Feedstock stover

Several researchers have shown that alkali present in the feedstock influences the yields and compositions of the pyrolysis products [56, 59]. An interesting result was reported by Brown and coworkers [60] who found that addition of (NH4)2S04 as catalyst to the pyrolysis of dematerialized (alkali free) corn stover resulted in a pyrolysis oil that contained 23 wt.% levoglucosan (normally 1-3 wt.% levoglucosan is present in pyrolysis oil). Levoglucosan is a component from which various fuel blends and chemicals can be produced. 

Present collection costs are 1.5-2 times the delivered cost target— 35/ dt, including 20/acre or more net income for the farmer. Bulk collection is likely needed, because baling adds cost, 15/dt, and no value. One-pass harvest can lower the delivered feedstock cost to < 20/dt within a 15- to 20-mi radius. Prototypes for one-pass harvest of straw and stover are under development, adapting existing equipment. Many variations are possible, but until a better market definition is available, a new design is probably limited to paper studies. 

Recent studies have proven ethanol to be an ideal liquid fuel for transportation and renewable lignocellulosic biomass to be an attractive feedstock for ethanol fuel production by fermentation (1,2). The major fermentable sugars from hydrolysis of lignocellulosic biomass, such as rice and wheat straw, sugarcane bagasse, corn stover, corn fiber, softwood, hardwood, and grasses, are D-glucose and D-xylose except that softwood... 

In addition to significant savings in time and money for routine process samples, rapid analysis methods can be used to provide levels of information that were not previously available. For example, feedstock assessment and genetic studies require the screening of hundreds, sometimes thousands of samples. These studies would have been too costly to pursue without the savings in time and cost provided by rapid analysis methods. For example, approximately 200 samples can be analyzed from a bulk corn stover feedstock in one day at a cost of less than 4000. This type of information has been used to develop... 

NIR data were converted to compositions using the stover 5c rapid analytical method developed at NREL.129 The ability of the stover 5C methods to accurately measure the composition of corn stover feedstock is shown in Fig. 33.17, where the composition, as determined by NIR/PLS, is compared to measurement of the same samples using standard wet chemical methods. 

Fig. 33.17. Comparison of corns stover feedstock composition as determined by wet chemical and NIR/PLS method stover 5C.

Hames, B. R., Thomas, S. R., Sluiter, A. D., Roth, C. J., and Templeton, D. W., Rapid biomass analysis New tools for the compositional analysis of com stover feedstocks and process intermedites from ethanol production. Applied Biochemistry and Biotechnology 2003, 105-108, Proceedings of the 24th International Symposium for the Biotechnology of Fuels and Chemicals, 1-12. 

Historically, pricing had been the biggest barrier to biodegradable polymer market development. However, growing volumes of production and the development of new technology should further allow bio-based resin makers to reduce costs. Using materials such as corn stover, wheat straw and rice straw, which remain in fields after crops are harvested, as resin feedstock, could also increase productivity and economic performance. 

Despite the variety of sources, all lignocellulosic material is composed primarily of cellulose, hemicellulose and lignin [22], Agricultural wastes such as bagasse, com stover and wheat straw are thus a relatively cheap source of these three biopolymers. The major challenge to using lignocellulosic biomass as a feedstock is the development of cost-effective methods to separate, refine and transform it into chemicals and fuels [20],... 

The scope of work in a first phase of the project included the adaptation of this peat pyrolysis system for conversion of agricultural residues, preliminary testing to identify operating problems, characterization of two feedstocks (oat straw and corn stover) and finally, experiments to determine product yield and composition at various operating conditions. 

The straw and stover feedstocks were analysed for C, H, 0, N, S, moisture, ash and volatile matter content, as well as for several metals to gain insight into the potential catalytical activity of the ash. Product gas samples were analyzed for H2 O2, n2> CHi, CO, COj and CxHy and the remainder of the gas was flared. Char samples were analysed for C, H, 0, S, N and moisture content (moisture content by oven drying at 378 K) the... 

Feedstock Characteristics. Feedstock characteristics are presented in Table I. Results of the metal analysis will be considered in Phase II of the project. Calorific values were approximated using Dulong s formula and not actually measured. The oat straw had a lower ash content than the stover and a correspondingly higher calorific value. Calorific values, calculated on a dry basis and including the latent heat of water vapour in the products of combustion (high heat value), were 17.9 MJ/kg for the straw and 16.0 MJ/kg for the stover. 

More than twenty years ago, it was recognized that cellulosic biomass, including agricultural residues (such as corn stover, rice and wheat straws, and sugarcane bagasse), municipal wastes (such as yard and paper wastes), and industrial wastes (such as wastes from paper mills), is an attractive feedstock for ethanol-fuel production by fermentation because cellulosic biomass is not only renewable and available domestically in most countries but also available at very low cost and in great abundance. 

The composition of com stover, LL hybrid poplar, and HL hybrid poplar is shown in Table 1. Moving fiom com stover to HL hybrid poplar, lignin content is increasing, and xylan content is decreasing. Among these three feedstocks, LL hybrid poplar is highest in carbohydrates. 

Table 1 shows the effect of ARP treatment on the composition and the digestibility of different feedstocks. The optimum conditions described earlier in Materials and Method were applied in these tests. The extent of delignification and xylan removal in com stover is much higher than hybrid poplar. With com stover, more than 50% xylan is lost to liquid. The glucan digestibility of ARP-treated com stover reached 90%. Xylan removal in LL and HL hybrid poplar were 22 and 33%, respectively. The glucan digestibilities of ARP-treated LL and HL hybrid poplar were 66 and 49%, respectively. 

---