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Wednesday, June 24, 2020

PHA: A biopolymer




At Silicon Valley Clean Water in Redwood City, California, an installation assembled from a shipping container, plastic piping, brackets, and a small steel reactor is testing technology that could lead to a more sustainable plastic.Mango Materials has run this pilot facility since 2015. Raw biogas—which contains methane, carbon dioxide, and hydrogen sulfide—from the water treatment plant bubbles through the reactor. Bacteria in the vessel metabolize the methane into the biopolymer poly(3-hydroxybutyrate), or PHB.“Once they are the fattest, happiest organisms possible, we have to break open their cells and get the polymer,” says Anne Schauer-Gimenez, Mango’s vice president of customer engagement. The polymer that Mango extracts, about 250 kg of it per year, is tested in applications such as fibers and packaging for beauty care products.Mango is among the dozens of firms attempting to create an industry around polyhydroxyalkanoates (PHAs), a class of biodegradable, biobased polymers. Executives with these firms are well aware of the PHA firm Metabolix , now called Yield10 Bioscience, which burned through hundreds of millions of dollars before it failed in PHAs 3 years ago. But Metabolix may have been ahead of its time.Public awareness of the mounting crisis in plastic waste, especially the plastic that ends up in the ocean, is rising. Governments are imposing bans on single-use plastics, and large consumer product companies are clamoring for solutions. A polymer that can disappear from the environment altogether might just be what the world needs.PHAs have a lot on their curriculum vitae that suggests they’re perfect for this moment. They occur in nature. Bacteria use them to store energy when they lack enough nutrients to reproduce. Scientists have found more than 150 PHAs with different polymer structures. The kind of bacteria and what they are fed—be it sugars, starches, glycerin, triglycerides, or methane—determines the PHA produced.Biodegradability is the most intriguing property of PHAs. The largest-volume biobased polymer, polylactic acid, also breaks down, but only in an industrial composting facility. PHAs will biodegrade in ambient environments, even in the ocean.The physical properties of PHAs are often compared to polyolefins such as polyethylene and polypropylene. Indeed, many of the applications that companies have in mind for the polymers—single-use products like food packaging, straws, and cutlery—currently belong to polyolefins. The New Plastics Economy: Rethinking the Future of Plastics, a seminal 2016 report by the Ellen MacArthur Foundation, even lists PHAs as potential substitutes for polyolefins as well as polyethylene terephthalate, polystyrene, and polyvinyl chloride.“There is such a wide array of different PHAs that, depending on what kind of PHA you produce, you can get similar properties to each one of those other materials,” says Phil Van Trump, chief technology officer for the PHA developer Danimer Scientific.An important distinction in PHAs is between short-chain and medium-chain polymers. Short-chain PHAs, such as PHB, are made of smaller monomers. Medium-chain PHAs, such as poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), are made of larger ones.“Pendant chains hanging off your molecule will influence your properties,” says Jan Ravenstijn, an independent biopolymer consultant and veteran of the polymer makers DSM and Dow. The short-chain polymers are more crystalline—hard but brittle. The medium-chain ones are tougher and more resilient.Ravenstijn says PHAs are best suited for those applications where “biodegradation is a must,” such as products that “inevitably end up in the environment.” He points to slow-release fertilizer coatings made of synthetic polymers like polyurethanes that don’t biodegrade.In another such application, the Italian PHA firm Bio-on recently launched a line of sun creams, called MyKai, with Unilever. The creams incorporate micropowders made with Bio-on’s PHB that can improve the effectiveness of ultraviolet light–reducing ingredients.“It is the perfect molecule for that kind of application,” Diego Torresan, Bio-on’s business development manager, says of PHB. The company makes the PHB from molasses and by-products of sugar beet production at its demonstration plant near Bologna, Italy. The facility started up last year with 1,000 metric tons (t) of annual capacity, which is dedicated to specialty products such as the powders for Unilever and microbeads for other personal care applications.

Bio-on has been busy developing other PHA applications as well. Late last year, it formed a joint venture, called Zeropack, with the Italian fruit distributor Rivoira to commercialize PHB packaging for fresh fruit and vegetables. Bio-on is also working on applications such as toys, auto parts, and furniture.
Danimer has PHA technology that it acquired from Procter & Gamble in 2007. The company is already a large compounder of polylactic acid, operating 50,000 t per year of reactive extrusion capacity. Its pilot plant in Bainbridge, Georgia, makes about 10 t of PHAs per month from rapeseed oil.
Van Trump says Danimer’s polymer formulation expertise, plus its versatile medium-chain PHA technology, allows it to pursue ambitious applications. For example, with PepsiCo’s Frito-Lay division, Danimer has been developing a snack bag material to replace the polypropylene film currently used. It is working on PHA water bottles with Nestlé.
With such heavy interest in their materials, PHA companies are ready to take the next step: building commercial plants.
Metabolix made it to this stage a decade ago, and its failure remains a cautionary tale for the rest of the industry. In 2010, the company started up a PHA joint venture with Archer Daniels Midland (ADM) in Clinton, Iowa, that boasted 50,000 t of annual capacity.
ADM shuttered the plant 2 years later due to slow adoption of the materials by customers. The plant couldn’t even meet a milestone of 500 t per year of sales. ADM had to write off $339 million. Metabolix struck out on its own but had to sell its technology to the South Korean firm CJ CheilJedang for $10 million in 2016. It changed focus to agricultural technology and changed its name to Yield10.
“They built too much capacity,” Ravenstijn says. “There was no market. And developing a market for a new polymer is something that goes step by step. My advice would always be to build demand ahead of capacity.” This, he believes, is the approach current PHA players are taking.
Bio-on has been developing a market for PHAs since it bought technology for making PHB and other PHAs from the University of Hawaii in 2007. “When we started, the environment was not ready to take on PHA,” Torresan says. That’s now changed, he says, because of greater customer and brand owner awareness of plastic waste.
Torresan also sees regulatory drivers, such as the European Union’s requirement to find sustainable alternatives by 2021 to fossil-fuel-based single-use plastic items such as cotton swab sticks, cutlery, plates, and straws. “It is among, if it is not the sole, solution for those kinds of applications,” he says of PHAs.
“It’s a perfect storm that is brewing,” Danimer’s Van Trump says. “There is more demand then there was 3 or 5 years ago.” The company demonstrated PHA straws last year. “Due to the plastics bans and folks not liking paper straws so much, there’s a lot of interest,” he says.
In Winchester, Kentucky, Danimer is building what will be the world’s largest PHA plant when it starts up in October with about 8,000 t per year of capacity. The $36 million project involves the conversion of an idle algae fermentation facility.
Bio-on’s model is not to build large capacity but to license its technology. While its demonstration plant near Bologna is making specialty products for Bio-on’s own sales, it is also meant to prove the process for licensees.
The company has inked a number of PHA licenses already. The family-owned company SECI plans to build a 5,000 t per year plant in Italy. The Russian firm TAIF took out a license to build a 10,000 t plant in the Republic of Tatarstan. Bio-on has also licensed its process to companies in France, Spain, and Mexico.
A few other firms are jumping into the business as well. Japan’s Kaneka is set to have 5,000 t of capacity for PHBH in Takasago, Japan, by the end of the year. CJ CheilJedang, with Metabolix’s technology in hand, plans to either build a pilot plant or outsource small-scale PHA production, Sim Do Yong, of the company’s business development team, tells C&EN. The company aims for commercial production in 2022.
RWDC Industries was cofounded by Daniel Carraway, who also founded Danimer but later left the company. It has raised $35 million from investors and plans to build a PHA plant in Athens, Georgia.
Mango Materials, meanwhile, has nearly completed a demonstration unit at the Redwood City site where it operates the pilot plant. The unit will run continuously and produce more than 100 kg of material per week. “We can derisk a few components of the technology while actually producing meaningful volumes of material to use it for applications,” Schauer-Gimenez says.
A commercial plant, she acknowledges, is still a few years away. Mango will soon close a fundraising round, Schauer-Gimenez says, with investors who appreciate the amount of time needed to get the technology off the ground.
“Patient capital is what’s really key for us right now,” she says. “We’re not an iPhone app. Your return doesn’t come overnight.”

Saturday, June 6, 2020

Gravitricity - fast, long-life energy storage


As the world generates more and more electricity from intermittent renewable energy sources, there is a growing need for technologies which can capture and store energy during periods of low demand and release it rapidly when required.

At Gravitricity is developing a novel storage technology which offers some of the best characteristics of lithium batteries and pumped storage.

Ideally suited to network-constrained users and operators, distribution networks and major power users, the technology operates in the 1MW to 20 MW power range and enables existing grid infrastructure to go further in a renewable energy world.


Patented technology is based on a simple principle: raising and lowering a heavy weight to store and release energy. The Gravitricity system suspends weights of 500 - 5000 tonnes in a deep shaft by a number of cables, each of which is engaged with a winch capable of lifting its share of the weight. Electrical power is then absorbed or generated by raising or lowering the weight. The weight is guided by a system of tensioned guide wires (patents applied for) to prevent it from swinging and damaging the shaft. The winch system can be accurately controlled through the electrical drives to keep the weight stable in the hole.

Gravitricity  technology has a unique combination of characteristics:

50-year design life – with no cycle limit or degradation

Response time – zero to full power in less than one second

Efficiency – between 80 and 90 percent

Versatile – can run slowly at low power or fast at high power

Simple – easy to construct near networks

Cost effective – levelised costs well below lithium batteries

Each unit can be configured to produce between 1 and 20MW peak power, with output duration from 15 minutes to 8 hours.

 The key requirement is a deep hole in the ground; it can be a disused mineshaft brought back into use, or a purpose-sunk shaft. Shaft depths can be from 150m for new shafts down to 1500m for existing mines.

The grid connection is through modern power electronics to permit rapid switching between generation and absorption of power and the system can deliver active as well as reactive power to help with grid stability.

While the weight system can be used on its own, the energy storage capacity of the overall system can be much increased when the shaft is used as a pressure vessel, allowing a compressed air energy storage (patent applied for.) to operate alongside the weight system.  This involves adding a pressure-tight “lid” to the top of the shaft and lining the shaft to prevent leakage. The ground provides the bursting resistance other than at the very top of the shaft. The winches and generators will be contained in the pressurized space so that only electrical cables need to penetrate the pressure vessel walls.

Initially we will prove the technology using existing mine shafts. Future deployments will be able to utilise existing mines or purpose-built shafts, allowing development wherever storage is required.

During 2019/20 we are undertaking sub-system design and will be building a 250kW concept demonstrator in 2020.  We aim to deploy our first full-scale prototype in 2022 or 2023 at a disused mine in the UK.

Gravitricity Ltd has patents dating 2011, 2013, 2017 and 2019.

Monday, May 25, 2020

Bio-based? Recyclable? Biodegradable? Your guide to sustainable plastics


With sustainability high on everyone’s agenda and technology advancing fast, the world of plastics is changing. Here’s what you need to know about modern plastic materials – and the sometimes confusing terminology, explained by science journalist Sandrine Ceurstemont.

But what about new, more sustainable plastics – will they help us tackle the plastic waste challenge? What do the terms bio-based, biodegradable or recyclable plastics actually mean, and how can they help us achieve ambitious sustainability targets and cut down the need for crude oil in plastics production?
We will take you through some of the most common terms associated with sustainable plastics and uncover the facts behind each one.

Bioplastics – plastics that are bio-based or biodegradable or both

Bioplastics is a term that is used to refer to plastics that are bio-based, biodegradable, or fit both criteria.
In contrast to traditional plastics made from fossil-based feedstock, bio-based plastics are fully or partly made from renewable feedstock derived from biomass. Commonly used raw materials to produce these renewable feedstock for plastic production include corn stalks, sugarcane stems and cellulose, and increasingly also various oils and fats from renewable sources. The terms ‘bioplastics’ and ‘bio-based plastics’ are often used interchangeably by laypeople but they don't actually mean the same thing.
Biodegradable plastics are plastics with innovative molecular structures that can be decomposed by bacteria at the end of their life under certain environmental conditions. Not all bio-based plastics are biodegradable while some plastics made from fossil fuels actually are. 

Bio-based – plastics that contain components produced from biomass

Plastics that are bio-based are partially or completely made from material that has been produced from biomass instead of fossil-based raw materials. Some are biodegradable but others are not.
In 2018, 2.61 million tons of bio-based plastics were produced worldwide, according to the Institute for Bioplastics and Biocomposites (IfBB). But that is still just less than 1% of the global plastic market. As demand for plastic continues to grow, so is the demand for more sustainable plastics solutions. Conventional fossil-based plastic can be replaced with drop-in plastic  a bio-based equivalent. This can help reduce the carbon footprint of the end product while the other characteristics of the product – its durability or recyclability – for example, remain the same. 
Polyhydroxyalkanoate or PHA, is a common type of biodegradable bio-based plastic, currently used to make packaging and bottles, for example. It is produced by industrial fermentation when certain bacteria are fed sugar or fat from feedstocks such as beets, sugar cane, corn or vegetable oil. But unwanted byproducts, such as waste cooking oil or molasses that remain after sugar manufacturing, could be used as alternative feedstock, freeing up food crops for other uses.

As demand for plastic continues to grow, wider range  of bio-based plastics have entered the market and should increasingly be used as an alternative

Some bio-based plastics, such as, drop-in plastics have identical chemical structures and properties to conventional plastics. These plastics are not biodegradable, and they are often used in applications in which durability is a desired feature.
Bio-based PET, which is partly made from the organic compound ethylene glycol found in plants, is used in many products such as bottles, car interiors and electronics. As customer demand for more sustainable plastics increases, the market for this plastic is expected to grow by 10.8% from 2018 to 2024, compounded annually.
Bio-based polypropylene (PP) is another drop-in plastic that can be used to make products such as chairs, containers and carpets. In late 2018, commercial scale production of bio-based PP took place for the first time, producing it from waste and residue oils, such as used cooking oil.

Biodegradable – plastic that decomposes under specific conditions

If a plastic is biodegradable, it means that it can undergo decomposition under certain environmental conditions and when in contact with specific bacteria or microbes – turning it into water, biomass and carbon dioxide, or methane, depending on aerobic or anaerobic conditions. Biodegradation is not an indication of bio-based content; instead, it is linked to the molecular structure of a plastic. Although most biodegradable plastics are bio-based, some biodegradable plastics are made from fossil oil based feedstock.
The term biodegradable is ambiguous since it doesn't specifiy a timescale or environment for decomposition. Most plastics, even non-biodegradable ones, will degrade if they are given enough time, for example hundreds of years. They will break down into smaller pieces that can be invisible to the human eye, but remain present as microplastics in the environment around us. In contrast, most biodegradable plastics will biodegrade into CO2, water and biomass if they are given enough time under specific environmental conditions. It is advised that detailed information about how long a plastic takes to biodegrade, the level of biodegradation and required conditions should be provided to better evaluate its environmental credentials. Compostable plastic, a type of biodegradable plastic, is easier to assess since it must meet defined standards to merit a label.

Compostable – a type of biodegradable plastic

Compostable plastic is a subset of biodegradable plastic. Under composting conditions,  it is broken down by microbes into CO2, water and biomass.
For plastic to be certified as compostable, it must meet certain standards. In Europe, that means that in a timeframe of 12 weeks, 90% of the plastic must decompose into fragments less than 2mm in size in controlled conditions. It must contain low levels of heavy metals so that it doesn’t harm soil.
Compostable plastics need to be sent to an industrial facility where heat and humid conditions are applied in order to ensure degradation. PBAT, for example, is a fossil feedstock based polymer that is used to make organic waste bags, disposable cups and packaging film and is biodegradable in composting plants.
Plastic that breaks down in open environments such as in household compost heaps is typically hard to make. PHAs, for example, fit the bill but are not widely used since they are expensive to produce and the process is slow and hard to scale up. However chemists have been working on improving this, for example by using a novel chemical catalyst – a substance that helps increase the rate of a chemical reaction.

Recyclable – turning used plastic into new products by mechanical or chemical means

If plastic is recyclable, it means that it can be reprocessed at an industrial plant and turned into other useful products. Several types of conventional plastics can be recycled mechanically – the most common type of recycling. But the first global analysis of all plastic waste ever generated found that only 9% of plastic has been recycled since the material started being produced about six decades ago.
Mechanical recycling involves shredding and melting plastic waste and turning it into pellets. These pellets are then used as a raw material to make new products. Plastic quality deteriorates during the process; therefore a piece of plastic can only be mechanically recycled a limited number of times before it is no longer suitable as a raw material. New plastic, or ‘virgin plastic’, is therefore often mixed with recycled plastic before it is turned into a new product to help reach the desired level of quality. Even then, mechanically recycled plastics are not fit for all purposes.

Chemically recycled plastic can replace virgin fossil oil based raw material in the production of new plastics

Chemical recycling, whereby plastics are transformed back into building blocks and then processed into virgin-quality raw material for new plastics and chemicals, is a newer family of processes that is now gaining momentum. It typically involves catalysts and/or very high temperature to break down plastic and can be applied to a wider range of plastic waste compared to mechanical recycling. For example, plastic films containing multiple layers or certain contaminants cannot usually be mechanically recycled but can be chemically recycled.
The raw materials created from plastic waste in the chemical recycling process can be used to replace virgin crude oil based raw materials in the production of new, high-quality plastics.
One of the main benefits of chemical recycling is that it is an upgrading process in which a plastic’s quality doesn’t degrade once processed unlike during most types of mechanical recycling. The resulting plastic can be used to make a wide range of products including food containers and items for medical and healthcare uses where there are strict product safety requirements.

Sandrine Ceurstemont is a science and tech journalist whose work has appeared in The Guardian, National Geographic, BBC Earth and Scientific American.

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