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Whilst the ability to produce fuels from renewable, organic matter has long been known, chemists are still unable to manufacture higher performance fuels, such as diesel, in an economically feasible way. This is a major problem for the biofuel industry and a global challenge for a world where so many goods sent via diesel engines on trucks and ships have an impact on climate change.

But now bio-engineers may be closer to solving this problem as they have genetically engineered a strain of yeast to convert sugars from organic matter to fats more effectively. While the breakthrough has only increased the process’s efficiency by 30%, it is thought that the research could be a breakthrough to making production of better performing biofuels, including bio-diesel, economically viable.

As professor Gregory Stephanopoulos, the Willard Henry Dow Professor of Chemical Engineering and Biotechnology, and one of the lead reseachers in the study conducted at MIT, notes, “Diesel is the preferred fuel because of its high energy density and the high efficiency of the engines that run on diesel. The problem with diesel is that so far it is entirely made from fossil fuels.”

The technical issue, according to the study published in the journal Nature Biotechnology, is that, “While microbial factories have been engineered to produce lipids from carbohydrate feedstocks for production of biofuels and oleochemicals, even the best yields obtained to date are insufficient for commercial lipid production.”

While there has been a lot of success in converting cooking oil to biofuel, this feedstock is in relatively short supply. More readily available biofuel feedstock, such as corn and sugar cane, requires converting carbohydrates into lipids, before they can be made into a fuel. The fact that this process is uneconomical when compared to fossil fuels, led the MiT team to look at ways of improving the efficiency of the process. They hope to be able to use cheaper and more abundant organic feedstock to make biodiesel.

The website MiT News explained the achievement as follows, “Stephanopoulos and his colleagues [including fellow leader, MIT postdoc, Kangjian Qiao] began working with a yeast known as Yarrowia lipolytica, which naturally produces large quantities of lipids. They focused on fully utilizing the electrons generated from the breakdown of glucose. To achieve this, they transformed Yarrowia with synthetic pathways that convert surplus NADH, a product of glucose breakdown, to NADPH, which can be used to synthesize lipids. Using this improved pathway, the yeast cells require only two-thirds of the amount of glucose needed by unmodified yeast cells to produce the same amount of oil.”

“It turned out that the combination of two of these pathways gave us the best results that we report in the paper,” Stephanopoulos said. Although the team also admits that, “The actual mechanism of why a couple of these pathways work much better than the others is not well-understood.”

So clearly there is still much work to do before renewable diesel is powering trucks on our highways. However, the researchers are continuing their work, funded by the U.S. Dept of Energy, with the ultimate aim of being able to use not just sugar cane and corn starch, but any, “plant material, such as grass and agricultural waste. [Although this] would require converting the cellulose that makes up those plant materials into glucose.”

As Stephanopoulos says, “There is still room for more improvement, and if we push more in this direction, then the process will become even more efficient, requiring even less glucose to produce a gallon of oil. What we’ve done is reach about 75% of this yeast’s potential, and there is an additional 25% that will be subject of follow-up work.”

When and exactly how this last 25% of the goal will be met is unknown, but biotechnology engineers and biofuel manufacturers are keeping a close eye on progress. With governments keen to lower their carbon footprint and dependency on oil, then the work being carried out at MiT could see a renewable biodiesel, at an economically viable process, much sooner than we think.

Photo credit: Jose-Luis Olivares/MIT

A group of researchers have developed a battery that is recharged with waste CO₂. The invention’s inexpensive materials and use of a waste product to produce electricity may not only lower energy prices, but also reduce carbon emissions at the same time. Given that power stations are releasing so much carbon dioxide that it is considered a pollutant, this discovery could prove revolutionary.

The breakthrough was made at Pennsylvania State University, where chemists Bruce E. Logan, Christopher A. Gorski and Taeyong Kim, were able to capture the chemical energy in the difference between industrial CO₂ emissions and ambient air. Whilst this has been achieved before, previous efforts produced only low power densities and required expensive ion-exchange membranes. This new technique however, is much more efficient, such that the researchers are hopeful that the process can be scaled up. As Gorski explained, “This work offers an alternative, simpler means to capturing energy from CO₂ emissions compared to existing technologies that require expensive catalyst materials and very high temperatures to convert CO₂ into useful fuels.”

Publishing their results in the American Chemical Society journal Environmental Science and Technology, the research team state that, “The pH-gradient flow cell produced an average power density of 0.82 W/m², which was nearly 200 times higher than values reported using previous approaches.”

Reporting on the breakthrough, the online science journal Phys.org describes the process as follows, “In order to harness the potential energy in this [CO₂] concentration difference, the researchers first dissolved CO₂ gas and ambient air in separate containers of an aqueous solution, in a process called sparging. At the end of this process, the CO₂-sparged solution forms bicarbonate ions, which give it a lower pH of 7.7 compared to the air-sparged solution, which has a pH of 9.4.”

It continues by identifying how the CO₂ solution is then used in a ‘flow cell’ to extract the chemical energy. “After sparging, the researchers injected each solution into one of two channels in a flow cell, creating a pH gradient in the cell. The flow cell has electrodes on opposite sides of the two channels, along with a semi-porous membrane between the two channels that prevents instant mixing while still allowing ions to pass through. Due to the pH difference between the two solutions, various ions pass through the membrane, creating a voltage difference between the two electrodes and causing electrons to flow along a wire connecting the electrodes.”

When the flow cell has been discharged, it can simply be recharged by switching the channels that the solution flows through. By alternating the solution that flows over each electrode, the charging mechanism is reversed so the electrons flow in the opposite direction. This process was found to be repeatable up to 50 times before the cell’s performance deteriorated.

The researchers also found that the higher the pH difference between the two channels, the higher the average energy density. Overall, the results were much better than other pH-gradient flow-cells, but were still some way off the power levels supplied by cells that included other fuels, such as H_2. But the research team is still continuing their study, in the hope that they can prove the technology to be workable on an industrial scale.

“We are currently looking to see how the solution conditions can be optimized to maximize the amount of energy produced,” Gorski said. “We are also investigating if we can dissolve chemicals in the water that exhibit pH-dependent redox properties, thus allowing us to increase the amount of energy that can be recovered. The latter approach would be analogous to a flow battery, which reduces and oxidizes dissolved chemicals in aqueous solutions, except we are causing them to be reduced and oxidized here by changing the solution pH with CO₂.”

Early results prove promising, with Gorski upbeat about the projects potential when he said, “A system containing numerous identical flow cells would be installed at power plants that combust fossil fuels. The flue gas emitted from fossil fuel combustion would need to be pre-cooled, then bubbled through a reservoir of water that can be pumped through the flow cells.”

While, this may seem some way off from a real-world application, many fuel-cell experts are already hailing the discovery as a crucial step towards both cheaper energy and reduced carbon emissions. However, what makes this new design so special is that it has many notable advantages over earlier ‘flow-cell’ models. Its use of inexpensive materials, its operation at ambient temperatures, and above all its use of CO₂ as a feedstock, makes this discovery an attractive and practical possibility for existing power stations.

Photo credit: Logan, Gorski and Kim

3D printing has become a much more versatile possibility thanks to the work of a team of researchers who claim to have invented the most elastic, 3D printable polymer in the world. The work is a result of a collaboration between researchers from the Hebrew University of Jerusalem (HUJI), and two teams from Singapore. One from the Singapore University of Technology and Design’s Digital Manufacturing and Design Centre (DManD), and another from the Campus for Research Excellence and Technological Enterprise (CREATE).

Publishing their results in the Journal of Advanced Materials, the research teams explain how their stretchable UV curable (SUV) elastomers can be, “stretched by up to 1100% and are suitable for digital light processing (DLP) based 3D printing technology. DLP printing of these SUV elastomers enables the direct creation of highly deformable complex 3D hollow structures such as balloons, soft actuators, grippers, and Bucky ball electronical switches.”

Elastomers are a valuable part of the polymer industry, with polymer manufacturers using their elastic properties for a wide range of applications. For example, they are used in the making of biomedical devices, as well as soft robotics, and are an invaluable addition to flexible electronics. However, uptil now their use has been restricted by their need for thermal curing. While silicon rubber-based materials , which are the most common form of elastomer, typically need traditional manufacturing via molding, cutting, and casting, which keeps costs high.

While the development of a highly elastic elastomer may not surprise many, polymer traders are seeing the new material as a possible game changer. As the plastics industry journal 3D Printer and 3D Printing News reports, “At this point, you may be telling yourself that you’re familiar with 3D printable elastomer materials, and that they do already exist. And while this is true—there are elastomer materials that are commercially available for UV light 3D printing—those on the market cannot stretch beyond 200% once they’ve been cured, a restriction that makes them much less useful for many professional applications.”

It also seems that the new polymer is durable enough to last sufficiently long in most practical situations. As 3D Printer and 3D Printing News explains, “The SUV elastomers have also reportedly shown good mechanical repeatability, making them suitable for use in flexible electronics. This feature was demonstrated by the researchers, who 3D printed a buckyball light switch using the elastomer, and pressed it 1000 times. After the testing, the light switch still worked normally.”

Co-leader of the research project, Professor Shlomo Magdassi, sumarised the discovery’s versatility and practical use, when he said, “Overall, we believe the SUV elastomers, together with the UV curing based 3D printing techniques, will significantly enhance the capability of fabricating soft and deformable 3D structures and devices including soft actuators and robots, flexible electronics, acoustic metamaterials, and many other applications.”

With the discovery of a much more elastic, printable polymer, surely it is only a matter of time before plastic manufacturers begin to design products that take advantage of the greater versatility of 3D printing. Added to this versatility is the fact that the new elastomer may allow for lower production costs. A point made clear, by another of the study’s co-leaders, Assistant Professor Qi Ge, when he said, “Compared to traditional molding and casting methods, using UV curing based 3D printing with the SUV elastomers significantly reduces the fabrication time from many hours, even days, to a few minutes or hours as the complicated and time-consuming fabrication steps such as mold-building, molding/demolding, and part assembly are replaced by a single 3D printing step.”

While the discovery of a highly flexible polymer that is 3D printable, may not stop the world from spinning, but its cheaper production and durability is likely to make waves in the elastomer industry. Given all these factors combined, how long will it be before 3D printing becomes a major method in the manufacture of plastic products? Or is that just stretching this new invention beyond 1100%?

Photo credit: 3D Printer and 3D Printing News