Biomass Feedstock Storage for Quantity and Quality Preservation - Engineering and Science of Biomass Feedstock Production and Provision - page 184

From a point of view of the complete biomass production and provision system,
the optimal storage option may be a combination of multiple storage methods and
locations. For example, Shastri et al. [ 1 ] recommended a combination of on-farm
open, on-farm covered (shed with no walls), and centralized (shed with four walls)
storage for the Miscanthus production system. Similar results were reported for
switchgrass [ 48 ]. In such a configuration, biomass stored in open can be shipped to
the biorefinery within a limited number of days while biomass stored in a covered
facility may be shipped towards the end of the season. However, such design
requires coordination of the whole system since all the farmers providing biomass
must know the delivery date. The implementation of systemic viewpoint, as high-
lighted in the next section, is therefore, critical.

7.7 Summary and Future Work

Storage of biomass feedstock is necessary to balance the seasonal availability of bio-
mass with the year-round biorefinery requirement. The low-density and low-value,
high-volume nature of the feedstock creates challenges for cost-effective storage.
Moreover, quantity and quality preservation during storage is important. An ideal
storage facility would minimize the dry matter loss, minimize the carbohydrate loss,
and prepare the feedstock for subsequent processing into fuel. This chapter reviewed
literature along these lines to present the current understanding of these issues.
The review showed that considerable efforts have been made to develop a mech-
anistic understanding of the biomass loss during storage, especially the loss of cel-
lulose. Different factors such as temperature, microbial activity, and moisture
content have been independently studied in the literature. The possible remedies to
minimize dry matter loss have also been proposed. Some options such as drying are
well known and practiced for conventional agricultural products. Therefore, theo-
retical foundations and design guidelines already exist, which can be used for bio-
mass feedstock. Some novel methods such as freezing though need to be studied
more rigorously. A combination of various alternatives as part of the same storage
facility may also be the optimal solution.
The topic of preparing biomass for further processing as part of storage has not
been studied that much. Mechanical treatments such as size reduction to increase
the surface area for enzymatic activity have been proposed and also implemented.
The suitability of causing chemical/compositional changes to the biomass needs to
be studied further. It would be important to ensure that the resultant intermediate
product is stable enough for further storage, transportation, and handling, before its
conversion to ethanol.
In addition to this, the following specific topics of future research have been
identified:

• A holistic model for biomass dry matter loss and quality degradation needs to be

developed. Such a model would combine the biomass properties, storage attri-
butes, and environmental conditions to provide accurate estimates of total dry