The early 2020s have brought many interesting innovations to the plastics industry. Several producers are trying to reduce the plastic material they use for their applications. Some are replacing plastics with a paper/plastic blend (which doesn't recycle well), others are replacing plastics with metals, and a few are turning to a bevy of bioplastics.
Not all bioplastics are created equal. For example, a particular bioplastic, PLA, is not home and garden compostable, and only sometimes, in a stringently particular environment, industrially compostable. Because PLA products must be exposed to temperatures over 55°C for several months on end for them to biodegrade completely, open-air commercial composting schemes cannot properly decompose PLA products. As a result, PLA has thrown consumers into a whirlwind of confusion.
There are, however, a handful of legit biodegradable plastics on the market. One is the bioplastic that Island Leaf Commodities is the registered sales agent for—Lastic Bamboo Resin. It's certified home and garden and commercially compostable. It's made from over 51% bamboo fiber, bio-based PBS, and starch.
Yet, in the last six months, we've noticed that another biodegradable polymer has gained prevalence. Polyhydroxyalkanoate—or, for the sake of the guy writing the blog, PHA, is the biopolymer in the spotlight.
PHA Overview
PHA producers have a factory-sized cornucopia of input options at their fingertips. The versatility of potential inputs that form PHA's building blocks allows for massive production potential. Manufacturers can make PHA from similar sources that PTT MCC Biochem uses to make the home and garden compostable bio-based PBS: sugar and cassava. Interestingly, PHA producers can also employ food waste, canola oil, and even treated sewage sludge (a challenging sell for any marketing team) to make their bioplastic. Like bio-based PBS production, PHA production involves the bacterial fermentation of these inputs; over two dozen known bacterial species can produce PHA.
Theoretically, the copious number of inputs and the slough of bacterial fermenters producers have at their disposal could lead to multitudinous plastic-replacement applications. While some producers currently use PHA to produce straws (more on this below), an abundant array of potential-plastic-replacing applications loom. Indeed, PHAs have properties like LDPE, PP, ABS, PS, and PVC. Thus, manufacturers can make PHA-made applications ranging from plastic liners and garbage bags to phone cases and surgical sutures.
Regarding the essential credentials that prove a material is compostable— both home and garden and commercially—most PHA resins and applications have been certified by a legitimate agency such as DIN CERTCO, TÜV Austria, or TÜV Rheinland. However, we found that a few PHA-made products hold a new type of biodegradable certification: Marine Biodegradable. Stamping such a credential onto a product might lead consumers to believe they can safely toss their PHA-made straw, from which they slurped several margaritas, into the ocean adjacent to their 5-star resort. In doing so, consumers wouldn't be littering. They would be adding nutrients back to the ocean. Unfortunately, this isn't congruent with reality. You'll have to read on to delve into our reasoning.
Current PHA Producers
A handful of PHA operations exist worldwide, accounting for potentially 200,000 MT of annual commercial production capacity. In the United States, a few significant players have a first-mover advantage.
Danimer Scientific
Bainbridge, Georgia-based Danimer Scientific is a major trailblazer in PHA applications. According to a November 2022 investor presentation, Danimer's proprietary PHA-resin, Nodax® (certified Home and Garden Compostable by TÜV Austria / Commercially Compostable through Biodegradable Products Institute), is used to produce the marine biodegradable (another certification by TÜV Austria) straws.
Danimer cut its polymer teeth by producing PLA, a product about which Island Leaf has written extensively. It wasn't until 2007, however, when Danimer began producing legitimate biopolymers. They did this by acquiring Procter and Gamble's PHA production pilot facility. The primary feedstocks that Danimer uses to make its PHA are canola and rapeseed oil.
Danimer leads the PHA field in production capacity. They have enough space to produce over 90,000 MT annually. In the next couple of years, the company anticipates even more production. Currently, they're building another resin-making plant in Bainbridge.
In the next few years, Danimer plans to supply a few companies with Nodax® for packaging and bottling applications, which is interesting because, at present, no true home and garden compostable film or bottles exist.
RWDC
RWDC has operations in both Singapore and the United States. They call their biopolymer Solon®. Like any other legit biopolymer, they hold certifications from TÜV Austria for commercial and home and garden composting.
According to RWDC's website, the company plans to release PHA-made straws in Singapore. However, RWDC did not give a precise timeline indicating when the release would happen.
Newlight Technologies
Newlight Technologies is the final PHA first mover. Located in California, Newlight began scaling its PHA production in the early 2010s. However, the most intriguing thing about Newlight is the method they use to produce their PHA.
The name Newlight gave to its resin is Air Carbon®. Not only does the name sound slick, but it also tells part of the story about how the resin is produced. Using elaborate carbon-capture technology, Newlight sucks carbon dioxide and methane out of the air. Then, inside a chamber, Newlight unleashes billions of ocean-originating microorganisms on the captive carbon gasses. These single-celled creatures devour all the carbon dioxide and methane. After they've gorged themselves to their mitochondrial content, they excrete a white powder. This powder is a type of PHA called polyhydroxy butyrate, or PHB. PHB is a type of PHA—welcome to the sometimes confusing biochemical world…but we digress. So, in a nutshell, Newlight produces its PHA by vacuuming carbon out of the air. They pride themselves on being carbon negative. Does everyone see the link between their trade name and their production process?
Today, Newlight produces PHA-made straws and utensils, which they provide to the popular American fast-food chain Shake Shack. In the next year or so, they hope to make single-use bottles from their Air Carbon® resin too.
Other Production
Germany, Italy, China, Brazil, Canada, and a few other countries are home to PHA pilot operations. So, we can see that PHA is a material to which many companies and investors are devoting time and money.
So what about this marine biodegradable accolade? Will it become a highly coveted, sought-after certification?
We don't think so. Read on to learn what compels our thinking.
Marine Biodegradable PHA Conundrum
Most PHA producers rightfully claim to sell a home and garden compostable product. We can verify this because these producers provide proper certification credentials on their websites. These producers are certified through TÜV Austria and hold the OK Home Compost and OK Commercial Compost certifications. While TÜV Austria's standards aren't as stringent as DIN CERTCO's (which holds the earthworm-health-conscious AS5810 and AS4736 standards for home and garden compostability and commercial compostability, respectively), products certified OK Home and Commercial Compost do legitimately degrade in home composting conditions.
Unfortunately, many PHA producers stumble over themselves to market TÜV Austria's Marine Biodegradable Certification. This certification is quite dubious, if not unethical, for two reasons. The first reason is that the "marine" testing environment reflects neither natural sea conditions nor the confounding elements manifested by oceans. The second reason is the time it takes to biodegrade under ideal conditions.
TÜV Austria's Marine Biodegradable Certification testing procedures present an issue with how some PHA becomes Marine Biodegradable certified. According to a 2020 article from the Wall Street Journal, TÜV Austria tested PHA material against the ASTM D 6691 method. This method mimics ocean conditions at a constant 30°C. Unfortunately, seawater temperatures worldwide vary drastically—oceans near the equator can exceed 30°C, while seas at the poles are under ice for part of the year. And seawater temperatures between the north and south poles differ drastically. Additionally, because of currents (see the below paragraph) the seawater temperature in one region can change in a few hours. So will a PHA straw certified to completely biodegrade at 30°C also completely biodegrade at 10°C or even 20°C? Judging by the fact that bacterial conditions differ at lower temperatures, we would say no.
Another temperature-confounding issue is seawater's constant state of flux. Unlike water in most lakes and other relatively still freshwater bodies, seawater moves (sometimes rapidly) around vast swathes of oceans. Popularly referred to as currents, these "rivers in the ocean" can move as quickly as 4 meters per second. Water depth, tides, air temperature, and wind are some of the many variables that determine a current's size and strength. Thus, it's probable that an object that begins floating in 30°C seawater may find itself in substantially cooler water within hours.
It doesn't take a massive current of cognitive electricity to realize that the oceans' mercurial nature obliterates any chance of maintaining a constant temperature at almost any given point in an ocean. So, a "marine biodegradable" straw that unfortunately makes it into an ocean will most likely continue to travel around that ocean and enter other oceans. The straw will encounter fluctuating temperatures during the journey. A constant warm temperature is vital for the biodegradation of any organic product. Therefore, fluctuating seawater temperatures make maintaining a continuous 30°C for disintegration a pipedream.
Another confounding factor related to marine biodegradation is the time it takes for complete disintegration to occur. According to the TÜV Austria standards, a product must decompose no less than 90% at a 30°C marine water environment in fewer than six months. However, scientists mentioned in the WSJ article above expressed skepticism toward this claim. While some PHA-producing companies state that their products will completely decompose in any marine environment in under 18 months, doubting scientists think it may take up to 30 years for PHA products to degrade in oceans.
Once again, readers don't need to use their imaginations to paint a picture of how much damage free-floating PHA straws and cups could pose to turtles, fish, multitudinous mammals, and other lifeforms—it's currently happening with the plastic-in-our-oceans crisis.
Our Final Thoughts...
While it's ultimately noble for companies to design a PHA-made straw with sea safety in mind, we don't think it's feasible. Fluctuating sea temperatures, the ever-changing position of seawater, and the fact that the products could harm sea life just moments after it touches the ocean are all reasons to advocate that all players—businesses, consumers, and government, do their darndest to ensure no rubbish reaches the sea. So we believe that calling a single-use product "marine biodegradable" is an expression of toxic optimism.
However, we're not against the concept of marine biodegradable products. But, because the marine biodegradable concept is so new, we think more studies need to determine a science that can guarantee that a product will actually biodegrade in current rich, temperature-changing seawater in a short timeframe. It's equally important products won't harm any sea life before they decompose. Scientists agree with this notion.
Until then, exercise extreme responsibility when consuming single-use products.
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