Renewable energy, its storage and conversion are necessary in dealing with climate change and for energy independence
The need to minimize the damage of climate change led world leaders to a global initiative to reduce the use of polluting fuels and switch to sustainable energy production technologies, explains Prof. Elbaz from the Chemistry Department at Bar-Ilan University. Prof. Elbaz is one of a growing group of researchers in the field of green energy, who work at Bar-Ilan University as part of The new center for energy and sustainability as well as lecturers in the various departments and touching on the field of renewable energy and green energy from many and varied angles.
The activity of the energy center focuses on the energy sectors which include solar energy, hydrogen economy and fuel cells, complex materials, development of biofuels, nanotechnology and artificial intelligence. The researchers at the center are engaged in the fields of energy conversion, such as energy accumulation and conversion systems, hydrogen generation and storage, development of rechargeable batteries, supercapacitors, electric grids, superconductivity and efficient switching, batteries with high energy density and large-scale energy storage systems.
Green or renewable energy is nothing new. It has been used throughout human history. Plows, millstones, carts, grinders and many other technologies were powered by the muscle power of people and animals. Wind was harnessed to power grain mills and pump water, and water currents were also diverted to power mills. Solar energy was harnessed to dry and heat food, hides, building materials and more. The type of energy that affects the atmosphere is that which involves fire, which in turn results in the emission of carbon dioxide - starting with the first fires lit by the ancient man and ending with the carbon-carbon power plants and car engines of our time. Carbon dioxide and other gases create the greenhouse effect that underlies the climate crisis that we are experiencing more and more tangibly in recent years. The research activity at Bar-Ilan focuses on the one hand on the production of clean energy, that is, with minimum emissions of greenhouse gases, and on the other hand, on the efficient storage and conversion of energy.
Prof. Elbaz, for example, is engaged in research in the field of energy storage, specifically in hydrogen cells. Although it is possible to generate enough energy from wind and sun, these sources are not available during all hours of the day and seasons. Therefore, there is a need for technologies to store and transport energy in large quantities. One of the most promising solutions is using hydrogen, which can be produced from water. At the heart of this concept lies fuel cell technology, which converts the chemical energy trapped in hydrogen directly into clean electricity in an electrochemical process.
In the last decade, there has been significant progress in technology, which today allows car manufacturers, power stations and more to base their products on fuel and hydrogen cells. The continuation of the work depends on the development of fuel cells that are not based on precious metals or metals concentrated in problematic places. For this purpose, effort is directed to the development of fuel cells based on common and cheap raw materials. A development made in Prof. Elbaz's laboratory makes it possible for the first time to follow the decomposition processes of catalysts - which are a central component of the electrochemical process that occurs in fuel cells - that are not based on critical raw materials. In a joint study with laboratories in the United States and Australia, Prof. Elbaz developed a method that makes it possible to separate the processes that occur on the catalyst and are related to it from other processes that take place in fuel cells. This method will enable the development of more active and durable catalysts and subsequently significantly reduce fuel cell technology.
While Prof. Elbaz deals with energy storage, Prof. Kahan, an expert in solar energy and especially photovoltaic cells from the Department of Chemistry and the Institute of Nanotechnology and Advanced Materials in Bar-Ilan, deals with the production of clean energy, in this case - solar energy.
The first significant commercial use of solar energy for electricity on Earth was in thermosolar power plants, where a fluid (usually oil) was heated, and the heat was used in the same way that fossil fuel-based power plants produce electricity: the heat is used to create hot air, or steam, that moves rapidly When blackened, the pressure is used to rotate loops made of conductive material, so that an electric current is created inside. Such stations, says Prof. Kahan, were established in the XNUMXs in the Mojave Desert in California by an Israeli company. At the same time, photovoltaic installations (what we call solar panels) were erected.
At the beginning, the production of electricity using a thermo-solar or photovoltaic approach was not effective. "If we compare it to the 'Orot Rabin' power plant in Hadera, the photovoltaic plants in the desert produced about 0.25% of daylight, and the first thermo-solar plants produced 0.4%-1.2% of the output of 'Orot Rabin' (which, by the way, still uses today, mainly in coal - which is bad, but produces electricity day and night - which is good) Prof. Kahn says. "The timing in the XNUMXs is a direct result of the search for alternative energy sources after the first energy crisis the world experienced due to the Yom Kippur War and the Iranian Revolution of the XNUMXs." Even today, in view of the war in Ukraine, the understanding of the importance of relying on local energy sources is growing.
The great advantage of photovoltaic cells is that if they are fixed and do not follow the sun depending on the time of day and the seasons, then there are no mechanically moving parts in them, which contributes to their durability. On the other hand, a thermoelectric station is similar in a certain sense to a power station powered by mineral fuel, to which more pipes and mirrors are added to create a complex chemical array, which has many moving parts. To some extent, this is the difference between conduction in cables and conduction in pipes. Other approaches to producing solar energy are through true thermoelectric generators. They are used in materials that produce an electric voltage between a hot part and a cold part. They are not very efficient, but very reliable, if heated by a reliable source.
Prof. Kahn points out that the outstanding technology in today's field is the photovoltaic. The main issue is the conversion efficiency between solar energy and electrical energy and reaching a high efficiency that will remain stable in the long term. At Bar-Ilan efforts are being made to focus on this issue and to find new materials with which it will be possible to produce very durable and stable photovoltaic cells.
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