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Cellulosic Ethanol Bio-Fuel

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Sarah Appelbaum

on 2 December 2013

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Transcript of Cellulosic Ethanol Bio-Fuel

Cellulosic Ethanol Bio-Fuel
What is a Bio-Fuel?
How does it all work?
What's wrong with using Corn for Ethanol Production?
There is not a good enough energy return (Energy Return on Energy Invested, EROEI, is about 5.0)
Corn is used for food production which raises food prices
There is a concern that growing a large quantity of corn can cause damage to the environment since it may be planted in areas which are easily subject to erosion. We are already losing topsoil. This would tend to cause us to lose topsoil more quickly.
The amount of ethanol produced using corn is expected to decrease over time
Ethanol Production by Switchgrass
Why Switchgrass and not another plant...
Lignocellulosic biomass consists of three polymeric components:
Hemicellulose
Cellulose
Lignan

Overall Process
Distillation and Dehydration
Cost Estimation
Minimizing Cost
Leslie Ovando
Desiree Kettell
Priya Chacko
Sarah Appelbaun
Svetlana Zeveleva
Ricardo Huang

Biofuels are a form of fuel derived from biomass, or biological materials. They differ from fossil fuels in that they are derived from renewable sources.
Switchgrass can yield 6 to 8 tons per acre, compared to 4 tons per acre for corn
Because it is native, switchgrass is resistant to many pests and plant diseases
Half the plants carbon is stored in its roots improving soil quality and preventing erosion
Poplar Trees
Poplar Trees can be genetically modified so that the sugars needed for ethanol can be easily separated from the lignin. However, Scientists think if the lignin is meddled with, the plant will be more susceptible to insects and diseases.
Hemicellulose
is a complex polysaccharide that contains pentoses such as xylose and hexoses such as glucose
A
cellulose
is a long chain of polysaccharides formed by D-glucose
A
lignan
is the main component of cell walls made to hold together cellulose and hemicellulose fibers
The main advantage of using switchgrass over corn or any other plant as an ethanol feedstock is its cost of production is relatively less, and more biomass energy per hectare can be captured in the field
Canola
Sugarcane
Palm Trees
Jatropha
Miscanthus
Poplar Trees
Willow Trees
Eucalyptus Tree
Pretreatment
Ammonia Fibre Expansion
Liquid ammonia is added to switchgrass under moderate pressure (100 to 400 psi) and temperature (70 to 200°C) before rapidly releasing pressure
Process decrystallises cellulose, hydrolyses hemicellulose, removes and depolymerises lignin
Increases the size and number of micropores in the cell wall
Significantly increasing the rate of enzymatic hydrolysis
Process Specifics
Ammonia to biomass loading 2.0 g/g dry bio-mass
Water loading 0.5 g/g dry biomass
140°C
Residence time 30 min
Enzymatic Reactor
(fermentation)
Environmental Impact
Switchgrass removes CO2 from the atmosphere and incorporates it into plant tissue, both above and below the ground.

Corn-based ethanol, which decreases emissions by 52%

Ethanol from cellulose reduces greenhouse gas emission (GHG) by 86%


Environmental Impacts
Switchgrass Enviromental Conditions:
Climate, Soil conditions, and crop rotation

Pre-Treatment Process:
- Nitrogen fertilizers
- Herbicide
- Lime
- Manganese

Rain causes Agricultural runoffs.

Causes negative impacts in categories such as eutrophication, photochemical oxidation, and toxicity (human and ecotoxicity) .


References
Comments?Questions?
- Careful management of switchgrass agriculture

- Management following EPA regulations (Sedimentation, nutrients, and Pesticides)

- Improved technologies in ethanol production may be pathways to reduce these environmental impacts.

Solution
Although the usage of Switchgrass as a biomass for ethanol production is not yet commercially viable, cost output is location specific. Studies shows an average of 182 districts compatible with the environment necessary to grow this crop in the US. Minimum cost switchgrass-ethanol production occurs in northern Texas, Oklahoma, and southern Kansas.
Capital cost for the 53.4 million gallon per year producing plant (53.4*6.60 lbs/gal = 352.44 lbs/year) is $408.63 million (2013$). Assuming a 20 year plant life, an interest rate of 8%, and an ethanol yield of 69 gallons per ton of biomass (YO), the per gallon capital costs [CK(Q0)] are $0.78. The economy of size factor (k) is generalized to be 0.75. Excess electricity from burning lignin (a co-product of processing) is to be sold to the power grid. Given co-product credit, operating costs (CO) are $1.52 per gallon.

Long-term biomass storage costs (S) for switchgrass (in the above plant size) are $16.07 (2013$) per dry ton based on values reported in Miranowski and Rosburg (2010). The variable transportation cost (t) for both feedstocks in all districts is $0.77 per dry ton per mile as assumed in Wright and Brown (2010b).
SSCF Step Two
Specifications
pH 5.2
30°C
180 rpm
84h
glucose concentrations increased to 15 g/L
glucose concentration .9 g/L (at the end)
xylose concentration remained the same at 19 g/L
26.3 g/L of ethanol produced
SSCF Step One
Specification
Yeast cells, SpezymeCP and, Novozyme 18 are added
pH 5.2
30°C
60h
glucose concentration 0.6 g/L (at the end)
xylose concentration 18.7 g/L (at the end)
10.6 g/L ethanol produced

Xylose is hydrolized and fermented yielding ethanol

Specifications:
4.8 pH
50 C
250 RPM
8h
8.1 g/L glucose
25.1 g/L xylose

Pre-Hydrolysis
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