The Climate Spectator has an article on research into the usefulness of ocean fertilisation as a geoengineering technique - A drop in the ocean.
Fertilizing the oceans to boost the growth of tiny plants that soak up greenhouse gases is unlikely to work as a way to slow climate change, a UN-backed study showed on Monday.
Such "geo-engineering" schemes would be hard to monitor and were likely to store away only small amounts of carbon dioxide, the main greenhouse gas, according to a report by the Intergovernmental Oceanographic Commission.
"Geo-engineering schemes involving ocean fertilization to affect climate have a low chance of success," according to the 20-page study by the Commission, part of the UN Education, Scientific and Cultural Organization (UNESCO).
The review, by scientists in seven countries, said 13 experiments in recent years showed faded optimism that iron dust or other nutrients could spur growth of microscopic marine plants and permanently suck carbon dioxide from the atmosphere.
Twenty years ago, scientists had optimistically reckoned that one tonne of iron could make the seas absorb 100,000 tonnes of carbon dioxide, it said. But one recent study suggested that one tonne of iron would only soak up 5,000 tonnes of the gas.
Firms including Climos, Atmocean and the Ocean Nourishment Corp. have been looking into ocean fertilization technology as a way of offsetting emissions of greenhouse gases from factories, power plants and cars.
But the study said that some absorbed carbon simply returns to the atmosphere. Just one to 15 per cent falls as what scientists call "marine snow" – dead plants, animals or their faeces – to be stored on the deep ocean floor.
"At best it can make a small contribution" to storing industrial emissions of carbon dioxide, Doug Wallace, lead author of the report at the Leibniz-Institut fur Meereswissenschaften, told Reuters.
In 2008, the UN's Convention on Biological Diversity imposed a moratorium on ocean fertilization experiments outside coastal waters, awaiting wider scientific evidence.
The study said that some experiments had successfully triggered a bloom of plankton and bacteria – such one in 2002 that produced a patch visible to satellites in the north-east Pacific Ocean.
But it was impossible to say how much of that carbon stayed in the oceans. And the extra plants might help fish grow in some areas by providing more food, but might also rob nutrients from other parts of the ocean.
Monitoring was vital, especially if ocean fertilization were ever to qualify for carbon credits under a UN deal meant to avert more floods, heatwaves, mudslides, or rising sea levels.
But it was far easier to monitor forests, which also soak up carbon as they grow. "A tree might burn next year but then at least you know it didn't work," Wallace said. "In the oceans you have a serious measurement problem."
SP at TOD ANZ has a summary of articles about the failure of the Zerogen clean coal project in Queensland - Carbonuncle.
"A carbuncle is an abscess larger than a boil, usually with one or more openings draining pus onto the skin."
A carbonuncle might be the future term used if injecting large quantities of CO2 into the ground has an unfortunate end result.
The Carbon Capture and Storage (CCS) project in Australia took a significant step backwards as Queensland Premier Anna Bligh announced that Queensland would not be providing further funding for ZeroGen to build what was supposed to be a landmark demonstration power station and that the state owned ZeroGen is to be sold.
Bligh denies clean coal 'bungle' Brisbane Time, Dec 19th. Queensland Premier Anna Bligh has denied walking away from the development of clean coal technology, after abandoning plans to build a central Queensland plant by 2015. The Queensland government had ploughed $102 million into the ZeroGen research project, which also attracted $92 million from the federal government and the coal industry. It had aimed to have a $4.3 billion coal-fired power station utilising carbon capture and storage technology – which would prevent greenhouse gas emissions from entering the atmosphere – built by 2015.
But the state government today confirmed it would not pursue a proposal to fund the proposed power station “at this time” because of concerns about its viability. It also plans to offload the state government-owned ZeroGen company, turning it into an independent entity owned and run by the coal industry.
"Reports this morning that the Queensland Government has scrapped our clean coal project ZeroGen or that it has been a waste of money are utterly wrong in every respect,” Ms Bligh told reporters in Brisbane.
“What we know now from the early research is that a fully functional power station by 2015 using this technology is technically possible but it is not economically viable.”
Ms Bligh said the technology “would drive up the cost of electricity beyond the reach of normal people” if proceeded with now.
The proposed plant had been expected to cost $4.3 billion.
“The Queensland Government cannot have its cake and eat it to, profiting from exports while being unwilling to invest in the [research and development] necessary to reduce emissions”, [said Federal Resources and Energy Minister Martin Ferguson].
Mr Bligh said she had spoken to Mr Ferguson this morning to explain what was happening with the ZeroGen project. “I think he understands like I do that the great discoveries of the world have had disappointments along the way,” she said.
Funding for this project came out of the CCS Flagship Program which had $5.1 billion to distribute. The stated objectives were ambitious;
The program supports the construction of 2 to 4 commercial scale CCS projects with an electricity generating capacity of 1000 mega watts or equivalent size for other industrial processes. This objective supports the G8’s call for the launch of 20 demonstration CCS projects worldwide by 2010, to be operational from 2015 and for commercial deployment by 2020.
The Minister for Resources and Energy called on the state and territory governments and the Australian Coal Association to nominate projects for consideration under CCS Flagships program in May 2009. Nominations closed on 14 August 2009.
ZeroGen was shortlisted for this money on December 8th 2009. Interestingly,this the last time the media centre at ZeroGen appears to have been updated. Mr Ferguson might be understandably disappointed that his energy partners appear to have let him down after just one year. Unlike that other "great" CCS demonstration project in Victoria which at least allowed the Emperor Minister to appear clothed in transparent greenish attire on national TV.
The research for the Ottway Basin Demonstration Project is being conducted by the CRC for Greenhouse Gas Technologies. Personally I am a bit skeptical of a CRC where the preponderance of the publications consists of brochures, grey literature, industry sponsored workshops and posters. I count only two refereed journal articles at the websites database. The website is beautiful though.
A commenter at the end of the Brisbane Times article provides a good link to The Economist. ...
Giles Parkinson has an article in The Business Spectator on an unusual way of sequestering carbon safely in the oceans - A carbon sink with fins.
Australian scientists have found another very good reason to protect the sperm whale, but please finish your breakfast or lunch before reading on.
Research led by Trish Lavery at the School of Biological Sciences at Adelaide’s Flinders University, suggests the poo of the sperm whale is particularly in rich in iron, and because it comes in liquid form and is excreted near the surface, it doesn’t sink rapidly to the ocean floor.
Instead, it inspires the growth of phytoplankton which in turn absorbs carbon dioxide from the atmosphere. It means that even after taking into account the considerable amount of carbon dioxide emitted when these giants of the sea respire, sperm whales are a highly effective, and highly mobile, carbon sink.
And more so than other whales, because as a deep diving feeder, the nutrients it defecates are additional to the total count – other sea animals tend to feed at the surface and simply recycle said nutrients.
Each sperm whale is estimated to absorb at least 35 tonnes of CO2 from the atmosphere each year. From the estimated population of 12,000 Southern Ocean sperm whales that remain after decades of hunting, that amounts to around 400,000 tonnes of CO2 per year.
According to the research, this carbon saved from the current numbers of Southern Ocean sperm whales amounts to just 0.05 per cent of the carbon emitted globally each year by fossil fuel burning, but the numbers of Southern Ocean sperm whales were once ten-fold the current population, and the paper estimates that two million tonnes of CO2 have been left in the atmosphere each year as a result of decimating the sperm whale population.
“This is a previously overlooked impact of industrial whaling,” the report says. Southern Ocean sperm whales, it notes, account for just 3 per cent of the world’s population of sperm whales, which means that the global sperm whale population may be a significant contributor to carbon drawdown. Whales had once been considered to be a net carbon emitter because of their respiration.
The latest paper suggests that other mammals and organisms that consume prey at depth and defecate nutrient rich waste near the surface could be performing a similar function – these include, pygmy whales, baleen whales and fin whales, and possibly also seals and sea-lions, though more research needs to be conducted to ascertain the liquidity and the buoyancy of their poo. A previous Australian-led study suggested that baleen whale faeces once accounted for more than 12 per cent of the iron in the Southern Ocean.
And the point of all this? Well, as nations meet and continue negotiations on how to remove the other 99.95 per cent of fossil fuel emissions under the UN-sponsored climate change talks, such biological solutions will become crucial, and become the basis for new market mechanisms and ascribe a value to hitherto unrecognised assets that will turn the business models of many industries on their head. And companies and their investors need to be aware of this.
It will happen in forestry, for that is what the REDD mechanism that is nearing agreement is designed to do – make the trees that stand in the world’s remaining rainforests more valuable alive than dead. It will likely occur in land use and farming, because these will form a fundamental part of the abatement proposals of the likes of Australia and some other industrialised nations.
Keith Johnson at The WSJ's Environmental Capital blog has a post on the importance of the gigantic carbon sequestration experiment about to be performed by the Gorgon LNG project on Barrow Island off Western Australia - Carbon Storage: Why the Gorgon Gas Play Might Be Really Important.
Under the terms of the agreement, the companies will be responsible for the storage of the carbon-dioxide resulting from the natural-gas project during its operating lifetime and for 15 years afterward, Bloomberg reports. After that, the Australian national and state governments will be responsible.
There are several ways to read that decision. It could be a supreme vote of confidence in the long-term security of underground storage of carbon dioxide. Companies that have spent years monitoring small carbon-storage operations have indeed found no cause for alarm so far. Australia might also figure that the economic and employment benefits associated with the project outweigh any slight future risk. Or, the Australian government might simply figure it’s a risk-free agreement since nobody in office will be alive in 2069 anyway.
The Brisbane Times has a jaundiced look at the shimmering mirage of clean coal, quipping that comparing clean coal to large scale renewables "(is) not a reasonable comparison, though, because solar thermal and wind power actually exist" - The planet-saver that's still just a pipe dream.
THERE may be a few forced smiles when Martin Ferguson dishes out $2.4 billion in funding for a handful of "flagship" carbon capture and storage projects (CCS), intended to clean up carbon dioxide emissions from coal-fired power stations.
As the Energy and Resources Minister knows, these CCS projects have taken one helluva time to get up and running - and it will be a long while yet before they make any significant contribution to Australia's CO2 emission reductions.
For at least a decade, the coal industry has promoted a range of clean coal technologies, including CCS, as an alternative to renewable energy. But as necessary emission reduction trajectories get deeper and steeper, the industry has been tardy - stubborn, even - about paying for it.
Instead the public will foot most of the bill for CCS, and will wear the liability if it goes wrong.
CCS projects have a conspicuous history of failure - here and overseas. Put simply, nobody has yet integrated power generation with carbon capture and storage at scale to create clean electricity, anywhere in the world.
And many experts, including from within the energy industry, believe CCS will remain prohibitively expensive and risky compared with known baseload power sources such as nuclear, or renewable sources such as geothermal or concentrating solar thermal which do not leave vast underground stores of carbon dioxide for future generations to worry about.
In April the CSIRO's energy chief, David Brockway, told a federal parliamentary inquiry on climate change that while he did not have a crystal ball, over the next 15 years wholesale electricity costs would roughly triple from the present $40/MWh, as CCS is incorporated into coal-fired power generation. That would bring it, he said, roughly into line with solar thermal - about $160-$200/MWh but falling fast - and wind energy, likely to remain stable at $100-$110/Mwh (other estimates are lower) because it is a mature technology.
It's not a reasonable comparison, though, because solar thermal and wind power actually exist. Iain MacGill, the joint director of the Centre for Energy and Environmental Markets at the University of NSW, says "all prices for CCS are projections right now, because they haven't actually done it yet. Until they can make CCS work, they're on a different planet."
The executive director of the Australia Institute, Richard Denniss, says he would love to see CCS work. But if it doesn't, he asks, "what's plan B?"
Federal and state governments are keen to support the coal industry, which provides cheap power, claims to employ 30,000 Australians directly and was our biggest export earner in 2008-09, with about $50 billion in combined overseas sales of metallurgical and thermal coal.
Especially vulnerable are the coal-reliant communities of the Hunter Valley and Victoria's Latrobe Valley. In both regions, local councils, environment groups and sections of the union movement are working to develop ''just transition'' plans to create green collar jobs - and avoid job losses - as part of an orderly switch to gas-fired or renewable power.
Not even the Greens are proposing, in Kevin Rudd's parlance, to "shut down the coal industry by Thursday" and abandon these communities.
The Institute for Sustainable Futures estimated annual national financial assistance for coal was more than $1.2 billion in 2005-06, in terms of direct subsidies, cheap fuel and accelerated depreciation. The industry pays cheap royalties to the states under a regime which is the envy of the gas lobby.
There is also infrastructure funding designed to ease years of capacity constraints - for example, last year's $1 billion-plus in federal rail funding to help double export capacity from the Hunter Valley coal chain by 2014, and the NSW budget's $205 million to expand Eraring power station on the Central Coast.
The Federal Government is proposing to issue $3.9 billion worth of free permits to coal-fired power generators under its carbon pollution reduction scheme, and is being urged to compensate power station owners for the anticipated loss in the value of their assets if or when such a scheme is introduced.
On top of that, in May the Federal Government announced $2.8 billion would be set aside to fund clean coal initiatives, including $2.4 billion to fund between two and four ''flagship'' coal- or gas-fired power stations with CCS over the next nine years.
The CCS flagships funding was part of a broader clean energy initiative, including $1.5 billion to part-fund a number of flagship solar power stations under a separate process, and a $500 million fund to support emerging renewable technologies such as wave and geothermal.
This month's edition of National Geographic has a feature article on "Soil", which looks at the steady degradation of agricultural land and the problem this poses in world where the population is heading for 9+ billion people - effectively calling attention to the "peak dirt" problem (however soil is renewable, so any "peak" should be able to be reversed if sufficient time and effort is put into doing so).
The article uses an acronym I've never come across before to describe the problem faced by those trying to draw attention to the issue: MEGO (My Eyes Glaze Over) - a phenomenon which should be familiar to anyone who has ever talked about peak oil, global warming or any of the other "limits to growth".
This year food shortages, caused in part by the diminishing quantity and quality of the world's soil, have led to riots in Asia, Africa, and Latin America. By 2030, when today's toddlers have toddlers of their own, 8.3 billion people will walk the Earth; to feed them, the UN Food and Agriculture Organization estimates, farmers will have to grow almost 30 percent more grain than they do now. Connoisseurs of human fecklessness will appreciate that even as humankind is ratchetting up its demands on soil, we are destroying it faster than ever before. "Taking the long view, we are running out of dirt," says David R. Montgomery, a geologist at the University of Washington in Seattle.
Journalists sometimes describe unsexy subjects as MEGO: My eyes glaze over. Alas, soil degradation is the essence of MEGO.
One subject that features in the article is soil restoration, including a look at "terra preta" - rich, fertile artificial soils found in the Amazon. In this post I'll have a look at modern day techniques to produce terra preta (often called biochar or agrichar) which have the potential to increase soil fertility, generate energy and sequester carbon all at the same time.
The History Of Terra Preta
Terra Preta ("dark earth") was discovered by Dutch soil scientist Wim Sombroek in the 1950's, when he discovered pockets of rich, fertile soil amidst the Amazon rainforest (otherwise known for its poor, thin soils), which he documented in a 1966 book "Amazon Soils". Similar pockets have since been found in other sites in Ecuador and Peru, and also in Western Africa (Benin and Liberia) and the Savannas of South Africa. Carbon dating has shown them to date back between 1,780 and 2,260 years.
Terra preta is found only where people lived - it is an artificial, human-made soil, which originated before the arrival of Europeans in South America. The soil is rich in minerals including phosphorus, calcium, zinc, and manganese - however its most important ingredient is charcoal, the source of terra preta's color.
It isn't entirely clear if the Amazon Indians whose old settlements terra preta is found at deliberately created the soils or if they were an accidental by-product of "slash and smoulder" farming techniques, though the emerging consensus seems to be that the Indians deliberately created the material, with some early European accounts in the area noting the practice still being performed.
The key ingredient is apparently the activated carbon in the charocal. Activated carbon has a complex, spongelike molecular structure - a single gram can have a surface area of 500 to 1,500 square meters (or about the equivalent of one to three basketball courts). Having this material in the soil has several beneficial effects, including a 20% increase in water retention, increased mineral retention, increased mineral availability to plant roots, and increased microbial activity.
It has also been shown to be particularly beneficial to arbuscular mycorrhizal fungi, which form a symbiotic relationship with plant root fibers, allowing for greater nutrient uptake by plants. There is speculation that the mycorrhizal fungi may play a part in terra preta’s ability to seemingly regenerate itself.
Pyrolysis and Eprida
Modern day producers of biochar (agrichar) take dry biomass and bake it in a kiln to produce charcoal. Biochar is the term not for what is left over after the energy is removed: a charcoal-based soil amendment - this process is called pyrolysis. Various gases and oils are driven off the material during the process and then used to generate energy. The charcoal is buried in the ground, sequestering the carbon that the growing plants had pulled out of the atmosphere. The end result is increased soil fertility and an energy source with negative carbon emissions.
Eprida is a company founded by Danny Day, which is attempting to commercialise the idea by building systems that turn farm waste into hydrogen, biofuel, and biochar (see here for a short movie explaining their process).
The Eprida technology uses agricultural waste biomass to produce hydrogen-rich bio-fuels and a new restorative high-carbon fertilizer (ECOSS) ...In tropical or depleted soils ECOSS fertilizer sustainably improves soil fertility, water holding and plant yield far beyond what is possible with nitrogen fertilizers alone. The hydrogen produced from biomass can be used to make ethanol, or a Fischer-Troupsch gas-to-liquids diesel (BTL diesel), as well as the ammonia used to enrich the carbon to make ECOSS fertilizer.
We don't maximize for hydrogen; we don't maximize for biodisel; we don't maximize for char...By being a little bit inefficient in each, we approximate nature and get a completely efficient cycle.
The potential power of biochar lies in this closed loop production process , where agricultural practices involving biochar production see increasing returns of crop yields, energy and soil fertility over time.
Biochar also has potential to address problems such as waste disposal and rural development. A significant proportion of the world's population relies on charcoal as a cooking fuel, the production of which drives deforestation in Africa and other places.
Replacing traditional charcoal kilns with modern pyrolysis units could reduce the demand for wood from forests by increasing the efficiency of energy production and adding the ability to use any source of biomass, including agricultural waste products. This would also help to reduce respiratory diseases in the developing world, particularly amongst children.
There has also been speculation that pyrolysis could be a useful technique for dealing with the huge swathes of Canadian forests that have been killed by pine beetles recently.
Some industry participants believe that energy, rather than agriculture, will be the key driver for adopting biomass pyrolysis. Desmond Radlein of Dynamotive Energy Systems has been quoted as saying "It is wishful thinking that people will switch to renewable fuels unless it is cheaper. All of this is tied to the price of oil; as it goes up, many more things are possible."
Another company active in the pyrolysis sector is Best Energies. Technical Manager Adriana Downey recently had an interview with Beyond Zero Emissions, talking about some of the pilot programs they have been running and plans to build the first fully commercial scale pyrolysis plant in Australia.
Lukas's program with the NSW DPI (Department of Primary Industries) in Northern NSW have basically taken some of the agrichar material that we've made here at Best Energies and they've been trialling that material in different agronomic applications to see how the agrichar, when its applied, can help crop-productivity and improve the sustainability of agriculture as well as, and what you guys are more interested in, sequester carbon long-term in soils and also decrease the potent greenhouse gas nitrous oxide emissions from soil. ...
The agrichar when it's applied to the soil has a good effect on the general physical structure of the soil. Because the agrichar has a really high surface area, it means that there's lots of pores in the soil which can then retain moisture and act as little reservoirs for the water to be retained in the soil. As well as this, all of the surface area helps to bind nutrients in the soil and also provides a microhabitat for micro organisms in the soil which are essential for the natural processes in the soil which allow micro organisms to flourish.
Carbon Capture Potential
There is a large difference between terra preta and ordinary soils - a hectare of meter-deep terra preta can contain 250 tonnes of carbon, as opposed to 100 tonnes in unimproved soils from similar parent material, according to Bruno Glaser, of the University of Bayreuth, Germany. The difference in the carbon between these soils matches all of the carbon contained in the vegetation on top of them.
It is not yet clear what the limits are to how much biochar can be added to the soils using these techniques, however some fairly extravagant claims about biochar's capacity to capture carbon have been made. Soil scientist and author of "Amazonian Dark Earths: Origin, Properties, Management" Johannes Lehmann believes that a strategy combining biochar with biofuels could ultimately offset 9.5 billion tons of carbon per year - an amount equal to the total current fossil fuel emissions. Lehmann also notes that unlike biodiesel and corn ethanol, biochar doesn’t take land away from food production.
If true, this would be an interesting form of geoengineering to try and reverse the effects of global warming (and one far less risky than some of the alternatives proposed) but I would still question our ability to turn all the world's oil, coal and gas reserves back into rich soil via burn - atmosphere - pyrolysis loop.
* The technology to implement the process is still immature. * Scientists don’t know how much charcoal farmers should use, how they should apply it, or which feedstocks work best. * Farmers are reluctant to spread unproven products on their fields, so the few companies manufacturing biochar have struggled to find buyers. * Charcoal production can generate toxic waste if performed incorrectly. * The energy needed to produce, transport, and bury biochar could outweigh the carbon savings. * Some analysts say the economics of the process will not be acceptable until carbon markets are established, allowing farmers to earn carbon credits for applying biochar to their fields. * Some environmental activists claim that applying the process on a large scale would result in further rainforest clearing which would actually degrade soil quality and increase global warming.
Rhizome In The Amazon
Jeff Vail recently had a post on a "Rhizome Template in the Amazon ?", which looked at a paper by Mark Heckenberger suggesting that a dense civilization of networked villages once existed in the Amazon, which Jeff noted was interesting because it "appears to show a form of organization that permits density without significant hierarchy".
The paper shows that the Xingu region of the Amazon was once populated by a grid-like pattern or villages, each connected by a precisely aligned network of roadways (the Xingu river is the Amazon's second longest tributary, with the region currently experiencing tension over plans to dam the river).
Here's an alternate mode of organization--a networked "grid," "lattice," or "peer-to-peer" structure of small, minimally self-sufficient villages, or "rhizome" as proposed in my article The Hamlet Economy. The Xingu settlement structure seems to consicously model itself in the latter pattern. Heckenberger even notes that each village was surrounded by a buffer zone of "managed parkland," exactly the kind of fall-back, resiliency-enhancing production zone that I recommended for rhizome. Here's a link to a satellite image of one section fo Xingu settlement.
Did this Xingu civilization really develop a dense, ecologically sustainable civilization without hierarchal structure? Or did they simply find a new way to impose hierarchy without developing the signatures of "central places"? Was this a conscious reaction to prior abuses of hierarchy, or simply an expedient to survival in the dense forrests and poor agricultural soils of the Amazon? We don't know the answers to these questions at this time, but the research of Heckenberger and his colleagues suggests that there is still a great deal for us to learn from the past about how we can best live in the future
Heckenberger also examined the terra preta pockets in the region, which is described briefly in an interesting article by Charles Mann in The Atlantic Monthly called "1491".
Scientific American also notes the correlation between the lost cities of the Amazon and terra preta in "Ancient Amazon Actually Highly Urbanized", as does The Vermont Quarterly in "Pay Dirt".
Terra preta, Woods guesses, covers at least 10 percent of Amazonia, an area the size of France. It has amazing properties, he says. Tropical rain doesn't leach nutrients from terra preta fields; instead the soil, so to speak, fights back. Not far from Painted Rock Cave is a 300-acre area with a two-foot layer of terra preta quarried by locals for potting soil. The bottom third of the layer is never removed, workers there explain, because over time it will re-create the original soil layer in its initial thickness. The reason, scientists suspect, is that terra preta is generated by a special suite of microorganisms that resists depletion. "Apparently," Woods and the Wisconsin geographer Joseph M. McCann argued in a presentation last summer, "at some threshold level ... dark earth attains the capacity to perpetuate—even regenerate itself—thus behaving more like a living 'super'-organism than an inert material."
In as yet unpublished research the archaeologists Eduardo Neves, of the University of São Paulo; Michael Heckenberger, of the University of Florida; and their colleagues examined terra preta in the upper Xingu, a huge southern tributary of the Amazon. Not all Xingu cultures left behind this living earth, they discovered. But the ones that did generated it rapidly—suggesting to Woods that terra preta was created deliberately. In a process reminiscent of dropping microorganism-rich starter into plain dough to create sourdough bread, Amazonian peoples, he believes, inoculated bad soil with a transforming bacterial charge. Not every group of Indians there did this, but quite a few did, and over an extended period of time.
When Woods told me this, I was so amazed that I almost dropped the phone. I ceased to be articulate for a moment and said things like "wow" and "gosh." Woods chuckled at my reaction, probably because he understood what was passing through my mind. Faced with an ecological problem, I was thinking, the Indians fixed it. They were in the process of terraforming the Amazon when Columbus showed up and ruined everything.
Scientists should study the microorganisms in terra preta, Woods told me, to find out how they work. If that could be learned, maybe some version of Amazonian dark earth could be used to improve the vast expanses of bad soil that cripple agriculture in Africa—a final gift from the people who brought us tomatoes, corn, and the immense grasslands of the Great Plains.
All in all I think biochar is worth exploring further in some depth.
This month's edition of National Geographic has a feature article on "
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