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In Antonietti’s scenario, every-thing that pollutes the countrysidetoday, everything that farmers plowunder to get rid of and everythingthat gardening enthusiasts toss ontothe compost heap or into the bio-waste container becomes valuableraw material. By way of coal, it canbe used to obtain gasoline, diesel fu-el or key chemicals, or it can betransformed into topsoil and evenused in fuel cells to obtain energydirectly. No additional carbon diox-ide is created in the process – infact, large quantities are actually

pulled out of the atmosphere andbound.

Is this utopian? A sophistry of anacademic crackpot? No. ChemistMarkus Antonietti takes a very fun-damental approach to the subject.For example, he first looked at theenergy landscape of various carboncompounds: “Ultimately, biomassconsists of sugar building blocks thatcontain a lot of energy. Using achemical process to break them downinto carbon and water doesn’t requireany further energy to be added, butrather, it actually releases additional

energy.” Nature showed us how it’sdone: over the course of millennia,coal, petroleum and natural gas werecreated from dead plants – in otherwords, biomass – deep within theEarth’s layers. We all learn this inschool. “But no one had previouslygiven much thought to how it reallyhappens,” Antonietti muses.

THE LIBERTY TO ASK

TRIVIAL QUESTIONS

His in-depth literature researchyielded many speculations and tru-isms – there is frequent mention of

Institute Director Markus Antoniettipulverizes a tiny crumb of coal on

his palm and inhales with obviouspleasure: “Mmmm, I like this smell!”A newly developed men’s cologne?No, but rather, perhaps, the begin-ning of a new era in the energy in-dustry. In Antonietti’s vision, carbontakes center stage – just as it alreadydoes in the real world: the fossil fu-els that we extract from the groundat a rate of billions of tons each yearkeep the economy running, form thebasis for power generation and serveas a raw material for the chemicals

industry. But the flip side is thatpractically all recovery methods ulti-mately produce carbon dioxide(CO2). It makes up 80 weight percentof the world’s entire industrial ex-haust. This means nothing more andnothing less than that we are con-verting our fossil deposits into gasand scattering them into the atmos-phere at an alarming pace. The bios-phere can bind only about a third of them globally. The results havesince become known: the green-house effect, global warming andclimate change.

Markus Antonietti wants to put anend to this, and he beats nature at itsown game: he invented an extremelysimple method that could revolu-tionize the industrial carbon cycle,as it uses the world’s enormous bio-mass stores to produce coal, humusor oil – directly and without any ofthe complicated process steps thatare commonly used in biomass uti-lization today. At the same time, thisprocess also releases energy. ThePotsdam-based chemist works withpure waste: straw, wood, wet grass,damp leaves.

ENERGY

Magic Coalfrom the Steam CookerProof that basic research is by no means confined to ivory towers,

but can indeed be useful in solving burning issues of practical

relevance, has been provided by MARKUS ANTONIETTI, Director

at the MAX PLANCK INSTITUTE OF COLLOIDS AND INTERFACES

in Potsdam. He has developed a process with which biomass

can easily be converted into valuable raw materials.

Producing the “magic coal” releases energy. An explosion in the lab on the roof of the Max Planck Institute of Colloids and Interfaces proved this very impressively.

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trode concepts in Mainz and toRobert Schlögl’s new methanol cat-alysts in Berlin. So the carbon vi-sion of the Potsdam-based instituteDirector is not the only result of thehigh-caliber collaboration. Key im-pulses for future energy conceptscan be expected from this group ofMax Planck scientists in the yearsto come.

Back to Markus Antonietti. His so-lution is impressively simple: putbiomass and water into a pressurecontainer, add a couple of bits ofcatalyst and heat it all up to180 de-grees Celsius in the absence of air.After 12 hours, allow the mixture tocool, open the “steam cooker” andyou have a black broth. “Our analy-ses showed that these are extremelyfinely distributed spherical coal par-ticles in water,” explains MagdaTitirici, who has since conductedhundreds of these experiments. Forthe experiment, their Director, An-tonietti, plundered his garden andbrought in oak foliage, pine needles,bits of wood and pinecones. That iswhy some of the newly formed coalcrumbs still contain fragrant resinsand smell pungent and spicy.

Biomass is already being used to-day, but in other ways – for examplein the form of biodiesel obtained

FOCUS ENERGY

from vegetable and animal fats.However, the facts immediatelyshow that it can do no more than filla niche: mankind currently con-sumes 4 billion tons of petroleumeach year, while global productionof fats is just 120 million tons. Thiswould be sufficient to supply allcars in Germany with biodiesel, butthen the world would have nothingleft to eat.

So valuable products such as fatsmust be avoided, and preference giv-en instead to cheap waste. Of coursewe can simply burn it, but that pro-vides little energy, because biomassis usually wet and must first bedried. Furthermore, burning it re-leases carbon dioxide. Anothermethod that is used today is fermen-tation of biomass, which producesethanol and, likewise, CO2. “Howev-er, alcoholic fermentation has an es-timated real efficiency of 3 to 5 per-cent of the primary energy stored inthe plants,” says Antonietti. “And af-terwards, the alcohol still has to beseparated from the water. It takes 30cubic meters of beer to get one cubicmeter of pure alcohol. That’s not agood solution for fuels.”

Furthermore, converting biomassinto biogas is not optimal from anenergy standpoint. “What we use as

an energy source is really a byprod-uct of microbial metabolism,” saysthe chemist, “and half of the carbonis released again as CO2.” This leavespyrolysis. This method carbonizesthe biomass by heating it to ex-tremely high temperatures in the ab-sence of air. However, this requiresthat the vegetable material be dry,otherwise the energetics of theprocess are not worth it.

A WONDERFUL

GIFT OF NATURE

Antonietti’s plan to use vegetablewaste is much cleverer, and that iswhy it will rule the future: his hy-drothermal carbonization completelyconverts biomass – even when it iswet – into carbon and water. “Andthat is the crux,” enthuses the MaxPlanck Director. “No CO2 is produced– the sole byproduct is simply water.All of the carbon contained in thematerial remains bound in the prod-uct. This means that our carbon effi-ciency is 100 percent. The carbon weput in at the beginning comes out ascarbon at the end – the best solutionfor the carbon balance. It isn’t possi-ble to sustainably bind more carbonthan that.”

The formula makes it obvious: ifyou remove five water molecules

from a sugar molecule, you get prac-tically pure carbon with a couple ofresidual hydrogen and oxygengroups: lignite. This is made up oftiny spheres and is extremelyporous, with a pore size of 8 to 20nanometers, which is very interest-ing for many applications. “This ispurely coincidence,” says Antonietti,“we never planned it – it is a gift ofnature.” The carbonized pineconestill retains its original form, but it isno longer a pinecone, but rather,strictly speaking, a nanoproduct.

Nature does exactly the samething, but very slowly. Peat takes500 to 5,000 years to form, lignite50,000 to 50 million years, and an-thracite formed from carbon is even150 million years old. The Potsdam-based researchers, on the other hand,can do it overnight. And their reac-tion is an exothermic one, meaningthat heat is created spontaneously. Infact, during one of the experiments,the reaction chamber exploded be-cause too much energy was released.“What is so ingenious about thisprocess is its simplicity,” saysMarkus Antonietti. But it is appar-ently too obvious to be included intextbooks. “Even Edgar Allan Poeknew that the best place to hide any-thing is in plain view.” ®

the “carbonization process,” but noone had yet advanced to the core ofthe issue, namely, how this actuallytakes place. Antonietti had thecourage to do just that. “Today I takethe liberty to ask such questions,”says the 46-year-old chemist, “evenat the risk of being considered acrackpot. I would rather put my rep-utation at stake than not come closerto the truth.” In the case of coal, hisvery first attempt met with success.The researcher not only found outhow coal forms but, quite incidental-ly, he even discovered a process thatcould well change the world.

Of course, the general public is ba-sically aware how important a sus-tainable energy supply is for the fu-ture of our society. What is far lessknown, however, is that there is stilla lot of research to do; and it is notjust about process technology andprocess control, or boosting outputand efficiency. No, even today, it isstill about very fundamental prob-lems that can be solved only throughbasic research – and that thus num-ber among the traditional domainsof the Max Planck Society.

To address this, in 2004, five MaxPlanck Directors joined to form theENERCHEM research network, a“project company for nanochemical

concepts for sustainable energy sup-ply.” The projects range from im-proved catalytic methods for gener-ating hydrogen to work on imitatingphotosynthesis and storing hydrogenin novel media (MAXPLANCKRESEARCH

2/2005, page 14 ff.).Antonietti’s work with coal also

fits into this organizational frame-work. “ENERCHEM offers the idealenvironment for this,” he empha-sizes, “we are well positioned withinthe organization and have all thecompetence we need to evaluate ourideas.” That is beneficial for every-one involved, in terms of patentrights, statutes, and even communi-cations: “All of the partners have thesame cultural background, even ifwe are very different personally. Thisway, we know that the signals wetransmit are received as intended.”

CREATIVE COLLABORATION

CREATES IMPETUS

All ideas, inventions and problemsare intensively discussed among thecolleagues, considered by expertsand critically tested. This appliesequally to Joachim Maier’s innova-tive battery concepts in Stuttgartand to Ferdi Schüth’s improved hy-drogen storage in Mülheim, to KlausMüllen’s nanotechnological elec-

Hydrothermal carbonization in a pressure container turns biomass, such as orange peels, into extremely fine powdered coal(left). On the right is the inventor of the method, institute Director Markus Antonietti, with his colleague Anna Fischer.

Put some biomass, such as greens, into a pressure container (left), add a couple of crumbs of a catalyst and heat it all up to 180degrees Celsius in the absence of air: 12 hours later, out comes the black powder consisting of coal nanospheres (right).

Alcohol

2760 kJ/mol

2 C2H5OH + 2 CO2

CE = 0.66 percent

Biogas

2664 kJ/mol

3 CO2 + 3 CH4

CE = 0.5 percent

Lignite

2135 kJ/mol

C6H2O + 5 H2O

CE = 1 percent

CO2 + H2OCarbon dioxide+ water0 kJ/mol

C6H12O6 (biomass)

3240 kJ/mol

+ O2

Anaerobic conversion

Hydrothermal carbonization

Combustion metabolization

Alcoholic fermentation

CE = 0

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So what is the coal-water mixturegood for? It could, of course, beburned as coal, but that would justbe the easiest solution and by nomeans the best one. It is much better,for example, to use this fine pow-dered coal and water mixture to op-erate a new kind of fuel cell. Theprototypes, which already exist to-day (for example at Harvard Univer-sity), have an efficiency of 60 per-cent. It is operated with “coal slurryin water” – like that formed in hy-drothermal carbonization.

To generate fuel with it, ratherthan electricity, the carbon-watermixture is simply heated up evenmore, as then an exothermic reactioncreates what is known as syngas, orcarbon monoxide and hydrogen.This can be used directly to producegasoline using the tried-and-testedFischer-Tropsch process. The bio-mass used has also become a veryvaluable source product that can bepiped out or converted to gasoline.“Instead of simply letting a cubicmeter of compost decompose in acorner of your garden, in the future,you could take it to a local factoryand get 200 liters of gas back,” saysAntonietti, envisioning the practicalimplementation.

1,300 LITERS OF

BIODIESEL PER HECTARE

There is plenty of biomass in theworld, although its potential is diffi-cult to assess. The International En-ergy Agency cites various studieswhose spectrum ranges from 9 tomore than 360 billion kilowatthours per year. One study by theWorld Energy Council even callsbiomass “the potentially largest andmost sustainable energy source inthe world.” However, experts alsoadd that: “Both the production andthe use of biomass still need to bemodernized.”

Indeed, current usage, for exampleas fuel, is not particularly efficient:when biodiesel is produced fromoleaginous fruit, one hectare offarmland yields about 1,300 liters offuel, because only the seeds of the

plants are used. “If fast-growingplants were cultivated there instead,such as willow wood, reeds or evenjust normal forest, and fuel then pro-duced from the entire biomassthrough hydrothermal carbonization,14 cubic meters of fuel could be ob-tained per hectare,” says Antonietti.That would be 10 times the amountcited above. According to estimatesof the Forschungszentrum Karlsruhe,Germany alone produces some 70million tons of dry biomass annuallyfrom biogenic residues and waste.That would be more than enough tosupply our fuel.

But it gets even better, becauseAntonietti’s process does muchmore: inside the steam cooker, bio-mass is not abruptly converted tocoal. Instead, gradual processes takeplace that form intermediate prod-ucts that are at least as useful as theend product carbon. If we open thecontainer after just a few minutes,we find a petroleum precursor. “Re-move, for instance, three watersfrom the sugar molecule, rather thanfive,” explains the researcher. Thisintermediate is still too reactive, butwith a bit of research, he hopes totame it to such an extent that “wecan also produce oil directly fromplant waste.”

Another intermediate of hydrother-mal carbonization is already moretechnically sophisticated: after theliquid phase, a pulpy solid forms in-side the pressure container. It is noth-ing other than what we buy at thegarden center as potting soil: humus.The Potsdam chemists are actuallyable to use their method to turn plantmatter into pure topsoil with 100 per-cent carbon efficiency. Natural com-posting, on the other hand, generallyproduces only about 10 percent soil,while the rest escapes into the air asmethane and carbon dioxide. “This isthe most important process in naturein which energy volatilizes,” explainsMarkus Antonietti.

Our predators, as it were, are mi-crobes. When we toss something intothe forest, such as straw, leaves orwood, it eventually just disappears –

but the energy associated with it dis-appears, as well. We feel good aboutit because we don’t see what hap-pens, but the truth is that, when wedo this, we are producing enormousamounts of carbon dioxide andmethane. In Markus Antonietti’swords: “Viewed this way, the forestis not just a blessing for the environ-ment, it is also the world’s biggestpolluter!”

A NEGATIVE CARBON

DIOXIDE BALANCE

If, however, we were to use the arti-ficially produced topsoil to vegetateeroded areas in southern Spain or inthe tropics, plant growth could beused to bind large quantities of car-bon dioxide in the air, creating anegative CO2 balance there. Foryears, Johannes Lehmann of CornellUniversity in Ithaca (USA) has beenworking on this method of makingburned soil along the Amazon fertileagain – with highly encouraging re-sults. However, Lehmann and his

colleagues have been using matterthat was produced by pyrolysis.

Markus Antonietti is proud of howhe and his team have achieved theirsuccesses: “We all looked at nature –we truly gave meaning to the wordbiomimesis. It’s the old familiartrick: if someone doesn’t knowsomething on a test in school, he sitsnext to the smartest kid in the classand tries to learn from his approach.After all, we live in a system that hasbeen functioning in a cycle for mil-lions of years. We can learn a lotfrom its rules.”

The researcher is well aware that itwill take time for his ideas to catchon: “I would be pleased if peoplewould come up and say: I want totake part. Owners of small gardencenters who want to try somethingout and be part of this change invalues. My hope is that people willsee a future again, and become pa-trons of science or perhaps even getactively involved.”

BRIGITTE RÖTHLEIN

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+H2

Inco

mpl

ete

carb

oniza

tion

Fischer-Tropschprocess

“NegativeCO2 balance” BriefcarbonizationComplete

carbonization

Ener

gy

New

pla

nts

+ CO2 + 3 CH4

Gasoline

More biomassCE >1

TopsoilCE ≈1

Gasoline

Biomass

Liquidintermediate

CE ≈1

Energy+ CO2

Carbonfuel cell

SyngasCO + H2CE ≈1

CarbonslurryCE ≈1

Biomass

Ener

gy

TopsoilCE ≈ 0.05

New

pla

nts

New biomass

Composting Fermentation Digestion Pyrolysis

BioethanolCE ≈ 0.66

Energy+ CO2+ CO2 + 3 CH4

+ CO2BiogasCE = 0.50

Combustion

SyngasCO + H2CE ≈1

Fischer-Tropschprocess

Gasoline

+ CO2

AN ALTERNATIVE VISION OF BIOMASS MANAGEMENT: Thevarious technologies of hydrothermal carbonization can be used to produce, with very highcarbon efficiency, artificial topsoil that sustainably improves the quality of barren soil. In this way, it serves to create greater quantities of biomass (negative CO2 balance). How-ever, the carbon slurry that forms upon “complete carbonization” of waste matter can also be used for energy, for example in central plants for manufacturing syngas. Or – according to one vision – it can be fed into carbon fuel cells. A better understanding of the processes that take place during carbonization should also make it possible to obtainliquid fuels directly. For this, however, due to the fundamental chemical equilibria involved,hydrogen has to be added from other sources.

THE THIRD ALTERNATIVE: Carbohydrates such as cellulose, starch andsugar are energy storage molecules that release a lot of energy when burned. Theo-retically, 15 percent of the stored energy is already lost when sugar is converted toalcohol, and two of the six carbon atoms are immediately released as CO2 (carbonefficiency CE = 0.66). In anaerobic conversion, when producing biogas, ideally, 18percent of the energy is lost, and half of the bound carbon is released again. How-ever, both alcoholic fermentation and biogasification are biological processes thatare not as efficient as theory predicts.

The hydrothermal carbonization method described here binds, in a chemical process,nearly 100 percent of the original carbon as coal or topsoil, retaining 66 percentof its original calorific value and the rest occurring as process heat. This thirdmethod makes sense anywhere that direct combustion isn’t possible, or where thematerial isn’t sufficiently accessible to the biological processes.

CE = Carbon efficiency:share of carbon

that remains bound

www.films.mpg.de

CE = Carbon efficiency:share of carbon

that remains bound

BIOMASS MANAGEMENT TODAY: By far the majority of biomass decom-poses directly into atmospheric carbon dioxide and methane right where it forms. Only very small quantities become topsoil or otherwise turn into a carbon sink (for instance inswamps or on the ocean floor). Current biomass utilization technologies include – apartfrom direct burning of wood and straw – alcoholic fermentation, biogas production in digesters, and direct syngas production.

ENERGY