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Study shows bamboo ethanol in China technically and economically feasible, cost-competitive with gasoline

1 December 2013

Bamboo, the composition of which is highly similar to energy grasses used for biofuel production such as switchgrass, is an interesting potential feedstock for advanced bioethanol production in China due to its natural abundance, rapid growth, perennial nature and low management requirements.

Now, researchers at Imperial College London have shown that bioethanol production from bamboo in China is both technically and economically feasible, as well as cost-competitive with gasoline. An open access paper on their study is published in Biotechnology for Biofuels.

Bamboo2
Bamboo3
China bioethanol pump price for five enzyme loading scenarios in (a) 2011 with a 16¢ per liter (60.6¢ per gallon US) subsidy and fuel excise and value-added tax exemptions, and (b) a prospective future scenario with no form of government support measures. Click to enlarge.

In 2011, China contributed 29% of world carbon dioxide emissions and therefore the country has a significant potential to influence the present and future global energy situation. Currently, almost half of China’s oil consumption is imported, and with the projection that demand for fossil fuel oil will reach 250 million tons by 2030, it is crucial for the country to consider biomass alternatives as part of their renewable energy plan. In 2009, the number of private cars owned in China exceeded the United States, resulting in it being the world’s largest auto market. Establishment of a biofuel industry in China is therefore an attractive solution to manage the problems of environmental pollution, energy independence and rural development within the transport sector.

In its development of biofuel policy, China’s 10th five-year plan (2001–2005) proposed a biofuel industry to utilize surplus grain stocks. Through the government’s support for biofuel production, China has become the third largest bioethanol producer in the world after the US and Brazil, with an overall fuel ethanol production capacity of 1.9 million tons in 2008. Now, approximately 10% of the total liquid fuel supply is accounted for by biofuels, and there has been an increase in pilot plant projects cropping up in Henan, Anhui, Jiangsu and other provinces. However, concerns regarding food security resulted in the government’s order to halt construction of corn-based plants and promote non-food feedstocks which can be grown on marginal and abandoned lands instead. … the lack of a key non-food feedstock that can be grown on such lands is the major constraint on the expansion of fuel ethanol production in China.

… As a member of the Graminae family, the composition of bamboo is highly similar to other grasses utilised for biofuel purposes (e.g. switchgrass, Miscanthus). Its cell wall is comprised of the polymeric constituents cellulose, hemicellulose and lignin. The complex physical and chemical interactions between these components prevent enzymes from readily accessing the microfibrillar cellulose during the saccharification stage of its conversion into biofuel. As a result of this recalcitrance, a pretreatment stage is needed to maximise hydrolysis of cell wall sugars into their monomeric form.

—Littlewood et al.

Bamboo
Schematic diagram of bamboo-to-bioethanol process in AspenPlus. Littlewood et al. Click to enlarge.

In their study, the Imperial College London team used liquid hot water (LHW) pretreatment to enhance sugar release from bamboo lignocellulose while minimizing economic and environmental costs. Pretreatments were performed at temperatures of 170-190°C for 10–30 minutes, followed by enzymatic saccharification with a commercial enzyme cocktail at various loadings. These data were then used as inputs to a techno-economic model using AspenPlus to determine the production cost of bioethanol from bamboo in China.

At LHW pretreatment of 190 °C for 10 minutes, 69% of the initial sugars were released under a standardized enzyme loading. Under this condition a greater proportion of sugar was released during pretreatment compared with saccharification, whereby the predominant sugars were xylose and glucose in pretreatment and saccharification, respectively.

They also found little improvement in total sugar release despite significantly increasing enzyme loading; even at the highest dosage a portion of cellulose (about 20%) remained resistant to enzymatic hydrolysis. Enzymatic saccharification with five loadings (10–140 FPU/g glucan) of Cellic CTec2 led to a total sugar release ranging from 59-76% of the theoretical maximum.

The economic analysis found that the lowest enzyme loading had the most commercially viable scenario (production cost of $0.484 per liter (US$1.83/gallon US) with tax exemption and a $0.16/liter (US$0.606/gallon US subsidy)) even though it produced the least amount of bioethanol and generated the greatest level of co-product electricity.

This economic result was primarily due to the significant enzyme contribution to cost, which at higher loadings was not defrayed adequately by an increase in the amount of sugar released, the team said.

A cost breakdown and sensitivity analysis of the 10 FPU/g glucan scenario demonstrated that the cost of raw materials was the greatest contributor, with bamboo and enzyme purchase accounting for 51% and 17% of the MESP, respectively.

The supply-chain model showed that bamboo would be competitive with gasoline at the pump in scenarios with enzyme loadings of 60 FPU/g glucan and lower. However the prospective scenario, which made the assumption of no tax breaks or subsidy, demonstrated that lower enzyme loadings would still permit bioethanol from bamboo to maintain its economic competitiveness with gasoline under the technical conversion efficiencies modelled.

Alternative approaches to reduce bioethanol production costs are still needed however, to ensure its competitiveness in a possible future scenario where neither tax exemptions nor subsidies are granted to producers. These measures may include improving sugar release with more effective pretreatments and reduced enzyme usage, accessing low cost bamboo feedstock or selecting feedstocks with higher/more accessible cellulose.

—Littlewood et al.

Resources

  • Jade Littlewood, Lei Wang, Colin Turnbull and Richard J Murphy (2013) “Techno-economic potential of bioethanol from bamboo in China,” Biotechnology for Biofuels 6:173 doi: 10.1186/1754-6834-6-173

December 1, 2013 in Cellulosic ethanol, China | Permalink | Comments (15) | TrackBack (0)

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Comments

Improving the feed stock and conversion methods will probably be required to compete with fossil fuels.

Limited land is available to grow feed stocks to produce bio-fuels.

I wonder if they've tried soaking it in ocean water?

Right, I am not convinced that their approach deserves much attention, bamboo is ok because it is a perennial crop, no need to plow re-seed, less soil erosion etc.. but ethanol not so much, they don't give how much tons of ethanol they can produce by ton of bamboo and neither they give the EROI.

Biofuel makes sense for aircrafts as we can't imagine aircraft flying on batteries or even hydrogen even on a remote future

I would suspect the "tons of bamboo" and EROEI are embedded in the cost.

The real question would seem to be whether there is adequate land to replace all gasoline or only a portion.

You can produce about 1000 gallons of synthetic gasoline per acre of Miscanthus, I would say this could be a similar yield. If you have to ferment to make ethanol, then gasify the rest to make DME and synthetic fuels.

The U.S. has 500 million acres of marginal pasture land not suited to farming. 100 million acres would produce 100 billion gallons of synthetic fuel per year then turn the marginal land into farm land with the root system and stored carbon.

You need to work with net, not gross generation. It would take some portion of the fuel generated to harvest and transport the feedstock.

Cool! Can I be first in line for the hunting license on the pandas? We might as well go ahead and kill them quickly rather than starving them out by taking all their food/land area they need to survive.

LMAO!!! Yes, that was sarcasm because this is a STUPID idea!

YOU HAVE DEGRADED LAND WHICH CAN BE USED FOR GROWING BAMBOO AND NOT LAND WHICH IS USED FOR AGRICULTURE OR FORESTED. RIGHT NOW THERE IS NO USE EXCEPT GROWING GRASS. SUCH LAND CAN SOAK CARBON AND CREATE GREEN FUEL.

If I were them I'd go with electrifying their transportation system and using the bamboo in construction. If you turn bamboo into fuel only the roots are storing carbon long term but if you turn it into laminated lumber the whole plant does.

A stand of bamboo generates up to 35% more oxygen then equivalent stand of trees each year. And because bamboo can be harvested every 4-7 years, which makes room for new growth, a hectar of bamboo ends up sequestering 62 tons of CO2/year while a hectar of young forest sequesters only 15 tons of CO2/year.

That would be a much better idea and it is being done on a very large scale. Laminated compressed bamboo flooring is excellent and last for decades.

The bamboo might be very hard to work with (for milling).

I was at a talk given by a farmer on biofuels and he had tried miscanthus (or maybe hemp), and he said it was so tough that it wrecked all his machines. The same might happen with bamboo.
(unless they genetically engineer it to be easier to work with [ which is possible ] ).
+
What happens to the land where you grow bamboo - can you crop it year after year without wrecking the soil quality ?

Clearly today machine to harvest straw are not suited to harvest Miscanthus, you need new tools capable or coping with stronger stems. that might be a limitation for fast harvest by the way. But in Canada they have machine that can cut 10 young pine trees at once, so i bet there is solution for bamboo large scale collections...

when you start to grow bamboo it is like sugar cane, you have a rhizome and keep re-growing for decades, you can't really use the soil for anything else. The organic matters accumulated in the soil probably improves the soil itself but I doubt that it turns a marginal land in arable land at the end.

Soil quality is not wrecked because the roots stay in place. Only 1/4 of the plant is cut each year and what remains feeds it; http://www.youtube.com/watch?v=sZHciYNiIAo

Less mono-culture and more rotations improving organic matter with potential benefits for food cropping systems (subsequent food crop yields in many cases are higher after a rotation with 6-10 years of a perennial)

http://bioenergycrops.com/blog/2013/05/29/bioenergy-crops-in-marginal-lands-lower-yields-can-have-lower-costs/

"Growing biofuel crops, such as Miscanthus, on marginal lands allows the highest quality land to be reserved for the sector in which it is most needed: food production. Biosolids, nutrient-rich organic byproducts of wastewater treatment, and FGD gypsum, waste by-products produced in coal-fired power plants, can be used to combat the problems associated with growing crops on marginal lands, including low fertility and high acidity."

http://elibrary.asabe.org/abstract.asp?aid=41822&t=2&redir=&redirType=

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