Cellulose feedstocks

The effects of feedstock cellulose content on cellulase enzyme activities in the digester system were examined in multiple laboratory-scale CSTR digesters operated under similar conditions with identical levels of feedstock organic loading (g VS/reactor d) but different levels of cellulose (Solka Floe). In general, all celli se enzyme... 

Figure 1. Comparison of the effects of feedstock cellulose content on specific ceUulase enzyme activities in sludge from 4 CSTR reactors operated under similar conditions. Although the cellulose content of the feedstock was varied, the total volatile solids content for all reactors was equivalent.

Feedstock Cellulose Oily products Aqueous products... 

Figure 3 shows the production of acetaldehyde in the years 1969 through 1987 as well as an estimate of 1989—1995 production. The year 1969 was a peak year for acetaldehyde with a reported production of 748,000 t. Acetaldehyde production is linked with the demand for acetic acid, acetic anhydride, cellulose acetate, vinyl acetate resins, acetate esters, pentaerythritol, synthetic pyridine derivatives, terephthaHc acid, and peracetic acid. In 1976 acetic acid production represented 60% of the acetaldehyde demand. That demand has diminished as a result of the rising cost of ethylene as feedstock and methanol carbonylation as the preferred route to acetic acid (qv). 

Cellulosic They are tough, transparent, hard or flexible natural polymers made from plant cellulose feedstock. With exposure to light, heat, weather and aging, they tend to dry out, deform, embrittle and lose gloss. Molding applications include tool handles, control knobs, eyeglass frames. Extrusion uses include blister packaging, toys, holiday decorations, etc. Cellulosic types, each with their specialty properties, include cellulose acetates (CAs), cellulose acetate butyrates (CABs), cellulose nitrates (CNs), cellulose propionate (CAPs), and ethyl celluloses (EC). 

Although most ethanol is now produced from corn, research has been done on producing this type of alcohol fuel from cellulosic biomass products including energy crops, forest and agricultural residues, and MSW, which would provide much cheaper feedstocks. The process of chemically converting these cellulosic biomass feedstocks is more involved and until this process can be simplified the price of ethanol will remain high. 

BP has investments in an ethanol plant with DuPont and Associated British Foods. It is also investing in cellulosic ethanol research and developing jatropha as a biodiesel feedstock. BP and DuPont are planning a biobutanol demonstration plant and BP would like to eventually convert their ethanol plant to biobutanol production. BP has a 400 million investment with Associated British Foods and DuPont to build a bioethanol plant in the U.K. that may be converted to biobutanol. It has spent 500 million over 10 years at the Energy Biosciences Institute in California to research future biofuels and 9.4 million over 10 years to fund the Energy and Resources Institute (TERI) in India to study the production of biodiesel from Jatropha curcas. It also has a 160 million joint venture with D1 Oils to develop the planting of Jatropha curcas. 

Royal Dutch Shell has invested in cellulosic ethanol company Iogan and Germany s Choren Industries, which is building a demonstration bio-mass-to-liquids plant using wood feedstock. Royal Dutch Shell has also partnered with Codexis in exploring biomass energy production. 

The bulkier biomass crops such as wood waste, switchgrass, miscan-thus or other cellulosic feedstocks have less sugar than corn or sugar cane, so it requires more biomass volume to yield the same quantity of ethanol that corn or sugar can produce. 

The commercial production of cellulosic ethanol is moving closer with advances in technology along with federal and private funding for new plants and research centers. These are accelerating the time to volume production which could push the cost of ethanol from cellulosic feedstocks to well under 1.00 a gallon below the cost of corn ethanol. 

In 2007 Verenium began work on a demonstration-scale cellulosic ethanol plant in Jennings, LA. The plant is expected to have an output of 1.4 million gallons a year, using sugar cane bagasse and a special breed of energy cane as feedstocks. 

Another option to extend the ligno-cellulosic feedstock base is the development of BTL through biomass gasification and subsequent Fischer-Tropsch synthesis. Although BTL is fully compatible with diesel fuel, ligno-cellulosic BTL has not yet been commercialised. 

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