Shulou(Shulou.com)11/24 Report--

This article comes from the official account of Wechat: ID:fanpu2019, author: Li Cunpu

Have you ever heard of liquid sunlight? In order to better store energy and reduce carbon, Chinese scientists have proposed a set of energy solutions-liquid sunlight. Turn the sun into liquid fuel, put it in a "bottle" and use it immediately.

Written by Li Cunpu (Professor, School of Chemistry and Chemical Engineering, Chongqing University)

Energy, the word sometimes makes people feel so far away that it seems that only talking about the conflict between Russia and Ukraine on the wine table can draw the distance between us and "energy", but it is so close to us that it is the foundation of human clothing, food, housing and transportation.

Energy is the cornerstone of modern society. We use energy to create new materials, and the application of all kinds of new materials makes the quality of human life change with each passing day; we consume energy to maintain a decent life, air conditioning, heating, cars, cooking and so on, so that human beings can live elegantly in any harsh environment and facilitate travel; we rely on energy to go up to heaven and earth, chase the stars and sea, overcome the bondage of gravity and the oppression of sea water resistance, and find more wonderful. Therefore, no matter for the individual or the country, the region or the world, all the ideals of the future are largely based on adequate energy. Be vigilant, so many people want endless resources.

1. The storage and transportation of solar energy leads to nothingness and reality. Most of the energy of the earth comes from the sun. As described in wandering Earth, the variation of the sun will be unbearable for all life on Earth. According to the generally accepted cognition, hundreds of millions of years ago to tens of millions of years ago, plants on the earth absorbed the energy of sunlight through photosynthesis and transformed into organic compounds in animals and plants, which went through a series of complex chemical / physical changes. it has been transformed into oil, coal and natural gas, and has become the main energy carrier in modern society.

Fig. 1 Oil and coal may come from ancient creatures, such as the Megazostrodon 200 million years ago, which makes it so important to save energy: turning on the gas stove burns not only methane, but also the "flame" of the free-running Tyrannosaurus Rex 7000 years ago; driving with one foot on the throttle, the cylinder spurts not only gasoline, but also a sneeze of the Megazostrodon walking leisurely 200 million years ago. The conversion of solar energy into oil, coal and natural gas is full of historical accumulation, heavy and precious, which we should cherish.

At the same time, the carriers of energy such as oil, coal and natural gas are converted into electricity, which is transmitted to thousands of households through the power grid, illuminating the modern society. The discovery and application of electric energy is a major change in the application of energy, so that energy is no longer dependent on the carrier (or "working medium, that is, the working material to realize the conversion of heat and work") can be used efficiently. Power plants obtain heat energy by burning oil, coal, natural gas and other energy carriers, and then convert it into electric energy. With a wire and a current, power plants have achieved the great achievement of transferring ancient solar energy to millions of contemporary households. The transmission of energy has never been so simple.

The storage of solar energy began hundreds of millions of years ago and is converted into real matter; this accumulated energy is sent to all parts of the world through oil and gas pipelines or coal trains to supply all aspects of society. some of the real energy carriers are converted into slightly empty currents, realizing the dreams of thousands of human beings.

2. The current application of solar energy is the hope of sustainable development. in terms of energy, human beings have been eating the old: eating all the life that has passed away since the birth of the earth. Would you be a little ashamed? Although "after my death, no matter the flood", but when the energy crisis does not seem to be so far away today, we have to face up to the energy sources of the future not too far away.

The sun is still reliable, as long as it still rises. The total energy the earth receives from the sun every year far exceeds the annual consumption of human beings. If the inexhaustible solar energy can be fully utilized, the energy problem will no longer exist. People have been trying to achieve this goal. In fact, hydroelectric power, which has long been widely used, is an indirect application of solar energy: the sun evaporates sea water inland, and after it rains, the stream becomes a river-driven generator, which is converted into clear hydropower and incorporated into the grid. This may be the reason why Hi-Fi users like to use "hydropower". Although it is less historical, it has more contemporary freshness. )

But water and electricity are far from enough. People have developed wind power, tidal power and other technologies to further use indirect solar energy, and invented a variety of solar cells to directly convert sunlight into electricity and connected to the grid. But all of these technologies face intermittent problems: they rely on steady winds, stable tides, stable light, but the rotation and rotation of the earth, as well as the complex geographical environment, the word "stability" contradicts grumpy solar energy.

Sustainable development requires stability, and we need to find ways to accumulate the sunshine that may not be stable every day to realize the dreams of future generations.

3. Plants accumulate sunlight, but it is too complicated. when we think of stable energy storage, plants think of it a long time ago. In fact, plant photosynthesis is the process of accumulating sunlight. They absorb CO2 and use solar energy to reduce CO2 to various organic substances, thus storing sunlight in cellulose, starch, sugar and other substances, so that sunlight energy has a carrier. So to a certain extent, if we spend some money and accumulate some energy to the forest, we are already accumulating strength for sustainable development. At the same time, we also note that photosynthesis can absorb a large amount of CO2, which also has an important contribution to the realization of the dual-carbon goal.

Fig. 2 the charcoal sellers pretreat the firewood to obtain charcoal with higher calorific value and lower water content and sell it to the exploiting class, so isn't it okay to have a variety of trees? Planting trees is good, but it is far from enough. Trees in a forest grow old, and when a tree grows old, its respiration emits more CO2 than it can fix-that is, it loses its role. Of course, we are not qualified to require any life to work, but apart from the fact that trees grow old, it is also very difficult to use solar energy fixed by plant photosynthesis. The ancient "charcoal sellers" had already mastered certain advanced energy use skills: firewood obtained from cutting wages had high water content and low energy per unit weight, and used for barbecue cooking was not only smoky, but also heated slowly. it is difficult to meet the landlord's pursuit of crispy cooking, so the charcoal sellers will first burn the "salary" into higher calorific value "charcoal" to sell, because the charcoal is clean and hygienic. And heat up quickly.

Unfortunately, the demand for energy in modern society has become more refined, and the solar energy fixed by plant photosynthesis is converted into a variety of different chemicals. And many chemicals mean that plants need to spend a lot of money to purify them at the application level-for example, we can't use crude oil directly and separate it into various components to support modern industry. So, can sunlight be "decomposed" and stored?

4. Keep it simple, keep it simple when you accumulate sunshine. Scientists who are good at reverse thinking have found a new breakthrough. Since coal and oil power generation is to convert the stored solar energy into electricity and transmit it to thousands of households, it is better to convert solar energy into electricity, and then store it and distribute it to users. But as mentioned earlier, whether it is direct or indirect solar energy, its intermittent application limits its promotion and application. Therefore, the two routes have been gradually developed. A kind of energy storage power station is built near the intermittent power generation device, which converts the unstable electric energy into chemical energy in the battery, and then integrates it into the power grid for distribution, that is, the "solar energy-electric energy-energy storage-application" route, referred to as "energy storage route" for short. The other is to convert unstable electric energy into a single, easy-to-use substance, which is distributed-generated-transported through the existing distribution of oil, natural gas and coal, that is, the route of "solar energy-electric energy-material-application". Referred to as "liquid sunshine route".

The liquid sunlight route may be more lasting than the energy storage route. The energy storage route depends on the construction of the energy storage power station, and the battery capacity of the power station can achieve the goal of buffering intermittent power connected to the grid, but it is difficult to complete the task of producing energy working fluid as a strategic energy reserve. Strategic energy reserves, which require that even in extreme cases such as severe natural disasters, wars, or even the destruction of the earth, provide energy for equipment-powered by matter rather than power grids-are clearly more reliable.

Figure 3 Liquid sunshine achieves the goal of storing solar energy into a single chemical for utilization. Bai Chunli, Zhang Tao, Li Jinghai and others of the Chinese Academy of Sciences put forward the concept of liquid sunlight (liquid sunlight) in 2018, which provides a possible energy solution for the future of fossil fuel depletion. The so-called liquid sunlight is a complete set of energy solutions-using sunlight, water and CO2 to produce stable performance, high energy density, suitable for international transportation and distribution of liquid alcohol fuel, and through the clean conversion of liquid alcohol fuel and the recycling of CO2 emissions, and finally achieve zero CO2 emissions. As shown in figure 3, liquid sunlight can not only fix solar energy and CO2, but also produce single chemicals such as methanol and ethanol, which can be used through existing crude oil and natural gas transmission systems or distribution routes, with low energy conversion cost and high efficiency, and is expected to become an important energy carrier in the future.

A single chemical is essential. As mentioned earlier, modern society is based on the creation of various substances and the use of energy, and the creation of new substances and energy use requires a single chemical substance rather than a complex mixture. In fact, the current energy consumption of separating a single substance from the mixture accounts for 10-15% of the world's total energy consumption. The simpler the material is, the more convenient it is to apply, which is also one of the major reasons for promoting garbage classification. Therefore, liquid sunlight can not only be used as an energy carrier in the future, but also promote the innovation and development of chemical industry, materials industry and other fields, forming multiple identities from energy carriers to material materials.

5. We don't have to wait for the future, although we seem to hear news or rumors about the further progress of controllable fusion every day, but the waves caused in our hearts are far lighter than those caused by the comprehensive promotion of the sixth national gasoline, or when we enter the gas station and find that only ethanol gasoline comes.

Advanced technologies such as controlled nuclear fusion sound very sci-fi, but another meaning of sci-fi may be a long distance, as if 50 years away. Liquid sunlight is much more pragmatic, even so simple that the existing internal combustion engine can use methanol and ethanol produced by liquid sunlight as fuel to drive the vehicle. In fact, the first thousand-ton liquid sunshine demonstration project in 2020 has been launched [4], and the industrialization of 100,000 tons is in the process of being implemented. When we look forward to a future full of science fiction, chemists are also pushing mankind to tomorrow and tomorrow step by step.

At present, the difficult problem in the research and application of liquid sunlight is how to efficiently reduce CO2 hydrogenation-deoxidation to alcohols. CO2 itself is a non-polar molecule with weak reaction activity, but people can efficiently add a molecule of H2 to CO2 on the electrode to obtain formic acid (HCOOH). However, the energy that formic acid can provide is very limited, how to further deoxidize and hydrogenate formic acid to obtain methanol (CH3OH) is the current academic research hotspot. On the one hand, the possible breakthrough route includes using the design of the catalyst to pull out the oxygen atom, and the other is considering learning from life to simulate biological processes such as photosynthesis to achieve the effect of oxygen dehydrogenation. In fact, in these studies, artificial intelligence has already played a role. After all, screening the best catalyst / biocatalysis route from existing human knowledge is reasonable and efficient.

But breakthrough development can not only rely on artificial intelligence, after all, the so-called "breakthrough" itself often means breaking away from traditional routines. The ingenious efforts of chemists have gradually pushed us into the future, and it is precisely because of these efforts that in the face of disasters and wars, we will not be controlled by others at the energy level, nor will we be said to be of the same level as me.

So before the helium flash, let's drink this glass of liquid sunlight.

reference

[1] https://en.wikipedia.org/wiki/Megazostrodon

[2] Shih C F, Zhang T, Li J, et al. Powering the future with liquid sunshine [J]. Joule, 2018.

[3] Sholl, D., Lively, R. Seven chemical separations to change the world. Nature 532,435-437 (2016). Https://doi.org/10.1038/532435a

[4] successful demonstration of the kiloton "liquid Sunshine" synthesis project-2020 [EB / OL]. (2021-01-08) [2022-12-23]. Https://www.cas.cn/ cg / cgzhld / 202101 / t20210112_4774334.shtml

Postscript:   @ ChatGPT, what do you think of the development of liquid sunlight? will it change the energy field?

ChatGPT: I am optimistic about the development of liquid sunlight, which will bring great changes to the energy sector. It can not only replace traditional energy, but also provide more efficient energy conversion in solar cells.

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