Energy between red and black

Weizmann Institute scientists are trying to compete with plants in the field of solar energy utilization. Do we have a chance to win this competition?

There is a future for alternative energy. Among other things, because what nature doesn't do, maybe the color will do. In the future, we may paint houses, cars, ships and planes with a thin layer of paint that will absorb solar energy and convert it into electricity or fuel. The choice of color will be done with aesthetics in mind, but energy considerations will dictate certain compromises. Ferrari cars, for example, will not necessarily be painted red. It is possible that the shade that will suit them - for the purpose of efficient production of energy - will actually be black. In fact, most vehicles will actually be painted in dark colors to absorb more solar energy.

Dr. Boris Rivchinsky, from the Department of Organic Chemistry at the Weizmann Institute of Science, finds in this "black vision" a reason for optimism. "In terms of energy use," he says, "we haven't made much progress." In order to obtain energy, we burn oil or coal, whose availability is finite and their burning is dangerous for the environment. At the same time, energy consumption in the world is increasing, and global climate warming is becoming more and more threatening. There is a very large gap between the intensity of the energy problem and the pace of our progress in finding alternative energy sources. Therefore, we must find new and creative ideas to deal with the problem."

The members of Dr. Rivchinsky's research group promote such a creative idea, which is based on photosynthesis, the process in which certain plants and bacteria turn sunlight into chemical energy using an organic dye - chlorophyll. Admittedly, there are artificial pigments that are much more effective than chlorophyll, but their integration into active systems is not simple. Dr. Rivchinsky aims to build "well-connected" molecular systems, which will absorb sunlight in a smart process that will enable the production of electricity and fuels using solar energy.

In fact, there are already solar cells that convert the sun's energy into electricity, but their use is limited, among other things, because of their high cost. Another problem is energy storage, since a solar cell only works when the sun is shining. A solution to this problem lies in our ability to convert solar energy into chemical energy, that is, to create fuel from available materials using light. This is exactly what photosynthesis does in nature. Dr. Rivchinsky aims to build artificial photosynthetic systems from organic materials that will be cheap and convenient. In the processes he hopes to develop, it may be possible to produce different fuels. Among other things, it is about producing hydrogen from water, or producing methanol (a type of fuel) from water and carbon dioxide. The solution lies in our ability to create complex systems that will allow us to control their interactions with light, as well as their electrical and chemical activity. Building and understanding such systems is a significant challenge. Dr. Rivchinsky believes that the understanding of photosynthesis in nature and achievements in the fields of organic chemistry and nanotechnology will enable innovative solutions.

There are no traditional solar collectors in Dr. Rivchinsky's laboratory. In fact, without an electron microscope it is impossible to see his solar systems, whose size does not exceed a few millionths of a millimeter. To produce these tiny systems, Dr. Rivchinsky uses the phenomenon of self-organization, which controls the formation of various systems. An important role in this process is reserved for water: different molecules are attracted to water molecules or repelled by them, and according to this property the place of these molecules is determined in different structures, including living cells and tissues. Dr. Rybczynski uses a series of advanced molecular methods to take advantage of the hydrophobicity (hatred of water) of certain organic molecules, and make them organize themselves into structures that are efficient for converting solar energy.

In one of these studies, Dr. Rivchinsky builds molecular "wires" designed to perform three functions, in ascending order of difficulty: to transmit photons while absorbing solar energy, as is done in the first stage of photosynthesis; to transfer electrons to pass electric current in solar cells; And finally, transfer electrons and protons to produce solar fuels.

At the same time, as part of the Weizmann Institute of Science's new initiative in the field of alternative energy research, he is collaborating with other scientists at the institute in building solar systems that will combine organic molecules, catalysts and nanoparticles to convert solar energy into electricity and fuel. "We strive to solve questions of basic science, which is the key to practical solutions in the field of alternative energy," he says. "Both I and the research students in my group are committed to this effort, which is a source of motivation for all of us."

In the long term, the scientists hope not only to reach the degree of efficiency of plants in the field of solar energy utilization - a huge challenge in itself - but also to surpass them and gain the ability to operate more efficiently. "Plants don't run around like we do, so our energy needs are infinitely greater than theirs," says Dr. Rivchinsky. "From here it is clear that we must produce more energy, more efficiently."