Qian Jinchuan (Wenzhou Gaoqi Hydrogen Technology Co., LTD.)

I. Green hydrogen under the premise of "carbon peak" and "carbon neutral"

According to the China Hydrogen Alliance, by 2030, China's demand for hydrogen will reach 35 million tons, and by 2050, hydrogen will account for at least 10% of China's terminal energy system. The annual output value of the industrial chain is about 12 trillion yuan, becoming a new engine for economic development.

Some experts say that the development of hydrogen energy technology is China's quest to solve the energy and resource crisis,

Accelerate the adjustment of energy structure and achieve the goal of "carbon peak" and "carbon neutral" as scheduled.

As we all know, carbon emissions are mainly caused by fossil fuels. Currently, Coal consumption in China accounts for almost half of the world's carbon emissions, making it one of the main sources of carbon emissions. With the acceleration of China's energy transformation, natural gas will gradually replace coal, thus reducing carbon dioxide emissions and realizing China's transition from high carbon to low carbon. With the accelerating development of hydrogen energy, hydrogen energy will play an important role in the ultimate realization of carbon neutrality and shoulder the irreplaceable mission.

National overall planning "carbon peak" and "carbon neutral" discussion

Peak carbon: when annual carbon emissions stop increasing, they reach a peak. The country aims to achieve this by 2030.

Carbon neutral: Humans emit carbon all the time, and absorb what cannot be reduced, when the amount absorbed equals the amount emitted. One of the important operations in carbon neutrality is carbon capture, the CO₂ discharge into the atmosphere to catch back, to truly achieve net zero emissions. China aims to achieve carbon neutrality by 2060, while some EU countries have proposed to achieve carbon neutrality by 2050.

In recent years, driven by energy policies, markets and related hydrogen utilization technologies, hydrogen energy has provided more viable and applicable options for industries and applications that are difficult to achieve electrification in integrated energy systems. The need for deep decarbonization of energy systems and the integration of a large number of fluctuating renewable energy sources into the grid will be the driving forces for the rapid development of hydrogen energy.

Second, to curb global warming, the first is to reduce emissions

Over the past 200 years, humans have discharged trillions of tons of CO₂ into the atmosphere, which is like building seven greenhouses for the earth, so that the earth can not heat, greenhouse gases with the imagination of human science and technology civilization at the same time, like shadow has intensified.

For example, in 2019 data show that carbon sources produce about 40 billion tons of CO₂/ year, of which 86% is fossil fuel output; Fourteen percent is produced by land. The carbon produced is basically carbon

In three ways: 46% sink into the atmosphere; 23% in the oceans; Thirty-one percent converge on land.

With the proposed carbon neutrality goal, the direction of China's future energy transformation development has been set. China's economy is expected to reach a per capita GDP of $48,000 by 2060, generating energy demand of 6.73 billion tonnes of standard coal, up 38% from today. If the current energy mix stays the same, it will result in carbon emissions of 16 billion tons of co2 per year.

If we want to reduce emissions, we need to start from the following three aspects:

2.1. Use clean energy (such as green hydrogen);

2.2. Improve energy efficiency;

2.3. Reduce the production of disposable goods.

There is no doubt that clean energy is a one-size-fits-all solution. Under the situation of global energy crisis, using hydrogen as a substitute for petroleum fuel has become the trend of The Times. With the rapid growth of the national economy and the continuous improvement of the quality of human life, the demand for hydrogen in all sectors of society is increasing day by day, and it is widely used. Hydrogen energy, especially green hydrogen produced from renewable energy such as wind power and photovoltaic, only consumes electric energy without other by-product emissions. Hydrogen purity is higher than 99.99% and has significant advantages such as zero carbon, high efficiency, storable, safe and controllable.

At present, the United States, Japan, the European Union and other major developed countries and regions have incorporated hydrogen energy into their energy development strategies, and hydrogen energy has gradually moved from its initial demonstration application to large-scale promotion. According to the International Hydrogen Council, hydrogen will create 30 million jobs, reduce carbon dioxide emissions by 16 billion tons, create a market value of 2.5 trillion DOLLARS, and account for 18% of global energy consumption by 2050.

Iii. Sources and classification of clean energy hydrogen

3.1. Route selection of hydrogen production technology

There are many ways to produce hydrogen in industry, which can be divided into three main categories. The second type is the conversion of fossil fuels to hydrogen, mainly including steam reforming of natural gas to hydrogen, coal gasification to hydrogen; The third type of hydrogen production is pressure swing adsorption (PSA) or membrane separation from other hydrogen containing tail gas.

Hydrogen production from coal gasification is a syngas of hydrogen, carbon monoxide and carbon dioxide produced by the reaction of oxygen with coal as raw material in the gasifier. After the conversion reaction of syngas, hydrogen composition is further increased and used as downstream raw gas. Through membrane separation or PSA separation, syngas can also be further obtained with higher purity hydrogen. Generally, this kind of hydrogen production route is used as coal chemical industry or ammonia industry, and in recent years, it is also used as the raw gas of refining and chemical industry, which is much larger than hydrogen production by hydrolysis. Coal gasification to produce hydrogen has a large scale and low cost, but the purity of hydrogen produced is low. The initial investment of coal gasification and purification device is also very large, and the carbon emission index is high.

Hydrogen production from natural gas is the reaction of natural gas and water vapor under the action of nickel catalyst at 820 ~ 950℃ to produce transformed gas, and then further PSA separation to obtain high purity hydrogen.

This route has low production cost and is suitable for small and medium scale hydrogen production.However, with the phenomenon of "gas shortage" in recent years, the cost of hydrogen production from natural gas is gradually increasing. Hydrogen production by separation of hydrogen containing tail gas is a method of purifying hydrogen containing tail gas such as synthetic ammonia and coke oven gas with pressure swing adsorption device. The production cost of this route is low, but it must have the production condition containing hydrogen. In essence, it's the conversion of fossil fuels to hydrogen.

As can be seen from the above, except for hydrolysis, the production process of other methods is complicated, the hydrogen production process will cause pollution to the environment, and the hydrogen produced is of low purity, and relatively effective separation technology is needed to purify hydrogen. As the raw material of hydrogen production, water is inexhaustible. Hydrogen production process will not cause environmental pollution and has sustainable development. At present, hydrogen production by electrolysis is widely used and the technology is relatively mature. The efficiency of hydrogen production by electrolysis is generally 65-85%, and the obtained hydrogen has high purity, short production process, low energy consumption and low production cost. Electrolytic water hydrogen production technology will gradually become the mainstream of hydrogen production technology in the future. In terms of practicality, economy, maturity, safety and other aspects of comparison, it is proposed to use hydroelectricity to produce hydrogen, especially green hydrogen powered by wind and photovoltaic, which is the mainstream of future development.

Hydrogen energy has obvious advantages of zero carbon, high efficiency, storable, safe and controllable, and can be widely used in transportation, industry, household and other fields. It has gradually become an important direction of the global energy technology revolution.

3.2 Classification of hydrogen: characteristics of green hydrogen, grey hydrogen and blue hydrogen

In the current field of hydrogen production, hydrogen production can be divided into: green hydrogen, gray hydrogen, blue hydrogen. The definitions are as follows:

Green hydrogen: hydrogen produced from renewable energy (such as wind power, hydropower, solar energy, etc.) has no carbon emission in the process of hydrogen production; This is also the ultimate goal of human development of renewable energy.

Grey hydrogen: hydrogen produced from fossil fuels, such as petroleum, natural gas and coal. When the C-H bond breaks, you have carbon emissions.

At present, the world needs 70 million tons of hydrogen each year, 98% of which is grey hydrogen from fossil fuels. This shows that the vast majority of the hydrogen we use comes from grey hydrogen.

Blue hydrogen: Hydrogen produced from fossil fuels with subsequent carbon treatment using carbon capture and sequestration.

3.3. Current status of green hydrogen

At present, hydrogen production from coal is still the mainstream, with grey hydrogen as the main source of hydrogen. Green hydrogen and blue hydrogen will be the way forward. Green hydrogen is a clean and versatile energy source with the potential to meet 15% of global energy demand. However, the production of green hydrogen and its use bottleneck are cost factors.

3.4 Cost analysis and control of green hydrogen

High cost is the biggest bottleneck: green hydrogen models predict it will cost $4.2 / kg in 2020, $1.9 / kg in 2030, and $1.0 / kg in 2050. If the price of green hydrogen is $0.8-1.9 / kg, then green hydrogen will have a strong market prospect. The above is only the prediction of the green hydrogen model, but the actual cost of green hydrogen is far higher than the prediction of the model. The cost of producing hydrogen from renewable sources remains high. Globally, hydrogen production from fossil fuels generally costs less than $2 /kg, while electrolysis of water often costs as much as $4-5 /kg. Therefore, from the economic point of view, the conditions for large-scale development of renewable energy hydrogen production are not yet available.

Electricity charges and equipment investment are the main costs of hydrogen production from water electrolysis of renewable energy. Theoretically, the electricity consumption required by electrolytic water to produce 1kg hydrogen is about 30kWh. Currently, the energy conversion efficiency of electrolytic water to produce hydrogen is generally about 60%, so the actual electricity consumption is about 50kWh/kg.

At present, the main difficulty of restricting the market of green hydrogen lies in the cost of electricity.

Under the background of carbon neutrality, hydrogen energy attribute is expected to gradually show its incomparable advantages. Especially in recent years, with the significant reduction of the cost of photovoltaic industry and the increasingly mature wind power generation technology, although photovoltaic and wind energy have many disadvantages, the large-scale production and application of green hydrogen has become possible.

At present, although China's wind resource concentration, large scale, generally in mengxi, Mengdong, Gansu, Northern Hebei four regions, basically accounted for more than 50% of the total installed wind power scale. But it consumes only 10% of the country's electricity. Therefore, wind power consumption is one of the most prominent problems in wind power generation. In addition, the existing wind field is far away from hydrogen load, thus increasing the storage and transportation process of hydrogen, thus increasing the cost of hydrogen use. Hydrogen could also be delivered across the country through existing natural gas networks of oil and gas companies, providing a new viable solution for long-distance hydrogen transport and sustainable hydrogen development. In order to ensure the healthy and orderly development of hydrogen energy industry, we should establish norms and standards for hydrogen production and transportation from water electrolysis at the management level in time.

For the production of green hydrogen, the selection of solar and wind energy can follow the corresponding standards to determine:

According to the Solar Energy Resource Evaluation Method (GB/T 37526-2019), determine the solar energy resources in this region and whether it is suitable for the construction of solar power stations; According to the wind power density grade evaluation standard of "Technical Provisions for Measurement and Evaluation of Wind Energy Resources in Wind Farms" (NB/T 31147-2018), the wind power density grade of wind farms, whether the wind energy resources are rich, and whether they have development potential are determined. With the determination of the above standards, so as to greatly reduce the blindness of the wind field and photovoltaic field.

For the fan, the wind speed of 3m/s can generate electricity, if to 10m/s fan can reach the rated capacity, because the power generation and wind speed is square; In addition, the selection of wind field: the average annual utilization hours should not be less than 2000 hours, usually the better wind field is generally 2200-2500 hours, only in this way, the wind field can have certain economic benefits, in the future operation process does not lose.

The northwest region of China is rich in wind and solar energy resources, while the southwest region is rich in hydropower resources. The corresponding electricity needs to be transmitted to the eastern region, which is the energy consumption center. China is also rich in offshore wind power resources, ranking third in the world after Britain and Germany in terms of offshore wind power. The rapidly developing offshore wind power needs to be connected to the power grid in the eastern coastal areas. This is also to reduce the thermal power generation in Our country this proportion is too large (thermal power generation accounted for 76%) pattern, provides a new emission reduction point.

If the utilization rate of wind abandoning and power limiting is guaranteed, the wind abandoning power in each power segment of the wind field can be fully absorbed by making the hydrogen production equipment of hydropower hydrolysis (using traditional alkaline electrolytic cell or PEM water electrolytic cell), but the green hydrogen will be obtained by the hydrogen production equipment of hydropower hydrolysis (using traditional alkaline electrolytic cell or PEM water electrolytic cell), and the utilization rate is very low. In order to ensure the utilization rate of hydroelectricity generation hydrogen equipment, as long as the equipment is relatively small, but it will make the utilization rate of power in the part of abandoning network and limiting power low, how to solve this contradiction is also a bottleneck of wind power generation hydrogen. Seen from the development trend of the past two years, alkaline electrolytic cells above 1000Nm3/h have become the mainstream in the future, thus solving the bottleneck of hydrogen production from renewable energy power generation. Corresponding demonstration projects have been widely carried out in the country, which has accumulated valuable experience in the early stage for the future market operation.

At present, hydrogen production from renewable energy accounts for a relatively small proportion, while hydrogen production from fossil energy is still the main source of hydrogen. Under the energy structure of "rich in coal, poor in oil and little in gas", the proportion of hydrogen produced from coal in China is more than 60% at present, and the proportion of hydrogen produced from electrolytic water is less than 2%. Therefore, renewable energy hydrogen production is still a long way to go and has a huge space for development in the future.

3.5 Development plans and objectives of green hydrogen at home and abroad

As major economies around the world have proposed long-term carbon neutrality targets in recent years, it is expected that the energy properties of hydrogen will gradually emerge, and its application fields will be gradually expanded to power, transportation, construction and other scenarios.

In recent years, major economies around the world have put forward plans and targets for hydrogen energy development, raising the development of hydrogen energy to a strategic height.

At the end of 2020, the U.S. Department of Energy released the Hydrogen Energy Development Plan, which made strategic plans for the hydrogen energy industry from multiple perspectives, including technology, development and application. It is estimated that hydrogen energy will account for 14% of the total energy consumption in the U.S. by 2050.

The European Union proposed the hydrogen energy development strategy in August 2020, focusing on the development of hydrogen production from renewable energy. It plans to deploy more than 6/40GW of hydrogen production equipment from renewable energy electrolysis water by 2024/2030, and achieve 100/10 million tons of hydrogen production from renewable energy respectively.

In the 14th Five-Year Plan for National Economic and Social Development and the Outline of 2035 Vision Goals, hydrogen energy and energy storage are also included in the forward-looking planning of the future industry, and will focus on the layout of development in the future.

In general, hydrogen production from renewable energy is a viable direction in the long run. The accelerating development of hydrogen energy will eventually achieve carbon neutrality and assume an important mission.

In the past 20 years, due to the rapid development of industrial production, the application of hydrogen is more and more widely, and the demand for hydrogen is also increasing year by year. Especially in the steel field, hydrogen replaces traditional carbon monoxide reduction, which opens up a new field for reducing carbon emissions.

According to the American Hydrogen Association, annual global production of hydrogen exceeded 50 million tons in 2007, and hydrogen is emerging as a low-carbon and zero-carbon energy source. At present, China uses 550 billion cubic meters of hydrogen each year, and hydrogen is used, among other things, to make ammonia and fertilizer. It is also used in unmanned aerial vehicles and automobile refuelling stations, metal metallurgy, gasoline refining processes, polycrystalline silicon, gold welding, weather balloon exploration and agricultural hydrogen-rich irrigation. In recent years, due to the reduction of the cost of renewable energy, it is possible to produce hydrogen from renewable energy raw materials and electrolysis hydrogen on a large scale by using the electricity generated by wind and photovoltaic. Some sectors, including refineries, the chemical industry, transportation and natural gas, are exploring the incorporation of large amounts of renewable hydrogen into their processes to reduce CO2 emissions. In addition, hydroelectricity generation technology can also provide load regulation, management and other services for the continuous development of power grid to enhance the reliability of power grid. Hydrogen production by hydroelectricity has a very low carbon footprint and a huge potential for hydrogen production. The increase in intermittent renewable power gives the electricity market greater flexibility and requires greater energy storage.

As a secondary energy, electric energy can be produced from various primary energy sources, such as coal, oil, natural gas, solar energy, wind energy, water, tidal energy, geothermal energy, nuclear fuel and so on. At present, the "process performance source" cannot be stored directly in large quantities, so cars, ships, aircraft and other modern transport vehicles with strong mobility cannot directly use the electric energy output from the power plant, but can only use "energetic body energy" such as diesel and gasoline. With the increasing consumption of fossil fuels, their reserves are decreasing day by day. One day, these resources will be exhausted, so it is urgent to find a new energy source with abundant reserves that does not depend on fossil fuels. Hydrogen energy is a kind of new secondary energy which is expected by people while developing new secondary energy when the conventional energy crisis appears.

The era of the "hydrogen economy" is at hand. Countries all over the world are stepping up their involvement in hydrogen energy development and utilization. According to the U.S. Hydrogen technology Roadmap, the U.S. will enter the era of "hydrogen economy" by 2040. At this stage, hydrogen energy will eventually replace fossil energy as the most widely used end energy in the market. China has abundant solar and wind energy resources. Converting water into hydrogen by electrolysis for energy conversion, storage and transportation may be one of the best ways to effectively solve the problems of peak valley, transmission and power grid fluctuation. There is a large potential energy difference between south China and southwest China, which is rich in water resources and developed in hydropower.

In terms of emissions, some forms of energy use in energy consumption are difficult to be replaced by electricity, so another form of energy is ultimately needed to achieve carbon neutrality. It is estimated that by 2060, if non-electric breakthroughs are not taken into account and the electrification rate in China is at 70%, there will still be 2 billion tons of standard coal energy to be decarbonized.

At present, fossil energy is still the main source of hydrogen, and natural gas replaces it to achieve high carbon to low carbon.

Providing the same amount of energy, natural gas emits 33% less carbon than oil and 53% less carbon than coal.

It is estimated that by 2030, the proportion of natural gas will increase by 6.9 percentage points, the consumption of natural gas will increase by about 400 billion cubic meters, and the carbon emission will be reduced by about 370-840 million tons.

In 2019, hydrogen energy was included in China's Government Work Report for the first time, and hydrogen energy was included in China's energy system for the first time. According to the white paper's roadmap, it is expected that by 2050, hydrogen will account for about 10% of China's energy system, demand for hydrogen will be close to 60 million tons, annual economic output will exceed 10 trillion yuan, and there will be more than 10,000 hydrogenation stations and 5.2 million fuel cell vehicles annually.

China has pledged to become "carbon neutral" by 2060, making it a tough task to cut emissions. To this end, China will build a clean, low-carbon, safe and efficient modern energy system in the future. One of the notable features is to significantly increase the proportion of renewable energy in primary energy consumption. Hydrogen and electric coupling is an important way to construct China's modern energy system. China is the world's largest renewable energy power generation country. Every year, about 100 billion KWH of electricity is discarded by wind power, photovoltaic power, hydropower and other renewable energy sources, which can be used to electrolyze water to produce about 2 million tons of hydrogen. In the future, with the continuous expansion of renewable energy, hydrogen production from renewable energy is expected to become the main source of hydrogen supply in China.

Achieving carbon neutrality requires the development and application of new technologies in the non-electric sector. Currently, there are three main solutions: hydrogen energy, carbon capture and biomass. However, considering the limitations of biomass resources and the policy requirements of carbon capture, hydrogen energy has a stronger advantage in industrial development and technological iteration, so it is more likely to be the final solution.

At present, mature hydrogen production means mainly include fossil energy reforming hydrogen production, industrial by-product hydrogen production and water electrolysis hydrogen production.Although carbon capture and storage (CCS) can reduce carbon emissions from hydrogen production from fossil fuels, only "green hydrogen" produced from water electrolysis, a renewable energy source, can achieve true zero carbon emissions in the long term.

Transition capacity of natural gas: China's natural gas supply security capacity is enhanced, and the future should realize domestic diversification and import multi-channel supply pattern.

Iv. Prediction of future application fields of green hydrogen

4.1 Application of green hydrogen in steel industry

Hydrogen energy is the ultimate solution to carbon emissions in steelmaking.

The steel industry is an important area of carbon emissions, especially for China, a steel powerhouse. At present, the carbon emission of steel industry accounts for about 15% of the total carbon emission in China, and it is the manufacturing industry with the highest carbon emission in China.

According to statistics, for every ton of steel produced, 2.5 tons of CO₂ is discharged by blast furnace. Converter production ton of steel CO₂ discharge 2.2 tons; The electric furnace process also emits 0.5 tons of CO₂.

Therefore, in the face of today's carbon emissions, carbon neutral, for are now in a critical phase of the transformation and upgrading of the iron and steel industry, improve the efficiency of energy use, adopting low carbon production process, to achieve maximum energy recycling, to realize the goal of "carbon neutral" in 2060, is the iron and steel industry is a key link, but also the priority of energy conservation and emissions reduction.

As is known to all, the traditional blast furnace ironmaking uses coke as one of the raw materials, which provides the heat required by the reduction reaction through coke combustion and produces the reducing agent carbon monoxide (CO). At high temperatures, oxygen is extracted from iron ore using CO, and iron ore is reduced to pig iron, producing a large amount of carbon dioxide (CO₂) gas. Pig iron is then further refined into steel.

In the field of steel, hydrogen is used to replace the traditional CO reducing agent. No CO₂ gas output, so the ironmaking process green pollution-free.

In the process of making iron, hydrogen (H₂) is added instead of traditional CO. And hydrogen production by hydroelectricity solution hydrogen supply (hydrogen energy sources from renewable energy: solar photovoltaic, wind power generation), plus into the furnace surplus reduction hydrogen recycling, to achieve the purpose of reducing CO₂ emissions.

Traditional CO reduction:

Fe₂O₃ + 3CO = 2Fe + 3CO₂;

2 co + co ₂ O ₂ = 2

There is a lot of CO₂ generated.

Add H₂ reduction:

Fe2O₃ + 3H₂ = 2Fe + 3H₂O;

2H₂ + O₂ = 2H2O

There is no CO₂, only water out.

It can be seen that:

1, replace carbon monoxide with hydrogen, no carbon dioxide discharged;

2. Hydrogen source: green hydrogen produced by renewable energy (such as wind or solar energy); Or hydrogen from water gas or natural gas;

3, the furnace to participate in the reduction of excess hydrogen, recycling;

4. With mature hydrogen recovery technology in the field of hydrogen, the excess hydrogen that has not been involved in reduction is first rinsed, then pressurized and dried (two or three towers), and the hydrogen from the hydrogen source is added to the ironmaking process route.

4.2 Electrical coupling of green hydrogen

Hydrogen and electric coupling is an important way to construct China's modern energy system. China is the world's largest renewable energy power generation country. Every year, about 100 billion KWH of electricity is discarded by wind power, photovoltaic power, hydropower and other renewable energy sources, which can be used to electrolyze water to produce about 2 million tons of hydrogen. In the future, with the continuous expansion of renewable energy, hydrogen production from renewable energy is expected to become the main source of hydrogen supply in China.

4.3 Predict the future development of green hydrogen

4.3.1 At the initial stage of application, the starting point is parity

In this stage, the application of fuel cell technology is accelerated, bringing scale and cost reduction from the terminal application level. Meanwhile, the benefit scale and link efficiency improvement of transportation and refueling at the energy supply end are rapidly reduced, bringing cost reduction in the parallel link of supply and application.

From the perspective of hydrogen energy, the cost of hydrogen production from natural gas/gas reforming + carbon capture is better than that from renewable energy electrolytic water in the short term. The cost constraint mainly comes from transportation and filling, which is limited by the imperfect application of high-pressure IV bottles, liquid hydrogen transportation and pipeline transportation. If green hydrogen is transported by pipeline in wind and photovoltaic fields, low-cost green hydrogen is expected to be applied on a large scale. Thus facilitating the terminal application of fuel cells.

4.3.2 Step into parity

It is predicted that the supply and application scale will increase greatly with the expansion of application fields from 2031 to 2050.

In this stage, the cost of hydrogen energy benefits from the low electricity price of new energy power generation in the power-rich region, and gradually complete medium and long distance transportation/pipeline, which gradually reduces the hydrogenation cost to nearly 20 yuan /kg. At the same time, new energy electrolysis of water hydrogen production will gradually become the mainstream mode of hydrogen energy supply. For fuel cell vehicles, when the rising carbon emission cost of diesel is not considered, the hydrogen cost drops to 20 yuan /kg, which can be directly equalized with diesel. In addition, this stage of the transportation in the price of hydrogen has gradually decreased from 18 to 20 yuan/kg (i.e., without considering the filling cost of filling stations), in the field of industrial and domestic heating has gradually have a certain economic foundation, through the early and the mixture of natural gas, and with hydrogen prices fall further, in the field of heating (in northern China, Natural gas heating has replaced traditional coal heating), hydrogen energy will also gradually improve the application permeability.

4.3.3 Step into parity

By 2051-2060, the goal of carbon neutrality will drive the permeability of other non-electric fields to increase.

In this stage, the cost of new energy generation will be further reduced, and the cost of application will be further reduced with the large increase of storage and transportation scale. The cost of hydrogen filling will be reduced to less than 20 yuan /kg, and the cost of hydrogen application in non-transportation will be reduced to less than 15 yuan /kg. The application fields will be fully expanded to non-electric fields such as heating, shipping and so on, to complement the puzzle of carbon neutrality in non-electric fields.

4.3.4 The use of green hydrogen promotes the overall cost reduction in the power market and greatly reduces carbon emissions

In addition to the reduction of the overall cost of new energy generation, the peak-valley price difference in the future power market will continue to widen, and there will be more available periods of low electricity price for hydrogen production from electrolysis water. As the proportion of new energy generation increases, the instability of power supply will continue to rise in the future, and the range of price fluctuation in the power market will also expand.

For hydrogen storage, seasonal electricity price fluctuations will bring potential intertemporal arbitrage space, and in the long run, there is a large room for improvement in the economy of hydrogen production from renewable energy.

In the future, wind power and photovoltaic power abandonment will become an important power source for electrolysis of water to produce hydrogen. In the power system with renewable energy as the main body, in order to ensure stable power supply, the degree of redundancy of installation will be significantly increased, so in the long term, the amount of power abandoned by wind and light will inevitably rise.

In the future, the absorption of wind and light power will become an important application scenario of hydrogen energy storage, and this part of the zero-cost or even negative cost of electricity can be used as an important power source for hydrogen production from water electrolysis.

In the electric power industry, China currently emits 0.8 to 0.9 kilograms of carbon dioxide per kilowatt hour of electricity. If the coal consumption per kilowatt hour is reduced by 1 gram, the country can reduce 7.5 million tons of carbon dioxide per year. Therefore, we should concentrate on accelerating technological transformation, promoting emission reduction of thermal power and implementing "green coal power" plan. This will be achieved mainly through the development of clean coal conversion and efficient utilization technology and the improvement of the efficiency of coal-fired power generation, which can achieve a 15% reduction in emissions. At present, efficient and clean coal power generation technologies with development prospects mainly involve integrated coal gasification combined cycle (IGC), circulating fluidized bed combustion (CFBC) and other technologies.

4.3.5 There is a large cost reduction space for electrolytic water hydrogen production equipment

Alkaline electrolysis and proton exchange membrane electrolysis are the main methods for hydrogen production by water electrolysis. At present, the industrialization degree of alkaline hydrolysis and PEM is relatively high. The advantages of the former are mature technology and low cost, but the rapid start-up and variable load capacity are relatively poor. The latter has the advantage of high efficiency, flexible operation and better adaptability with wind power and photovoltaic, but the current cost is still high.

Electrolytic cell is the core part of hydrogen production system by electrolysis of water. Electrolytic water hydrogen production system is composed of electrolytic cell and auxiliary system, the electrolytic cell is the main place where electrolytic reaction occurs.

In terms of cost structure, electrolytic cells account for about 40%-50% of the total cost of hydrogen production system, in addition, power conversion system, water recycling system and hydrogen collection system also account for a high proportion of the total cost.

Through the optimization of materials and design, the cost and performance of electrolytic cell will be greatly improved in the future. Alkaline water electrolysis cell technology has been relatively mature at present, the main cost of the diaphragm and the electrode (nickel plated stainless steel), the main path of the authors is follow-up for the development of the thickness is thinner, the conductivity higher new diaphragm (such as is now widely used to replace traditional asbestos diaphragm PPS PPS), at the same time improves the life span of electrode and catalyst in alkaline environment and the cost.

By 2050, the cost of alkaline water electrolytic cells and PEM electrolytic cells is expected to reach less than $100 /kW, down more than 60% from the current level.

The reduction of the total cost of electrolytic cell greatly promotes the production of green hydrogen.

In addition to the technological progress, the improvement of industrialization will also make a positive contribution to the reduction of the cost of electrolytic water hydrogen production system. On the one hand, the unit cost of modules such as power conversion and gas treatment will be diluted with the expansion of the scale of equipment. On the other hand, the expansion of production scale will also reduce the allocation of manufacturing costs per unit of equipment, the two complement each other.

4.3.6 Emission reduction in the construction sector

In the field of architecture, 60% of urban carbon emissions come from the maintenance function of buildings. It is extremely important to build a green building technology system and develop low-carbon buildings. The key is to optimize the low-carbon control of the whole process of building planning and design, construction, use, operation, maintenance, demolition and reuse. For example, in the construction process, roof photovoltaic power generation technology can be used to realize the effective integration of natural light and lighting. Unpowered roof ventilation equipment can be built to adjust the wind speed and drive the fan to generate electricity. In the process of use, green roof can be built by planting rooftop flowers, which can not only achieve cooling effect, save air conditioning power, but also absorb air pollutants; In the process of demolition, construction waste can be effectively recycled to prevent secondary pollution.

Referring to the development process of photovoltaic and lithium battery industries, with the improvement of scale and industrialization, the average cost of electrolytic water hydrogen production equipment is expected to enter a channel of rapid decline.

Five, the conclusion

Reviewing the history of human development, people can find that every energy technology innovation and breakthrough has brought significant and far-reaching changes to the development of productive forces and society. As of now, 80% of the energy system we rely on for survival depends on fossil fuels. Coal, oil and natural gas are non-renewable resources, and the earth's stock is limited. The production of green hydrogen, from the earliest demonstration projects, usually equipped with hydrolysis hydrogen production equipment is less than 60Nm3/h. At present, the specific application of more than 1000Nm3/h, with the increasingly mature wind power and photovoltaic power generation and the continuous reduction of cost, in addition to the future renewable energy production, the volume of a new energy containing energy -- green hydrogen. Through the pipeline to replace the traditional storage and transportation. It is not only in line with the low carbon economy advocated by mankind at present, but also meets the promotion requirements of "carbon peak" and "carbon neutral". The wide utilization and implementation of new energy is the dream of mankind. Low carbon economic model has been accepted by human beings, they determine the future of mankind. It could also slow the accelerating warming of the global climate. All of these provide a wide range of feasible prospects for the application of green hydrogen. As human beings continue to explore and recognize new energy sources, we believe that hydrogen energy, especially green hydrogen, which is a highly concerned and rapidly developing field, will definitely benefit human beings. We believe that the 21st century green hydrogen era is approaching with us!

221 Wei15 Road, Leqing Economic Development Zone, Wenzhou, Zhejiang

Wenzhou Gaoqi Hydrogen Technology Co. LTD. Qian Jinchuan

Electrolytic hydrogen production driven by renewable energy is considered to be a good helper to improve global climate and energy problems. Alkaline electrolytic cell is known as the key equipment for large-scale hydrogen production of renewable energy. With the rising voice of green hydrogen development, electrolytic water hydrogen production is ushering in a new round of development opportunities.

According to China Hydrogen Energy Industry Association data: in the first half of the year, China's hydrogen output increased by 25% compared with last year, during which the proportion of hydrogen production using new energy increased by 30% compared with last year.

Bloomberg New Energy Finance forecasts that China's electrolytic cell market will double this year and quadruple by 2022, with the country expected to account for 60-63% of the world's installed capacity, thanks to the country's impressive growth in hydrogen production in the first half of the year.

With the rapid development of wind, light, water and other renewable energy sources in China, the skills and use of electrolytic water hydrogen production will enter a steadily rising period. "Green hydrogen" with the fire of electrolytic cell, the in-depth development and use of renewable energy, and extend the energy production of carbon free road, the development of electrolytic equipment ushered in a historic opportunity.

At a press conference on China's renewable energy development held by the State Information Office, the National Energy Administration said that by the end of the 14th Five-Year Plan, renewable energy will become the main part of the increase in energy and electricity consumption, instead of the original incremental supplement. With the continuous expansion of photovoltaic installed capacity in recent years, China's new installed capacity in 2020 is 48.2GW. Under the guidance of the dual carbon target, photovoltaic will enter the next stage of rapid development. According to the report of China Photovoltaic Industry Association, "the annual average installed capacity of photovoltaic in China reached 70GW-90GW during the 14th Five-year Plan period.

With the increasing number of photovoltaic installations, the consumption problem becomes more prominent and becomes one of the bottlenecks restricting the large-scale development of photovoltaic.

With the transformation of green and low-carbon energy in China, hydrogen energy has also witnessed rapid development. The "photovoltaic + hydrogen production" model will effectively solve the consumption problem and other development bottlenecks of renewable energy. It can also effectively solve the problem of high cost and green production of hydrogen.

The "PHOTOVOLTAIC + hydrogen" model is not simply to give up electricity and produce hydrogen energy, but to improve energy efficiency and produce clean energy.