Dalian Institute of Chemical Technology directly converts carbon dioxide into gasoline? what do you think?

Recently, the issue of sustainable energy was involved in the preparation of the oral presentation. I have seen many friends put forward the problem of energy conversion in thermodynamics, that is, if you use a lot of energy to prepare hydrogen, and provide high enough temperature or overpotential to reduce carbon dioxide to prepare methanol, the energy provided cannot exceed the energy consumed. This is a very good and sharp question. In fact, the chemical energy for preparing methanol may only account for 65,438+00% or less of the consumed electric energy or heat energy, and the consumption of these methanol will produce the same amount of carbon dioxide. In addition, the carbon dioxide released during the cracking of oil and natural gas to produce hydrogen seems to have not decreased. This almost makes this article and research in similar fields a joke. In fact, scientist is best at accounting (otherwise, phd salary would not be so low, and people in NSF and NSFC are not stupid, and they will not spend money in completely useless places.

There are several concepts that need to be understood clearly. There is a lot of energy on the earth, and we are not short of energy, but there is very little energy that can be directly used. Why do you say that? In addition to fossil energy, we have countless rich energy sources such as wind energy, hydro energy, geothermal energy, solar energy and nuclear energy, but the only energy source that can be directly utilized is biomass energy that can be directly burned. Chemical energy is converted into power through internal combustion engines, and the conversion efficiency is about 40%-50%. Of course, we also use electricity, and electricity is also a kind of clean energy that we can use directly. Unfortunately, electric energy is not energy, and there is no mine with unlimited electric energy for human beings to directly plug in one billion charging treasures for power supply. There are countless ways for human beings to generate electricity, but there are not enough effective ways to store electricity. My father is engaged in the research of water conservancy industry and computer field, and participated in the automatic control of hydro-generators in Gezhouba and Three Gorges Dam. When I was a child, when my father told me about the dam storing water to generate electricity, I asked him why he didn't put away the stored water to solve the problem of insufficient power supply in summer. In fact, the current generated by hydropower plants and thermal power plants is directly connected to the power consumption system through numerous substations and transmission lines. According to the minimum Planck principle, the input power is actually determined by the output power, that is, how much electricity is generated, and all the excess electricity is wasted in the power grid and cannot be saved.

Although we have capacitors, supercapacitors, lithium-ion batteries, lead sulfate batteries and other energy storage equipment. In the final analysis, we still convert electric energy into chemical energy and electric potential energy. The design purpose is to charge and discharge circularly rather than to store energy. It is inevitable that it is impossible to make tens of billions of lithium-ion batteries to store electric energy for a long time. Therefore, the biggest purpose of the Three Gorges Dam is not to generate electricity, but to store and adjust the distribution of energy, store energy in the form of gravitational potential energy, and properly release water to generate electricity in dry season. Therefore, every year when the floodgate is forcibly opened to adjust the flood peak, you can see a dull pain in the face of the Minister of Water Resources, because all the energy and glistening money are released.

Solar energy and wind energy can provide abundant but unstable energy, so they cannot be connected to the power grid for normal use for the time being. Solar energy, in particular, is greatly influenced by the environment and has no stable output. Then we urgently need clean and pollution-free substances to store electric energy, which one is best to use directly? The answer is obvious, fuel. Fuels include but are not limited to hydrogen, ammonia, methane, methanol, ethanol, alkanes with 4-8 carbon atoms, etc. How to make the best use of these energy sources has been studied for many years. After all, theoretically, there is an upper limit to the efficiency of internal combustion engines. At present, the best use seems to be 3. The theoretical upper limit of fuel cell is 100%, and the efficiency of motor is much higher than that of internal combustion engine, so the design of fuel cell will gradually replace internal combustion engine. Anyway, besides the catalyst problem of the fuel cell itself, where does the fuel come from? Fossil energy will be exhausted one day, and this day is really not far away. Other fuels, such as hydrogen-oxygen fuel cells, contain oxygen in the air. What about hydrogen? At present, most of the artificially produced hydrogen comes from steam reforming of methane, which consumes a lot of energy. The amount of hydrogen used only to provide ammonia accounts for 65,438+0% of global annual energy consumption and 3% of annual carbon dioxide emissions. So, of course, we can't produce hydrogen for fuel cells by consuming fossil energy. My wife is a loser. Petroleum industry can not only provide gasoline, but also provide almost all raw materials for organic synthesis industry, and most of these raw materials can not be synthesized by simple inorganic molecules at present.

4. How to get hydrogen without oil? We have abundant electricity, but we can't store it. Electrolyzing water is a good way to store energy. Hydrogen precipitates at the cathode, oxygen precipitates at the anode, and electric energy is converted into chemical energy and stored in hydrogen. At the same time, electrolytic water and solar cells can be combined to prepare PEC for photolysis of water, and the ubiquitous solar energy can be used to decompose water to store energy. As a gas, hydrogen is naturally difficult to store, such as difficult to compress, inflammable, explosive and unstable, and difficult to release, so it is a new field to store hydrogen with MOF and Pd materials. What else can the prepared hydrogen do? Reducing carbon dioxide to produce methanol or multi-carbon alcohol hydrocarbons, or reducing nitrogen are all good choices. What's more, when a voltage is applied, water and carbon dioxide directly generate oxygen and alcohols. This device is called artificial blade, which can fix carbon and nitrogen through artificial photosynthesis. Yang Peidong and Yaji of Berkeley are both outstanding in this field. Therefore, when photolysis technology and electrocatalysis technology are mature and commercialized, hydrogen and energy for reducing carbon dioxide can completely come from solar energy and water, so we don't have to worry about the energy conversion efficiency of production. We just store a part of countless energy sources that cannot be directly used, and we will always make money (even the desalination technology needs further development).

Back to the problem itself, carbon dioxide itself is one of the chief culprits of the greenhouse effect that we hate. Internal combustion engines and thermal power will inevitably cause a lot of carbon dioxide emissions, and countries will not easily reduce emissions for economic development. At this time, the conversion of carbon dioxide is particularly important. Since there is hope to see carbon dioxide converted into fuel by solar energy and wind energy, industrial feed will replace the increasingly scarce fossil energy, so why not? There is still a long way to go in this field. Some people think it is a pit, some people think it is impossible to commercialize, some people think that this article is only a small progress, not even a breakthrough, and some people say that scientific research is using money to do meaningless grandstanding. But you should see from the description in the first paragraph that this direction is one of the most suitable methods that materials scientists can think of to solve problems at present (of course, biology and geology have their own set of ideas), and this method is not a single field, but a superposition of dozens of fields, and each field is responsible for solving some problems of this technology. Therefore, when you look at each field in isolation, you often feel that this research is meaningless or even absurd. But when you look at the problem as a whole, look down and see how the solution to the whole problem is pieced together into an accurate behemoth, you will sigh the greatness of the light of human wisdom. Every article is trying to solve a small technical problem, trying to provide a new way to solve the problem, or to prove or falsify the views put forward by others. It is the efforts and preventive measures of all researchers that will make us not panic and panic in the face of possible crises in the future. (However, when chatting with my classmates the other day, I also said that the priority of scientific research is definitely lower than economic development, agricultural development, military affairs and education. It is appropriate to invest a lot of extra money in scientific research in order to ensure that human beings can survive and people can live and work in peace and contentment. Most of the achievements of basic scientific research cannot be directly transformed into core competitiveness and money for many years, so it is understandable for Trump to cut research funding and build the Great Wall on the border. After all, the damage caused by global warming is far less direct and rapid than the threat of a five-point increase in unemployment rate and the enemy's newly deployed nuclear weapons, not to mention the Higgs particles, gravitational waves of dark matter, cosmic microwave background radiation and cancer cell mutation, which are completely different from daily life. )