Canadian Academy of Engineering, Leo International Chief Scientist Zhang Jiujun: the key to the development of solar energy storage
Dec 08, 2017
On December 8, 2017, Zhang Jiujun, Academician of the Canadian Academy of Engineering and Leoch International Chief Scientist, made a speech titled "Solar Energy Storage and Its Related Electrochemical Energy Technology" at the Solar plus International Forum Shenzhen and the 12th Annual Meeting of New Energy Technology Theme sharing. The following is the record of the meeting:
In 2016, the investment in solar energy reached 442 billion
At present, the development of new energy has two major driving forces. First, human development and sustainability must have energy and must be new energy and clean energy. Second, human beings must have a clean environment for sustainable development. Solar inexhaustible, as a new energy with natural and unparalleled advantages.
Why develop new energy? In fact there are two driving forces behind this first driving force is the development of mankind and sustainability must have energy, and is also new energy, clean energy. Secondly, for mankind to achieve sustainable development, there must be a clean environment. Nowadays, the air pollution in many cities is so severe that this does not work. Our water quality is also seriously polluted. This is unsustainable. Therefore, there are two major driving forces that make mankind on earth develop new energy.
What are the sources of energy? There are two major categories of energy listed here. The first is Renewable Energy, which is either clean or sustainable, including hydro, solar, biomass, wind, geothermal, and so on. The second category is Fossil Energy, which is non-renewable energy, with a little less, including natural gas, oil, nuclear energy.
If we develop new energy sources, the first is the solar energy, we look at the solar energy is what kind of situation, here is listed in different regions of the world, different regions from 2011 to 2040 solar power generation forecast. We can see that by 2040, the solar power on earth will emit 1 trillion kilowatts of electricity per year, which is equivalent to 10-12 times the power output of the Three Gorges hydropower plant.
At present, the overall solar energy conversion efficiency still needs to be improved. The current solar panel we use is about 18% -23% conversion efficiency, of course, some laboratories can do more.
In 2016, the global investment in R & D of renewable energy technologies is very large, including solar energy, wind energy and bioenergy. In the field of solar energy investment reached 442 billion yuan, which is a very large number. China's solar currently accounts for 40% of the world's solar energy.
Let us look at the current new energy sources account for the total amount of energy we use, here I list a few, here we can see that 26% of the current burning energy is natural gas, 36% is oil and 8% is nuclear energy, of which Solar energy accounts for 20% and sustainable energy only accounts for 9%. Is a small part. At present, our solar energy accounts for only 2% of the total energy, so this is a very small part.
We know that solar energy is a sustainable energy source. Why development is so slow? We can see there are a few big challenges here. The first one is that solar energy or wind energy is unstable. For example, it can generate electricity when there is the sun, When the sun is low, the light intensity is not the same. The electricity it sends is not very smooth. Unlike the traditional energy generation, the generated electricity is the same. The solar power generation changes with time and is like a noise Similarly, if you do not smooth it, it is a waste of electricity. This is the point that it is unstable and not reliable enough. The second challenge is the distribution of electricity, transportation is also very difficult. The third challenge, due to the two previous questions, is that when the electricity goes to the grid, if it is not smooth, he will not let you go inside. The fourth challenge, solar power plant investment is large, the return on investment is relatively low, the return on investment for a long time.
In order to overcome these four points, we must develop an energy storage technology that turns solar and wind-generated energy into an energy source and stores it in use. The only way to have a smooth electric energy to lose inside. Therefore, energy storage must be developed. Energy storage is currently required in the field of solar energy or wind power.
Which energy storage method to choose?
What are the current energy storage technology? Listed here several, the first is electrochemical energy storage, lithium-ion battery in the phone is this way of storing energy. Lead-acid batteries, lithium batteries, which are called electrochemical technology, the solar power into the battery reserve up, when you need to release the electricity, this release is very smooth. The second is the fly wheels, this is not much to say, and the third is compressed air, the air pressure to a deep underground place, when used to release it, using mechanical energy, of course, this efficiency is very low. The fourth is when the hydropower station does not need electricity, but also to drain, the water through the hair of the electricity drawn into a sub-reservoir inside, and then when the electricity generation. In these ways, electrochemical energy storage is the most reliable way, and is the most effective way.
We look at the electrochemical storage of what ways, I listed about 10 species, in fact not limited to these 10 species, including lithium batteries, lead-acid batteries, fuel cells, electrolyzed water, etc., these are the electrochemical storage Can battery. Inside the big grid, the future smart grid, the battery to become a core unit. Now in the development of micro-grid, which is more important electrochemical elements.
This is a book that I have put together with my postdocs, teachers, friends, and colleagues over the past 10 years. All of these electrochemical energy sources are included in this book. Each book covers a technique where everyone feels If you are interested, you can surf the Internet and read about 20 books.
I will discuss in detail below the advantages of a variety of batteries, and its problems. The first is currently the forefront of development, but has not yet commercialized, is the liquid aluminum battery, which stores the energy inside the electrolyte, it can arbitrarily expand its electrolyte, electrochemical active material inside the electrolyte, not inside the battery , So it has such advantages. Its current development is very fast, in this area the main research direction is the development of new materials, including electrolyte materials, electrode materials, membrane materials, increase its energy density and increase its life expectancy, and then the system to be optimized, Reduce the price of materials, which is liquid aluminum battery.
The second one is the aluminum ion battery. At present, a lot of aluminum ion batteries that can not be used in automobiles are still at least 70% or 70% used for energy storage. The advantages of aluminum ion batteries is the energy density and functional density are high, its life expectancy for energy storage is quite good, but it also has its problems, if used inside the car, it's life is not long enough, the other is Its security problem, now we are using a liquid aluminum ion battery, so here is the use of liquid electrolyte, when we do, especially when the high current discharge may produce high fever, if the heat can not go out, it It will burn or explode. In particular, we now have to develop a ternary system. The activity of the ternary system is very high. If anything is too active, its stability will be poor. At present, it is the most used in new energy vehicles, of course, there are many energy storage now in use. The main research direction, now the energy density of aluminum ion battery has reached a bottleneck, how to increase its energy density, how to increase its life, but also the need for further development of new materials, as well as the optimization of the electrode layer, which is aluminum Ion battery.
Here's some of the work we did with aluminum ion batteries, which synthesized some nanomaterials as the cathode material for aluminum ion batteries.
The third is lead-acid batteries, the battery is Leoch International's main business now, lead-acid batteries appear to be the most reliable, the most commercially available energy storage, large-scale, medium-scale, small-scale are more reliable, this There are several benefits of lead-acid batteries, the first is cheaper, we now develop any battery are not lead-acid batteries cheaper, the second is safety, it is more safe than aluminum-ion batteries, you have not heard of that lead-acid batteries on fire Or the explosion of aluminum-ion battery to the ground after the fall, maybe explode, but how the lead-acid batteries fall will not explode, so it is safe. The third is the overall lead-acid battery materials can be completely recycled, the battery loss, I can put all the materials back inside to re-use, the advantage is that other batteries can not.
Therefore, lead-acid batteries are the most successful and reliable way currently available in energy storage, especially in new energy storage. We are in the development of new energy storage to develop lead-acid batteries, how the development of lead-acid batteries? There are several aspects, its energy density is not high enough, so the first is to electrode components, the active ingredient Optimize, add some carbon, etc. The second is to make it lightweight, reduce the amount of lead, the lead into a carbon network. The third is to remove an electrode, there are such three lead-acid battery research. Lead-acid batteries if it can reach about 80 energy density, we can replace a lot of batteries.
The other is a super capacitor, which is also an energy storage method, we have heard of super capacitor, its biggest advantage is that the charge and discharge time is particularly fast, you can finish in seconds, it's power density is very high, but The energy density is very low, so the supercapacitor also needs to be developed. One is to use it for poor life. The second one is its high industrial density, which can be used to increase its energy density.
Another direction is the electrolysis of water, the electricity emitted by the solar energy, the water into hydrogen decomposition, hydrogen itself is a carrier of energy, we use hydrogen gas through the fuel cell into electricity, so that an energy storage aims. However, at present, its energy efficiency is relatively low, and its technology is still relatively mature. Therefore, this is also a hot spot for energy storage.
In addition, let me talk about carbon dioxide and electrochemical reduction, and now we have a lot of carbon dioxide row, can the carbon dioxide through electrochemical methods, through electricity, into useful small molecules, into formic acid, methanol, etc., so to achieve a The effect of energy storage, and achieve another purpose of reducing carbon dioxide emissions. At present, Canada is also doing a lot of work in this area. The challenge now is that catalysts have a short life expectancy. At present, this is also the focus of our research and the research currently supported by the Ministry of Science and Technology of China. This is a way to have long-term strategic prospects.
Energy storage market in the end how much?
What is the current market size of energy storage? We have listed here a few, one is the liquid aluminum battery, then the aluminum ion battery, there are lead-acid batteries and super capacitors, we can see that by 2025, the overall market situation, liquid aluminum batteries will probably reach 38 Billion dollars, aluminum ion battery can reach 26 billion US dollars market, lead-acid battery market is still the largest, up to nearly 40 billion US dollars in the market, the super capacitor is relatively smaller, but similar to the liquid aluminum battery.
Therefore, we use solar energy storage market is a huge potential, so we not only to develop solar energy, but also the development of energy storage, energy storage should be developed.
