‘Flame that doesn’t burn’ to produce fuel and plastics without CO2 emissions

‘Flame that doesn’t burn’ to produce fuel and plastics without CO2 emissions

New lab on Brightlands Campus for research into plasma technology

15-12-2021 · Science

The climate goals are clear: over the next decades CO2 emissions must be reduced drastically. How can this be done in the chemical industry, where burning fossil fuels is still an important source of energy? Maastricht researchers are focussing on a sustainable alternative: the electrical plasma flame. “We expect important breakthroughs for the energy transition.”

It is only a small reactor, no bigger than a shoebox, located in the Brightsite Plasma Lab on the Brightlands Chemelot Campus in Sittard, which was opened last month. But the small viewing hole reveals something spectacular: a red-orange flame of about five to ten thousand degrees Celsius. This has not resulted from burning fuel, a process that produces the greenhouse gas CO2. Instead, this so-called plasma flame is generated by electricity. A process that is completely ‘clean’ if the electricity itself has been produced sustainably, for example by wind turbines or solar panels. Moreover, it can be used to facilitate chemical reactions. Thus, the flame constitutes a ‘green’ alternative for the incineration ovens in the chemical industry.

Nevertheless, the technology is not being applied on a large scale so far, even though it already exists for over a century, says Gerard van Rooij, professor of Plasma Chemistry at the UM since 2020, and head of the lab. “Because fossil fuels were always cheaper than electricity, it was never considered a serious option for industry. Compare it to an electric car: it already existed before the car with an internal combustion engine, but for a long time nothing was done with it.”

Microwave

This means that there is also a lack of in-depth knowledge about the technology. The plasma lab should change that. “Fortunately, we don’t need to start from scratch,” says Van Rooij. All the necessary technology and knowledge to create a plasma flame is already available. “In principle, we use the same technology as in the microwave oven in your home. Except, this reactor doesn’t heat the entire oven, but we concentrate the microwaves on a tube in which there is a so-called plasma. This is a gas in which some particles have lost an electron. Under the influence of electric fields, in our case from microwave radiation, the electrons start to move. They subsequently clash against molecules at high speed, transferring energy that makes chemical reactions possible. During this entire process you don’t need to take energy from fossil fuels.”

So much for the theory. But is the technology also suitable for efficient use in practice? The plasma reactors in the new lab – a total of five, one of which is already working at the moment – are supposed to provide insight in that. “Using laser technology, we can look ‘inside’ the flame, something that happens in only a few labs in the world. In this way, you can find out where in the plasma flame certain reactions are the most efficient, and at what temperatures. Apart from that, we don’t exactly know the chemistry at these high temperatures. We will most likely come up against unexpected reactions, which may also be useful.”

Two assistant professors, three postdocs and three PhD students, who came to Maastricht especially for the lab, are going to focus on this together with Van Rooij in the coming years. Students from the bachelor’s of Circular Engineering, that was launched this academic year, can also carry out research there. This doesn’t just concern gaining fundamental knowledge about plasma chemistry, but also the testing and improving of possible applications for industry. “Important questions include what is the best way of controlling the plasma flame, and how you can use this at an industry-relevant scale,” says Van Rooij.

Valuable CO2

The lab is open to collaboration with business parties. It is expected that this will happen intensively, because many businesses want to decrease their CO2 emissions considerably, in the coming decade or even reduce them to zero. But Van Rooij also see other advantages in addition to sustainability. “In the energy transition, green energy will become increasingly cheaper compared to fossil fuels, which makes the technology financially more attractive.”

Moreover, it makes other chemistry possible, he continues. “You switch the plasma on and off in less than one millisecond. And because of the high temperatures, the reactions take place quickly. Unlike in a combustion furnace, you can therefore make minor, rapid adjustments, giving you much more control over the final products. It is like having always sailed with an oil tanker, and now suddenly having an advanced fighter jet at your disposal, which you can control quickly and precisely.”

The necessary raw materials are also different to what one is used to using in the current industry: the plasma flame can revalue ‘bad stuff’ for the environment and climate into useful materials. For example, CO2 can be transformed into ‘clean’ synthetic fuels. “Unfortunately, this is still challenging with CO2 from the atmosphere. In order to use that, you need to filter the CO2 from the air and concentrate it, which costs a lot of energy. But you could think about the use of biogas, almost half of which consists of CO2.”

Recycling

In addition, plasma can revalue nitrogen into fertilizer, and methane into clean fuels as well, but also into raw materials for the production of plastics. This will make it easier to create circular, more sustainable processes, says Van Rooij. “Methane is a molecule that is released in various and cannot currently be used as a raw material. That is why it is often burnt, which releases additional CO2. Using plasma chemistry, you can use it to make plastic. And from recycled plastic, you can subtract methane, which brings you in the direction of a closed cycle.”

Van Rooij thinks that if the plasma flame proves to be efficient for commercial applications, the technology could take off quickly. “The required technology exists, is relatively cheap, and doesn’t need scarce materials, as is the case with electric car batteries. This means that you can scale up fairly easily.”

And it doesn’t need to be limited to the chemical industry. Because the plasma reactor is relatively small and does not need to be on 24/7, it could be connected locally to a wind turbine or solar park, for example. Although only time will tell what the applications will be, says Van Rooij: “It is extremely interesting to experience this at close range.”

Photo: Brightsite Center

Categories: news_top, Science
Tags: science,chemistry,plasma,plasmalab,brightlands,chemelot,CO2,fuel,plastics,renewable energy,energy,sustainable energy,climate change

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