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Keeping you informed about TecEco sustainability projects. Issue 68, 17 June 2007
Every now and again I think of my Uncle Tim (his name is really Paul but we all called him Tim) who died a couple of years ago. Tim had a very fertile and inventive mind. Considering the plight our farmers are in we have been remiss not to include details of Uncle Tim's drought busting water trough. So if you know a farmer or there is one in the family - please pass this on with the compliments of John Harrison and TecEco.
One or more long (longer than in the graphic) metal pipes with a nice smooth surface are placed into a water trough (Tim used to use old baths which he got for free and bent or leaky irrigation pipes) so they are vertical or nearly so they are held in place by brackets and some guy wires.
The dew point of air is the temperature to which it must be cooled, at constant barometric pressure, for water vapour to condense into water, or dew.
When the dew point temperature falls below freezing it is called the frost point as the water vapour no longer forms dew but but frost or hoarfrost by deposition. The graph below shows the maximum percentage of water vapour that can exist in air at sea level across a range of temperatures. Note that with higher temperatures the equilibrium partial pressure of water vapour increases thus more water evaporates. The behaviour of water vapour does not depend on the presence of air. The formation of dew would occur at the dew point even if the only gas present were water vapour.
At a given barometric pressure, independent of temperature, the dew point indicates the mole fraction of water vapour in the air, or, put differently, determines the specific humidity of the air. If the barometric pressure rises without changing this mole fraction, the dew point will rise accordingly. Reducing the mole fraction will bring the dew point back down to its initial value. In the same way, increasing the mole fraction after a pressure drop brings the dew point back up to its initial level.
Alternatively, at a given temperature but independent of barometric pressure, the dew point indicates the absolute humidity of the air. If the temperature rises without changing the absolute humidity, the dew point will rise accordingly. Reducing the absolute humidity will bring the dew point back down to its initial value. In the same way, increasing the absolute humidity after a temperature drop brings the dew point back up to its initial level. If the dew point and temperature in two places are the same, then the mass of water vapour per cubic meter of air will also be the same in those two places.
The dew point is associated with relative humidity. A high relative humidity indicates that the dew point is closer to the current air temperature. If the relative humidity is 100%, the dew point is equal to the current temperature. Given a constant dew point, an increase in temperature will lead to a decrease in relative humidity. It is for this reason that equatorial climates can have low relative humidity, yet still feel humid.
Water vapour from air naturally condenses on cold surfaces such as uncle Tim's long metal pipe into dew. Water vapour will only condense onto another surface when that surface is cooler than the temperature of the water vapour, or when the water vapour equilibrium in air, i. e. saturation humidity, has been exceeded. When water vapour condenses onto a surface, a net warming occurs on that surface. In the case of Tim's water collector trough this warming is reduced and the pipe stay cold because metal is a good conductor of heat and any heat produced is conducted away into the body of the water in which the pipe is immersed at the bottom end.
In the case of my Uncle's invention, the longer the pipe the better. When the air gets colder at night it sinks, so the air closer to the ground and in hollows is colder than air above it. A long metal pipe is colder than the warmer air above because any heat it absorbs is quickly conducted away to the cooler bottom part of the pipe. In this manner more dew forms on the colder than surrounding air surfaces higher up.
It only takes one dew drop to coalesce with the next and a chain reaction is started whereby the mass of the rapidly growing drop will cause it to go down the pipe collecting more drops in its path. Get enough drops doing this (with more pipes if necessary) and it is possible, depending of course on the night time dew, to keep the water trough full.
Not always. In some areas dew just does not form much for various reasons. Unfortunately we are also very busy so we will not be able to help you further in your efforts to keep your stock troughs or water tanks full!
Carbon dioxide concentration in the atmosphere is likely to reach the first climate change danger level by 2028 and if emissions growth continues at the present rate, the point of no return will be reached with dire consequences by 2046, according to new scientific research published at the National Academy of Sciences.
A paper published late May in the Proceedings of the National Academy of Sciences details a finding that carbon emissions, the principal driver of climate change, are growing a far greater rate than expected over recent years. According to the paper, the average growth rate of carbon dioxide emissions increased from 1.1% a year in the 1990s to a 3% increase per year in the 2000s.
Lead author of the paper, Dr Mike Raupach from CSIRO Marine and Atmospheric Research and the Global Carbon Project, says that nearly eight billion tonnes of carbon were emitted globally into the atmosphere as carbon dioxide in 2005, compared with just six billion tonnes in 1995. He says, that while deforestation has also been an important factor, contributing about 1.5 billion tonnes of carbon emissions into the atmosphere, burning fossil fuels is the main culprit.
What's more, if emissions continue at the present rate, the world will hit its first danger point of carbon dioxide atmospheric concentration of 450 parts per million by 2028 to 2030. At present, the world is at 380ppm, while the pre-industrial age levels were at 280ppm.
"The consensus is that if we manage to bring CO2 to equilibrium at 450ppm, we would be looking at a temperature rise of 1 to 1.5 degrees above pre- industrial levels, some changes to rainfall patterns, some melting of the Arctic, significant acidification of the oceans through CO2 rise and so forth. But these are issues which would not cause widespread devastation," Dr Raupach told iTWire.
"If we reach 550ppm, we're getting into 2 to 2.5 degree temperature rise and the amount of climate damage that we would be looking at will in some cases would probably involve crossing thresholds that we can't recover from. If we keep on the present growth projectory then we get there by about
According to Dr Raupach, reasons behind the increasing inefficiency lay with both developing and developed countries.
"A major driver of the accelerating growth rate in emissions is that, globally, we're burning more carbon per dollar of wealth created," Dr Raupach says. "In the last few years, the global usage of fossil fuels has actually become less efficient. This adds to pressures from increasing population and wealth."
"As countries undergo industrial development, they move through a period of intensive, and often inefficient, use of fossil fuel. Efficiencies improve along this development trajectory, but eventually tend to level off. Industrialised countries such as Australia and the US are at the leveling-off stage, while developing countries such as China are at the intensive-development stage. Both factors are decreasing the global efficiency of fossil fuel use," says Dr Raupach.
According to Dr Raupach's figures, China with nearly five times the population of the US is now emitting almost as much carbon per year as the US but is a much lower emitter per person.
He says that China's emissions per person are still below the global average. "On average, each person in Australia and the US now emits more than five tonnes of carbon per year, while in China the figure is only one tonne per year. Since the start of the industrial revolution, the US and Europe account for more than 50% of the total, accumulated global emissions over two centuries, while China accounts for less than eight per cent. The 50 least developed countries have together contributed less than 0.5 per cent of global cumulative emissions over 200 years."
Dr Raupach says that Australia, with 0.32 per cent of the global population, contributes 1.43 per cent of the world's carbon emissions.
He says recent efforts globally to reduce emissions have had little impact on emissions growth. "Recent emissions seem to be near the high end of the fossil fuel use scenarios used by the Intergovernmental Panel on Climate Change (IPCC). Our results add to previous findings that carbon dioxide concentrations, global temperatures and sea level rise are all near the high end of IPCC projections."
Dr Raupach led an international team of carbon-cycle experts, emissions experts and economists, brought together by the Global Carbon Project, to quantify global carbon emissions and their drivers.
"In addition to reinforcing the urgency of the need to reduce emissions, an important outcome of this work is to show that carbon emissions have history. We have to take both present and past emissions trajectories into account in negotiating global emissions reductions. To be effective, emissions reductions have to be both workable and equitable," he says.
Dr Raupach says there are four technical ways that the world can employ to slow the carbon emissions rate: conservation of energy; non-fossil fuel energy; more efficient of fossil fuels, including clean coal; and avoiding deforestation.
Thanks to Greenleaps and BZE www.beyondzeroemissions.org for sourcing this article.
Particle packing is taught as part of basic materials processing courses at engineering schools but is poorly understood in the concrete industry. An understanding of the basics is important when making concrete and TecEco are working on software that will incorporate the science of particle packing as the lack of understanding is proving a problem for the implementation of our cements.
To understand particle packing start with a very basic packing of uniform sized round particles. Perfect spheres of the same size result in the least-dense packing, with approximately one-third of the volume being voids. Any deviation from perfect spheres or uniform size, and particles intrude into the nearby void space, reducing the void volume.
The size of spheres does not matter A roomful of basketballs or ping-pong balls still gives roughly one-third free volume. Particle packing for perfect spheres all of the same size is easily calculated.
Very few people seem to be able to understand the importance of particle packing for making a good Eco-Cement.
Too often the focus is on ease of use rather than end result, For example in the most used 1:1:6 or 1:2:9 (pc, lime, aggregate) type mortar mixes, the aggregates used are generally much too fine and well graded for the lime to serve as much other than a plasticiser. Given the increasing popularity of these mortars and the possibility of carbon credits for sequestration it is essential that the industry get its act together.
Using standard concrete spec sands in Eco-Cement Concretes will not result in good carbonation
Global warming is a major issue and the huge potential in the built environment for sequestering carbon cannot be ignored. There is therefore an urgent need to reconsider the merits of properly carbonating concretes (including mortars) in this context. Cementitious materials like Eco-Cements that go the full thermodynamic cycle gain strength by carbonation and have tremendous potential because the CO2 chemically released during manufacture can be recaptured resulting in significant overall sequestration. With capture during manufacture using the TecEco Tec-Kiln re-carbonation results in sequestration which given the size of the built environment is potentially on a massive scale.
Eco-Cements have the advantage over lime mortars of forming hydrated carbonates which go further as most of their volume is CO2 or water. Being fibrous or acicular they also add microstrucutral strength
Eco-Cements require a highly interconnected void space to allow air to pass through and are are thus best made with relatively mono-graded materials. When choosing aggregates for Eco-Cement Concretes it is therefore best to try to keep the particle sizes as close to the same as possible, so there is a maximum amount of free space available for air flow.
The relatively permeable matrix of Permecocrete is what allows water to pass through so it can act as a permeable or pervious pavement. If water can pass through so can air allowing the Eco-Cements that is holding the stone together.to set by carbonation relatively rapidly.
Most other concretes including Tec-Cement concrete require dense packing in order to minimise void space.
If the voids left by successively smaller particles are filled the density of packing can be substantially increased. Density can also be increased by using non round particles.
The main goal of TecEco technology is to improve the sustainability of cementitious binders.
Three are several ways in which particle packing interacts with this goal. Eco-Cements only absorb CO2 if they are sufficiently permeable and this requires an understanding of relatively mono-graded aggregates lacking fines. On the other hand the denser Tec-Cements can be made the less binder required.
Optimising the particle packing of Tec-Cement concrete not only results in improved strength but also possibly reduces the porosity, the segregation potential and increases durability. Another way of increasing the sustainability of concrete is to use waste as aggregates and the aim of TecEco is to incorporate as much waste as possible in concretes used in the built environment. Unfortunately few wastes are suitable for use either because of their chemical nature or because of their size distribution. The problem of internal reaction is solved by the chemistry of the new TecEco calcium-magnesium blends whilst more optimal particle packing will by modification allow wastes to be used as aggregates. By the addition of corrective aggregates the overall size distribution can be improved and thus performance. At TecEco we believe the improvement in sustainability that can be achieved with more optimal particle packing to be significant..
The Romans had two distinct types of concrete mortar and they understood the particle packing requirements of both. One was made with simple lime and river sand, mixed at a ratio of three parts sand to one part lime. The other type used pozzolan instead of river sand and was mixed at a ratio of two parts pozzolan to one part lime. The former required coarse gritty aggregates described below whilst the latter was even tamped into position to increase density.
The oldest record we have come across addressing the issue of sands for carbonating cements is book II, chapter IV of the Ten Books of Architecture by Vitruvius Pollio (Vitruvius). According to Vitruvius “the best (sand for carbonating mortars) will be found to be that which crackles when rubbed in the hand, while that which has much dirt in it will not be sharp enough. Again: throw some sand upon a white garment and then shake it out; if the garment is not soiled and no dirt adheres to it, the sand is suitable” Vitruvious was talking about gritty sand with no fines.
There is no doubt that sand grading is one of the most important parameters for mortar and concrete. As a further example of older literature supporting our view that coarse sands lacking in fines are required for carbonating mortars are the comments by the 16th century architect Andrea Palladio, renowned for "The Four Books of Architecture" which were translated into English in the early 18th century and used as a principal reference for building for almost two centuries (Palladio, Isaac Ware translation, 1738). In the first book Palladio says, inter alia, "the best river sand is that which is found in rapid streams, and under water-falls, because it is most purged". In other words, it is coarse. Compare this with most sand for use in mortar today.
The excellent text book by Francois de Larrard provides a full mathematical analysis of particle packing. Experimental work backed up by the mathematical theory of Larrard (1999) indicates that the mean particle size of the magnesium oxide we use at around 8 micron is not far off the right size for ideal packing with Portland cement which in Australia has a mean particle size of around 20 um. (Thomas 2006 ). Assuming spheres Larrard calculates a ratio of 1:2.41 (Larrard, 1999).
Conference paper 25 by John Harrison our managing director.
 de Larrard, F. (1999). Concrete Mixture Proportioning: A Scientific Approach, E & FN Spon.
 Tony Thomas, chief concrete engineer for Boral Limited in Australia. Personal communication.
 Harrison, John (2005) Carbonating and Hydraulic Mortars - the difference is not only in the binder. Aggregates are also important. Proceedings Concrete 05, Concrete Institute of Australia, 17-19 October, 2005, Melbourne
NEW YORK – NASA and Columbia University Earth Institute research finds that human-made greenhouse gases have brought the Earth’s climate close to critical tipping points, with potentially dangerous consequences for the planet.
From a combination of climate models, satellite data, and paleoclimate records the scientists conclude that the West Antarctic ice sheet, Arctic ice cover, and regions providing fresh water sources and species habitat are under threat from continued global warming. The research appears in the current issue of Atmospheric Chemistry and Physics.
Tipping points can occur during climate change when the climate reaches a state such that strong amplifying feedbacks are activated by only moderate additional warming. This study finds that global warming of 0.6ºC in the past 30 years has been driven mainly by increasing greenhouse gases, and only moderate additional climate forcing is likely to set in motion disintegration of the West Antarctic ice sheet and Arctic sea ice. Amplifying feedbacks include increased absorption of sunlight as melting exposes darker surfaces and speedup of iceberg discharge as the warming ocean melts ice shelves that otherwise inhibit ice flow.
The researchers used data on earlier warm periods in Earth’s history to estimate climate impacts as a function of global temperature, climate models to simulate global warming, and satellite data to verify ongoing changes. Lead author James Hansen, NASA Goddard Institute for Space Studies, New York, concludes: “If global emissions of carbon dioxide continue to rise at the rate of the past decade, this research shows that there will be disastrous effects, including increasingly rapid sea level rise, increased frequency of droughts and floods, and increased stress on wildlife and plants due to rapidly shifting climate zones
The researchers also investigate what would be needed to avert large climate change, thus helping define practical implications of the United Nations Framework Convention on Climate Change. That treaty, signed in 1992 by the United States and almost all nations of the world, has the goal to stabilize atmospheric greenhouse gases “at a level that prevents dangerous human-made interference with the climate system.”
Based on climate model studies and the history of the Earth the authors conclude that additional global warming of about 1ºC (1.8ºF) or more, above global temperature in 2000, is likely to be dangerous. In turn, the temperature limit has implications for atmospheric carbon dioxide (CO2), which has already increased from the pre-industrial level of 280 parts per million (ppm) to 383 ppm today and is rising by about 2 ppm per year. According to study co-author Makiko Sato of Columbia’s Earth Institute, “the temperature limit implies that CO2 exceeding 450 ppm is almost surely dangerous, and the ceiling may be even lower.”
The study also shows that the reduction of non-carbon dioxide forcings such as methane and black soot can offset some CO2 increase, but only to a limited extent. Hansen notes that “we probably need a full court press on both CO2 emission rates and non-CO2 forcings, to avoid tipping points and save Arctic sea ice and the West Antarctic ice sheet.”
A computer model developed by the Goddard Institute was used to simulate climate from 1880 through today. The model included a more comprehensive set of natural and human-made climate forcings than previous studies, including changes in solar radiation, volcanic particles, human-made greenhouse gases, fine particles such as soot, the effect of the particles on clouds and land use. Extensive evaluation of the model’s ability to simulate climate change is contained in a companion paper to be published in Climate Dynamics.
The authors use the model for climate simulations of the 21st century using both ‘business-as-usual’ growth of greenhouse gas emissions and an ‘alternative scenario’ in which emissions decrease slowly in the next few decades and then rapidly to achieve stabilization of atmospheric CO2 amount by the end of the century. Climate changes are so large with ‘business-as-usual’, with additional global warming of 2-3ºC (3.6-5.4ºF) that Hansen concludes “‘business-as-usual’ would be a guarantee of global and regional disasters.”
However, the study finds much less severe climate change – one-quarter to one-third that of the "business-as-usual" scenario – when greenhouse gas emissions follow the alternative scenario. “Climate effects may still be substantial in the 'alternative scenario’, but there is a better chance to adapt to the changes and find other ways to further reduce the climate change,” said Sato.
While the researchers say it is still possible to achieve the “alternative scenario,” they note that significant actions will be required to do so. Emissions must begin to slow soon. “With another decade of ‘business-as-usual’ it becomes impractical to achieve the ‘alternative scenario’ because of the energy infrastructure that would be in place” says Hansen.
For related images and more information on this story, please go to:
For more information about the NASA Goddard Institute for Space Studies and the Columbia University Earth Institute visit:
"As cities produce three-fourths of the carbon emissions, we must act," said London Mayor Ken Livingstone, the head of the C40 large cities, describing climate change as "the single biggest threat to the future of humanity."
"Whatever the discussions within our governments, as cities we are not waiting," he told leaders from 46 of the world's most polluted cities, from Cairo to Shanghai and Los Angeles to Bangkok.
Livingstone said the summit aimed to "create a critical mass that puts the world on the path to avoid a catastrophic climate change... We came to take decisive actions to reduce our own carbon emissions," he said.
The summit, which opened late Monday and runs through Thursday, is expected to include several joint initiatives that harness the cities' combined purchasing power.
The event is being organized in conjunction with the Clinton Climate Initiative, part of the foundation set up by former US president Bill Clinton, who is due to address the summit on Wednesday.
The summit has also attracted dozens of major corporations, including GE, Deutsche Bank, Swiss Re, JP Morgan Chase, Shell and Siemens, who are either offering technological expertise or financial backing for green projects.
New York Mayor Michael Bloomberg criticized governmental inaction on climate change, telling delegates: "We need no new technology, we need no new invention, all that is required is political will."
"If they don't act, we will. Shame on them but we cannot sit around and watch our environment deteriorate and put this world in jeopardy," he said. "We are willing to stand up, we think it is one of the seminal issues of our time."
Other topics up for discussion at the summit include beating traffic congestion, making water systems more efficient, adopting renewable energy sources, increasing recycling, reducing waste and improving mass transit.
When London hosted the inaugural large cities summit in 2005, only 18 cities took part. With climate change now one of the most pressing hot-button issues, the number of cities represented has more than doubled.
"Even here in the United States things are beginning to move," said New York's deputy mayor, Daniel Doctoroff. "The time for debate is over, the time for action is now."
He explained how a plan to manage an expected boom in the city's population over the coming decades had evolved into proposals to trim carbon emissions by 30 percent before 2030 and restrict vehicle access into Manhattan. "So many companies are now taking it seriously," he said.
Some 500 US mayors were also at the summit to show their objections to the policies of President George W. Bush, who has refused to sign up to the Kyodo Protocol, which commits countries to reduce greenhouse gas emissions.
"Mayors took action because we have to, because the federal government was silent," said Douglas Palmer, head of the United States conference of Mayors.
This article is reproduced with kind permission of Agence France-Presse (AFP) For more news and articles visit the AFP web site.
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Crude takes a step back from the day to day news to illuminate the Earth's extraordinary carbon cycle and the role of oil in our impending climate crisis. Nearly seven billion people have come to depend on this resource, yet the Oil Age that began less than a century and a half ago, could be over in our lifetimes.
"A Crude Awakening looks into the question at how much fossil fuels we still have on this planet"
"This is not an issue of whether market forces are at play or not. This is more a geological issue," he said, pausing to clear his voice. "There is no doubt oil and gas are finite resources. There's a given amount of it on the planet and we can use it up, and that's what we're doing. It's not like wheat. We're not growing it every year."