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In Amyris's process, sugarcane stalks are crushed and the juices are then placed in 5,000-liter fermenters with the company's engineered yeast, which makes a diesel-precursor molecule. (The company has tested the process in 60,000-liter fermenters, but the demonstration plant is not yet operating at this scale.) As the oily molecules are produced, they separate and float to the top of the solution, aided by a centrifuge. The low energy required for this separation, says Renninger, is one of the cost advantages of making hydrocarbons rather than ethanol. Centrifugation requires just one-ten-thousandth of the energy content of the diesel fuel; water-soluble ethanol, by contrast, must be distilled from fermentation solution, a process that takes one-third of its energy content. The hydrocarbons are then hydrogenated at low temperature and low pressure to make diesel or other compounds.
Sugarcane also comes out ahead of corn on environmental measures. Compared with petroleum fuels, the use of corn ethanol leads to a net 10 percent decrease in greenhouse-gas emissions. Burning sugarcane ethanol instead of petroleum leads to a 60 to 80 percent decrease in greenhouse gases, says Renninger. Relative to sugarcane ethanol, the company says, the Amyris fuels made from sugarcane release another 10 percent less.
However, many experts say that it will be far more environmentally beneficial to use biomass other than crops to make biofuels. Techniques for converting fast-growing, fibrous crops like poplar and switchgrass into fermentable sugars are still in development and are currently too expensive. "Cellulosic conversion has to come down in price," says Helena Chum, a research fellow at the National Renewable Energy Laboratory. Amyris plans to expand into the United States once technologies for doing this conversion economically are further developed. The company's business strategy--to start producing in Brazil, where costs are low, and then expand when cellulosic technologies are ready--is "very smart," says Chum.
A startup says it can make sugar for biofuel from wood chips at a fraction of the normal cost.
Newly engineered E. coli streamline the conversion of cellulose into fuel.
I overlooked the fact that this company is creating hydrocarbon fuel, rather than ethanol. However, since their feedstock is the same (sugar, rather than the cellulosic parts), the energy yields should be comparable.
Sadly, the comment is factually challenged. The Amazon is simply not suitable climatically for sugarcane production. Secondly, soon as the cellulosic ethanol production technology matures, potential yields will be over 12,000 litres ethanol/ha. But since great strides are being made in eliciting the production of biobutanol and hydrocarbons, soon as the technologies are scaled commercially, ethanol will invariably be displaced as a fuel of choice for the reasons stated (e.g. low energy denisty).
Not All is Rosy With Biodiesel
Please have a look at this research concerning carbonyl emissions from biodiesel: http://politicalecology.xyvy.info/?p=1333
Thanks
One more option for fuel from Sugarcane.Brazil being leader in ethanol production will be leader in the above production also.
Dr.A.Jagadeesh Nellore(AP),India
E-mail: anumakonda.jagadeesh@gmail.com
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demre
4 Comments
This is a farce
You overlooked an obvious environmental problem. Have you done the simple back-of-the-envelope calculation, on how much land this technique consumes? I'll tell you: it would take three Amazon rainforests of land to meet present oil consumption (which is of course rapidly RISING as the developing world ascends). In short, it is completely unscalable and hence worthless as a practical, world-size energy resource.
In numbers: a typical yield figure for sugar-cane ethanol, according to A. da Rosa, "Fundamentals of Renewable Energy Processes, 2005" (via wikipedia), is 4,000 litres/hectare-year (for Americans, 430 gallons/acre per year. A hectare is (100 meters)^2 or 10,000 meters^2).
http://en.wikipedia.org/wiki/Sugarcane#Cane_ethanol
2008 world crude oil production was 81.8 million barrels/day, or (an oil barrel being 159 L) 4.75 trillion litres per year.
http://www.bp.com/sectiongenericarticle.do?categoryId=9023770&contentId=7044467
http://en.wikipedia.org/wiki/Barrel_(volume)#Oil_barrel
Ethanol has 65% of the volumetric energy density of crude oil, 24 megajoules/litre vs. 37 MJ/L:
http://en.wikipedia.org/wiki/Energy_density#Energy_densities_ignoring_external_components
And the Amazon rainforest has a total area of 5.5 million km^2, or 550 million hectares:
http://en.wikipedia.org/wiki/Amazon_Rainforest
So, put together: the sugar ethanol potential of the entire Amazon, is 550 M ha * (4000 L/ha*year) = 2.2 trillion L/year of ethanol. This is the energy equivalent of 1.4 trillion L/year of crude oil, or under 1/3rd of current world production.
For those checking this, I recommend Google Calculator, if you haven't yet discovered it.
http://www.google.com.au/help/calculator.html
There is no way around it: growing sugar cane is an absurdly inefficient use of resources. There is no chance of replacing oil with Brazilian ethanol, and even a making a tiny contribution would have gigantic environmental effects, such as deforesting large parts of the Amazon (besides less newsworthy effects such as fertilizer runoff and algal blooms.)
Any serious candidate for replacing oil would need to be an exceedingly energy-dense resource, just like oil deposits are. The measly 0.3 W/m^2 of sugar cane ethanol isn't a candidate. Nuclear reactors are the best bet, creating synthetic fuels such as methanol or dimethyl ether (using atmospheric CO2 as a feedstock - analogous to biofuels, except with high-power industrial chemistry in place of photosynthesis), or hydrogen or its derivatives (ammonia or metal hydrides). A single 3 gigawatt reactor, with 50% efficient conversion of heat to fuel, would equal 5,000 km^2 of sugar cane plants. A thousand such reactors are equal to the whole Amazon rainforest converted into a fuel plantation. Three thousand would completely replace oil on earth.
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gametheoryman
21 Comments
ethanol is only for a transition
First, traditional ethanol is only for a transition to cellulosic ethanol. The infrastructure is necessary for a quick introduction of cellulosic ethanol. Not only are energy yields per hectare higher if you grow some feedstock for it, you don't need to grow anything extra for it at all. Available waste feedstock is huge. Not just agricultural wastes, but forestry waste.
From the same fields, without any additional crops, you then have corn going for food and waste stover for ethanol, sugar for food and waste bagasse for ethanol. From the forests, without any additional lumbering, waste wood chips from existing lumbering, from downed or diseased trees, and from fire reduction efforts goes to ethanol.
Second, for most of the world, ethanol from any source is not intended to replace gasoline or diesel entirely. Oil and natural gas are still going to be used, but more slowly. Also, with ethanol always available, the higher octane and cooling properties from ethanol allow gasoline engines to be optimized for it to increase the efficiency of gasoline by a third.
Third, the eventual long-term replacement for fossil fuels is not ethanol, but renewable sources of electricity.
Reply
decook2
1 Comment
nuclear poor sole source of energy
Just doing some more back-of-the-envelope calculations. 3 gigawatt power plant with a conservative capital cost of $5000/kwh (http://energyscience.org.au/FS01%20Economics.pdf) would have a total capital cost of $15 billion. there are very few utilities, even on joint ventures that could raise this kind of money. To go one step further, 3000 3-gigawatt plants would require $45 trillion in investment. For comparison, this would be a large percentage of the world's assets. Furthermore there is the issue of increased capital costs of electric powered cars running on either rechargable or dry-cell (hydrogen or other fuel cell).
All of this seems a bit far fetched, I would suggest continuing along a path of multiple prong approach; fuel diversity and decreased demand by behavior and efficiency improvements.
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