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First published September 2007, updated November 2009
Clean coal is a term you're likely to hearing a lot of. 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 create 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 are the challenges of liquefying 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
Other clean coal complications
As mentioned, the processes to make clean coal are energy intensive and this
requires more coal to be mined and burned. In this respect, it's a great thing
for the coal mining industry and shareholders rather than the burden that some
make it out to be; but this also means even more of our planet being stripped
and gouged to mine the stuff and more streams poisoned from mining operations.
It also means increased water usage during power generation and more in the
way of toxic byproducts such as lead and arsenic in fly ash. Additionally, low
emissions coal technologies do nothing to prevent mercury
emissions - and the coal fired power generation industry is already the
largest single contributor to airborne mercury emissions in the world.
Clean coal also doesn't mean the continuation of cheap energy. The added costs
of creating low emissions coal will be worn by the consumer - and in a big way. According
to a recent report from the Global Carbon Capture and Storage Institute the
costs will be as much as 78% on top of normal electricity rates.
Given all this, does it make sense to keep viewing coal a long term
proposition?
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 globally
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. Business and governments like energy sources that
makes individuals dependent. In that respect, coal is a wonderful control tool.
While we won't be able to do without coal in the immediate 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. However, it has been encouraging in recent times to seeing
questions being raised and the coal industry's marketing spin torn down to the
point that some regions are not allowing new coal fired power generation
stations to be constructed.
Still, the consumption of coal overall is increasing. Will "clean
coal" technology be available in time to help prevent catastrophic climate
change from occurring or at least somewhat limiting the effects? The Global
Carbon Capture and Storage Institute report mentioned earlier states that clean
coal technologies will not be commercially viable for another 20 years. Even if
it were viable much sooner, would low emissions coal technologies offset the
various known and unknown effects created by such a huge forecasted increase in
consumption?
Learning 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.
It's also important for us to remember that the greenest watt isn't generated
by solar or wind power - and certainly isn't by "clean coal" or nuclear either.
It's the one that doesn't have to be created; i.e. energy efficiency.
This is where most of us have some power to effect positive change. We can
all play a role in energy efficiency, even while our collective energy future is pretty much
being decided for us by others. Pick up some simple
tips for saving electricity.
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