Tuesday, 8 April 2014

G3E4O Geoengineering and the Engineers of Gaia

Earthrise seen by the Apollo 8 crew, 1968. Credit: NASA
Blog by Nils Roenner and Guillermo Rein, Department of Mechanical Engineering at Imperial College London.


Because of global concerns on climate change, engineers are called to have a leading role in tackling the problem, and a new discipline is being proposed: Geoengineering (G3E4O(IN)2R).
The realisation that man has an impact on Earth has led to the idea of the Anthropocene which signifies the current geological epoch, ‘the recent age of man’. Humans are being viewed as a factor and intricate part of nature. This is in agreement with Dr Lovelock’s Gaia hypothesis, introduced in 1979, a revolutionary view of the Earth not as a simple accumulation of systems but as one self-regulating system encompassing everything, including life.
Sketch of the Earth as system of systems with interdependencies and feedback lines outlined. Adopted from Rial et al. 2004 (10.1023/B:CLIM.0000037493.89489.3f).
In an article we wrote in 2013, The Engineers of Gaia, by using the concept of Gaia and the Anthropocene as starting points, we argue that the control system view of Earth is a vital part of geoengineering. It is not about one mechanism, it is about the self-regulating system as a whole. But if geoengineering was to apply a forcing too large or at the wrong place, such that positive feedback loops overtake, the results could be drastic and unpredictable. Careful and robust control is required when engineering something as vital as the system Earth, and this argument is often invoked to stop geoengineering proposals. Paraphrasing Prof Henry Petroski, for us, the premise would be that geoengineers welcome all the relevant science they can muster, but cannot wait for complete scientific understanding before acting to save life or create a new planet-saving technology. We also maintain that up until the moment when adequate understanding and models of the system are found only reversible and well controlled geoengineering interventions should be applied on a large scale, in order to prevent uncontrollable feedback being set off or reaching tipping points by accident.

The term geoeneering has only recently gained traction in the public debate, and its definition still varies according to the source. We think this can be defined as the large-scale anthropogenic intervention into the system Earth in order to adjust planetary mass and heat transfer processes, such that global catastrophes can be mitigated. Geoengineering opens up a broad range of measures with which global climate change can be tackled. No geoengineering approach should be viewed as a single solution to all of the problems associated with climate change. Most likely a combination of approaches will yield long term success. 

Our article briefly evaluates four promising applications of geoengineering using a set of criteria by which geoengineering proposals can be evaluated in term of feasibility, effectiveness, safety, geointervention, and costs.  These are summarized here:

Carbon Capture and Storage is a good option for rich countries aiming at reducing its CO2 emissions from power plants. Apart from its high cost, this method is very feasible and effective with low levels of geointervention and risks.

Biomass Burial is a good option for countries that have suitable and extended land. It is a lower cost approach and can be scaled up to have a larger impact. Low cost, feasibility, effectiveness and low levels of geointervention speak in favour despite some risks, like fire, which need to be managed.

Iron Fertilisation of oceans is an option for countries with coastal access. The low cost involved and the proven feasibility make this method appealing. But concerns about low effectiveness, high level of geointervention and high risks question the validity of the approach.

Cool Roofing of Building is a good approach for densely populated areas or countries with high annual level of sunshine. The low cost, risks and level of geointervention of this feasible option are attractive but on the other hand, it has a weak effectiveness and cannot control secondary effects.

Illustration of the strengths and weaknesses of the proposals under study.
It can be said for all geoengineering proposals, that due to our incomplete understanding of all feedback and threshold points in the global system of the Earth, the topic has to be approached with great caution. But its potential in helping to solve the great problem of climate change, make the efforts put into research and experiments worthwhile.


Tuesday, 1 April 2014

Welcome Francesco to Imperial Haze Lab

Today was the first day of Francesco Restuccia at Imperial College London as new PhD student in m group. He joins the Imperial Haze Lab in the Department of Mechanical Engineering.

Francesco is from Italy. He became  a Mechanical Engineer from the University of Edinburgh in 2012, and then obtained an MSc degree from California Institute of Technology in 2014. At Caltech, Francesco studied numerically the problem of accidental ignition of liquid fuel tanks. At Edinburgh, he worked on smart distribution networks and renewable energies. He also spend time conducting experiments at CERN Cryogenics.

The preliminary title of his thesis is "Computational Study of Porous Reactive Media" and is funded by a Scholarship from the Department of Mechanical Engineering. The aim of the thesis is to provide a better understanding of fundamental smouldering phenomena to aid in the mitigation and prevention of peat and coal fires. This is frontier research at the interface between combustion science and Earth sciences.

Friday, 7 March 2014

Welcome Izabella to Imperial Haze Lab

Izabella, new PhD student
Last week was the first day of Izabella Vermesi at Imperial College London as my new PhD student. She joins the Imperial Haze Lab in the Department of Mechanical Engineering.

Izabella is a Civil Engineer from the Technical University of Cluj-Napoca, Rumania, since 2011. She then obtained an MSc degree from the Technical University of Denmark (DTU) in 2013. At DTU, Izabella worked on multiscale modeling of tunnel fires and assisted in the teaching of Building Fire Safety course.

The preliminary title of her thesis is "Computational Pyrolysis and Ignition under Transient Radiation", and is funded by FM Global USA.


She is to conduct a computational study of pyrolysis on a range of solid fuels when subjected to a radiant source whose power is transient, a long pulse, as opposed to the constant power typical assumed in ignition theory. This scenario, rarely studied in fire science, is related to flame spread, secondary ignition, travelling fires in compartments, and wildfires. The framework of study will be such that work goes from simple to more complex models and fuels and that the computational complexity is added only when actual results justify it.

Monday, 24 February 2014

The pyrolysis history of Perspex

We sent the image below, The pyrolysis history of Perspex, to the Fire Science Image competition at the 11th International Symposium on Fire Safety Science.


Photo by N. Roenner and G. Rein (Imperial College London) and R. Hadden (University of Edinburgh)
This composite shows the pyrolysis and burning of a sample (10 cm x 10 cm x 1.5 cm) of transparent Poly-methyl methacrylate (PMMA, Perspex) inside a Fire Propagation Apparatus (FPA).
The central image shows the diffusion flame established on top of the sample which is surrounded by the infrared lamps emitting a transient heat flux peaking at 30 kW after 300 s. The series to the right show the evolution of the PMMA sample during the fire. This was created by extracting samples at different times from identical experimental repeats.
PMMA is typically chosen for fire experiments because it is the polymer for which the flammability behaviour is best known. Despite this, the intricacy involved is patent. The melting, bubbling and pyrolysis mechanisms all contribute to create a dynamic image of the sample's history which illustrate the high complexity and beauty of fire phenomena. 
Licensed under a Creative Commons CC BY-NC-ND 3.0.

Computational Smouldering Combustion

I am delighted to announce that our work won the award for the Best Student Poster at the 11th International Symposium on Fire Safety Science, with the research on peat fires led by my PhD student X. Huang.

Fire Watch Constellation

I am delighted to announce that we won the award for the Best Fire Science Image at the 11th International Symposium on Fire Safety Science, with our entry titled Fire Watch Constellation (reproduced below).


 Photo by E. Rackauskaite, X. Huang and G. Rein, Imperial College London. 
This composite shows a constellation of combined visual and infrared imaging of a smouldering combustion front spreading radially over a thin sample of dry peat. The central watch is created by a series of twelve wedges. Each edge is extracted from a photo taken every 5 min from an elevated view looking down into the sample during the one-hour lab experiment. The circular peat sample (D=22 cm) was ignited on the centre by an electrical heater. The average radial spread rate was 10 cm/h and the peak temperature 600˚C. The top figures show the virgin peat (left) and the final residue (right). The bottom figures show the wedges in visual (left) and infrared (right) imaging. Smouldering combustion is the driving phenomenon of wildfires in peatlands, like those causing haze episodes in Southeast Asia and Northeast Europe. These are the largest fires on Earth and an extensive source of greenhouse gases, but poorly studied. Our experiments help to understand this emerging research topic in climate-change mitigation by characterizing the dynamics of ignition, spread and extinction, and also measure the yield of carbon emissions. 

Licensed under a Creative Commons CC BY-NC-ND 3.0.

Friday, 31 January 2014

Wind Turbines on Fire

In a few weeks, we are presenting in Christchurch, New Zealand, a brief paper [1] on the impact of fire in wind turbines.


The wind energy is one of today’s leading industries in the renewable energy sector, providing an affordable and sustainable energy solution. However, the wind industry faces a number of challenges, one of which is fire and that can cast a shadow on its green credentials.


We have found that fire is the second leading cause of catastrophic accidents in wind turbines (after blade failure) and accounts for 10 to 30% of the reported turbine accidents of any year since 1980’s. 

Update: The video of the talk, presented by co-authored Dr Carvel, can be watched here:

  
The total number of turbine accidents recorded in the period 1995-2012 was 1328. The most common cause of accidents in wind turbines is blade failure with 251 registered instances (19%). It is closely followed by fire with a total of 200 incidents recorded, which is 15% of all the reported accidents. This represents on average 11.7 fires per year (~one fire accident per month). This figure of turbine fires per year may not seem a great number compared to the fact that there were ~200,000 wind turbines worldwide in 2011. However, due to the excessive financial loss that a fire can cause, especially in a small wind farm, it is an issue that owners and insurers are keen to address. But we argue that this is only the publicly available tip of the iceberg representing about 10% of the total number of fires. A rough average estimate of the real figure is 117 fire accidents per year (ten times the figures reported publicly).

Instances of reports about fires in wind farms are increasing, yet the true extent of the impact of fires on the energy industry on a global scale is impossible to assess at the moment. Sources of information are incomplete, biased, or contain non-publically available data. The poor statistical records of wind turbine fires are a main cause of concern and hinder any research effort in this field. This paper aims to summarise the current state of knowledge in this area by presenting a review of the few sources which are available, in order to quantify and understand the fire problem in wind energy.


 

The three elements of the fire triangle, fuel (oil and polymers), oxygen (wind) and ignition (electric, mechanical and lighting) are represent and confined to the small and closed compartment of the turbine nacelle. Moreover, once ignition occurs in a turbine, the chances of externally fighting the fire are very slim due to the height of the nacelle and the often remote location of the wind farm.

The main causes of fire ignition in wind turbines are (in decreasing order of importance): lighting strike, electrical malfunction, mechanical malfunction, and maintenance. Due to the many flammable materials used in a wind turbine (eg. fiberglass reinforced polymers, foam insulation, cables) and the large oil storage used for lubrication of mechanical components, the fuel load in a turbine nacelle is commonly very large. Our paper [1] finishes with an overview of the passive and active protection options and the economics (costs, revenue and insurance) of wind turbines to put in context the value of a loss turbine compared to the cost and options of fire protection.

We hope that this paper will encourage the scientific community to pursue a proper understanding of the problem and its scale, allowing the development of the most appropriate fire protection engineering solutions.

[1] Overview of problems and solutions in fire protection engineering of windturbines, by S Uadiale, E Urban, R Carvel, D Lange and G Rein, 11th Symposium of the International Association for Fire Safety Science, New Zealand, Feb 2014.

Wednesday, 13 November 2013

Reply to 'FDS and the Challenge of Big Data'

While on the Tube's District Line from the office, I read the most recent blog article written by the developers of FDS. It is titled "FDS and the Challenge of Big Data".

For those of you who do not know it, FDS stands for Fire Dynamics Simulator, and it is the state of the art in fire modelling. It is a fine, advanced and excellent code of Computational Fluid Dynamics  (CFD), especially developed to simulate the behavior of flames and smoke in buildings and large open spaces. Its source code, in FORTRAN, is open and freely avaible to all. The work of development and maintenance is mostly carried by staff at NIST (VTT at Finland also plays a major role). NIST stand for National Institute of Standards and Technology, and it is a USA government agency which mission is to "promote U.S. innovation and industrial competitiveness by advancing science and technology".

Their blog article is mostly a complain. It is formulated around the apparent lack of good collaborations from academia around the world to support their difficult task of developing and maintaining FDS. They think the reason for this is down to the "publish or perish" stereotype, and use a blog article from a Cosmology researcher who expresses similar frustrations with academia.

I have four points to make regarding the FDS blog article:

0) Thank you. I felt bad that you think your contributions go thankless.This is unfair, because FDS is the state of the art, it is provided without cost and openly for all around the world to use. It has tremendously helped the Fire Safety Engineering community to develop further.

1) Test You Hypotheses. You should make sure you know and understand your potential collaborators, specially before you criticize them in the open. For example, the "primary currency of the academic reward structure" in engineering departments is funding and industrial relevance, not published papers. Be aware of using a Cosmology case to run your arguments against academic users of FDS who are mostly from engineering departments. Also, note that there are more jobs for research in Cosmology than for research in Fire Safety, so I find your final kick "there are only so many jobs available in cosmology" ill suited to the critique.

2) More Carrots. Find some of the true rewards that match the motivation of your potential collaborators. For example, I suggest you create the yearly NIST Award for Outstanding Contributions to FDS. This would create recognition and esteem which are highly valued in academic CVs, more than a bunch of papers, and in some cases it is the key for obtaining a position or promoting.

3) Elephant in the Room. Lets we forget that academia has played an essential role in the success of FDS, maybe also a thankless task. I have said in the past [*] that I believe the industrial success of FDS lies on three pillars; it is free, it is excellent for research, and there are hundreds of papers showing good modelling results (just google it). The third point is because no other fire code has ever received so much publication attention. The difference with other fire codes being of two orders of magnitude. This very high number of journal papers and the multiple open discussions taking place in any fire conference every single year have promoted somehow the image that FDS is 'the validated', 'the accepted' or 'the standard' model for a wide range of industrial designs. And industry uses FDS extensively, in thousands of fire protection projects worldwide in any one year, with the approval of the corresponding authorities. Hence, FDS contributes to fulfill the mission of NIST, and promotes innovation and industrial competitiveness by advancing science and technology, in the USA and also in the rest of the world. This industrial projection is thanks to all the research users of FDS who decided to publish and go public at some point. Thanks go to them too.

[*] Advantages and Disadvantages of Fire Modelling, Irish Chief Fire Officers Association Annual Conference, Dundalk, May 2012.

Wednesday, 30 October 2013

Fin's and Candle's Creative Contests: towards the motivation of engineering students

We engineers are in general not the best communicators nor the best at appreciating arts. These are not really topics of interest during university studies in Engineering Schools around the world. This was the theme of a latest editorial in Ingenia, the magazine of the Royal Academy of Engineering, where Dr Steedmand said "Engineers are rarely taught about public engagement and as a result are often criticised for lacking communication skills. A few engineers, through their work, do spend time with the public, but this is not enough. We need much more public engagement if we are to raise the awareness and understanding of engineering and its role in society".

I wanted to build on this in the two courses I teach at Imperial College, ME2 Heat Transfer and ME4 Combustion. I also wanted to boost somehow students' motivation. So I organized Creative Contests at the beginning of the new academic year. The instructions to participate were the following:



"I have three extra copies of the textbook to give away. If interested, send me a poem, comic, drawing, painting, song, video, or anything creative that explains why you are taking this course. Art, wit and humour are allowed". 

And I gave them one week to submit their pieces. I received several submissions and found three winners for each course. Congratulations to the winners, hope you use extensively your new gifted textbooks.

Submissions to the 2013 Fin's Creative Contest in ME2 Heat Transfer:
(first three are the winners. Each received a hardcopy of Incropera's Foundations of Heat Transfer)

by Keon - Heat transfer is not a lie - Click for song . Click for lyrics.
by Hugh  - Amazing Heat Transfer Acrostic

 



By Eifion - Heat Transfer Limericks



By Kathryn- why study heat transfer?
By Robert - Five reasons why I am studying heat
transfer?







Submissions to the 2013 Candle's Creative Contest in ME4 Combustion:
(First three submissions are the winners. Each received a hard copy of McAllister's Fundamentals of Combustion Processes).

By Christian - Combustion, it blows you away!
By Wayne - Little deyas

By Maria - Flames estatue

by William - Combustion
 
Miles sent this photo by McLaren of an P1 exhaust flame

Boris - Hot air balloon in Morocco

Guillaume - First bone fire in human history - synchronistic style

Walaa selected the poem Fire by 'livin the night life'