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Can biochar help save the world? (2)

Producing "dark earth" on an industrial scale by traditional charcoal-making methods is impractical. New ways are being explored, but rolling out the technology will be a mammoth task, writes Fiona Harvey.

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Charcoal is, of course, nothing new. People have been making it for millennia, chiefly for fuel. The process is simple: take wood, or straw or the waste from crops, and heat it in the absence of oxygen. Traditionally, this was done by heaping earth on top of the lit biomass so that it smouldered for a long time. Modern kilns can make the process more efficient, but the principle remains the same.

There is much about biochar that remains a puzzle, however. Take the soil-fertility effects. What is it about biochar that improves soil so much? "The simple answer is that we don't know exactly," says Simon Shackley of the University of Edinburgh. "It's probably a combination of several factors. Charcoal is very porous, so it acts like a sponge in retaining water, and the nutrients dissolved in water, which is something poor soils aren't very good at. And [its porous nature] also means it provides a good material for the growth of lots of important bacteria."

Another factor in its favour is that using biochar as a fertiliser can displace artificial nitrogen fertilisers, which give off nitrous oxide, a greenhouse gas 300 times more powerful than carbon dioxide. And biochar is not toxic, adds Tim Lenton of the University of East Anglia. "No one has yet said there is some great hidden danger associated with it."

But Saran Sohi, a lecturer in soil science, warns that anyone hoping that biochar alone will solve fertility problems is probably deluded; biochar is not enough by itself to make the difference that terra preta -- "dark earth" --does to thin Brazilian soils. "Terra preta soils also contain other nutrients, from the other substances they contain -- things like bones, which are rich in phosphorus" [essential for healthy plant growth], he says. The biochar undoubtedly plays a role in holding these nutrients together, ensuring they remain available to plant roots, but the nutrients must be provided by other means. "No one has yet succeeded in recreating terra preta," Shackley adds.

To produce biochar on an industrial scale, traditional methods of charcoal production would be impractical. Instead, researchers are looking to pyrolysis -- a form of controlled thermal decomposition of organic material in the absence of oxygen, at heat that can reach 500° to 600° degrees Celsius.

Using pyrolysis also allows the capture of the syngas and the tarry liquid byproducts, both of which can be used as fuel to generate electricity or for the heating process.

The amount of biochar to be produced depends on accelerating or slowing down the pyrolysis process: fast methods produce 20% biochar and 20% syngas, with 60% bio-oil, while slow methods produce about 50% char and far smaller quantities of oil. "It's much easier to do slow pyrolysis as well," notes Adrian Higson of the United Kingdom's National Non-Food Crops Centre (NNFCC). "And cheaper." As modern pyrolysis plants can be run entirely from the syngas, the output is between three and nine times the energy input required, according to the Institute for Governance and Sustainable Development (IGSD).

What to use to make the char? Tearing down forests to turn into charcoal would be insane in climate-change terms. But there is plenty of other material. Agriculture produces large amounts of plant and animal waste -- straw, husks, dung. Even human waste -- sewage sludge, or some forms of household rubbish -- could be used.

And using waste products creates a double carbon saving: if left to rot, they produce methane, a greenhouse gas 20 times more powerful than carbon dioxide. But the difficulty is in gathering the waste -- and making it economic to do so. Farmers will require some persuasion that the trouble of conserving and cooking their waste to a charcoal makes financial sense, and they may need new machinery to do so. At a municipal waste level, the problem will be sorting the organic waste, which can be turned to char, from the rest of the rubbish -- and proving that this is cheaper and more beneficial than merely burying it.

The IGSD suggests a way of marrying small-scale and industrial methods for producing the char, that if refined could enable the economically viable production of biochar in urban, rural and even poor regions. It suggests three possible systems. The first is a centralised scheme, whereby all waste biomass in a given region would be brought to a central plant for processing; the second is a decentralised system in which each farmer or a small group of farmers would have their own fairly low-tech pyrolysis kiln.

The third system proposes a mobile alternative, in which a vehicle equipped with a pyrolyser -- powered using syngas -- would visit small farms, returning the biochar to the farmers to use, while collecting the bio-oil to be transported to a refinery and turned into liquid biofuel for vehicles. As an example, the IGSD cites Brazil's sugar cane industry, in which the tops of the canes, normally burned in the field, and the bagasse -- the residue from sugar production -- could be turned efficiently into biochar. It estimates that of the 460 megatonne annual sugar cane harvest, as much as 230 megatonnes could be available for pyrolysis.

A clutch of companies is now working on these problems, and seeking to commercialise biochar as a medicine for both climate and soil, and as an energy source.

As Mike Mason, founder of the carbon-offsetting company Climate Care, bought by JP Morgan, somewhat ruefully notes, he had been planning by now to spend most of his time charging round Africa looking at elephants. But instead he decided that climate change was too great a problem to leave alone, and with his new company, Biojoule, has been investigating ways to turn biochar into a viable business. In Ontario, Canada, Dynamotive is making biochar and up to 130 tonnes a day of bio-oil at a wood-products mill. Crucible Carbon, based in Australia, predicts that its technology will allow carbon sequestration from biochar at the cost of about US$13 (20 Australian dollars) a tonne.

Yet even without the logistical problems, others are less sure of the absolute benefits of the product. Robert Trezona, head of research and development at the Carbon Trust, a UK government-funded body that helps businesses cut their greenhouse-gas emissions, worries that seeing biochar as the main output from cooking biomass might be to miss the point.

The Carbon Trust is running a competition to develop pyrolysis plants, but with the aim of manufacturing liquid transport fuels from biomass, using fast pyrolysis techniques, to which biochar is merely a byproduct of questionable usefulness. "Producing liquid biofuels for transport is going to be very important in cutting emissions. We don't know the same about biochar," Trezona says. In fact, encouraging small farmers to produce biochar by traditional, low-tech methods may actually result in more greenhouse-gas emissions than simply burning the plants for fuel or discarding them, he says.

"This is very much unproven," Trezona asserts. "You want to be able to show that it stays in the soil for hundreds of years, and to prove that is difficult."

The Carbon Trust is not allowing companies applying to it for funding to count the biochar byproduct of pyrolysis as part of the carbon savings they produce. "We are a long way from having enough technical evidence to create a proper case for biochar," says Trezona. "Even the soil-improvement benefit is a new unexpected finding."

Flannery disagrees. "At least half of the carbon in charcoal is still sequestered 500 years later. This has been known for a long time, from radiocarbon dating from charcoal by paleontologists," he says.

Even if biochar does not fulfil all of the potential claimed for it, it could still make an important contribution. Al Gore, the former US vice-president and environmental campaigner, likes to point out that the search for a "silver bullet" to solve the problem of climate change has been a distraction. Instead, he argues, though there may be no silver bullet, "there is silver buckshot". Only by bringing many different methods of cutting emissions or absorbing carbon to bear can we reduce atmospheric levels of carbon to within the limits of safety. And of those possible methods, few are as simple and cheap as biochar.

Johannes Lehmann of Cornell University makes the point that "biochar sequestration does not require a fundamental scientific advance and the underlying production technology is robust and simple, making it appropriate for many regions of the world".

But no one should doubt that rolling out this technology will be a mammoth task. The problem is twofold: developing a model for biochar production that reliably reduces greenhouse gases but is easily replicable in small farms in poor countries; and in the developed world, changing the business model of large farms so that collecting and cooking their waste is a better option than not.

The huge US agribusinesses may be easy to reach, and good candidates to start using their waste for char, but they are likely to need financial incentives before they begin to see the point. The poor farmers of the developing world might be glad of the husbandry advice and techniques that would help them revitalise their own soils with biochar -- but how to reach them all? That may prove impossible.

These problems of economics and communication will be the real hurdles at which biochar may fall, just as they have been the reasons why we have failed to capitalise on other ways of cutting carbon, from the very simple -- small alterations to wood-fired cooking stoves in Africa and India can reduce the indoor air pollution from cooking fires that kills millions, yet hardly any homes have them -- to the complex challenges, such as adopting renewable energy. A massive effort will be required to overcome the inertia that has been the downfall of other great climate ideas.


Homepage photo by Biochar.org

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Copyright The Financial Times Limited 2009

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Default avatar
匿名 | Anonymous

差距!?

像生物炭这种可能用于减缓气候变化的措施很多发达国家都在研究,要么国家有基金支持,要么私人投资机构去做。诸如铁肥等项目,对于中国很多科学家根本就不知所云。这是一种差距还是其他方面的问题。在缓解气候变化的过程当中,中国应该也必须扮演什么样儿的角色呢,中国的发展到底是为了谁的发展,谁从这样的发展中受益,大家都很郁闷,好像又都必须要按一定的套路走。
谁知道前途在何方,反正很多东西并不掌握在中国人的手中,中国人好像总是觉着这些都是杞人忧天的事情。
中国人总会落了又起,分了又合。
大家不知道是清楚还是糊涂反正就这样过了五年多年。

A lag?!

Many developed countries are searching for climate change solutions like biochar, either through country funds or private investment organizations. However lots of Chinese scientists haven’t any knowledge about certain things – ferric fertilizer is a typical example. Is this a lag or another type of problem? What role should China play in solving the climate change issue, who exactly is China developing for and who is actually benefitting from this kind of development? Everyone feels gloomy, and it seems as if everything is just following some fixed route. Who knows where it is going to lead. Actually many of these things are not held in the hands of the Chinese people. Chinese people seem to always worry about these kinds of ungrounded things. But Chinese people are always able to fall before rising again, scatter before reuniting. Whether people are conscious of it or befuddled, it has been this way for the last 5000 years.

(translated by Fangfang CHEN)

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匿名 | Anonymous

关于生物碳

联合国防治沙漠化公约委员关于气候变化的意见/联合国气候变化框架公约长期合作行动特设第5工作组,
“计算土地中的碳含量及在补充土壤碳层中生物碳的重要性,修复土壤的肥力,增强对二氧化碳的吸收”,http://www.unccd.int/publicinfo/AWGLCA5/menu.php 新的国会研究服务专题报告(由Kelsi Bracmort撰写)是迄今以来我所见到最好的的关于长期政策和技术的小结,http://assets.opencrs.com/rpts/R40186_20090203.pdf.
鉴于如今关于能源,土地可持续性,食品Vs.生物燃料,气候变化等的“危机”气氛,哪个问题能将它们一并囊括在内呢?对于长期的管理和可持续性来说,这种土地纳米技术,代表着最为全面,成本低廉和富有成效的方式。对于碳储存,土壤是唯一的无处不在、经济可行的地方。
(田亮翻译)

UN & CRS on Biochar

UNCCD Submission to Climate Change/UNFCCC AWG-LCA 5
"Account carbon contained in soils and the importance of biochar (charcoal) in replenishing soil carbon pools, restoring soil fertility and enhancing the sequestration of CO2."
http://www.unccd.int/publicinfo/AWGLCA5/menu.php

This new Congressional Research Service report (by analyst Kelsi Bracmort) is the best short summary I have seen so far - both technical and policy oriented.
http://assets.opencrs.com/rpts/R40186_20090203.pdf .

Given the current "Crisis" atmosphere concerning energy, soil sustainability, food vs. Biofuels, and Climate Change what other subject addresses them all?

This is a Nano technology for the soil that represents the most comprehensive, low cost, and productive approach to long term stewardship and sustainability.

Carbon to the Soil, the only ubiquitous and economic place to put it.

Default avatar
匿名 | Anonymous

成本

太阳能、风能、核能,无一不是需要先进的技术、长期的惊人投入才能得到实现的,生物碳,一旦成功,或许会是一个经济可行的解决之道。

Cost

Solar energy,wind energy and nuclear power all require advanced technology, and expensive longterm input before they can be realised.
Once it is successful, biochar may become a cheap and effective future solution.

Default avatar
匿名 | Anonymous

简化方案重启碳循环

地球和国家正处在深深的麻烦之中,严重污染将会导致蜜蜂、花粉及人类小消失。生物碳及开放式堆肥造成严重的CO2e排放。文章提到黑土,这是中国农民延续数千年的方式,直至入侵停碍了这种做法。花费4年时间让C3作物通过光合作用,紧接着耗费3年时间让C4种子生长。C3排放的CO2气体恰好被C4吸收。我们已经同中国就C4二氧化碳方面开展了大规模的合作,以期通过改善荒漠、重启碳和微量元素循环,来重新开始雨循环。符合联合国气候变化框架公约的作物,可帮助数目可观的农民回到可持续耕作。降低二氧化碳的唯一方式是适当的C4运用。

Simple solution -- restart the Carbon cycle

The Planet and the country are in serious trouble. Serious pollution with no bees, no pollen, no mankind. Bio-char or open composting produces serious CO2e emissions. The articles references to black soil, which is what Chinese Farmers have produced for thousands of years until invasions stopped such practices. They grew for 4 years C3 photosynthesis pathway crops then 3 years allowing C4 weeds to grow. The C3 emit CO2 the C4 sequester such. We have commenced with PRC on large scale C4 CO2 sinks to reverse deserts and restart Carbon and trace element cycle aiding in restarting the rain cycle. The plantations meet UNFCCC rules, are halophytic and will help large numbers of Farmers to get back to sustainable farming. The only process to lower CO2 is appropriate C4 sinks. See Google Robert Vincin Beijing

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new_biochar_land

有关生物碳的书籍

如果你想知道有关生物碳的所有奥秘,这本书会帮到你http://www.biochar-books.com/。在《生物碳革命》一书中,理论和实践相生,该书揭露了隐秘的科学秘密——生物碳。

biochar book

You want to know all the secrets about biochar
This book will help
http://www.biochar-books.com/
Here practice and theory merge under a single cover of "The Biochar Revolution " and reveals hidden secrets of science called Biochar