In a fascinating development, Integro Earthfuels is planning to build its first of ten commercial torrefaction plants in the US. Torrefaction of biomass is one of the most promising bioenergy technologies, because it transforms bulky biomass into a high-quality product that can be readily co-fired with coal, without the need to change anything to a coal plant. Torrefied biomass allows us to 'take over' dirty coal plants, and convert them to entirely green power facilities, without the need to build new infrastructures or dedicated power plants.

More than half of all the electricity produced in the US comes from coal fired utilities. Coal is therefor the number one target for CO2 reduction and the primary industrial cause of global warming. Closing down coal plants is a radical step, but 'sneaking' green energy into them might be a smarter, more transitional process.

Co-firing biomass with coal is being practised widely in Europe, but the technique presents logistical, processing and combustion challenges that limit the fraction of biomass that can be co-fired to around 10-15%. Costs are also relatively high, even though at current coal prices, co-firing raw biomass has become competitive. Building entirely new, dedicated biomass co-generation facilities is an option, but it is more expensive still.

Raw biomass for co-firing has several disadvantages: the fuel is bulky and can therefor only be transported economically over medium distances; it cannot be stored together with coal, but needs new, dedicated infrastructures; the biomass also needs to be crushed or processed in separate facilities to make it ready for co-firing; and finally, given its different combustion properties, it may make the co-firing step itself difficult and require modifications to boilers.

By first torrefying biomass, all these challenges can be overcome in a single stroke (previous post). Torrefied biomass:

• has a much higher energy density than raw biomass
• it allows for a dramatic increase in the distance over which the biomass can be transported to the plant (some studies show distances can be squared)
• because torrefied biomass is hydrophobic, it can be stored in the open, for long times, in the same infrastructures as those used for coal
• it requires less energy to crush, grind or pulverise torrefied biomass than it takes to crush coal, and the same tools can be used
• given its excellent combustion properties, the fuel can be readily co-fired with coal

In short, torrefaction is a process that turns raw, bulky, moist biomass into a kind of 'green coal'. Torrefaction is a technology first developed in the coffee processing industry. It boils down to 'roasting' the biomass at temperatures ranging from 200 to 300 °C, in a low oxygen or no-oxygen atmosphere (figure 1, click to enlarge).

The conversion process
Woody biomass - the main feedstock - consists of hemicellulose, cellulose, lignins and extractants (chemicals absorbed during the growing cycle through air and dirt, generally less than 3%) (figure 2, click to enlarge). During torrefaction the molecular structure of the wood is altered, enhancing some of the wood’s physical properties. Torrefaction liberates water and releases volatile organic compounds (VOC) through the devolitization of primarily the hemicelluloses and extractants. The lignins are loosened and have limited devolitization while the cellulose is nearly unimpacted at these temperatures. As the hemicellulose, which binds the cellulose, is burned away, the wood is unbound making it more brittle. This increases the grindability of torrefied wood and makes its handling properties more like coal. This unbinding also releases the last of the water not stored at the cell level, leaving the wood hydrophobic. During the torrefaction process most of the energy value of the wood is preserved with the product losing 20-30% of its mass while retaining 90% of its energy. The calorific value of the wood increases to 9,500-11,500 Btu per pound.

Commercialisation
So far, there is only one commercial torrefaction plant operating in the world, located in the Netherlands. It supplies torrefied biomass pellets to large coal-fired power plants, who get a green credit for each ton of biomass they burn. Integro Earthfuels is now planning to open a similar plant in Roxboro County, North Carolina. The $12 million plant will have an initial capacity to produce up to 84,000 tons of torrefied biomass annually:
biomass :: bioenergy :: wood :: co-firing :: energy density :: biomass logistics :: torrefaction :: climate change ::

Currently, Integro is finalizing off-take agreements with local utilities and Universities with their own heat and power plants to provide them with a majority of the supply beginning in 2009. Integro will build 10 additional facilities over the next 6 years to meet the demand from coal-fired electricity producers.

Integro lists the following benefits of torrefied biomass for the coal-fired electrical utility:

1. Each ton of torrefied wood burned in the facility reduces their carbon output by up to 2.4 tons, earning them an estimated $72 in carbon credits.
2. Torrefied wood can be handled just like coal. It can be placed on the coal pile and processed alongside the coal. It has been tested to 10% and will likely go to 30% mix with coal.
3. It does not take on water so it can be left uncovered like coal.
4. It has lower levels of NOx and SOx than coal—primary pollutant emissions by EPA—lowering emissions and associated costs
5. During the torrefying process, most volatiles are burned off, eliminating the concerns over slagging in the boiler.
6. Because torrefied wood is handled identically to coal, little or no CapEx is required of the utility.

Integro’s torrefied biomass solution overcomes the limitations previously attributed to biomass co-firing through its unique treatment process. It produces a high-grade, smokeless fuel suitable for co-firing in coal powered electric plants.

CCS no match
Integro's ambition to build 10 plants is not unrealistic. Torrefaction holds a tremendous potential precisely because the fuel it generates can be used directly by existing coal plants and requires little, if any, capital investment on the part of utilities.

Coal plants need to clean up their act, and their only option is to make massive investments into untested carbon capture and sequestration (CCS) technologies.

Switching to torrefied biomass offers a much more competitive option, requiring none of these investments. According to Integro, the fuel can already be delivered below the cost of coal when carbon credits are factored in. This will allow coal-fired utilities to meet their clean energy obligations without a significant increase in the cost of electricity to consumers.

References:
Roxboro Courrier: Commission must authorize special use permit before ‘green coal’ plant can be built - November 8, 2008.

Integro Earthfuels: co-firing torrefied biomass with coal.

Biopact: Dutch partners agree to build commercial scale biomass torrefaction plant - November 12, 2007

Biopact: Torrefaction gives biomass a 20% energy boost, makes logistics far more efficient - July 25, 2008

Biopact: Study: solid biofuels 570% more efficient than corn ethanol in reducing GHG emissions - September 10, 2008

A unique fungus that makes diesel compounds has been discovered living in trees in the rainforest, according to a paper published in the November issue of Microbiology. The fungus is potentially a totally new source of green energy and scientists are now working to develop its fuel producing potential.
This is the only organism that has ever been shown to produce such an important combination of fuel substances. The fungus can even make these diesel compounds from cellulose, which would make it a better source of biofuel than anything we use at the moment. - Professor Gary Strobel, Montana State UniversityThe fungus, which has been named Gliocladium roseum, produces a number of different molecules made of hydrogen and carbon that are found in diesel. Because of this, the fuel it produces is called "myco-diesel".

Gliocladium roseum lives inside the Ulmo tree in the Patagonian rainforest. The researchers were trying to discover totally novel fungi in this tree by exposing its tissues to the volatile antibiotics of the fungus Muscodor albus. Quite unexpectedly, G. roseum grew in the presence of these gases when almost all other fungi were killed. It was also making volatile antibiotics. Then when they examined the gas composition of G. roseum, the researchers were totally surprised to learn that it was making a plethora of hydrocarbons and hydrocarbon derivatives. The results were totally unexpected.

Many microbes produce hydrocarbons. Fungi that live in wood seem to make a range of potentially explosive compounds. In the rainforest, G. roseum produces lots of long chain hydrocarbons and other biological molecules. When the researchers grew it in the lab, it produced fuel that is even more similar to the diesel we put in our cars.

When crops are used to make biofuel they have to be processed before they can be turned into useful compounds by microbes, said Professor Strobel. G. roseum however can make myco-diesel directly from cellulose, the main compound found in plants and paper. This means if the fungus was used to make fuel, a step in the production process could be skipped:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: ethanol :: cellulose :: fungus :: genome ::

Cellulose, lignin and hemicellulose make up the cell walls in plants. Lignin is the glue that holds the cellulose fibres together and makes the plant stand up. These compounds form the part of the plant that most animals cannot digest. They makes up non-foodstuffs like stalks, sawdust and woodchip. Nearly 430 million tonnes of plant waste are produced from just farmland every year; a huge amount to recycle. In current biofuel production, this waste is treated with enzymes called cellulases that turn the cellulose into sugar. Microbes then ferment this sugar into ethanol that can be used as a fuel.
We were very excited to discover that G. roseum can digest cellulose. Although the fungus makes less myco-diesel when it feeds on cellulose compared to sugars, new developments in fermentation technology and genetic manipulation could help improve the yield. In fact, the genes of the fungus are just as useful as the fungus itself in the development of new biofuels. - Professor StrobelThe discovery also questions our knowledge of the way fossil fuels are made. The accepted theory is that crude oil, which is used to make diesel, is formed from the remains of dead plants and animals that have been exposed to heat and pressure for millions of years, added Professor Strobel. If fungi like this are producing myco-diesel all over the rainforest, they may have contributed to the formation of fossil fuels.


Picture 1: Colorized environmental scanning electron microscope photo of Gliocladium roseum, an endophtic fungus that produces myco-diesel hydrocarbons. Credit: Gary Strobel.

Picture 2: Culture plate of Gliocladium roseum, an endophtic fungus that produces myco-diesel hydrocarbons. Credit: Gary Strobel.

References:
Gary A. Strobel, Berk Knighton, Katreena Kluck, Yuhao Ren, Tom Livinghouse, Meghan Griffin, Daniel Spakowicz and Joe Sears, "The production of myco-diesel hydrocarbons and their derivatives by the endophytic fungus Gliocladium roseum (NRRL 50072)". Microbiology 154 , 3319-3328; 2008, doi: 10.1099/mic.0.2008/022186-0

There has been a lot of criticism about monocultures at the margin of the tropical forest frontier, but researchers have now found that certain models of plantation farming can in fact help sustain the biodiversity of these forests. The scientists found that an areca nut plantation in south-west India supported 90% of the bird species found in surrounding native forests. The low-impact agriculture system has been used for more than 2,000 years and should be considered as a new option for conservation efforts, they added. The findings appear in an open access article in the Proceedings of the National Academy of Sciences.

The team of scientists from the US and India chose the site on the coastal fringes of the Western Ghat mountain range because it met a number of attributes the study required:

• a long history of continuous agricultural production
• intense human pressure
• extensive natural areas still remaining

The landscape consisted of a mixture of intact forest, "production forest" (where non-timber products, such as leaves, were allowed to be removed) and areas of cash crops, primarily areca nut palms (Areca catechu).

The researchers found a total of 51 forest (bird) species in this study system, they wrote. These species were broadly distributed across the landscape, with 46 (90%) found outside of the intact forest. Within areca nut plantations, they recorded threatened forest species, such as the great hornbill (Buceros bicornis) and the Malabar grey hornbill (Ocyceros griseus).

The team said the combination of the height of the areca nut palms (Areca catechu) and the plantations' close proximity to the intact forest created the necessary ecological conditions to support forest bird species.

They added that data showed the distribution of species in the area had been relatively stable for more than 2,000 years, before the first farmers cultivated the area.

As well as having a high ecological value, the plantations were also economically productive. The areca nut is consumed by about 10% of the world's population, predominantly Asian communities.

The shade provided by the palms' canopy also created the conditions that allowed farmers to grow other high-value crops, such as pepper, vanilla and bananas.

Rather than expanding the plantations, the farmers relied upon the leaf litter from the surrounding production forests to produce mulch for their crops, rather than using costly fertilisers. The researchers also said alternative crops that could be grown in the wet lowlands, such as rice, yielded lower returns both economically and ecologically:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: tropical :: plantation :: biodiversity :: forest ::

Lead author Jai Ranganathan, from the US National Center for Ecological Analysis and Synthesis (NCEAS), said the findings provided another option for conservationists to consider
If it is not possible to make places completely protected areas then they can look at whether a system like this will help support the rich biodiversity. [...] It identifies another tool that can be used by conservationists. - Dr Jai Ranganathan
While the production system delivers economic and environmental benefits, health officials have voiced concerns about how the areca nut, which contain a stimulant called arecoline, is primarily consumed.

It is chewed either by itself or as a part of "betel quid", which generally consists of a betel leaf (from the Piper betle vine) wrapped around pieces of areca nut, slaked lime (calcium hydroxide) and generally tobacco.

In 2003, the International Agency for Research on Cancer (IARC) issued a warning that linked chewing areca nuts to an increased risk of cancer.

Dr Ranganathan said the researchers were aware of the health concerns associated with the areca crop, but the purpose of the study was to understand how tropical agriculture and biodiversity could co-exist in close proximity.

Areca nut cultivation has an extremely long history in south and south-east Asia and is likely to continue for the foreseeable future, he said. Given this persistence, I feel that it would be a shame to overlook the potential benefits of this cultivation system for biodiversity.

Dr Ranganathan said that he intended to look for further examples of established agriculture and cultivation practises in the region that provided habitats that supported a high level of biodiversity.

The research indicates that low-impact tropical biofuel plantations can be made equally sustainable, even at the forest frontier, and possibly help millions of the world's poorest.

References:
Jai Ranganathan, R. J. Ranjit Daniels, M. D. Subash Chandran, Paul R. Ehrlich, and Gretchen C. Daily, "Sustaining biodiversity in ancient tropical countryside", PNAS published early edition, November 3, 2008, doi:10.1073/pnas.0808874105

Americans are choosing to enter a bright new era. A time in which the relations between nations will be based on respect and reason; a time in which the excluded and the weak are no longer ignored; a time in which the fragility of our planet will be understood and natural resources managed more sustainably.

Congratulations!

An interesting article in the Journal of Natural Resources and Life Sciences Education discusses the decline in the number of soil science students at universities across the United States. This trend is worrying, but it may soon reverse, as soil science is becoming a very important topic in a wide range of crucial fields that deal with renewable energy, climate change, biodiversity and economic development. Soil science is no longer the sole realm of those active in agriculture. Soils are the key to a whole range of extremely important ecosystem services that may soon receive a real market value. In short, soils are sexy. And so are the scientists studying them.

Soils have become the nexus at which a set of pressing world problems converge: from the destruction of forests in the tropics - fueled by declining soil fertility - to the capacity of soils to sequester vast amounts of carbon and to mitigate climate change; or from the role soils play in cleaning up water and air, to the wealth in biodiversity they represent as the home to a great variety of (unknown) microorganisms that may play a role in the production of next-generation biofuels or new pharmaceuticals.

But notwithstanding these fascinating topics studied by modern pedologists, it is worth asking the question as to why the number of young people studying soil science as a major, has been declining across the United States. Mary Collins, University of Florida, Gainesville, analysed the trend and looks for explanations.

Collins notes that the faculties who work closely with undergraduate students have seen this steady decline for several years. And there are many reasons one can give for why this is happening. This decline affects not only the students but also the courses offered, the quality of graduate students, and the possible merger of departments, says Collins.

The National Academy of Sciences through the National Committee for Soil Science established a subcommittee to study the declining trend of low enrollments in the major. The outcome of the subcommittee work and international commentaries on this subject are reported in Collins' article. The international soil science education community is also facing a similar tendency.

Today many of America's graduate students come to soil science with various undergraduate backgrounds including non-science disciplines. Collins explains, "These graduates may be outstanding, but they do not have the fundamental educational background in soils common at the undergraduate level."

How can U.S. universities increase the enrollment in their courses and major, Collins asks:
energy :: sustainability :: bioenergy :: agriculture :: ecosystem services :: innovation :: conservation :: climate change :: pedology :: soil science ::

Possible solutions include recruiting the “undecided” students already on-campus; having the best lecturer in the department teach the normally high enrolled introductory soils course; discussing with your colleagues if the courses offered have been static; changing the names of the courses; offering courses through distance education; establishing a combined B.S/M.S. degree program; and advertising how a student can major in soil science and still prepare for a professional school.

So what are the conclusions about the declining enrollment of undergraduate students majoring in soil science? Collins gives several of her concerns as she sees it from her experience at the University of Florida. She ends her article with one final question: Will the soils exhibit at the Smithsonian Institution, which opened this past July, have any influence on the millions of children visiting the exhibit to choose soils as a major?


Biopact would want to add an example of how soil science can be very innovative and lead to fascinating careers. The discovery of ancient 'terra preta' soils in the Amazon initially brought together archaeologists, anthropologists and soil scientists. The latter are now trying to uncover the secrets of these highly fertile soils. At the same time they're experimenting with modern-day replications of the ancient soil enhancement technique.

These experiments and the contemporary version of 'terra preta' - known as biochar or agrichar - have opened up an entirely new area of very exciting research, which now brings together experts from fields as diverse as climate change, bioenergy, agronomy, conservation and development economics. Because if the terra preta soil enhancement technique can be made to work today, it could become a strategy to address some of the most important issues of our times: biochar could help tackle climate change, generate carbon-negative renewable energy, reduce fertilizer use, counter tropical deforestration and enhance farming amongst the world's poorest communities.

In short, soil scientists show that their field is not limited per se to the study of the chemical, physical and biological processes at work in soils. In fact, their work is at the center of a series of highly intertwined and broad environmental issues. The soil scientists are often the ones who succeed in weaving these topics together and so present surprising new areas of research that may help solve grand problems.


Picture: soil science students at work in professor Johannes Lehmann's lab, Cornell University. Lehmann pioneers research into biochar. Credit: Cornell University, Dept. of Crop & Soil Science.

References:
Mary E. Collins, "Where have all the soil students gone?", Journal of Natural Resources & Life Science Education, Vol. 37 2008, pp. 117-124.

SSSA is the founding sponsor of an approximately 5,000-square foot exhibition, Dig It! The Secrets of Soil, which opened on July 19, 2008 at the Smithsonian's Natural History Museum in Washington, DC.

In one of the largest renewable energy deals of this year, Drax Group announced an investment of up to £2 billion (€2.5/$3.2bn) into 900 MW of dedicated biomass baseload power, together with Siemens Project Ventures GmbH. This is one of several multi-billion dollar biomass investments announced so far this year, making the bio-power sector the leading renewable energy sector once again. This single investment will supply an estimated 15% of all of the UK's planned renewable power and generate clean energy for 1.3 million British households.

In its ambitious 'Biomass Growth Strategy' Drax, which operates Europe's largest power plant, says it plans to build three new 300MW power plants in the UK that will exclusively burn biomass, including energy crops and agricultural or forestry waste such as elephant grass, straw and peanut husks.

The plants will be built in partnership with Siemens of Germany, with Drax owning 60 per cent of the project and operating the plants and Siemens owning 40 per cent and supplying the technology. It is proposed that the plants will use Siemens' turbine technology. Drax will manage the biomass supplies.

Building on Drax's expertise in biomass co-firing, the expansion of its renewables business is expected to deliver significant attractive long-term growth opportunities. Each plant meets a mid-teens equity return hurdle based on current market scenarios; and each plant is expected to have a pay-back period of within 6 years from commencement of operations, which is fast, compared to any other type of renewable energy venture.

The new plants once operational will deliver essential baseload generation capacity to the UK electricity market, both making a significant contribution to the UK's renewables target and supporting national security of supply requirements. Note that none of the other major renewables offer baseload power, and remain dependent on fossil fuels.
We are strongly of the view that investment in the generation sector will provide attractive returns. We believe our venture into dedicated biomass-fired generation underpins our commitment to reducing the carbon footprint of electricity generation from the continued, but necessary, reliance on fossil fuels, whilst delivering secure and reliable supplies of electricity. - Dorothy Thompson, Chief Executive of DraxBased on current estimates, once all three plants are operational Drax will be responsible for supplying at least 15% of the UK's renewable power and up to 10% of total UK electricity. Of all the large EU member states, the UK has been slowest in taking up the implementation of renewables and is behind schedule to meet its EU targets. This biomass investment however changes its position.

The reasons as to why Drax chose to go for biomass are manifold. Biomass-fired generation has a strong strategic fit with Drax's existing business and will enable the company to deliver additional value from its core competencies of production, trading, biomass procurement and handling and project execution:
energy :: sustainability :: co-firing :: energy crops :: waste :: biomass :: bioenergy :: renewables :: baseload ::

Drax already produces power by co-firing biomass and is well advanced in its project to increase its biomass co-firing capability to 500MW by mid-2010, which will make Drax Power Station the largest biomass co-firing plant in the world.

Drax has an established biomass business management team in place and already purchases significant volumes of biomass in accordance with its established sustainable sourcing policy. No commitments to construction contracts or financing have been made to date and Drax expects to finalise these arrangements over the next 12-18 months.
We believe that the development of dedicated biomass plant will make a significant contribution to the renewable energy needs of the UK going forward and importantly help to address the challenge of climate change facing the sector. As a leading technology company we are used to providing solutions to such important issues. - Dr. Wolfgang Bischoff, Managing Director of Siemens Project Ventures
Drax also announced a new distribution policy: the company will distribute excess cash generated from operations in 2008 and 2009 and then target a pay-out ratio of 50% of underlying earnings from 2010 onwards to complement the expected growth potential of the group.

Drax has already secured rights to port sites at Immingham and Hull for two of the proposed biomass plants. The Company is also progressing a number of options for the third site, including land at Drax Power Station. The planning application process for each of the two secured sites, including required consents, has recently commenced.

Current estimates of the total capital cost of the investment programme are around £2bn, including investments in ancillary biomass logistics and processing facilities. Construction of the first plant is targeted to commence in late 2010, following execution of the construction and financing contracts and agreed capital commitment, with the first plant expected to be operational in 2014.

In order to fund the expansion of the biomass business, Drax today also announces a change to its distribution policy. For 2008 and 2009, the Company will distribute all excess cash generated from operations after meeting business requirements in each year. Any refinancing proceeds will be used to fund Drax's equity investment in the new biomass business. For 2010 and beyond, Drax will target a pay-out ratio of 50% of underlying earnings in each year, adjusted for non-cash accounting items (principally accounting for derivative contracts).

References:
Drax Group Plc: Biomass Growth Strategy - October 23, 2008.

The Congo War was the deadliest but most underreported conflict since WWII, killing more than 5 million people. The current situation in Eastern Congo is edging towards yet another humanitarian catastrophe. According to the UN, around 1 million people are now fleeing the violence. There is news of refugee camps being emptied, burned, and looted. Cities are no longer safe-havens and people are retreating to the forest again, to hide.

Political tensions between Congo and Rwanda are growing. There are signs that both camps are scrambling their allies to prepare for war.

Obviously, no matter how hard we and many others try to help Central Africa's rural populations combat poverty, all these efforts will have been in vain if war breaks out again. Likewise, all conservation efforts - be they related to forest or wildlife protection - will have been futile, as war ravages entire ecosystems (the first Congo wars have led to an ecological disaster of unprecedented proportions in Congo).

So please help in keeping this crisis on the top of the agenda of the international media and of those who can make a difference.

Write to any of the following people in power and urge them to intervene, either on the front of diplomacy or militarily, if you think that's wise. France, Belgium and other EU member states want to send troops to stabilize the situation and to strengthen the U.N. Peacekeeping force MONUC.

European Union
Mr Louis Michel
European Commissioner for development and humanitarian aid
Louis.Michel@ec.europa.eu

Mr Javier Solana
Secretary-General and High Representative for common foreign and security policy, European Council
Via his spokesperson Cristina GALLACH
cristina.gallach@consilium.europa.eu

Mr Bernard Kouchner
Minister of Foreign Affairs of France (Currently holding the EU Presidency)
https://pastel.diplomatie.gouv.fr/bacou/default.asp?lang=gb

U.N. Security Council
Mr Jan K.F. Grauls, Ambassador Extraordinary and Plenipotentiary for Belgium
jan.grauls@diplobel.fed.be

African Union
H.E. Dr. Jean PING
Chairperson of the African Union
chairperson@africa-union.org

H.E. Mr. Ramtane Lamamra
Commissioner for Peace and Security
LamamraR@africa-union.org

Mrs. Julia Dolly Joiner
Commissioner for Political Affairs
JoinerDJ@africa-union.org


United Nations news focus on the situation in the Democratic Republic of Congo.
biomass :: bioenergy :: agriculture :: energy :: sustainability :: environment :: development :: war :: Congo ::

After eight years of near-zero growth in atmospheric methane concentrations, levels have again started to rise. This is bad news for future global warming, says CSIRO’s Dr Paul Fraser, who co-authored a paper to be published in Geophysical Research Letters, a journal of the American Geophysical Union.

Over recent years, the growth of important greenhouse gases, namely methane and the CFCs, had slowed. This tended to offset the increasing growth rate of carbon dioxide that results mainly from large increases in the consumption of fossil fuels, particularly in the developing world. But now that methane levels have resumed their growth, global warming may accelerate.

Methane is the second most important greenhouse gas in the atmosphere after carbon dioxide, accounting for nearly 20 per cent of global warming since the industrial revolution. Methane is emitted to the atmosphere from natural wetlands, rice fields, cattle, forest and grassland fires, coal mines, natural gas leakage and use, and other sources.

Over the past decade these methane sources have been close to balancing the absorption of methane through atmospheric oxidation and into dry soil, Dr Fraser says. This fragile balance has resulted in little growth of methane in the atmosphere. Apparently some sources have been increasing, such as from fossil fuel use, cattle, and rice, while others have been decreasing, particularly natural tropical wetlands. However, over the past year, the total sources have overwhelmed the total sinks, and methane has again started to rise.

Dr Fraser says that recent analyses of global data by CSIRO and collaborators at the Massachusetts Institute of Technology, Scripps Institution of Oceanography and the University of Bristol suggest that the methane increase is, at least in part, due to methane releases in the high latitudes of the Northern Hemisphere.

One surprising feature of this recent growth is that it occurred almost simultaneously at all measurement locations across the globe. However, the majority of methane emissions are in the Northern Hemisphere, and it takes more than one year for gases to be mixed from the Northern Hemisphere to the Southern Hemisphere. Hence, theoretical analysis of the measurements shows that if an increase in emissions is solely responsible, these emissions must have risen by a similar amount in both hemispheres at the same time.

A rise in Northern Hemispheric emissions may be due to the very warm conditions that were observed over Siberia throughout 2007, potentially leading to increased bacterial emissions from wetland areas. However, a potential cause for an increase in Southern Hemispheric emissions is less clear.

An alternative explanation for the rise may lie, at least in part, with a drop in the concentrations of the methane-destroying OH. Theoretical studies show that if this has happened, the required global methane emissions rise would have been smaller, and more strongly biased to the Northern Hemisphere. At present, however, it is uncertain whether such a drop in hydroxyl free radical concentrations did occur because of the inherent uncertainty in the current method for estimating global OH levels:
energy :: sustainability :: biomass :: bioenergy :: land use :: wetlands :: emissions :: methane :: climate change :: atmosphere ::

To help pin down the cause of the methane increase, Ronald Prinn - TEPCO Professor of Atmospheric Chemistry, in MIT's Department of Earth, Atmospheric and Planetary Science - said, "the next step will be to study this using a very high-resolution atmospheric circulation model and additional measurements from other networks." But doing that could take another year, he said, and because the detection of increased methane has important consequences for global warming the team wanted to get these initial results out as quickly as possible.

"The key thing is to better determine the relative roles of increased methane emission versus an idecrease in the rate of removal," Prinn said. "Apparently we have a mix of the two, but we want to know how much of each" is responsible for the overall increase.

It is too early to tell whether this increase represents a return to sustained methane growth, or the beginning of a relatively short-lived anomaly, according to Rigby and Prinn. Given that, pound for pound, methane is 25 times more powerful as a greenhouse gas than carbon dioxide, the situation will require careful monitoring in the near future.

The Intergovernmental Panel on Climate Change (IPCC) has identified the need to understand causes of the variations of methane growth rates as a priority area of research. The reality is that scientists have only a very basic understanding of these methane variations, Dr Fraser says.

In order to predict the future contribution of methane to climate change, continuing high-quality observations, in particular in tropical and boreal locations, are required as input to, and verification of, sophisticated climate models.

References:
M. Rigby, R. Prinn, P. Fraser, P. Simmonds, R. Langenfelds, J. Huang, D. Cunnold, P. Steele, P. Krummel, R.Weiss, S. O’Doherty, P. Salameh, H. Wang, C. Harth, J. Mühle, L. Porter. "Renewed growth of atmospheric methane", Journal of Geophysical Research. 28 pages 2008