Specialty chemicals: Enablers of sustainable development
We live in chemophobic times: The media and general public view chemicals as enemies of theenvironment. But this perspective is flawed because it overlooks the essential role of chemicals - particularly specialty chemicals - as enablers of sustainable development.
Produced responsibly - as the vast majority of chemicals are - specialty chemicals and polymers support key sustainable development goals, including clean water, clean energy, and the preservation of life below water. They enable society to satisfy its current needs without compromising the ability of future generations to meet their own requirements.
Clean water is the foundation of a healthy society. But clean water doesn't just happen. All water - even water from a pristine mountain reservoir - requires treatment before it is suitable for human consumption or industrial use. And water also requires treatment after use so it can be safely returned to the environment. Specialty chemicals - and specialty polymers in particular - play important roles in a range of water treatment processes (see Chart 1). These processes include drinking water production, wastewater treatment, and industrial water treatment. Specialty polymers:
- Reduce turbidity and accelerate the settling of suspended particulates in the production of potable water
- Thicken and dewater sludge in wastewater treatment
- Inhibit the formation of scale (mineral deposits) in boilers and cooling towers
Worldwide consumption of specialty polymers in water treatment exceeds one million metric (mm) tons per year. Polyacrylamide, the largest volume water-soluble polymer used in water treatment, plays important roles in drinking water production and wastewater treatment. Polyacrylate, the second largest volume polymer, prevents scale formation in industrial equipment. Quaternary ammonium polymers and polyamines are used primarily in the production of potable water.
Wind is crucial to today's global energy market, and its importance as source of clean, renewable energy continues to grow. In 2010, wind made up less than 4% of global power capacity. In 2018, wind accounted for more than 8%.
The turbines that transform wind into clean electricity depend on specialty materials. Each wind turbine incorporates 25 to 100 metric tons of specialty resins and reinforcements. Unsaturated polyester resins, epoxy resins, glass fiber, and carbon fiber are standard construction materials for wind turbine blades.
Size matters in wind energy. Turbine height, blade length, and power output are increasing, and so is the amount of resin and reinforcements required to produce a wind turbine. The largest turbine blades in commercial production are more than 88 meters long (about the length of a football field) and require more than 100 metric tons of resins and reinforcements.
Economics is driving this trend. Larger wind turbines are more efficient, resulting in lower power generation costs. Energy from a modern wind farm with large turbines is cost-competitive with energy from conventional sources such as coal and natural gas.
Preserving Life Below Water
Nutrient pollution is the enemy of underwater life. Surplus nutrients, typically nitrogen or phosphorus, lead to algae blooms in lakes, rivers, and coastal waters. Excessive algae growth creates dead zones - depleting oxygen and blocking sunlight from underwater plants- making life below water untenable. Some algae blooms also produce toxins that are harmful to humans.
Excess nutrients can come from many sources, including laundry detergents. Traditionally, laundry detergents included phosphate "builders" for improved performance, especially in hard water. Phosphate builders are inexpensive and effective, but they also serve as nutrients. In contrast, specialty chemical builders - zeolites, citric acid, and polyacrylates - enhance detergent performance without causing algae growth. These specialty chemicals do everything that builders are supposed to do - soften water (by sequestering calcium and magnesium ions), disperse dirt, and prevent soil redeposition - without nourishing algae blooms.
Global consumption of zeolites, citric acid, and polyacrylates in laundry detergents is about two mm tons per year. Developing markets are driving demand growth for these specialty builders. In contrast, demand for specialty builders in the mature markets of North America, Western Europe, and Japan is expected to be flat, in part because these regions are moving on to new and greener formulations. Increasingly, mature markets are turning to liquid and unit-dose formats instead of powder laundry detergents. The new formats rely on greener builders, such as sodium gluconate and the sodium salt of glutamic acid, N,N-diacetic acid (GLDA). These chelating agents are both biodegradable and bio-based, as their raw materials include glucose and glutamic acid, respectively.
Looking Ahead: Opportunities for Green Innovation
Specialty chemicals may play an even larger role in sustainable development in the future. Opportunities for green innovation are substantial. Specialty chemicals are sold on the basis of performance or function, not chemical composition. Consequently, price is important but not imperative. In addition, specialty chemicals are closer to the consumer than commodity chemicals. Products that include "green" specialty chemicals can tap into consumer interest in the environment and bio-based ingredients. Paths to greener specialty chemicals include the use of:
- Sustainably produced renewable feedstocks. In general, bio-based materials have smaller carbon footprints (cradle-to-factory-gate greenhouse gas emissions) than their petrochemical counterparts. But there is a caveat: Feedstock provenance matters. Land use changes can have a major negative impact on carbon footprint. Specifically, the drainage and deforestation of peatland to make way for oil palm plantations increases the environmental burden of palm oil, palm kernel oil, and their methyl ester derivatives. Because of land use change, these materials have large positive carbon footprints. In contrast, coconut oil and coconut methyl ester have negative carbon footprints - that is, their production removes carbon dioxide from the environment.
- Biocatalysts and biotechnology. Biotechnology offers a sustainable route to value-added products. A case in point is stevia sweeteners. First-generation stevia sweeteners are extracted from the leaves of the stevia plant. The extracts contain many components but only traces of the best tasting sweeteners. Next-generation stevia sweeteners (such as Reb M and Reb D) are produced from corn or sugarcane by yeast fermentation. Reb M and Reb D are intensely sweet with zero calories and no aftertaste. They show great promise as sugar replacements in soft drinks and other beverages.
- Waste materials as feedstocks. Using waste materials as feedstocks supports the circular economy by recycling "waste" into useful products. Examples of specialty chemicals that can be produced from waste materials include polyols from waste gas (such as flue gas from steel mills and off gases from refineries); furfural from biomass (such as corn stover, corn cobs, and sugarcane bagasse); and polyhydroxyalkanoates - biodegradable polymers - from biogas (through anaerobic digestion).
Sustainable development matters. To paraphrase Moses Henry Cass: We have not inherited this planet from our parents - we have borrowed it from our children. Specialty chemicals can help us preserve this world for future generations.
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