It is possible to keep algae tanks clean while allowing more photosynthesis. If a small amount of electricity is added, it can prevent the walls of the algae tank from becoming cloudy and hazy.
Algae grown in transparent tanks or tubes that have carbon dioxide pumped in can turn this gas into something else like food supplements or fuel. However, the walls start to get covered by algae which makes it hard for light to pass through, causing a decrease in efficiency and requiring cleanup every weeks or so.
MIT scientists have developed an easy and cheap method to reduce the bad effects of global warming. This can help us use unwanted gases in the atmosphere to make valuable products more efficiently and without spending too much money.
Scientists have figured out a way to put tiny electric charges on transparent containers. They do this by coating the container with an electric charge-holding material and then giving it a very small voltage. So far, the test have been successful in labs and hopefully, this technology can be used for commercial purposes in a few years.
On April 13, 2023, a group of researchers released their discovery in the journal Advanced Functional Materials. This group included Victor Leon, who graduated from MIT that year, Kripa Varanasi who is a professor of mechanical engineering, former postdoc Baptiste Blanc and undergraduate student Sophia Sonnert.
Even if we are able to stop emissions of carbon, there will still be an excessive buildup of it in the air for centuries. So, according to Varanasi, we should also look for ways to take out greenhouse gases from the environment or even stop them from escaping into the atmosphere before they even get released.
When people think of ways to reduce carbon dioxide, they often first think of planting or saving trees since they absorb atmospheric carbon. But there are other ways too. Marine algae are responsible for taking in 50 percent of the world’s carbon dioxide today and they grow much faster than land plants–ten to fifty times faster. Plus, they don’t use as much space–the ponds or tanks needed can take up only one-tenth the area that regular land plants need.
The good thing about algae is that it is made up of proteins, vitamins, and other important nutrients. Professor Varanasi said that it produces more nutritionally valuable output than usual farm crops if used in the same amount of land.
Algae is able to attach itself to the smoky gas from coal and gas power plants. It then feeds on carbon dioxide given off by the smoke, as well as nitrogen and sulfur present in the gas. Scientists estimate that for every 2-3kg of CO2, 1kg of algae can be created. This algae can then be used for creating biofuels, Omega-3 or even food!
Omega-3 fatty acids are vitamins found in food that your body needs but cannot make on its own. They are important for healthy cell membranes and other parts of your body. “Omega 3 is very important because it’s also a higher-value product,” Varanasi says.
Normally, algae are grown in ponds across farms, but there’s also another way to grow them – in tubes called photobioreactors. These tubes can make a lot more yield than the ponds, which sounds great. But that comes with some difficulties too: the algae often stick to the sides of the tubes, and so they must be cleaned frequently. This takes just as long as it takes to actually produce yield and thus cuts total productivity by half, making production more expensive.
Fouling can cause problems when building a system. The tubes have to be large enough so that the fouling doesn’t block the flow of water through the bioreactor or require more pumping.
Varanasi and his team thought of using something natural on the algae cells in order to stop fouling. Since these cells have small negative charges on their outside shells, they should be able to push each other away by electrostatic repulsion.
We wanted to make the vessel walls have a negative charge, which would cause the electric field to push the algae cells away. To do this, we needed a special type of material called a “high-performance dielectric” that works like an insulator but can produce a bigger change in surface power with less voltage.
Leon says that usually people use electricity on bioreactors by using special surfaces that conduct it. But what they’re doing now is different; they are using surfaces that don’t conduct electricity.
He explains: “If it’s electrically conductive, then electricity is allowed to flow and the cells will get shocked. So, what we’re trying to do is create a sort of force field that keeps the cells apart by using negative charges so they don’t touch each other. It’s like having an invisible shield in between them so they can’t shock each other.”
The team experimented with different types of materials when making photobioreactors, such as silicon dioxide (which is basically glass) and hafnia (hafnium oxide). They found out that these materials are really good at stopping materials from sticking to the photobioreactor and clogging it. This special coating can be very thin – around 10-20 billionth of a metre thick. Just a little bit of this special coating can cover an entire photobioreactor system!
“We are so excited that just by changing the electric charges, we can control how cells stick to each other,” Varanasi explained. “It is like having a switch which either turns this on or off.”
Leon said that the electrostatic force they used can’t only work with algae cells, but also may be applicable with other types of cells such as mammal cells, bacteria, and yeast. We might even use it to help with spirulina, which is a type of algae used in food supplements.
The same system can be used to make things go away or come close, depending on the thing we want to do. For example, instead of algae (which is a type of plant), this setup could also be used with human cells to create artificial organs by making them move in the right way through electricity.
In our study, we have solved a big problem that has been blocking the success of photobioreactors. This technology will help us make full use of these systems and it needs some extra work to be able to work well on the commercial level. We believe that in 3 years time with the right resources, this technology can become available for everyone.
A research study was recently conducted by Victor J. Leon, Baptiste Blanc, Sophia D. Sonnert and Kripa K. Varanasi and published in a journal called Advanced Functional Materials on April 13th. The purpose of the study was to find out how electricity can be used to change the stickiness of cells with nanometric high-k dielectric films (tiny pieces made from very special material). This experiment was funded by an energy company called Eni S.p.A., through something called the MIT Energy Initiative.
