How knowledge of photosynthesis leads to production of clean energy.

Photovoltaik-Anlagen sieht man heutzutage überall. Neuartige Modelle können ihren Wirkungsgrad noch übertreffen. Ihr Funktionsprinzip basiert auf dem Wissen über Photosynthese

Photovoltaic systems can be seen everywhere these days. Novel models can exceed their efficiency. Their principle of operation is based on the knowledge of photosynthesis. Sebastian GansoPixabay 

Fundamental research has the purpose of understanding the universe and the life in it. This work is like the basis that is needed to create applications. These applications can be new technologies or the cure for a disease. In this way, the fundament of knowledge is useful for the universe and the life in it.

Much of what we know today, was first discovered in plants. This includes the construction of cells or the concept of genetics (Mendel’s famous experiment about the color of pea flowers). Another interesting example is the principle of photosynthesis. Swiss scientists are currently finding ways in which they can use this knowledge to produce clean energy. With regards to the climate crisis and an increasing demand in energy, this is now more important than ever.

But back to the basics; The research on the principle of photosynthesis took a long time. In the 1950th the puzzle of this biochemical reaction was finally solved. And one of the scientists, professor Calvin, was awarded the Nobel Prize for his findings in 1961. But the story does not end here. The gained knowledge was used to find a technical application. During photosynthesis, sunlight causes an electrical charge, when it reaches pigments in a leaf. These electrons are directly used, to fuel the biochemical reaction that results in the production of oxygen. In principal, plants can produce electricity. The swiss scientists, professor Grätzel and his team, make use of this principle to produce clean energy. They were able to build solar panels in which sunlight creates an electrical charge, when it reaches the pigments. The electrons are then transported by the carrier material inside the panels. This way, they can be integrated into a current circuit. Electricity is created, that can be used by all kinds of devices that are connected to it. The principle is similar to that of classical silicon based solar panels. But the amount of electricity that is won with the photosynthesis-based technology is much higher. In addition, the panels are much flatter and can have any kind of shape. In current tests of long-term endurance, the panels are used as part of the facade of houses.  Like for the facade of the Gratz Science Tower.

The technology behind the so-called pigment-solar panels is at the moment premature. Ironically, the panels are sensitive to light, as well as heat and moisture. The research group around professor Grätzel is currently improving this, before the panels can be used commercially. In addition, they are creating storage facilities for the energy. This is needed, since the electricity is created by day, but much of it is demanded by night. And the technology for energy storage is based on knowledge gained from plants as well. They use energy to split water molecules into oxygen and hydrogen. The latter can be seen as storage medium for energy, as it releases it, only when it is burned. This way, it is applicable as car fuel. And hydrogen is a source of clean energy, since it turns into water, when it is used as fuel.

Graphic designed by Katrin Heidemeyer

This is an example that shows how roughly seventy years old fundamental research can lead to technologies, that have the capability to change the world. Professor Calvin and his colleagues have probably not imagined this, when they were busy in the lab. They only wanted to find out, how plants use the carbon-dioxide that they take up each day. And this is true for many researchers. We are driven by our curiosity and a desire to solve the riddle that is life itself. While the results that come from the work can be beneficial for everyone.

You can find out exactly how the process of photosynthesis proceeds and how the principle for the dye solar cell was changed here.

Photosynthesis is a process during which several molecules are converted in a number of separate steps. The most important ones are described here; Light hits pigments that are embedded in leaf cells. The energy of the light results in the release of electrons. These electrons are in return needed to build the molecules that allow for oxygen production. Here, electrons are like the energy from coffee that is necessary to get started with work in the morning. This initiating energy is needed to form NADPH and ATP. NADPH helps to combine carbon-dioxide and water, to make oxygen and sugar. ATP is the fuel for this reaction. Both are consumed in the process and must be replaced, with the help of more electrons. But they are now missing from the pigments and must first be restored. This is done with sun light too. Its energy can split water molecules. The resulting electrons migrate into the pigments, oxygen is released into the air, and the formed protons (H+) help making ATP. The whole process is comparable to a cycle of build-up and break down that continues as long as the sun is shining.

Inside the pigment solar panel, the electrons that result from sun light, are not used in chemical reactions. They are directly transported away via the carrier material. However, just like in plants, the electrons must be replaced. This is solved by connecting the panels to an electrical current. It is another kind of cycle in which energy is created, transported, and some of it returns. Once the technology is sophisticated enough, it can be part of the solution to fight climate crisis while meeting increasing demands for energy.


References:

Geschichte der Biologie. 3. Aufl., Sonderausgabe Nikol, Hamburg 2004, S. 515–518.).  

SWR TV Show; Teleakademie, ausgestrahlt am 16.6.2019 um 7:30 Uhr.

Website of the EPFL research institute in Lausanne, Switzerland (https://www.epfl.ch/labs/lpi/graetzel/)

Published by Katrin Heidemeyer

Katrin Heidemeyer ist Doktorandin im Bereich Biochemie an der Wageningen University and Research. Durch ihre Arbeit möchte sie das Wissen über die Spezifität von Hormon-Signalen in Pflanzen erweitern. Da ihre Interessen über Pflanzenbiologie hinausreichen, schreibt sie in ihrer Freizeit über diverse Themen. Von Ernährung zu Psychologie, der Neugierde sind keine Grenzen gesetzt.

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