Development of the Integrated Biomass Supply Analysis and Logistics Model (IBSAL)

The Integrated Biomass Supply & Logistics (IBSAL) model is a dynamic (time dependent) model of operations that involve collection, harvest, storage, preprocessing, and transportation of feedstock for use at a biorefinery. The model uses mathematical equations to represent individual unit operations. These unit operations can be assembled by the user to represent the working rate of equipment and queues to represent storage at facilities. The model calculates itemized costs, energy input, and carbon emissions. It estimates resource requirements and operational characteristics of the entire supply infrastructure. Weather plays an important role in biomass management and thus in IBSAL, dictating the moisture content of biomass and whether or not it can be harvested on a given day. The model calculates net biomass yield based on a soil conservation allowance (for crop residue) and dry matter losses during harvest and storage. This publication outlines the development of the model and provides examples of corn stover harvest and logistics

Climate risk management for the U.S. cellulosic biofuels supply chain

As U.S. energy policy turns to bioenergy, and second-generation biofuels in particular, to foster energy security and environmental benefits, consideration should be given to the implications of climate risk for the incipient bioenergy industry. As a case-in-point, we review evidence from the 2012 U.S. drought, underscoring the risk of extreme weather events to the agricultural sector in general, and the bioenergy supply chain in particular, including reductions in feedstock production and higher prices for agricultural commodities and biofuels. We also use a risk management framework developed by the Intergovernmental Panel on Climate Change to review current understanding regarding climate-related hazards, exposure, and vulnerability of the bioenergy supply chain with a particular emphasis on the growing importance of lignocellulosic feedstocks to future bioenergy development. A number of climate-related hazards are projected to become more severe in future decades, and future growth of bioenergy feedstocks is likely to occur disproportionately in regions preferentially exposed to such hazards. However, strategies and opportunities are available across the supply chain to enhance coping and adaptive capacity in response to this risk. In particular, the implications of climate change will be influenced by the expansion of cellulosic feedstocks, particularly perennial grasses and woody biomass. In addition, advancements in feedstock development, logistics, and extension provide opportunities to support the sustainable development of a robust U.S. bioenergy industry as part of a holistic energy and environmental policy. However, given the nascent state of the cellulosic biofuels industry, careful attention should be given to managing climate risk over both short- and long-time scales

Oxidative torrefaction for cleaner utilization of biomass for soil amendment

Growing concerns of emissions from wildfires and burning of crop residues demand cleaner and efficient technologies to convert and utilize this residual biomass. The present study demonstrates a pilot scale moving bed biomass torrefaction reactor operating in oxidative medium to produce biochar for soil amendment. A series of experiments are conducted on pine shavings and rice husk, at conditions corresponding to different values of index of torrefaction (Itorr), ratio of higher heating value of torrefied biomass (i.e. biochar) to that of raw biomass. Air-biomass equivalence ratio dominantly governs the operating temperature and affects torrefaction more than the residence time. Product yields of scaled-up reactor differed from those of a smaller bench-top reactor, primarily because of differences in heat transfer within reactor and losses to the surrounding. A relatively linear relationship of Itorr is observed with biochar properties such as specific surface area, water retention capacity, bulk density, and electrical conductivity. When tested for soil amendment, the raw biomass and biochar treatments reduced soil pH by 0.2–0.3 in a season, with lowest pH values in case of pine shavings. Estimated nitrogen release and organic matter decreased with increasing Itorr, but most amendments had no significant effect on seed germination and the number of green shoots. Comparatively, heavy torrefied biomass treatments showed highest shoot heights and crop yield followed by light torrefied or raw biomass and control. Successful demonstration of a pilot scale reactor and encouraging effects on soil and plant growth suggest that commercial-scale oxidative torrefaction of various residual biomass is possible for soil amendment application

Off-Gassing of VOCs and Permanent Gases during Storage of Torrefied and Steam Exploded Wood

Thermal treatment for upgrading of low-value feedstocks to improve fuel properties has gained large industrial interest in recent years. From a storage and transport perspective, hazardous off-gassing could be expected to decrease through the degradation of reactive biomass components. However, thermal treatment could also shift chemical compositions of volatile organic components, VOCs. While technologies are approaching commercialization, off-gassing behavior of the products, especially in terms of VOCs, is still unknown. In the present study, we measured off-gassing of VOCs together with CO, CO₂, CH₄, and O₂ depletion from torrefied and steam exploded softwood during closed storage. The storage temperature, head space gas (air and N₂), and storage time were varied. VOCs were monitored with a newly developed protocol based on active sampling with Tenax TA absorbent analyzed by thermal desorption-GC/MS. High VOC levels were found for both untreated and steam exploded softwood, but with a complete shift in composition from terpenes dominating the storage gas for untreated wood samples to an abundance of furfural in the headspace of steam exploded wood. Torrefied material emitted low levels of VOCs. By using multivariate statistics, it was shown that for both treatment methods and within the ranges tested, VOC off-gassing was affected first by the storage temperature and second by increasing treatment severity. Both steam exploded and torrefied biomass formed lower levels of CO than the reference biomass, but steam explosion caused a more severe O₂ depletion