engineered

A New Super-Enzyme For Breaking Down Plastic | Earth Wise

November 13, 2020 By EarthWise Leave a Comment

The problems caused by plastic waste continue to grow. Plastic pollution is everywhere, from the Arctic to the depths of the ocean. We consume microplastics in our food and breathe them in the air. It is very difficult to break down plastic bottles into their chemical constituents in order to make new ones from old ones. Therefore, we continue to produce billions of single-use plastic bottles, creating more and more new plastic from oil each year.

Scientists at the University of Portsmouth in the UK have developed a new super-enzyme that degrades plastic bottles six times faster than before. They believe that the new enzyme could be used for plastic recycling within a year or two.

The super-enzyme was derived from bacteria that naturally have the ability to eat plastic. The researchers engineered it by linking two separate enzymes, both of which were found in a plastic-eating bug discovered in a Japanese waste site in 2016. They revealed an engineered version of the first enzyme in 2018, which started breaking down plastic in a few days. They had the idea that connecting two enzymes together would speed up the breakdown of plastic. Such linkage could not happen naturally in a bacterium.

Carbios, a French company, announced a different enzyme in April that can degrade plastic bottles within 10 hours but requires heating above 160 degrees Fahrenheit. The new super-enzyme works at room temperature.

The team is now examining how the enzymes can be tweaked to make them work even faster. Meanwhile, they plan to work in partnership with companies like Carbios, to bring super-enzymes for breaking down plastics into commercial use.

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New Super-Enzyme Can Break Down Plastic at Rapid Pace

Photo, posted March 24, 2017, courtesy of the USFWS – Pacific Region via Flickr. Photo credit: Holly Richards/USFWS.

Earth Wise is a production of WAMC Northeast Public Radio.

Plants Paying For Biofuels | Earth Wise

May 7, 2020 By EarthWise Leave a Comment

Biofuels are an important element in broader strategies to replace petroleum in transportation fuels like gasoline, diesel, and jet fuel. The idea is that biofuels recycle carbon by getting it from growing plants rather than from fossil sources. The biggest problem with biofuels is that they cost more than conventional petroleum fuels, so there is economic incentive to keep burning the fossil fuels.

One strategy to make biofuels cost competitive is to have the plants provide additional economic benefits beyond being a feedstock for fuel. This in principle can be done by engineering plants to produce valuable chemical compounds, or bioproducts, as they grow. Bioproducts include such things as flavoring agents and fragrances as well as biodegradable plastic. These bioproducts can be extracted from the plants and then the remaining plant material can be converted to fuel.

Researchers at Lawrence Berkeley National Laboratory recently published a study to determine what quantities of bioproducts plants need to produce to result in cost-effective biofuel production.

The study looked at a compound called limonene, which is used for flavoring and fragrance. They calculated that if this compound was accumulated at 0.6% of the biomass dry weight, it would offer net economic benefits to biorefineries. This corresponds to recovering 130 pounds of limonene from 10 tons of sorghum on an acre of land.

Such quantities are completely practical but, on the other hand, none of these substances are needed in huge quantities. Just six refineries could supply the world with limonene. So, fuel crops would need to be engineered to produce a broad range of bioproducts to enable a viable cost-effective biofuel industry.

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Making Biofuels Cheaper by Putting Plants to Work

Photo, posted September 28, 2019, courtesy of Michele Dorsey Walfred via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Another Way To Make Solar Cells

March 21, 2019 By EarthWise Leave a Comment

Millions of rooftops now contain solar panels and the majority of the solar cells that make up those panels today are made from silicon. Silicon solar cells require expensive, multi-step processing conducted at very high temperatures in special clean room facilities. Despite these complications, the price of solar panels has continued to drop dramatically over the years.

But even as the price of solar cells gets lower and lower, there are still widespread efforts to find even better ways to make them. One of those ways is with perovskite solar cells. Perovskites are materials with a characteristic crystal structure and are quite common in nature. Perovskites can be formed with a wide range of elements and can exhibit a variety of properties.

They were first used to make solar cells about 10 years ago and those first cells were unimpressive in most respects. However, there has been steady progress since that time. The potential advantages of perovskite solar cells are that they can be made from low-cost materials and can be manufactured using liquid chemistry, a far cheaper process than what is used to make silicon cells.

Researchers at MIT and several other institutions have recently published the results of research on how to tailor the composition of perovskite solar cells to optimize their properties. What used to be a trial-and-error process can now become much more engineered and should lead to perovskite solar cells with performance that could exceed that of silicon cells.

Silicon solar panels are a huge, worldwide industry and displacing them in favor of an alternative technology is a tall order. But if perovskite cells can be optimized for large-scale manufacturability, efficiency and durability, they could definitely give silicon a run for its money.

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Unleashing perovskites’ potential for solar cells

Photo courtesy of Ken Richardson/MIT.

Earth Wise is a production of WAMC Northeast Public Radio.