Biomedical subjects

Shahab Sokhansanj

Publications and source records attributed to Shahab Sokhansanj.

4 recordsLinked to original sources

PubMed2006

Switchgrass (Panicum vigratum, L.) delivery to a biorefinery using integrated biomass supply analysis and logistics (IBSAL) model.

This study develops cost, energy input and carbon emissions for a number of switchgrass supply options. The Integrated Biomass Supply Analysis and Logistics (IBSAL) model developed at Oak Ridge National Laboratory is used to evaluate the delivery systems. Three biomass collection systems: baling, loafing and ensiling are evaluated. The number and operational performance of equipment are specified to complete collection operations within 120 days of harvest after August 1. Bales are stacked and tarped on the farm side. The transport of biomass from the farm side to a biorefinery takes place over a full year cycle, i.e. 365 days. Supply quantities range from 454 to 4540 dry tonnes/day (500-5000 dry tons/day). Delivered costs to a biorefinery with capacity of 1814 dry tonnes/day (2000 dry tons/day) are: 44-47 dollars/dry tonne for delivered bales (round and square); 37 dollars/dry tonne for delivered loafs (size 2.4 m x 3.6 m x 6 m); 40 dollars/dry tonne for chopped biomass; and 48 dollars/dry tonne for ensiled chops. These costs do not include any payment to the farmers or switchgrass farming cost. Based on the data from literature, the switchgrass farming cost can range from 30 to 36 dollars/dry tonne. These costs would be additional to the switchgrass collection and transportation cost. Switchgrass collection is generally less expensive than collection of straw or corn stover because of the assumed high yield of 11 dry tonnes/ha and a denser biomass. Energy consumption for delivery systems at this capacity ranges from 4.8% to 6.3% of the energy content of switchgrass. Additional 1% of the energy content of switchgrass is consumed in its farming. At 1814 dry tonnes/day (2000 dry tons/day) capacity, greenhouse gas emissions ranges from 75 to 100 kg of CO2/dry tonne of switchgrass delivered.

Air Pollution↗

PubMed2006

Compression of fractionated sun-cured and dehydrated alfalfa chops into cubes--specific energy models.

The objective of this study was to determine the specific energy requirements for the compression of fractionated sun-cured and dehydrated alfalfa chops, when subjected to different pressures and holding times. The compression behavior of fractionated sun-cured and dehydrated alfalfa chops was studied using a single cubing unit capable of making one cube in a single stroke of the plunger. The cube die dimensions were 30 mm x 30 mm in cross-section and an effective depth of compression of 0.38 m. The initial moisture content of dehydrated and sun-cured chops were 6% and 7% (wb), respectively. A stack of two sieves (instead of five) was used along with a pan to achieve leaf and stem separation. The nominal opening sizes of two sieves with square holes were 3.96 and 1.17 mm, respectively. Leaf and stem fractions were combined later to obtain five different samples each for sun-cured and dehydrated alfalfa with leaf content ranging from 0% to 100% by mass in increments of 25%. The chop moisture content and preheat temperature before compaction was 10% (wb) and 75 degrees C, respectively. The cube die temperature was maintained at 90+/-5 degrees C. The mass of chops used for making each cube was 23+/-02 g. A hydraulic press was used to apply 9.0, 12.0 and 14.0 MPa of pressures through a plunger. After compression, the plunger was held in place for 10 and 30s, before the compacted forage was extracted. Empirical equations were fitted to the data relating specific energy for cube making to pressure, residence time, and leaf content.

Biomass↗

PubMed2006

Development of a multicriteria assessment model for ranking biomass feedstock collection and transportation systems.

This study details multicriteria assessment methodology that integrates economic, social, environmental, and technical factors in order to rank alternatives for biomass collection and transportation systems. Ranking of biomass collection systems is based on cost of delivered biomass, quality of biomass supplied, emissions during collection, energy input to the chain operations, and maturity of supply system technologies. The assessment methodology is used to evaluate alternatives for collecting 1.8 x 10(6) dry t/yr based on assumptions made on performance of various assemblies of biomass collection systems. A proposed collection option using loafer/ stacker was shown to be the best option followed by ensiling and baling. Ranking of biomass transport systems is based on cost of biomass transport, emissions during transport, traffic congestion, and maturity of different technologies. At a capacity of 4 x 10(6) dry t/yr, rail transport was shown to be the best option, followed by truck transport and pipeline transport, respectively. These rankings depend highly on assumed maturity of technologies and scale of utilization. These may change if technologies such as loafing or ensiling (wet storage) methods are proved to be infeasible for large-scale collection systems.

Biomass↗

PubMed2005

Specific energy requirement for compacting corn stover.

Corn stover is a major crop residue for biomass conversion to produce chemicals and fuels. One of the problems associated with the supply of corn stover to conversion plants is the delivery of feedstock at a low cost. Corn stover has low bulk density and it is difficult to handle. In this study, chopped corn stover samples were compacted in a piston cylinder under three pressure levels (5, 10, 15 MPa) and at three moisture content levels (5%, 10%, 15% (wb)) to produce briquettes. The total energy requirement to compress and extrude briquette ranged from 12 to 30 MJ/t. The briquette density ranged from 650 to 950 kg/m3 increasing with pressure. Moisture content had also a significant effect on briquette density, durability and stability. Low moisture stover (5-10%) resulted in denser, more stable and more durable briquettes than high moisture stover (15%).

Agriculture↗