Biocrude

D. K. SchmaUer and co-workers. Biocrude Suitabilities for Petroleum Refineries, ANL/CNSV-69, Argoime National Laboratory, Argoime, lU., June 1988. 

Another emerging area m biofuels is pyrolysis, which is the decomposition of biomass into other more usable fuels using a high-temperature anaerobic process. Pyrolysis converts biomass into charcoal and a liquid called biocrude. This liquid has a high energy density and is cheaper to transport and store than the unconverted biomass. Biocrude can be burned in boilers or used in a gas turbine. Biocrude also can be chemical by altered into other fuels or chemicals. Use of pyrolysis may make bioenergy more feasible in regions not near biomass sources. Biocrude is about two to four times more expensive than petroleum crude. 

Conversion of lignocellulose into biocrude via pyrolysis and hydrothermal treatment [30-32, 72]. 

Figure 2.13 did not include all the biomass conversion processes discussed above. It only considered those that produce transportation fuels. The processes that convert bio-feedstock into biocrude or electricity could not be included because their products have a different value than the transportation fuels. Such a comparison can be attempted by displaying the total manufacturing cost of biobased products in a graph that shows typical relationships between the price of crude and that its derivatives, i.e., of fuel oil, transportation fuel and electricity. This has been done in Fig. 2.14 for the lignocellulose conversion processes. 

Obviously, a single collection area of 25 km radius could only feed a plant of half the size assumed here. Since plant costs scale with the plant capacity raised to the power 0.65-0.8, such a two-fold smaller plant would have a 20-25% higher capital charge (per ton of product). This would result in additional processing cost and total production cost of 1-2 GJ 1 for biocrude plant, 2-5 GJ-1 for a biofuel plant and 5-6 GJ-1 for a power plant. 

The projections of liquid hydrocarbon yields from the Brazilian tree C. multijuga in plantation settings and the yields of biocrude from E. lathyris and E. tirucalli have been quite optimistic. However, the main difficulties with the concept of natural hydrocarbon production from biomass are that most of the species that have been tested exhibit low liquid yields compared to the mass of biomass that must be harvested, and the naturally produced liquids are complex mixtures and not pure hydrocarbons (or glycerides). Moreover, the relationship between the minimum hydrocarbon content of dry biomass and biomass yield required to sustain a terpene yield of 25 bbl/ha-year tends to preclude sustainable production at this level. This is perhaps best illustrated by Fig. 10.2. The curve is constructed by assuming the density of terpene hydrocarbons is in the range 0.1347 t/bbl, which is the literature value for... 

FIGURE 10.5 Conceptual processing sequence for recovering biocrude, sugars, and bagasse from Euphorbia lathyris. 

Field trials to study the growth and compositional characteristics of E. lathyris indicated that biocrude would have to sell for 150- 200/bbl, even... 

TABLE 10.9 Mass and Energy Balances for Recovery of Biocrude, Sugars, and Bagasse by Solvent Extraction of Whole Euphorbia lathyris ... 

TABLE 10.11 Estimated Costs for Integrated Growth of Four Biomass Species and Recovery of Biocrude and Power Production in Arizona at Feed Rate of 272,000 Dry Tonne per Year ... 

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