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Biotechnology: an enabling technology
Modern biotechnology is a powerful and versatile tool which can compete with chemical and physical means of reducing energy and material consumption and minimizing the generation of waste and emissions.
Biotechnology is an increasingly powerful tool for achieving industrial sustainability.
Biotechnology offers one important path to cleaner products and processes. However, it is simplistic to see biotechnology as inherently clean. Biotechnology per se is not necessarily clean, just as chemical of industrial processes, both because it is so versatile and because its power continues to grow. Living systems manage their chemistry rather more efficiently than chemical plants and their
wastes are generally recyclable and biodegradable. This, along with our increasing ability to manipulate biological materials and processes, strongly points to a significant impact on the future of manufacturing industry.
It can help reduce atmospheric pollutants, waste, and energy and raw materials use.
Biotechnology can help lower the production of greenhouse gases and acid rain. Using biorenewable feedstocks instead of fossil fuels can slow atmospheric build- up of carbon dioxide and help alleviate other problems of atmospheric pollution.
| Biotechnology and CO2 emissions |
Fossil carbon is the single most important raw material for energy generation and chemicals manufacture, but its use often produces carbon dioxide (CO2), an important greenhouse gas. Any means of reducing fossil carbon consumption, either by improving energy efficiency or substituting alternative resources, directly results in lowered CO2 production and reduces global warming. Biomass,
which yields only as much CO2 as it takes up during growth, can serve as a chemical feedstock or a source of energy.
Biomass can be consumed directly (incinerated) to produce energy. It can also be converted into a wide range of chemicals and liquid fuels. In energy terms, annual production of biomass is some five times global energy consumption but currently provides only 1% of commercial energy. At present, however, it is much more expensive than fossil fuels and has penetrated the market only where
governments have effectively subsidized its use.
Bioethanol is a CO2-neutral alternative liquid transportation fuel. As new technologies and more efficient separation techniques are developed, bioethanol will compete on cost with gasoline. Over the next two decades, US ethanol production from lignocellulosic waste could reach 470 million tons a year, the equivalent in energy terms of present gasoline consumption. |
Substances made from renewable raw materials can now compete with the chemical alternatives.
A wide range of chemicals and structural materials can be made from biological raw materials (biomass), including biodegradable plastics, biopolymers and biopesticides, and novel fibers and timbers. As it grows, biomass consumes CO2 so that, unless fossil fuel is used, there is a zero net contribution to atmospheric greenhouse gases.
In the past, cheap raw materials based on fossil fuels underpinned the rapid growth of petrochemical alternatives, but environmental considerations are directing renewed attention to bioresources. Thus, while chemists have long worked to duplicate plant materials, it may now be advantageous, from a global environmental perspective, to return to starches, cellulose, vegetable oils and proteins
as potential alternative raw materials for industrial production.
| The soya bean: an important renewable resource |
The soya bean has long been used to develop products ranging from food and diesel fuels to polymers, fabric softeners, solvents, adhesives, linoleum, rubber substitutes, printing inks, and plastics. Recent advances in recombinant genetic biotechnology have made it possible to alter the lipid composition of soya beans to increase the variety of biohydrocarbons available for industrial
applications. Amides, esters and acetates of biohydrocarbons are currently used as plasticizers, blocking/slip agents and mold-release agents for synthetic polymers. Biohydrocarbons linked to amines, alcohols, phosphates and sulfur groups are used as fabric softeners, surfactants, emulsifiers, corrosion inhibitors, anti-static agents, hair conditioners, ink carriers, biodegradable solvents,
cosmetic bases and perfumes. In combination with aluminum and magnesium, the soya bean is used to produce greases and marine lubricating materials. |
Carbon dioxide is a virtually unlimited raw material with many uses.
Carbon dioxide is the fundamental source of renewable organic compounds. Microalgae can be used to produce lipids, biodiesel fuels and the antioxidant vitamin beta-carotene. Though algae-derived biodiesel has only been produced at laboratory scale and only 10 tons of beta-carotene are produced world-wide, carbon dioxide use could easily be expanded by orders of magnitude if new or improved
processes could be developed.
Biotechnology is gaining ground for the production of commodity chemicals
Commodity chemical production, where both chemical and biotechnological approaches are used, is a pioneering field for biotechnology. In the United States, commodity chemicals currently derived largely from plant matter include ethanol (3.8 million tons a year), cellulose esters and ethers (0.5 million tons a year), sorbitol (0.19 million tons a year) and citric acid (0.16 million tons a year).
New processes and renewable resources for other commodity chemicals such as succinic acid and ethylene glycol, are in the pilot stage in government-sponsored programs in partnerships with private enterprise. These are currently made almost exclusively from petrochemical feedstocks.
Genetically engineered microorganisms can be used to replace toxic industrial processes.
Because microorganisms can synthesize a wide range of compounds, using carbohydrates as the sole energy and carbon sources, companies are exploiting them to obtain specialty chemicals. In ancient times, indigo, which is used today for dyeing denim, was obtained from plants; today, it is synthesized from toxic chemicals, including aniline, formaldehyde, and sodium cyanide. Through genetic
engineering, an indigo produced from a microorganism will soon be on the market.
| Chemicals from biological feedstocks |
It is no longer necessary to start with a barrel of oil to produce chemicals. Corn, beets, rice - even potatoes - make great feedstocks. The transformation of sugars into alcohol by microorganisms has been known for a very long time. But only since the advent of genetic engineering is it feasible to think about harnessing the sophistication of biological systems to create molecules that
are difficult to synthesize by traditional chemical methods.
For example, compared to traditional polyester (2GT), the polymer polytrimethylene terephthalate (3GT) has improved properties. Yet commercialization has been slow because of the high cost of making trimethylene glycol (3G), one of 3GT's monomers.
The secret to producing 3G can be found in the cellular machinery of certain unrelated microorganisms. Some naturally occurring yeasts convert sugar to glycerol, while a few bacteria can change glycerol to 3G. The problem is that no single natural organism has been able to do both.
Through recombinant DNA technology, an alliance of scientists from DuPont and Genencor International has created a single microorganism with all the enzymes required to turn sugar into 3G. This breakthrough is opening the door to low-cost, environmentally sound, large-scale production of 3G. The eventual cost of 3G by this process is expected to approach that of ethylene glycol (2G).
The 3G fermentation process requires no heavy metals, petroleum or toxic chemicals. In fact, the primary material comes from agriculture - glucose from cornstarch. Rather than releasing carbon dioxide to the atmosphere, the process actually captures it because, although microbes do produce CO2 during fermentation, corn absorbs CO2 as it grows. All liquid effluent is easily and harmlessly
biodegradable. What's more, 3GT can readily undergo methanolysis, a process that reduces polyesters to their original monomers. Post-consumer polyesters can thus be repolymerized and recycled indefinitely.
Source: Scientific American, May 1997, DuPont advertisement, p. 22. |
Biocatalysts, notably enzymes, offer an extremely promising source of improved processes.
Biotechnology enables the rapid and controlled production of biological catalysts - living organisms and their catalytically active constituents - particularly enzymes. Because they are more specific and more selective than their non-biological counterparts, biological catalysts yield fewer by-products (specificity) and start with less purified raw materials (selectivity). They are also amenable
to continuous improvement. Despite their advantages, they still present problems for industrial applications, as they may be fragile, require large amounts of water, and are costly. Many of these problems have been addressed and overcome using new bioreactor designs and improved catalysts.
Biotechnology can be used in all phases of an industrial process.
In integrated bioprocessing, biocatalyst activity can simplify the overall process by reducing the number of stages. For example, cellulose can simultaneously be broken down and fermented to glucose with the use of enzymes. Yeast is used to ferment the glucose to ethanol in order to prevent feedback inhibition of the cellulose hydrolysis. Ethanol, in turn, depresses the fermentation rate and is
therefore extracted using a water-immiscible solvent, oleyl alcohol. All these reactions take place in a single reactor vessel.
It is essential to determine whether biotechnology-based processes are cleaner than traditional ones ...
Clearly, biotechnology-based manufacturing is gaining ground and has a great deal to offer. Enzyme-based processes operate at lower temperatures and produce fewer and less toxic by-products and emissions than conventional chemical processes. Use of biotechnology has already succeeded in reducing energy use in certain industrial processes. However, the key issue is whether, overall,
biotechnology-based processes are significantly cleaner than traditional chemical processes.
... and life cycle assessment is currently the best way to do so.
There are a number of "tools" for measuring the effect of technology on the environment. Of these, the best is life cycle assessment (LCA), which is a way of evaluating the environmental impact of alternative products and processes in terms of their use of energy and materials. LCA takes into account the entire life cycle of a process or product from the "cradle to the grave".
Life cycle assessments of biotechnological operations confirm their superior cleanliness.
Because it is global and holistic, that is, because it can cover everything from obtaining the raw materials to disposing of the product at the end of its useful life, whatever the geographic location, this type of analysis offers a way to:
- decide whether a process, product or service is in fact reducing the environmental load or merely transferring it upstream to resource suppliers or downstream to treatment or disposal;
- determine where in a process the most severe environmental impact is felt;
- make quantitative comparisons of alternative process options and of competing technologies.
Although LCA was first developed over two decades ago, it has been little used so far for bioprocesses and products, partly because of biotechnology's relatively late arrival on the industrial scene and partly because it raises particular methodological problems. However, where it has been used, it has generally confirmed that biotechnological operations are cleaner and more economical.
The attractiveness of LCA lies in its use of the life cycle concept for products/systems and the possibility of objective or fair comparisons of industrial systems. It defines clearly the scope and goals of a specific evaluation and sets its boundaries (where, in other words, the assessment starts and stops); it collects data on the relevant inputs and outputs (use of energy and resources,
emissions into the environment); and it assesses the impact of the various parameters on the ecological system and on human health.
| Life cycle assessment of proteases |
Proteases, which remove protein impurities, are essential components of modern detergents. Because of their catalytic effect, low concentrations (0.1-1.0%) are used. Similar washing performance cannot be achieved by substituting other substances or by raising the washing temperature.
An LCA was made to compare the production processes for proteases obtained from a traditional microorganism and one from a genetically modified organism in order to determine the pollution linked to enzyme production and to reveal any weaknesses in the production process.
The assessment only covered enzyme production, not the whole life cycle of detergent proteases. It included all processes from raw materials to the finished granulated product as well as transport of raw materials from the individual manufacturers to the enzyme producers.
To produce a quantity of enzyme with an equivalent washing performance from the recombinant organism required 34% less raw material. The change from conventional production to production using the new organism reduced the demand for process energy by 60%. In terms of the manufacturer's total annual requirements, this energy saving corresponds to the annual primary energy consumption for
laundry purposes of about 170,000 households. Application of the new enzyme produced with genetically modified organisms made it possible to reduce annual emissions by approximately 170 tons of carbon and 190 tons of sulfur dioxide. Atmospheric emissions were assessed in terms of impact on global warming, development of acid rain, and smog formation. Aquatic emissions were assessed according to
the yield of nutrients in water and related oxygen consumption. The assessment clearly confirmed the claim that the use of the new organism reduced consumption of energy, resources and emissions by a factor of 3 to 4. |
A steady stream of biotechnological innovations offers new opportunities for industry
In sum, biotechnology can offer a wide-ranging set of tools for improving large-scale fermentations to produce chemicals such as ethanol, at one end of the spectrum, to using minute parts of biological molecules as sensors in analytical devices, at the other. New products from industrial biotechnology include more functional products, often at approximately the same price as traditional ones,
such as biodegradable polymers, optically active chemicals, and enzymes for use in detergents and feeds. The ability to alter the characteristics of living organisms and their constituent parts is now such that many industries are actively investigating the opportunities and many new possibilities are emerging from R&D.;
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Industrial Sustainability
