Hydrogen energy, humanity's "only ultimate energy"?

In 2021, "carbon peak" and "carbon neutrality" were written into the government work report for the first time as China's strategic goals at the two sessions, demonstrating China's determination to adhere to the path of low-carbon development.

In the context of accelerating the transformation of the energy industry, hydrogen energy with zero pollution, high energy, rich resources, wide range of uses and other advantages, once again ushered in a "boom", many people even regard hydrogen energy as the key to the future of green energy.

According to the data of China Hydrogen Energy Alliance, in 2018, China's hydrogen production was about 21 million tons, accounting for 2.7% of the total terminal energy. It is expected that by 2030 and 2050, the demand will reach 35 million tons and 60 million tons, respectively, and the terminal energy will account for more than 5% and 10%, respectively. The bright future of hydrogen energy seems to be at hand.

However, since the Russians put hydrogen in the first place in the periodic table in 1869, people have never stopped the research and use of hydrogen, but the ultimate ideal of hydrogen energy is still only in the imagination.

Is hydrogen, which has been called the "only ultimate energy source" of mankind, really that powerful? At the current node, from the perspective of the industrial chain, what are the opportunities and pain points of hydrogen energy development?

1. From zero to one, is hydrogen really that strong?

The major nodes in the process of human industrialization are always accompanied by the large-scale use of energy.

First, it started with coal, and then with the progress of exploration and exploitation technology and the energy revolution, fossil energy such as crude oil and natural gas with higher energy density and less pollutant emissions gradually began to replace coal.

But in the process of energy combustion and conversion, carbon dioxide emissions always follow.

In recent years, more and more attention has been paid to energy and environmental issues. In the context of carbon neutrality, how to choose cleaner energy has become a real problem faced by all countries.

Compared with traditional coal and fossil energy, hydrogen energy has almost zero carbon emissions during the conversion process.

In addition, hydrogen energy also has many advantages:

Good combustion performance: hydrogen has a wide flammable range when mixed with air, and the combustion speed is fast.

Abundant: Hydrogen is the most widely distributed substance in the universe, it constitutes 75% of the mass of the universe, but mainly in the form of a combined state, separation and purification requires a certain cost.

High calorific value: in addition to nuclear fuel, the calorific value of hydrogen is the highest in all fossil fuels, chemical fuels and biofuels; Three times the gasoline, nearly four times the ethanol, and five to six times the coal.

A variety of forms: can be gaseous, liquid or solid metal hydrides appear, can adapt to a variety of storage and transportation and application environment of different requirements.

The hydrogen production method using coal, natural gas and other fossil energy as raw materials is relatively mature, but the hydrogen production process produces carbon dioxide emissions, and the hydrogen generated is called "gray hydrogen", which is not a clean energy in the real sense.

In addition to hydrogen production from fossil fuels, hydrogen production from electrolytic water is another important way, which is often referred to as "green hydrogen" in the industry, with green environmental protection, flexible production, high purity (usually more than 99.7%) and high value oxygen as a by-product.

However, at present, electrolytic water hydrogen production accounts for 4% of the global hydrogen production scale, and less than 1% in China. Mainly because production costs are too high.

The unit energy consumption of hydrogen production by electrolytic water is about 4-5 KWH/cubic hydrogen, and the electricity price accounts for more than 70% of the total cost. If existing electricity is used for production, the cost of hydrogen production is about 30-40 yuan/kg. When the electricity price is lower than 0.3 yuan/KWH, the hydrogen production from electrolytic water has a better economy.

At the same time, at this stage, the domestic thermal power is relatively large, and it will still face the problem of carbon emissions.

However, in the future, with the parity of renewable energy generation online, the cost of hydrogen production by electrolytic water will continue to decline, and hydrogen production by electrolytic water will become the mainstream way to produce green hydrogen in the future.

3. Core focus of transformation and upgrading

Storage and transportation of hydrogen is a difficult point in the hydrogen supply chain and an important reason for the high terminal price of hydrogen.

Hydrogen is the first element in the periodic table, the gas state is very small density, but also grumpy, the slightest mistake, it will explode in situ in minutes to show you.

Therefore, in the process of large-scale transportation, it must be compressed and stored, so that hydrogen appears in a high-density gaseous or solid, organic form.

According to the different states of hydrogen, hydrogen transport can be divided into gaseous hydrogen transport, liquid hydrogen transport and solid hydrogen transport.

Gaseous hydrogen is usually transported by long tube trailers and pipelines. Liquid hydrogen is usually transported by tanker; Solid hydrogen transport can directly transport hydrogen storage metal.

Technically speaking, the gas-hydrogen trailer is the most important and more mature way of transporting hydrogen in China, which is suitable for short-distance transportation.

Although the transport capacity of liquid hydrogen tank truck is 10 times that of gas hydrogen trailer, the liquefaction process costs more and is more suitable for medium and long distance transport.

According to the forecast of CITIC Securities, by 2050, the cost of liquid hydrogen storage and transportation will be reduced to 6 to 8 yuan /kg when the transportation distance is 500km. With the gradual maturity of low-temperature liquid hydrogen storage technology, the cost of liquid storage and transportation will gradually reduce, and liquid hydrogen tank truck transportation will gradually replace the gas-oxygen trailer.

In addition, pipeline transportation similar to natural gas is also one of the solutions for hydrogen transmission and distribution. And the hydrogen transported by pipeline is in a low pressure state, which is cheaper than the cost of high pressure hydrogen transport. When the transportation distance is 500km, the cost is about 3 to 3.1 yuan /kg.

But don't think that the high cost of hydrogen storage and transportation can be easily solved by pipeline transportation, because existing natural gas pipelines cannot be used directly to transport hydrogen.

Generally, natural gas is transported using steel pipes, and hydrogen molecules will dissolve in steel to produce hydrogen embrittlement, exceeding the strength limit of steel. Therefore, to use pipelines to transport hydrogen, it is necessary to use materials with very low carbon content, and the cost is generally twice that of natural gas pipeline materials.

Natural gas and hydrogen can also be used for mixed transportation, but the proportion of hydrogen is strictly required, not more than 20%. There is also a loss of value in mixing expensive hydrogen with cheap natural gas.

With the increase in demand for long-distance hydrogen transportation, pipeline transportation will become the best choice for long-distance transportation in the future, but the initial investment is huge, the utilization rate of equipment is also low, the liquefied gas pipeline is used to transport hydrogen, and the corrosion and strength changes of the pipeline need to be further studied。

4. Application: Who can hydrogen be used for?

From the current demand structure, the industrial color of hydrogen energy application scenarios is still very strong, and hydrogen is mainly used in ammonia synthesis, petroleum refining and other fields. The proportion of civilian hydrogen is very low, and the largest application scenario that can be imagined at present is hydrogen fuel cell vehicles.

Hydrogen fuel cell vehicles are more convenient and more durable than power battery vehicles, and they have clean and environmental protection characteristics compared with fuel vehicles, but the limitation of the technical level is still "hard" :

First of all, the hydrogen produced from fossil fuels is gray hydrogen, which contains more impurities, so it needs to be further purified before it can be used as a fuel cell raw material, which increases the use cost of hydrogen;

Secondly, although the energy density of hydrogen energy in the liquefied state is higher than that of fuel oil and much higher than that of lithium batteries, hydrogen liquefaction is difficult and costly. Currently, automotive hydrogen is still mainly a gaseous state, requiring extremely high injection pressure and high strength hydrogen storage bottle materials that can prevent hydrogen escape.

In addition, the development of hydrogen fuel cells is still relatively lagging behind, the life of domestic homemade hydrogen fuel cells is short, can only meet thousands of hours of driving, and including membrane electrodes and other materials are heavily dependent on imports;

Finally, hydrogen fuel cell vehicles are mainly commercial vehicles such as logistics vehicles and buses, and the proportion of passenger vehicles is very small, which is mainly due to the network of hydrogen refueling stations is still not popular enough, so the current hydrogen fuel cell vehicles are more suitable for models with fixed routes and certain commercial nature to offset high costs.

Although the cost of passenger cars in the future will drop to a level similar to that of lithium battery cars, the important factor restricting the promotion of passenger cars is that the initial promotion of hydrogen fuel cell vehicles is the car level, the lack of other low-level consumer goods, and the lack of infrastructure support such as hydrogen refueling stations.

Therefore, although the growth of hydrogen energy fuel vehicles in the future is the general trend, the improvement of its penetration rate may be relatively slow.

In addition, hydrogen energy also has application space in industrial emission reduction, gas storage, energy supply and cogeneration, and the future demand is still considerable.

With hydrogen subsidies and encouragement policies gradually put on the agenda, from hydrogen production to hydrogen storage and transportation to application, it is expected to usher in a wide range of updates and growth.

However, the technical route of hydrogen energy is still not mature enough, many technical problems need to be solved, and there is still a long way to go from large-scale marketization.