Friday, 30 September 2011

Accidental combustion of a coal waste heap in Scotland burning since 2009

Researchers at the Universities of Edinburgh and Strathclyde have studied a burning Bing. A 30 m high waste heap at Bogside, North Lanarkshire, Scotland, started to smoulder (flameless combustion) in 2009, approximately 80 years after the closure of the pit.

 The work was presented at the Geological Society of America Annual Meeting in Minneapolis, USA. Presentation reference: Investigation of self-sustained combustion of a coal waste heap in Scotland. And it has featured in the The Scotsmant, Edinburgh website, Strathclyde website, and Vision Systems (on our use of thermal imaging).

Photo composition, clik to enlarge.

Coal mining was widespread in the central belt of Scotland from 1830 until the 1970’s and created a legacy of waste heaps or ‘bings’ that still dot the landscape. High content of coal fines and carbonaceous shales, make bings very prone to self-heating and smoldering combustion.

Chemical, geotechnical and physical parameters of the Bogside Bing have been studied. A combustion front is moving from west to east along the axis of the bing at an approximate rate of 1m/month. Three well-defined zones were identified and mapped using thermal imagery and temperature probes: the undisturbed zone, the preheating plus drying zone and the combustion zone. The subsurface fire results in a detrimental effect to the vegetation and structural integrity of the heap.

Spread of the combustion is accompanied by the development of vents ahead of the front, fissures that run parallel to the direction of heating and smaller landslips along the flanks. Changes to the heap's soil mechanics induced by the smouldering front create a network of fissures, some running deep, that supply the front with enough air to sustain the process.

Analysis of gas from the vents, show elevated CO2, CO, CH4 and SO2, and partially depleted in oxygen. All these are indicative of smouldering activity within the bing. The primary environmental concerns are likely to be from SO2 release and metals leaching from waste material (i.e. Pb, Se, Cr). The stability of the structure may be compromised as smouldering progresses. Bogside Bing continues to release products of combustion and represents an accidental source of fossil fuel burning.
Dr G Rein next to a water vapour vent on top of the Bogside Bing

Full reference of the presentation:
K Torrance, C Switzer, G Rein, R Hadden, C Belcher, R Carvel, Investigation of self-sustained combustion of a coal waste heap in Scotland, Paper No. 282-8, 2011 GSA Annual Meeting, Minneapolis 9–12 Oct. 2011.

Thursday, 29 September 2011

Abysmal technical gaps in Scientific American

I recently sent a Letter to the Editor of Scientific American calling her attention to the abysmal technical gaps in the September issue article "Castles in the Air" by Mark Lamster where the failed prophecy that the attacks of 9/11 were to end the age of the skyscraper is discussed. The letter can be read here and is reproduced below. 

UPDATE Sept 2011: This letter was followed by two more from Dr Bisby and Hilditch
UPDATE Dec 2011: The letter of Dr Bisby has been published in the December 2011 issue of Scientific American

(email sent on Thur 15 Sep 2011 to

Dear Editor of Scientific American,

Your September issue included the piece "Castles in the Air" by Mark Lamster where the failed prophecy that the attacks of 9/11 were to end the age of the skyscraper is discussed.  The article highlights that 2011 will be the single greatest year for the construction of tall buildings in history. That China is leading the skyscraper boom, yet their engineering design is dominated by American firms.

The article discusses design issues on evacuation. But the World Trade Center was designed to evacuate rapidly, and so both towers WTC1 and 2 did below the impact floors on 9/11. WTC7 was also evacuated in time.

The article also discusses design issues on aircraft impact. But the World Trade Center was designed to withstand the impact of a large aircraft, and so both towers WTC1 and 2 did on 9/11. They collapsed because of fire. WTC7 was not hit by an aircraft, but collapsed due to fire as well.

The article goes to imply that the design of tall buildings for protection against terrorist attacks is mostly about aircraft impact and evacuation. It does not discuses fire. But WTC 1, 2 and 7 collapsed because of fire.

So they only issue that is not addressed in the article is the one that brought World Trade Center down, and the one where design advances over the past decade have been most marginal. This is a thin favour to fire engineering and to the safety of tall buildings.

Dr Guillermo Rein
Senior Lecturer in Mechanical Engineering
University of Edinburgh
"so easy it seemed, Once found, which yet unfounded most would have thought, Impossible!" J Milton 

Friday, 23 September 2011

Disasters of divine origin and Engineering

Yesterday, on the train from King's Cross to Waverly, I read in History Today an interesting article about the other Great Fire of Rome (AD 192), second after that with Nero's infamous role in AD 64:

A newly rediscovered ancient letter by the great physician Galen offers a prime example of how fire was seen as a act of god against which humans could do little. These two excerpts serve as example:

"There was no massing of dark clouds, but a preliminary earth tremor was felt. There was no thunderstorm present when either a bolt of lightning struck, or a fire broke out as a result of the tremor. The entire Temple of Peace, the largest and most beautiful of all the buildings in the city, was burnt to the ground"
 "[Sudden weather changed to heavy rain] For this reason it was known that the disaster was indeed of divine origin. For people now believed that the fire was started, and stopped, by the will and power of the gods"

Unfortunately, this tradition permeated with time so deep into human culture that it is still possible to recognize it in many reactions to the fire problem. For example, see the recent reaction of the Governor of Texas who asked for praying to solve the extreme drought that now has led to extreme fire behaviour (Texan megafires). NOTE: I have nothing against praying. I pray some times, but not in profesional activities.

We teach better at engineering schools. The incoming generations of engineers are taught to solve the problems faced by society using the best tools available (eg, analitical skills, design, science, technology and creativity), and not to rely on divine intervention. In particular for fire safety engineers, they are taught to design to protect life and property against the detrimental effects of heat and smoke produced by accidental fires.

Tuesday, 13 September 2011

Accidental Burning of Fossil Fuels

(aka, Accidental Emissions from Fossil Fuels)
Next week, I will present at the Royal Academy of Engineering a brief poster summarizing the work that I have developed with the generous funding of the RAEng/Leverhulme Fellowship. The poster is here (pdf). A related seminar I gave at UC Berkeley in July can be watched in youtube here (and see at the end of this post). The following reproduces the content of the poster:

World energy use and climate change science have led to concerns on sustainability, man-made burning of fossil fuels, and carbon emissions. Most attention is paid to energy efficiency, clean technologies and new resources. But unintentional and non-anthropogenic sources contributing to the problem have been ignored. Smouldering megafires, the largest and the longest-burning fires on Earth (>6,000 years), take place in all continents except Antarctica, and burn fossil fuels accidentally.

Smouldering of carbonaceous media (flameless combustion) is the most persistent fire phenomenon on Earth. Photo by Jens Buurgaard Nielsen (wikipedia).
Very large smouldering fires of carbonaceous natural media (coal seams and peatlands) have burnt since past millennia for long periods of time (months, years, decades). Peat fires burn during the warm/dry season in Indonesia, Canada, Russia, and USA. Hundreds of coal fires continuously burn in USA, China and India. Globally, the problem has grown to a current carbon release equivalent to 10-30% of man-made emissions, and a coal consumption rate five times faster than that of Germany.

Oct 1997: aerosol imaging by NASA TOMS shows the vast smoke haze released by smouldering peat fires in Indonesia. Photo by NASA.
Smouldering phenomena involve the burning of fossil fuels and are carbon-positive. This creates a positive feedback mechanism in the climate system: Moisture deficit and self-heating of carbonaceous media are enhanced under warmer climates and lead to more frequent smouldering fires. Warmer temperatures at high latitudes are already resulting in large smouldering fires in the Arctic (e.g., Alaska 2010).

Positive feedback by smouldering fires in the climate system (topics I study are represented by red arrows)

Stopping these fires is an engineering task at the Earth-scale. RAEng states that “geoengineering provides options in which the Earth’s climate is deliberately manipulated to offset the effects of global warming due to increasing levels of greenhouse gases”. I am contributing to this through the study of the ignition, spread, emissions, and suppression of smouldering phenomena. I aim to develop both fundamental understanding and technological solutions to this problem.

Accidental Burning of Fossil Fuels (RAEng 2011)

Friday, 2 September 2011

Smouldering wildfire burning in New Orleans

The organic soil of Loiusiana marshes near New Orleans is smouldering in at least two separated locations. The fire continues to slowly spread after several days, and the smoke is now affecting town up to 160 km away. The Louisiana National Guard has been called in to help in the suppresion.

Smouldering fires of organic soils like peat burn underground and are the most difficult fire pheonmena on Earth to extingish. The top firefighter in Loiusiana said it better: "Once it’s underground, it’s next to impossible to fight. You can’t bring enough water to wet down that soil".

And note that the same article where the coment was made, report that the smouldering peat fires are still smouldering in the Great Dismal Swamp even after the arrival of hurricane Irene!