that makes individuals dependent.
While we won't be able to do without coal for the forseeable future, a major concern is there's no slowdown in sight for coal consumption either. In fact, The International Energy Agency predicted a 43% increase in its use from 2000 to 2020. Will "clean coal" technology offset the effects created by such a huge increase in consumption?
Reading about the various challenges of clean coal technologies continually brings me back to better use of the great thermonuclear reactor in the sky - the sun; solar power, and the byproduct of the sun's energy, wind power. Why must we always dig, rip, tear and burn?
