On the surface, solar photo-chemical conversion seems to be very limited in our production and life, but in fact, in the use of solar energy, this is a more extensive and important subject. It is like an iceberg floating on the sea. What we can perceive is only a small part on the water. The more mysterious solar photo-chemical conversion content is deeply hidden in the surging waves of the sea. Down. Further in-depth development and research on solar photo-chemical utilization issues occupy a very important strategic position in the development and utilization of human solar energy. In order to have a deeper understanding and understanding of the photo-chemical conversion of solar energy, we need to change from another angle. The following first discusses the issue of changes in the ecological environment of the earth’s biosphere, which is closely related to the photo-chemical conversion of solar energy.
According to a survey report published by the World Wide Fund for Nature (WWF), covering the status of 3,000 vertebrate species, the world’s population has doubled from 3.7 billion in 1970 to 7 billion in 2010. The number of wild animals has dropped by 52%. In order to have a scientific and quantitative description of species changes. Biologists from the United States and other countries organize joint research studies. Scientists define the number of extinct species per 1 million species each year as the death rate of the species; the survey found that the current extinction rate of species from the earth is at least 1,000 times that of humans before the earth appeared. That is to say: if the death rate of species on the earth was about 1 before the emergence of human beings, then the death rate is now at least 100 to 1,000 species death rates, which symbolizes the deterioration of survival and the ecological environment. The production and survival activities of human beings are the most important factor leading to the deterioration of the earth’s environment and the increase in the rate of species extinction. If it is allowed to continue, the result will lead to the arrival of the “sixth period of biological extinction”. WWF claims that the rate at which humans squander the generous gifts of nature exceeds the rate that nature can maintain, and this behavior will affect the future of all mankind. The world’s population is expected to reach 9.6 billion in 2050 and to exceed 11 billion in 2100. By then, the earth’s per capita ecological carrying capacity will further shrink. All signs fully indicate that our blue planet has entered the initial stage of a new round of mass extinction. And one of the most important factors that caused this crisis is that human beings have carried out uncontrolled emissions of greenhouse gas-CO2 into the earth’s atmosphere in the past years.
It took more than 7,000 years for the concentration of carbon dioxide on the earth to rise by 80ppm during the “Ice Age”; and it took only 55 years for modern human society to emit the same amount of greenhouse gases into the earth’s atmosphere. The monitoring report issued by the Naloa Observatory stated that the station has been monitoring the carbon dioxide content in the Earth’s atmosphere since 1958, and the value measured that year was 315pm; since then, it has risen all the way and now reaches 399ppm; it will soon exceed the 400ppm mark and create The highest value in 3 million years. Scientists believe that when the carbon dioxide concentration reaches 450ppm, the earth’s climate change will enter an irreversible critical value, beyond which the global temperature will rise by 2℃; Mauna Loa Observatory predicts that this critical value will be around 2037. arrival. Scientists also predict that even if the concentration of carbon dioxide in the atmosphere remains at today’s level, the sea level will rise by 0.6 m in 70 years, and will rise to 2.4 m in 2200; if the situation develops to that point, the world will be better. Hundreds of coastal cities and small island nations are at risk of disappearing. If we do not take any measures to allow the concentration of carbon dioxide in the atmosphere to continue to climb to 1,000 ppm, then all hope will be dashed. With global warming, rising sea levels, severe droughts, famines, and the collapse of ecosystems, the earth is no longer suitable for human habitation, the end of the world is bound to come; nature will be irretrievably destroyed! If we want to delay the arrival of the “sixth period of biological extinction”, scientists have proposed that we must try to cool the earth. To do this, we must try to recycle the carbon dioxide that has been released into the atmosphere through various means since the Industrial Revolution, re-recover and solidify it and bury it in the ground. One of the preferred ways to remove carbon dioxide from the earth’s atmosphere is to use photosynthesis in the photo-chemical conversion of solar energy, through the most adaptable organisms on the earth-diatoms; to invest iron powder in certain sea areas to promote The water temperature in the shallows of the sea increases, which promotes the double growth of seaweeds. Under the sunlight, the chlorophyll of this single-celled organism absorbs carbon dioxide in the air through a photo-chemical reaction and leaves carbon molecules in the algae to release Oxygen is released, so as to achieve the purpose of removing carbon dioxide in the atmosphere. The above photosynthetic reaction can be expressed as follows:
At present, when it is difficult to remove carbon dioxide from the atmosphere on a large scale, the only way out is to take all necessary measures to drastically reduce the total amount of carbon dioxide emissions. Scientists have noticed that if methanol fuel is widely used, it can effectively reduce carbon dioxide emissions in production and living activities. Therefore, methanol can be used as a low-emission motor vehicle fuel. Using methanol fuel to replace gasoline can not only effectively reduce carbon dioxide emissions, but also make up for the lack of global petroleum resources. Reducing the consumable combustion of fossil fuels for vehicles is of greater significance in reducing the emission of black particulate PM2.5 in the urban atmosphere that seriously affects human health. According to a paper by an expert from the Institute of Atmospheric Environment of the Chinese Academy of Environmental Sciences, every cubic meter of PM2.5 in the atmosphere increases by 10 micrograms, and the daily mortality rate of Chinese residents rises by 0.31%. What’s more, not only PM2.5 is emitted from automobile exhaust, but the nitrogen oxides in it will also undergo photochemical reactions under sunlight to generate ozone. Ozone in a low-altitude environment will cause irritation to the human respiratory tract. If exposed to a high-concentration ozone environment for a long time, the probability of human death from respiratory diseases will increase by 50%. In the presence of oxygen, the combustion of methanol produces carbon dioxide and water. Scientists have been looking for a simple reverse reaction catalyst, hoping to convert carbon dioxide and water back into methanol, thereby reducing greenhouse gas emissions. Recently, Canadian scientists announced that they have found two catalysts that can promote the above-mentioned reverse reaction. One is borane (BH3) and the other is phosphine. The process of converting carbon dioxide into methanol requires a hydrogen source and chemical energy. Alkane (BH3) as a catalyst can not only double the conversion efficiency of other catalysts, but also produce less waste without destroying the catalyst. Only by adding new reactants, it can be reactivated. The current problem is that the synthesis of borane (BH3) requires a lot of energy, making it more expensive than methanol. Once scientists have solved the efficient synthesis of catalysts, or found other hydrogen sources that can greatly increase production, it may be another major measure to save the living environment of the entire biosphere and make a historic contribution. I hope that the feat of scientists to remove greenhouse gases from the atmosphere and cool the earth can be successful, so as to benefit human society and prevent the occurrence of the “sixth mass extinction” event.
In fact, the earth, the cradle of human life, under the shining of the sun, is undergoing various solar photo-chemical reactions that we can perceive, or that we can’t perceive at all. Some scientists have calculated that the annual “photosynthesis” of plants on the earth through the sun, that is, the total amount of organic matter produced by green plants is 1.8 x 1011t. Among them, 70% are produced on land and 30% are produced in the ocean. These biomass energy is equivalent to 3×1022J of energy. If we develop part of the biomass energy to replace part of the fossil energy facing depletion under the premise of protecting the ecological environment, then the world will become more harmonious and beautiful. The conversion technology and conversion methods of biomass energy include: ①Direct combustion: cutting out firewood or solidifying biomass for use as fuel; ②Biomass conversion: such as using bio-starch to produce fuel ethanol or biogas fermentation to extract methane as fuel; ③Chemical conversion: Biomass pyrolysis gasification is used to produce fuel gas methanol, and vegetable oil is used to refine and produce biodiesel.
The direct burning of biomass seems to be the same thing as the burning of coal. In fact, although the direct combustion of biomass also eliminates carbon dioxide, it hardly produces sulfur dioxide. Burning biomass and developing fuelwood forests can just achieve a balance between carbon dioxide absorption and release, and will not increase the total amount of carbon dioxide emissions in the atmosphere. In industry, biomass is directly burned, and its purpose is more for waste-to-energy. Humans all over the world produce tens of millions of tons of domestic waste every day. These wastes are treated in a harmless manner. Except for recyclable plastic products, non-ferrous or black metal parts, most of the biomass is organic waste. As garbage, three treatment methods can be used for harmless treatment and utilization: ① return the compost to the field as organic fertilizer after fermentation; ② enter the biogas digester to produce methane gas; ③ send it to the garbage power station for combustion and power generation.
Using a specific solar photo-chemical reaction phenomenon to carry out large-scale industrial and agricultural production and utilization, it should be said that there are still many potentials to be developed. For example, in the 1970s, scientists tried to use solar radiation energy to Dissociating water, directly extracting hydrogen from water as energy, fundamentally solve the problem of energy shortage in human society. However, no effective photocatalyst has been found in the experiment. It has been reported on the website of the journal Nature Nanotechnology that decades ago until recently: “Researchers at the University of Houston, including Chinese scientists, have discovered a This kind of (cobalt oxide) nanoparticles can use sunlight to quickly produce hydrogen from water as a catalyst.” Researchers use cobalt oxide nanoparticles as a catalyst, and through natural light irradiation, water is almost immediately decomposed into hydrogen and oxygen; and The hydrogen produced in the experiment is twice that of oxygen, and the ratio of hydrogen to oxygen in water molecules is the same. At present, there are two more problems: one is that the conversion efficiency of sunlight into hydrogen is only 5%, so it has no commercial value; the other is how to reduce the cost of producing catalysts and prolong the service life of cobalt oxide nanomaterials. We are convinced that if one day human beings realize the use of solar thermal radiation, water molecules can be dissociated into hydrogen and oxygen, and then hydrogen can be stored on a large scale to become a stable and pollution-free energy source that can satisfy the production and life of human society. Therefore, human society will usher in the era of hydrogen energy without any worries.
As a matter of fact, human beings are still at a low level in the development and utilization of solar photo-chemicals, and they have not done enough in their actions. In other words, the application of solar photo-chemical conversion has always been a weak link in the development and utilization of solar energy. Since the development and utilization of coal and fossil energy, industrialization has been promoted, the environmental and ecological crises caused by the large-scale emission of greenhouse gases have pushed human society to the brink of survival. Unless carbon dioxide, the greenhouse gas that was released from the magic bottle, is reloaded into the magic bottle and buried in the deep sea, mankind will have no safe future. The means to achieve this goal depends to a large extent on the in-depth development of solar photo-chemical technology. I believe that with the unremitting efforts of mankind, solar photo-chemical applications will continue to flourish and bloom more brilliantly. Exotic flowers.