Chapter 15 reports cellulosic butanol production from agricultural biomass and residues: recent advances in technology while Chap. 16 describes the technology concept of consolidated bioprocessing of lignocellulosic biomass for biofuels pro­duction. The research opportunity here is the possibility of converting vast amount of lignocellulosic plant biomass materials such as cornstover, wheat straw, switch — grass, and woody plant materials into usable biofuels such as ethanol and/or butanol. Recently, bisabolane has also been identified as a terpene-based advanced biofuel that may be used as an alternative to D2 diesel [13]. This field of cellulosic biofuels has been active for more than 25 years and it still remains a hot topic because of its significant potential. One of the major challenges is known as the “lignocellulosic recalcitrance” which represents a quite formidable technical barrier to the cost — effective conversion of plant biomass to fermentable sugars. That is, because of the recalcitrance problem, lignocellulosic biomasses (such as cornstover, switchgrass, and woody plant materials) could not be readily converted to fermentable sugars to make ethanol or butanol without certain pretreatment, which is often associated with high processing cost. Despite more than 25 years of R&D efforts in lignocel — lulosic biomass pretreatment and fermentative processing, the problem of recalci­trant lignocellulosics still remains as a formidable technical barrier that has not yet been fully eliminated so far. This problem is probably rooted from the long history of natural plant evolution; plant biomass has evolved effective mechanisms for resisting assault on its cell-wall structural sugars from the microbial and animal kingdoms. This property underlies a natural recalcitrance, creating roadblocks to the cost-effective transformation of lignocellulosic biomass to fermentable sugars. Therefore, one of the R&D approaches is to unlock the sugars by re-engineering the cell wall structure through molecular genetics. Chapter 17 describes the synthesis, regulation, and modification of plant cell wall carbohydrates (lignocellulosic bio­mass) as a resource for biofuels and bioproducts while Chap. 18 reports genetic modifications of plant cell walls to increase biomass and bioethanol production. Other approaches include but are not limited to developing more effective pretreat­ment, enzymes, and microorganisms that could help convert the biomass materials into biofuels. Chapter 19 reviews the structural features of cellulose and cellulose degrading enzymes and describes the technology concept of designer enzymes/cel — lulosomes for cellulose-based biofuels production.