Biobased products enable farmers to cash in by growing a new crop, finding a new market or making use of farm waste products. The development of biobased products, made from renewable resources such as wood, grass, crops, organic waste products or even algae, has the potential to shrink our carbon footprint; reduce dependency on petroleum and other nonrenewable sources we rely on not only for fuel, but as the basis of many consumer products; and provide us with safer chemicals.
Innovations in use of biofuels include corn or sugar beet ethanol; biodiesel from canola, sunflowers or soybeans; woody biomass crops such as shrub willow or perennial grasses, which can be combusted or modified into ethanol; or algae-based fuels. Product and infrastructure development to support this emerging biofuel industry has been in the news with increased frequency as the specter of climate change has grown over the past decades.
But biobased fuels are not the only option for biobased product development, nor are they new: Henry Ford’s first cars could run on biobased fuels, and he was a well-known biofuel advocate. Ford predicted that fuel would come from fast-growing trees, potatoes, apples, sawdust or weeds, not petroleum. While Ford’s predictions of a future energized by biobased fuels has not yet been fully realized, a new focus on a biobased economy is emerging today.
Biobased products are an expansive category. Many consumer products have traditionally been derived from natural materials. Cellulose, a plant material, is used in the production of a diverse array of items, including paper; cellophane; film; varnishes; textiles; and many other common household goods. Plastics, commonly derived from petroleum, can also be biobased.
Bioplastics, feedstocks and agriculture
The USDA has a program designed to support the use of biobased feedstocks in the creation of consumer products. The BioPreferred Program, originally created in the 2002 Farm Bill and expanded in 2014, has as its goal the mission “to increase the purchase and use of biobased products. Biobased products are derived from plants and other renewable agricultural, marine, and forestry materials and provide an alternative to conventional petroleum derived products. Biobased products include diverse categories such as lubricants, cleaning products, inks, fertilizers, and bioplastics. For purposes of the BioPreferred program, biobased products do not include food, animal feed or fuel.”
According to a 2014 NewBio report “Market Opportunities for Lignocellulosic Biomass,” bioplastics can be glucose-based, which are derived from polylactides (PLA), or starch-based. Glucose-based products include plastic bottles, carpeting and clothing. Glucose-based bioplastics have been made from cellulose for over 100 years. Starch-based bioplastics are commonly used in food-service ware and can come from a variety of sources such as potato, corn and cassava.
But it’s not that simple. The report stated that “currently, producing bio-based polymers using bacteria to ferment sugars into polymers remains more expensive than using fossil fuel-based inputs.” Even products made from nature-based materials often use petroleum and other nonrenewable resources in the manufacturing process.
Researchers today, however, are working to develop processes that rely solely or primarily on renewable resources to create these biopolymers. There are numerous biopolymers that can be used in plastics production to replace petroleum-based processes. These polymers can be derived from a variety of agricultural feedstocks.
One concern with biobased feedstocks as building blocks of consumer products has been the potential conflict between food use and feedstock use. When crops are utilized for uses other than human consumption, concerns emerge. But not all bioplastic feedstocks are traditional agricultural crops.
According to the Bioplastic Feedstock Alliance:
“Bioplastic Feedstocks are generally divided into first generation (traditional agricultural crops), second generation (cellulosic crops as well as residue and agricultural waste products) and third generation (nontraditional organisms like some forms of algae and nonagricultural wastes).”
Types of bioplastics
Polyhydroxyalkanoate, or PHA, is a biodegradable plastic polymer. It can be created in various ways from organic resources. Bacteria convert the carbon from the organic materials into PHA, and with at least 300 known wild bacteria species able to do so when conditions are right, these “production workers” are readily available.
One agricultural feedstock that can be used for PHA production is manure. According to Erik Coats, P.E., Ph.D., associate professor of civil engineering at University of Idaho, PHA granules are raw plastic, with the same material properties as thermoplastics. Coats has led research developing PHA from fermented manure liquids. During fermentation, some manure converts into organic acids. Bacteria can feed on these, and then store any excess carbon as PHA. Killing the bacteria and extracting the PHA makes it available for use in manufacturing bioplastic products. Coats has predicted that moving these processes from the laboratory and small-scale fermenters and scaling up for production purposes could be done in an economically viable manner sooner rather than later.
PHA can also be made from methane gas. Manure produces methane gas, contributing to global warming. Methane can also be captured from landfills. Captured methane gas not only can serve as a renewable energy source, it can also serve as a bioplastics feedstock.
Mango Materials, along with University of California researchers, have utilized methane from waste sources as a PHA feedstock. The process has received funding from the National Science Foundation, aimed at developing the process for commercialization. The process here, like with Coats’ method, is born in a fermenter.
Using a waste crop such as manure or methane gas reduces the cost of the feedstock, enhancing the potential for economic viability of the bioplastics industry, and eliminates the controversy that can arise when first generation feedstocks are used. Utilizing manure or the methane captured from manure can also offer a boon to the livestock industry, helping it to become climate friendly – a big industry issue today.
Coats emphasized that creating PHA from manure is compatible with the use of methane digesters. The anaerobic digestion process uses the solid manures, not the liquid, and PHA production can be readily integrated into a digester, potentially enhancing the economics of on-farm anaerobic digester use, making digester installation economically feasible for more farms.
For farms with covered manure pits, capturing the methane and flaring it is one method of reducing greenhouse gas emissions. If that methane could be used as a bioplastic feedstock, it could represent potential income and help to offset the cost of manure storage covers, enabling more farmers to invest in this climate-saving practice.
PHA plastics are extremely biodegradable under wet – but not dry – conditions, Coats said. Single-use goods would be a good match for PHA, including agricultural products such as seed coatings, erosion control matting and weed barriers. In the Mango Materials system, the PHA products can be anaerobically broken down, creating methane in the process, which would then be reused as a feedstock for more PHA production.
While both of the manure-based bioplastic feedstocks aforementioned utilize wild, commonly occurring bacteria, PHA has also been made using genetically modified bacteria fed a plant-based sugar feedstock, and some plant-to-polymer research has focused on genetically modifying plants to produce PHA directly. However, the manure and methane methods can be feasibly produced without genetic modifications, avoiding controversy and expense.
Grasses provide livestock with energy, nesting birds with habitat, act as feedstocks for bioenergy production, and prevent soil erosion and nutrient runoff in riparian areas. They can also provide a sustainable alternative to petroleum-based plastic production, and its accompanying waste and pollution. PHA plastics can be made from native C4 grasses – the warm season perennials, including native big bluestem, little bluestem and switchgrass (panicum virgatum). Native grasses can be grown on marginal lands not suitable to food crop production. Because the grasses play a role in ecosystem enhancement; as a biomass/biofuel feedstock; and for other uses such as bedding, feed or pulp; farmers growing this crop have a variety of potential markets, and can use these grasses for dual purposes.
Polyethylene furandicarboxylate (PEF), is an alternative to polyethylene terephthalate, or polyester, (PET), which is derived from petroleum and natural gas, and is used in many consumer plastics today. PEF instead utilizes 2-5-Furandicarboxylic acid (FDCA) from biobased processes, and is being researched at Stanford University.
Instead of using sugar from corn to make FDCA, the Stanford team has been experimenting with furfural. Furfural is derived from organic sources, typically wheat bran, corn cobs, oat hulls and sugarcane residues that don’t compete with crop production.
The process of conversion into FDCA, however, involves carbon dioxide and toxic chemicals. By eliminating the chemicals, and potentially using waste CO2 from industrial sites to fuel the reaction, Stanford researchers have been able to create a fully biobased PET alternative.
Polylactic acid-based plastics (PLA) are currently commercially produced by Cargill Industry’s NatureWorks Inc., among others, and used commercially, including in beverage bottles, clothing and food service cartons. This bioplastic comes from dextrose derived from corn. NatureWorks “Ingeo” bioplastic polymer is primarily made of PLA, and is compostable, as per the company’s website. It can also be broken back down into its lactic acid components, which can then be reused. The company emphasizes that the amount of corn utilized is minute, and does not affect the food supply.
Taking a naturally derived product and creating polymers for plastics production, or taking other biobased materials for use in common commercial applications, can be a key to a more sustainable economy. But creating this bio-based economy isn’t simple. Many factors come into play. Land use, food security, the technology to “harvest” the bio-based building blocks and then to create plastic or other products, and the energy needed to do so, are other considerations.
The emerging bioplastics industry has plenty of room for farm-based feedstocks, utilizing either farm waste products such as manure, crop residue, or methane; non-food crops such as native grasses; or food crops such as corn, grains, potatoes or sugar beets. The development and commercial production of bioplastics can provide farmers with another incentive to – once again – enhance sustainability, reduce their carbon footprint and gain economic viability. From energy crops to consumer good feedstocks, a biobased economy relies on farmers not only to feed the world, but also to provide it with life’s other necessities, too.