A new, inexpensive innovation can restrict the accumulation of algae on the walls of photobioreactors that can assist transform co2 into helpful products. Decreasing this fouling prevents expensive cleanouts and enables more photosynthesis to occur within tanks. Credit: Jose-Luis Olivares, MIT
Applying a small voltage to the walls of algae-growing tanks can prevent cloudy buildup and enable more photosynthesis to happen.
Algae grown in transparent tanks or tubes provided with carbon dioxide can convert the greenhouse gas into other substances, such as food supplements or fuels. But the procedure results in a buildup of algae on the surface areas that clouds them and minimizes effectiveness, requiring tiresome cleanout procedures every couple of weeks.
MIT scientists have actually created a easy and inexpensive innovation that could considerably limit this fouling, potentially enabling for a far more efficient and cost-effective way of transforming the undesirable greenhouse gas into helpful products.
The secret is to coat the transparent containers with a material that can hold an electrostatic charge, and after that using a very small voltage to that layer. The system has actually worked well in lab-scale tests, and with additional development may be used to commercial production within a few years.
The findings were reported on April 13, 2023, in the journal Advanced Functional Materials, in a paper by current MIT graduate Victor Leon PhD 23, professor of mechanical engineering Kripa Varanasi, former postdoc Baptiste Blanc, and undergraduate trainee Sophia Sonnert.
The team figured that electrostatic repulsion might be utilized to push them away due to the fact that the algae cells naturally carry a little negative electric charge on their membrane surface area. Credit: Courtesy of the researchers
No matter how successful efforts to eliminate or reduce carbon emissions may be, there will still be excess greenhouse gases that will remain in the environment for centuries to come, continuing to affect worldwide climate, Varanasi mentions. “Theres currently a great deal of co2 there, so we have to look at unfavorable emissions innovations also,” he says, referring to methods of removing the greenhouse gas from the air or oceans, or from their sources prior to they get released into the air in the very first place.
When people think about biological methods to carbon dioxide decrease, the very first idea is typically of planting or safeguarding trees, which are certainly a vital “sink” for atmospheric carbon. But there are others. “Marine algae represent about 50 percent of international carbon dioxide soaked up today on Earth,” Varanasi states. These algae grow anywhere from 10 to 50 times quicker than land-based plants, and they can be grown in ponds or tanks that take up only a tenth of the land footprint of terrestrial plants.
Whats more, the algae themselves can then be an useful item. “These algae are abundant in proteins, vitamins and other nutrients,” Varanasi states, noting they might produce even more dietary output per unit of land utilized than some standard farming crops.
If connected to the flue gas output of a coal or gas power plant, algae could not only thrive on the carbon dioxide as a nutrient source, however a few of the microalgae species could likewise take in the associated nitrogen and sulfur oxides present in these emissions. “For every 2 or 3 kilograms of CO2, a kilogram of algae could be produced, and these could be utilized as biofuels, or for Omega-3, or food,” Varanasi states.
Omega-3 fats are an extensively used food supplement, as they are an important part of cell membranes and other tissues however can not be made by the body and needs to be gotten from food. “Omega 3 is particularly appealing since its likewise a much higher-value product,” Varanasi states.
The majority of algae grown commercially are cultivated in shallow ponds, while others are grown in transparent tubes called photobioreactors. Televisions can produce seven to 10 times greater yields than ponds for an offered amount of land, however they deal with a major problem: The algae tend to develop up on the transparent surface areas, requiring regular shutdowns of the entire production system for cleansing, which can take as long as the productive part of the cycle, therefore cutting total output in half and adding to operational expenses.
The fouling also restricts the design of the system. Televisions cant be too little due to the fact that the fouling would start to obstruct the circulation of water through the bioreactor and need higher pumping rates.
Varanasi and his team chose to try to use a natural characteristic of the algae cells to prevent fouling. The team figured that electrostatic repulsion might be utilized to press them away because the cells naturally carry a small unfavorable electrical charge on their membrane surface.
The concept was to develop an unfavorable charge on the vessel walls, such that the electric field requires the algae cells away from the walls. To produce such an electric field requires a high-performance dielectric product, which is an electrical insulator with a high “permittivity” that can produce a big modification in surface area charge with a smaller sized voltage.
” What individuals have done before with applying voltage [to bioreactors] has actually been with conductive surface areas,” Leon explains, “however what were doing here is specifically with nonconductive surfaces.”
He includes: “If its conductive, then you pass present and youre sort of stunning the cells. What were attempting to do is pure electrostatic repulsion, so the surface would be negative and the cell is negative so you get repulsion. Another way to explain it is like a force field, whereas before the cells were touching the surface and getting shocked.”
The group dealt with two different dielectric materials, silicon dioxide– basically glass– and hafnia (hafnium oxide), both of which ended up being much more efficient at decreasing fouling than conventional plastics used to make photobioreactors. The material can be applied in a covering that is vanishingly thin, simply 10 to 20 nanometers (billionths of a meter) thick, so really little would be needed to coat a full photobioreactor system.
” What we are excited about here is that we have the ability to reveal that simply from electrostatic interactions, we are able to manage cell adhesion,” Varanasi states. “Its almost like an on-off switch, to be able to do this.”
Furthermore, Leon says, “Since were utilizing this electrostatic force, we dont really anticipate it to be cell-specific, and we believe theres potential for using it with other cells than just algae. In future work, we d like to try using it with mammalian cells, bacteria, yeast, and so on.” It might likewise be utilized with other valuable kinds of algae, such as spirulina, that are extensively utilized as food supplements.
The exact same system could be used to either fend off or bring in cells by just reversing the voltage, depending upon the specific application. Instead of algae, a similar setup might be utilized with human cells to produce synthetic organs by producing a scaffold that might be charged to draw in the cells into the right setup, Varanasi suggests.
” Our study basically resolves this significant issue of biofouling, which has actually been a traffic jam for photobioreactors,” he states. “With this technology, we can now really achieve the complete capacity” of such systems, although more advancement will be needed to scale as much as useful, industrial systems.
As for how soon this might be all set for extensive deployment, he says, “I dont see why not in three years timeframe, if we get the right resources to be able to take this work forward.”
Recommendation: “Externally Tunable, Low Power Electrostatic Control of Cell Adhesion with Nanometric High-k Dielectric Films” by Victor J. Leon, Baptiste Blanc, Sophia D. Sonnert and Kripa K. Varanasi, 13 April 2023, Advanced Functional Materials.DOI: 10.1002/ adfm.202300732.
The study was supported by energy business Eni S.p.A., through the MIT Energy Initiative.
“Marine algae account for about 50 percent of worldwide carbon dioxide taken in today on Earth,” Varanasi says. What were trying to do is pure electrostatic repulsion, so the surface would be unfavorable and the cell is negative so you get repulsion. Another way to describe it is like a force field, whereas before the cells were touching the surface and getting stunned.”
Additionally, Leon says, “Since were utilizing this electrostatic force, we do not actually anticipate it to be cell-specific, and we believe theres potential for applying it with other cells than simply algae. It might likewise be utilized with other important types of algae, such as spirulina, that are widely utilized as food supplements.
By David L. Chandler, Massachusetts Institute of Technology
April 16, 2023
