Enviado por Jim Thomas el
Jim Thomas
Written for The Ecologist - February 2009
The next big hit fuelwise will have corporations falling over each other to claim plant life, but the comedown could leave us in a sticky mess
What runs our economy after oil? How about sugar? All those acres of corn and cane being liquefied into biofuels– that’s sugar replacing oil. Those bioplastics that your food now comes wrapped in: sugar. By 2015, the chemical industry expects that a fifth of all its production of chemicals will be based on sugar. As petroleum (fossilised sugar) becomes less accessible, the new feedstock of choice for our industrial system appears to be the white stuff.
Or more precisely the green stuff – because the type of sugars you and I put on cornflakes is only a fraction of what is being eyed up for fuels, plastics and chemicals production. This new sugar-fuelled economy is being labelled ‘the new bioeconomy’ and at a glance, the opportunity seems huge. Looked at from space, the Earth is after all a sugar-coated planet. If you were to boil down all the green parts of the picture – the forests, the prairies and the blooms of algae – you’d find that most of what you were left with (about 75 per cent) would be sugars: a mix of carbon, oxygen and hydrogen atoms arranged into glucose, sucrose, xylose, galactose, mannose, arabinose, hemicellulose and cellulose.
Cellulose in particular is the most common organic compound on Earth. About 33 per cent of all plant matter is cellulose (in wood that figure is 50 per cent, in cotton, 90 per cent). The problem with cellulose is that it usually comes bound up with a hard-to-breakdown fibrous substance called lignin. As a result, there is now a concerted effort underway to liberate the world’s cellulose from its lignin captor. Biotech companies such as Genencor, Novozyme and Verenium are developing powerful new enzymes, known as cellulases, which will munch through lignin so that cellulose can be fermented into fuels and plastics. Synthetic biology researchers are building designer bugs that will turn ligno-cellulosic material directly into high value chemicals. US and European research money is pouring into designing sugar platform factories, known as biorefineries that, in time, might transform cellulose and lignin into almost any chemical compound you care to make.
Of course, the new green gold of this sugar economy is plant biomass – whether wood chips or prairie grasses or left over corn stalks on fi elds. That which was previously considered worthless plant trash is now a potential source of high value fuels, chemicals and plastics. Expect to see a concerted corporate grab on plant-life in the coming years – on forests, seaweeds and set-aside farmland. For industry, the coming switch to cellulose represents an opportunity to commercialise the 76 per cent of the earth’s plant matter grown every year that has not yet been appropriated for human use – a large new source of capital.
Which begs the question: do we want to see the chemical and fuels industry lay claim to all of the worlds living plant matter? What looks like a gleaming industrial opportunity will be sold as a green lifestyle option, but may in fact be an ecological disaster. It would be wrong to portray that 76 per cent of uncommodified plant-life as ‘unused’. Far from having a surplus of plant matter we may in fact already be well overdrawn. Those ‘unused’ forests clean our air and water, algae regulates our climate and crop waste rebuilds our soils.
Far from having a surplus of plant matter we may in fact already be well overdrawn.
Every year the Global Footprint Network calculates how much new plant-life we can afford to consume before destroying the ecosystem functions performed by those plants. Since the mid-1980’s, we have been exceeding the carrying capacity of the Earth and eating into stocks of plant-life that we cannot afford to destroy. In 2008, we had used up all the new plant-life available to us by September 23 – a date ominously designated ‘Earth Overshoot Day’. Unfortunately, Earth Overshoot Day is coming earlier every year and with the advent of the sugar economy the term ‘overshoot’ may prove too benign. As any sugar addict can tell you, after the sugar rush there’s always the sugar crash. If Earth’s overshoot gives way to a planetary sugar crash, we might rue moving our economy from petroleum to sugar as switching from one unsustainable feedstock to another.