Green Chemistry Principle #7
Use of Renewable Feedstocks
A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable.
By Dr. Richard Wool, Professor of Chemical and Biomolecular Engineering and Director of the Affordable Composites from Renewable Materials program, University of Delaware.
The concept of making all our future fuels, chemicals and materials from feedstocks that never deplete is an interesting concept which at first glance seems impracticable. Mankind currently removes fossil fuels, coal, oil and natural gas from the ground and extracts minerals for profit until they are exhausted. In particular, our fossil fuels for carbon-based chemicals and materials are being rapidly depleted in a predictable manner with the expected rise of global populations and expanding energy intensive economies on several continents. The impacts on human health and the environment are significant and present major challenges for our scientists and leaders in the next 50 years.
Can we address these global problems by using Green Chemistry Principal #7? Yes, we will get our feedstock, as if by magic, from “thin air” and it will be renewable. The carbon in the air is in the form of carbon dioxide CO2 and methane CH4 and is removed by photosynthetic processes powered by the sun to form plants, trees, crops, algae, etc., which collectively we call “biomass”.
Nature produces about 170 billion tons of plant biomass annually, of which we currently use about 3.5 % for human needs. It is estimated that about 40 billion tons of biomass, or about 25 % of the annual production, would be required to completely generate a bio-based economy. The technical challenge in the use of such renewable feedstocks is to develop low energy, non-toxic pathways to convert the biomass to useful chemicals in a manner that does not generate more carbon than is being removed from “thin air”; the difference between C(in) from the air, and C(out) from the energy used, is the carbon footprint ΔC. Ideally, when using Principal #7, all carbon footprints by design should be positive such that C(in) >> C(out). This leads in a natural way to the reduction of global warming gasses impacting our current climate change. We should also insure that the new chemicals and materials derived from renewable resources are non-toxic or injurious to human health and the biosphere.
In 2002, the U.S. Department of Energy in their Vision for Bioenergy and Bio-based Products in the United States stated:
“By 2030, a well-established, economically viable, bioenergy, and bio-based products industry is expected to create new economic opportunities for rural America [globalization through localization], protect and enhance the environment, strengthen the U.S. energy independence, provide economic security, and deliver improved products to consumers.”
In the past 10 years, significant advances have been made in the development of fuels, chemicals and materials from renewable feedstocks. These for example, have included biodiesel from plant oils and algae, bioethanol and butanol from sugars and lignocellulose, plastics, foams and thermosets from lignin and plant oils, and even electronic materials from chicken feathers. In terms of Green Chemistry Principal #7, our future is bright and laced with optimism due to the ongoing fruitful collaborations between several disciplines involving biotechnology, agronomy, toxicology, physics, engineering and others, where new fuels, chemicals and materials are being derived from renewable feedstock from “thin air” with minimal impact on human health and the environment.
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