Biomass transportation

Recycle of the carrier fluid will often be required in biomass transport by pipeline, both because large quantities of water will not be available at the inlet end and because discharge of water that has carried the biomass will, in some jurisdictions, be prohibited. This requires that a second pipeline and set of pumping stations be constructed. 

Rt was 50-80 % of Ro, and contributed significantly to decreasing Rtf. Because Dr was much longer, CO2 release fiom the biomass transport process contributed to 80 % of/tr- This means that decreaang Cn is necessary to increase Rn. 

Particle Size Reduction. Changes in the physical characteristics of a biomass feedstock often are requited before it can be used as a fuel. Particle size reduction (qv) is performed to prepare the material for direct fuel use, for fabrication into fuel pellets, or for a conversion process. Particle size of the biomass also is reduced to reduce its storage volume, to transport the material as a slurry or pneumatically, or to faciHtate separation of the components. 

Still another possibiUty is a marine biomass plantation such as that envisaged for giant brown kelp grown off the California coast and conversion of the kelp to methane in a system similar to that shown in Figure 19. The location of the SNG plant could be either on a floating platform near the kelp growth area or located on shore, in which case the biomass or fuel transport requirements would be different. 

Thermochemical Liquefaction. Most of the research done since 1970 on the direct thermochemical Hquefaction of biomass has been concentrated on the use of various pyrolytic techniques for the production of Hquid fuels and fuel components (96,112,125,166,167). Some of the techniques investigated are entrained-flow pyrolysis, vacuum pyrolysis, rapid and flash pyrolysis, ultrafast pyrolysis in vortex reactors, fluid-bed pyrolysis, low temperature pyrolysis at long reaction times, and updraft fixed-bed pyrolysis. Other research has been done to develop low cost, upgrading methods to convert the complex mixtures formed on pyrolysis of biomass to high quaHty transportation fuels, and to study Hquefaction at high pressures via solvolysis, steam—water treatment, catalytic hydrotreatment, and noncatalytic and catalytic treatment in aqueous systems. 

Biofuels. Biofuels are Hquid fuels, primarily used ia transportation (qv), produced from biomass feedstocks. Identified Hquid fuels and blending components iaclude ethanol (qv), methanol (qv), and the ethers ethyl /-butyl ether (ETBE) and methyl /-butyl ether (MTBE), as well as synthetic gasoline, diesel, and jet fuels. 

Biofuels are used to create a wide variety of energy sources. Ever since the harnessing of fire, biomass has been used for heating and conking. Residential burning of biomass continues to be a primary source of fuel in less industrialized nations, but also has been used as fuel for electricity generation, and converted to liquid transportation fuels. 

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. 

The role of water in the life of plants is well known. In terms of its major effects this role consists in transporting the mineral nutrition, maintenance of intracellular pressure responsible for the vertical growth of plants and, finally, participation in photosynthesis which provide the biomass growth, or plainly speaking, the crop production. 

Certainly, photochemical air pollution is not merely a local problem. Indeed, spread of anthropogenic smog plumes away from urban centers results in regional scale oxidant problems, such as found in the NE United States and many southern States. Ozone production has also been connected with biomass burning in the tropics (79,80,81). Transport of large-scale tropospheric ozone plumes over large distances has been documented from satellite measurements of total atmospheric ozone (82,83,84), originally taken to study stratospheric ozone depletion. 

The subsequent fate of the assimilated carbon depends on which biomass constituent the atom enters. Leaves, twigs, and the like enter litterfall, and decompose and recycle the carbon to the atmosphere within a few years, whereas carbon in stemwood has a turnover time counted in decades. In a steady-state ecosystem the net primary production is balanced by the total heterotrophic respiration plus other outputs. Non-respiratory outputs to be considered are fires and transport of organic material to the oceans. Fires mobilize about 5 Pg C/yr (Baes et ai, 1976 Crutzen and Andreae, 1990), most of which is converted to CO2. Since bacterial het-erotrophs are unable to oxidize elemental carbon, the production rate of pyroligneous graphite, a product of incomplete combustion (like forest fires), is an interesting quantity to assess. The inability of the biota to degrade elemental carbon puts carbon into a reservoir that is effectively isolated from the atmosphere and oceans. Seiler and Crutzen (1980) estimate the production rate of graphite to be 1 Pg C/yr. 

Fig. 14-4 Schematic representation of the transport of P through the terrestrial system. The dominant processes indicated are (1) mechanical and chemical weathering of rocks, (2) incorporation of P into terrestrial biomass and its return to the soil system through decomposition, (3) exchange reactions between soil interstitial waters and soil particles, (4) cycling in freshwater lakes, and (5) transport through the estuaries to the oceans of both particulate and dissolved P.

---