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Diesel from Cellulose by bacteria

Page history last edited by PBworks 12 years, 1 month ago

Genetic engineering, widely decried by enviromentalists as interfering

with good old Mother Nature, may ultimately provide critical

componants of the mess we're in as a species and as a planet. Just as

some folks are working to engineer a bug (bacteria, i.e.) that can

produce molecular hydrogen in commercial quantities, while others are

training germs (bacteria - we sure have a lot of slang words for these

guys don't we??) to turn cellulose into fuel in an energy-efficient

manner, other bio-engineering companies are coaxing bacteria to

produce biofuels that WON'T harm the biosphere - well certainly not as

much as planting hundreds of km2 of sugar cane or palm trees on top of

precious mature ecosystems.....one HAS to ask, however: Why aren't

governments around the world funding this kind of research??? Are

they too much in the pockets of Big Oil, Agribusiness giants and other

corporate interests that stand to lose market share if biotech firms

come up with better solutions than they do? Or are there other reasons

also?

Ross Mayhew - Climate Concern

 

http://www.enn.com/pollution/article/37480

 

The biofuels of the future will be tailor-made

 

BURIED in the news a few weeks ago was an announcement by a small

Californian firm called Amyris. It was, perhaps, a parable for the

future of biotechnology. Amyris is famous in the world of tropical

medicine for applying the latest biotechnological tools to the

manufacture of artemisinin, an antimalarial drug that is normally

extracted from a Chinese vine. The vines cannot produce enough of the

stuff, though, so Amyris?s researchers have taken a few genes here and

there, tweaked them and stitched them together into a biochemical

pathway enabling bacteria to make a chemical precursor that can easily

be converted into the drug.

 

But that is not what the announcement was about. Instead, it was that

Amyris was going into partnership with Crystalsev, a Brazilian firm,

to make car fuel out of cane sugar. Not ethanol (though Brazil already

has a thriving market for ethanol-powered cars), but a hydrocarbon

that has the characteristics of diesel fuel. Technically, it is not

ordinary diesel, either: in chemist-speak, it is an isoprenoid rather

than a mixture of alkanes and aromatics. But the driver will not

notice the difference.

 

The point of the parable is this: biotechnology may have cut its teeth

on medicines, but the big bucks are likely to be in bulk chemicals.

And few chemicals are bulkier than fuels. Where Amyris is leading,

many are following. Some small firms with new and interesting

technologies are trying to go it alone. Others are teaming up with big

energy firms, in much the same way that biotech companies with a

promising drug are often taken under the wing of a large

pharmaceutical company. The big firms themselves are involved, too,

both through in-house laboratories and by giving money to

universities. Biofuels, once seen as a cross between eccentric

greenwash and a politically acceptable way of subsidising farmers, are

now poised to become big business.

 

The list of things that need to be done to create a proper biofuel

industry is a long one. New crops, tailored to fuel rather than food

production, have to be created. Ways of converting those crops into

feedstock have to be developed. That feedstock has then to be turned

into something that people want to buy, at a price they can afford.

 

All parts of this chain are currently the subjects of avid research

and development. Some biofuels were already competitive with oil

products even at 2006 oil prices (see table 5). The R&D effort will

bring more of them into line, as will any long-term rise in the price

of crude oil.

 

As far as the crops themselves are concerned, there are three runners

at the starting gate: grasses, trees and algae. Grasses and trees are

grown on dry land, but need a lot of processing. The idea is to take

the whole biomass of the plant (particularly the cellulose of which a

plant-cell?s walls are made) and turn it into fuel. At the moment,

that fuel is often ethanol. Hence the term "cellulosic ethanol" that

has gained recent currency. Algae, being aquatic, are more fiddly to

grow, but promise a high-quality product, oil, that will not need much

treatment to become biodiesel.

 

One of the leading proponents of better grasses is Ceres, a firm based

in Thousand Oaks, California. The species it has chosen to

examine—switchgrass, miscanthus, sugarcane and sorghum—are so-called

C4 grasses. These are favourites with the biofuel industry because

they share a particularly efficient form of photosynthesis that

enables them to grow fast. Ceres proposes to make them grow faster

still, using a mixture of "smart" breeding techniques (in which

desirable genes are identified scientifically but assembled into

plants by traditional hybridisation) and straightforward genetic

engineering.

 

The chosen grasses also thrive in a range of climates. Switchgrass and

miscanthus are temperate. Sugarcane and sorghum are tropical. Ceres

proposes to extend their ranges still further by creating strains that

will tolerate heat or cold or drought or salt, allowing them to be

grown on land that cannot be used for food crops. That will make them

cheaper, as well as reducing the competition between foods and biofuels.

 

Trees, meanwhile, are the province of firms such as ArborGen, of

Summerville, South Carolina. Like Ceres, ArborGen is working on four

species: eucalyptus, poplar, and the loblolly and radiata pines. It is

applying similar techniques to those used by Ceres to speed up the

growth of these trees and to increase their tolerance of cold.

Although creating raw materials for biofuels is not this company?s

only objective (paper pulp and timber are others), it sees such fuels

as a big market.

 

Algae, too, are up for modification. One problem with them is

harvesting the oil they produce. That means extracting them from their

ponds, drying them out and breaking open their cells. This process is

so tedious that some companies are considering the idea of burning the

dried algae in power stations instead.

 

One firm that is not is Synthetic Genomics, the latest venture of

Craig Venter (the man who led the privately funded version of the

Human Genome Project). Dr Venter hopes to overcome the oil-collection

problem by genetic engineering. Synthetic Genomics?s algae have been

fitted with genes that create new secretion pathways through their

outer membranes. These cause the algal cells to expel the oil almost

as soon as they have manufactured it. It then floats to the surface of

the pond, allowing it to be skimmed off like cream and turned into

biodiesel. The algae are also engineered to make more oil than their

wild counterparts.

 

Harvesting useful fuels from vascular plants, as grasses, trees and

their kind are known collectively, is a trickier business. These

plants are composed mainly of three types of large molecule. Besides

cellulose, there are hemicellulose and lignin. Each is made of chains

of smaller molecules, and all three are often bound together in a

complex called lignocellulose, particularly in wood. There are many

ways these long-chain molecules might be turned into fuel, but all of

these processes are more complex than for algae.

 

As chart 6 shows, turning sunlight into biofuel involves three steps,

though different methods may miss out some of these steps. Algae can

make the leap from start to finish directly, whereas vascular plants

cannot. One way of dealing with them is to dry them and then heat them

with little or no oxygen present. This is called pyrolysis and, if

done correctly, results in a mixture of carbon monoxide and hydrogen

called "syngas" (short for synthesis gas). With suitable catalysts,

syngas can be turned into fuel.

 

This is the approach taken by Choren Industries in Freiburg, Germany,

and Range Fuels in Treutlen County, Georgia. In both cases the

feedstock is chippings and other leftovers from forestry and

timbermills. Choren is making hydrocarbon diesel and Range ethanol.

Both factories, therefore, are steps on the road to making fuel from

trees. Syngas can also be turned into ethanol by bacteria of the genus

Clostridium (a group better known for the chemical used in botox

treatment). That is being done by Coskata, a firm based in

Warrenville, Illinois. General Motors (GM) likes this idea so much it

has bought a share of the company.

 

An alternative to the syngas method is to break the cellulose and

hemicellulose up into their component "monomer" molecules. That is

easier said than done, particularly if lignin is involved, since

lignin is resistant to such conversion. The amount of coal in the

world is proof of its resilience. Coal is composed mainly of lignin

from plants that failed to decompose completely and were fossilised as

a result.

 

Many firms, however, have developed enzymes that break down biomass in

this way. Iogen, of Ottawa, Canada, was one of the first. Its enzymes

decompose cellulose and hemicellulose into sugar monomers. (The lignin

is burned to generate heat for the process.) Abengoa, a Spanish firm

that is also involved in solar energy, uses this approach as well.

 

Once you have your sugar, you can ferment it. These days that need not

mean using yeast to make ethanol. A whole range of bugs, some natural,

some engineered, can now be deployed to make a whole range of

products. Amyris?s souped-up micro-organisms (some are bacteria, some

yeasts) turn sugar not into ethanol but into isoprenoids, at a cost

competitive with petroleum-based diesel. LS9, based near San

Francisco, uses a similar method but is turning out alkanes (for

petrol) and fatty acids (for biodiesel). It, too, is starting to scale

up production. Synthetic Genomics is doing something similar, though

the firm is cagey about which fuel is being produced. In each case,

however, what is made is a chemical precisely tailored to its purpose,

rather than the ad hoc mixture that comes out of a refinery. The rival

companies thus argue that their products are actually better than

oil-based ones.

 

At least one firm, Mascoma, of Cambridge, Massachusetts, employs a

single species of bug, Thermoanaerobacterium saccharolyticum, both to

break down the biomass and to digest the resulting sugar. Mascoma will

use both grass and wood as feedstocks. In May it signed deals with GM

and Marathon Oil.

 

It is also possible to use purified enzymes to do the conversion from

sugar to fuel, as well as from biomass to sugar, and at least two

firms are working on applying them to the whole process. Codexis,

based in Redwood City, California, has created a range of enzymes by a

method akin to sexual reproduction and natural selection. Last year it

signed a deal with Shell to use this technique to produce biofuels of

various types. And a Danish firm, Danisco, has teamed up with DuPont

to do the same thing with its own proprietary enzymes.

 

Shell is also involved in a project to turn sugar into hydrocarbons,

this time by straight chemical processing. It is putting up the money.

The technology (the most important part of which is a set of

proprietary non-biological catalysts) is provided by Virent Energy

systems, of Madison, Wisconsin.

 

Which of these approaches will work best is anybody?s guess. But their

sheer number is proof that the most radical thinking in the field of

renewable energy is going on in biofuels. It is in this area that the

most unexpected breakthroughs are likely to come, says Steven Koonin,

BP?s chief scientist. BP is backing one of the biggest academic

projects intended to look into biofuels, the Energy Biosciences

Institute (EBI), to the tune of $500m, which suggests that the

company?s board agrees with him. The EBI is a partnership of the

University of California, Berkeley, the Lawrence Berkeley National

Laboratory and the University of Illinois.

 

One of the people involved, Steven Chu, the head of the Lawrence

Berkeley laboratory, is a man with a grand vision. This vision is of a

"glucose economy" that will replace the existing oil economy. Glucose,

the most common monomer sugar, would be turned into fuels and maybe

even the bio-equivalents of petrochemicals—bioplastics, for example—in

local factories and then shipped around the world. That would be a

boon to tropical countries, where photosynthesis is at its most

rampant, though it might not play so well to James Woolsey?s security

fears, since it risks replacing one set of unreliable suppliers with

another.

 

However, there is plenty of biomass to go around. A study by America?s

Departments of Energy and Agriculture suggests that even with only

small changes to existing practice, 1.3 billion tonnes of plant matter

could be collected from American soil without affecting food

production. If this were converted into ethanol using the best

technology available today, it would add up to the equivalent of 350

billion litres of petrol, or 65% of the country?s current petrol

consumption. And that is before specially bred energy crops and other

technological advances are taken into account. If America wants it,

biofuel autarky looks more achievable than the oil-based sort. And if

it does not, then the world?s hitherto impoverished tropics may find

themselves in the middle of an unexpected and welcome industrial

revolution.

 

 

posted to ClimateConcern

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