Hybrid corn. Hybrid cars. Is it time for ... Hybric chemistry?

There has been a lot of interest concerning the possibility of using biomass as an alternative to petrochemicals. This excitement has been muted within the industry as attractive business opportunities that are not supported by government subsidies or mandates are difficult to find. This article explores the primary constraints to the development of biobased opportunities, and points to direct ways the chemical and biotechnology industries could work together more effectively to overcome these constraints.

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The problems facing the evolution of products derived from biomass are very different than the challenges that the petrochemical industry faced 100 years ago. A century ago, the petrochemical industry was just beginning to create products that would replace bioproducts. The challenge was to develop plastics that could serve as replacements for silk, wood, or ivory. Consumers do not purchase plastics, and they did not choose plastic materials over biobased ones because they preferred plastics. Consumers in the last century acted as consumers do now. Their purchasing decisions were based on cost with acceptable performance. Billiard balls made from Bakelite replaced ivory because they were less expensive without a significant sacrifice in function. Plastic telephones replaced wood ones because they were less expensive. Nylon replaced silk because it provided a cheaper alternative while fulfilling the same basic purpose. To win back at least a portion of the stage, new products developed from biomass must compete on price without sacrificing performance.

Cost drivers

This would be an even more daunting task if the cost of petroleum and the cost of biomass were remaining constant at early 20th century levels. Increases in the cost of petroleum are often portrayed as a driving force behind the need to shift to bioproducts. This may be less than half the truth the decrease over time in the relative price of agricultural commodities is at least as important in increasing the cost competitiveness of biomass with petroleum.

The recent spike in corn prices has only kept pace with the recent spike in petroleum prices with the margin between the two staying constant over the past decade (see Figure 1). Biomass is worth exploring now as an alternative to petroleum because it has improved in terms of competitive pricing.

Technology drivers

So, it makes sense to explore the use of biomass as an alternative to petroleum for economic reasons. Why have bioproducts only seen success in areas where government subsidies have created artificial economic incentives? The answer, as always, represents a constraint and an opportunity. We have not developed cost-effective technologies capable of converting carbohydrates (such as glucose) to hydrocarbons. Glucose is by far the primary constituent of biomass. The composition of this chemical is the key to driving bioproducts towards cost-competitive applications. Glucose is composed of 6 parts carbon, 12 parts hydrogen, and 6 parts oxygen--very symmetrical. It is, unfortunately, very different from the hydrocarbons that our fuel and petrochemical industry is based on. Hydrocarbons, by definition, contain no oxygen, and therefore have higher than 2:1 ratios between the remaining hydrogen and carbon.

Almost all development in this area can be described as explorations in either fermentation or combustion. Fermentation is nature's way of breaking down biomass, and it seems like a good place to look for cost-effective approaches. If anything, nature has a reputation for being frugal. Unfortunately, during fermentation processes, oxygen is evolved as either [H.sub.2]0 or, in the case of ethanol fermentation, as C[O.sub.2]. This results in a waste of either carbon or hydrogen. Fermentation also leads to the formation of alcohols and acids, both of which still contain oxygen. Biological means of removing this remaining oxygen do not exist. Nature has never really seen the need to make hydrocarbons.

This leaves us with combustion. At present, traditional chemistry approaches to biomass conversion hold the most promise for the future. The less than subtle approach of blowing it up into a gas, and then reforming the constituent chemicals in the presence of a catalyst (Fischer-Tropsch), has been successfully commercialized in coal-to-liquid applications, and is on the verge of being commercialized for biomass to liquid in several countries. This approach has lower operating costs as it is intrinsically more efficient, but is constrained by high capital costs. The chemical industry is not intimidated by high capital cost, but they are hesitant about introducing an altogether new technology. Combustion approaches are also necessarily energy intensive, and given their lack of subtlety, lead to the formation of a range of end products. The chemicals produced by living organisms are different than those produced by thermal cracking in a petroleum refinery. Biological chemicals tend to occur as only one isomer and in only one chiral form. This purity of structure has potential advantages in the construction and functionality of polymers that is lost in a biomass to liquid refining process.

The future will clearly not be based entirely on petrochemicals. Nor will it be based entirely on biomass. The future will be full of composite products that maintain functionality while decreasing cost. The use of biopolyols in polyurethane foam products provides an excellent example. At present, certain technologies allow polymeric biopolyols created from soybean oil to replace a portion of the propylene and ethylene oxide-based polyols while maintaining overall functionality. The biopolyols reduce the cost of product formulation, but are not yet capable of replacing petrochemical polyols completely without an unacceptable loss of performance. Too much research has been focused on the complete replacement of existing polymers (such as polyethylene with biobased polylactic acid) rather than exploring ways in which the chemical substituents could be combined to reduce cost while maintaining functionality. The first, and potentially more sustainable product successes will be made through the creation of hybrid polymers. Canada has the potential to emerge as a global leader in the actual commercialization of bioproducts by focusing on compelling business sense rather than satisfaction of political pressures for environmental responses or relieving farm debt. Compelling business sense is not limited to just the chemical, plastics, or fuel industries. To be sustainable, the definition of compelling business sense must extend throughout the value chain from on-farm production through biomass process and on to the traditional components of the petrochemical industry.

If the future will be constructed with hybrid polymers, why not also consider hybrid approaches to the production of these chemicals? The incredible advances made in biotechnology over the last fifty years have left us with a tool kit that is still more powerful than our imagination in using it. Global creative talent has focused on understanding how life works, and why sometimes it fails to work properly. We are starting to think of biological constituents, such as glucose and fatty acids, as different kinds of bricks, and biotechnology as a means to assemble these bricks into walls and structures that life never imagined.

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New opportunites require new approaches

We all know Darwin's Theory of Evolution, "the survival of the fittest," the slow progress of complexity from the primordial ooze. The evolution of species has limitations however. It is never about the best that is possible, it is only about being better than your neighbour. Aristotle would have approved of evolution; extremes in any one direction are not desirable--checks and balances are. Nature approves of cautious bankers much more than aggressive entrepreneurs. This does not, however, lead to the creation of necessarily the best possible enzymes for driving biological processes. Modern biotechnology has enabled us to take evolution into our own hands. We can set the rules of the game. Through directed evolution, we can drive the selection of individual enzymes, separate from the cells in which they were designed to work, and drive them towards maximum performance in non-biological settings. We can drive improved enzyme performance under any range of pH, temperature, or pressure that we want. What is amazing is how well the machinery of life responds, and that it is possible to create designer enzymes at will.