中文版
ENGLISH
| Spring of energy storage |
| Release time:2023-02-10 14:13:20| Viewed：103 |
Silicon material plummeted
Price trend of silicon material in the past year
At the beginning of last year, the biggest change in the photovoltaic industry came from the rapid return of silicon price.
Previously, the mismatch of capacity expansion in each link of the industrial chain made the silicon material link with the longest production cycle earn enough excess profits. With the double release of new production capacity, the pattern of supply and demand has been reversed, and the price avalanche has become its due meaning. With that, the price decline is transmitted along the industrial chain, from silicon chips, battery chips, to terminal components.
The fundamental driving force for the development of the photovoltaic industry cannot be separated from the technological iteration at the research and development end and the lean management at the manufacturing end. The final core industry indicator is the cost of kilowatt-hour electricity from the perspective of customers.
In various application scenarios, centralized large power stations are most sensitive to price changes. This round of component price reduction will significantly promote the continuous expansion of photovoltaic ground power stations, and further promote the further increase of the installed share of renewable energy.
The installed share of renewable energy, or more accurately, the continuous increase in the share of power generation, not only represents the green future of energy supply, but also has clear external constraints. The core part of the solution is to vigorously develop the matching energy storage system.
It can be said that the spring of energy storage has come.
System change
On January 6, this year, the National Energy Administration issued a draft of the Blue Book for the Development of New Electric Power Systems. In short, the so-called new power system refers to the power system with photovoltaic, wind power and other renewable energy as the main supply. The draft proposed that in the process of transforming to a new type of power system, the system form will change from three elements of "source network load" to four elements of "source network load storage".
The traditional power system, which takes fossil energy generation as the main body, does not need energy storage because fossil energy itself plays the role of energy storage. At the same time, by controlling the combustion scale of the generator set, the power supply can be flexibly increased or decreased to match the real-time demand of the power load.
However, renewable energy has the characteristic of "relying on nature", which makes the supply side naturally unstable. For example, the daily fluctuation range of wind power output can reach 80%, the peak of output is around the morning, and it reaches the lowest point in the afternoon. The "reverse load" feature is very obvious; The maximum fluctuation range of PV in the day can reach 100%. The peak and valley characteristics are distinct. The peak of the day is reached at noon, and there is a uniform decline around noon. The output at night is 0.
At the initial stage of development, renewable energy accounted for a relatively low proportion, and this instability can still be accommodated by the power system. It is like that a little turbulence can be incorporated into the tide.
With the continuous growth of the installed scale of solar power in China, the proportion of solar power generation is getting higher and higher, and the accumulation of solar power gradually reaches the critical point.
According to the latest data of the National Energy Administration, the total installed capacity of power generation in 2022 will be about 2.56 billion kilowatts. Among them, the installed capacity of wind power is about 370 million kilowatts, accounting for 14.45%; Photovoltaic installed capacity is about 390 million kilowatts, accounting for 15.23%.
More importantly, in 2022, the new installed capacity of wind power PV accounted for 78% of the new installed capacity of the country, and the new generation capacity of wind power PV accounted for more than 55% of the new generation capacity of the country in that year. Wind power PV gradually became the main body of the new installed capacity and new generation capacity.
The original turbulence seems to have become a new tide.
At this time, the shortage can no longer be ignored. Energy storage, as the core means of stable supply of renewable energy, has officially come on the stage. Furthermore, the key elements of the power system have changed from the three elements of "source network load" to the four elements of "source network load storage".
This is a qualitative change driven by quantitative change.
Between delivery and use
The in-depth development of renewable energy means that the power system should have sufficient capacity to integrate flexible power supply, and also match the same flexible power consumption.
At present, the key to integration and matching is to systematically introduce diversified energy storage units.
According to different application scenarios, energy storage can be divided into three types: power supply side, power grid side and user side. As a high-quality flexibility resource, energy storage can play a key role in all three scenarios.
The essence of energy storage is to improve the mismatch between power supply and demand. Therefore, the business model of energy storage is based on the improvement of demand for supply and demand of relevant parties. For example, large power stations on the power generation side hope to reduce power abandonment and increase power generation revenue; The industrial and commercial park on the user side hopes to ensure power supply and reduce power consumption costs.
This improvement has its own cost. When the improvement cost is lower than the mismatch loss, the energy storage will have the profit space.
Therefore, at the power system level, it is necessary to establish a mechanism to measure the degree of mismatch and give corresponding pricing.
That may be a bit abstract. Let's give a concrete example. At the end of 2022, many families in Shanghai found that the electricity bill was soaring, and so was our family. For this reason, I checked the daily electricity consumption data in December through the APP of the State Grid of China, and multiplied it by the peak and valley electricity prices. The result of the calculation is not bad.
There are two basic reasons for the sharp rise in electricity bills: first, low temperature+epidemic situation at home increases the power consumption for heating such as air conditioning; Second, at the end of the year, the ladder electricity price reached the third level, and the unit price of kilowatt-hour electricity jumped.
Similarly, at the end of last year, Shanghai, Henan, Jiangxi, Hubei and other places adjusted the time-of-use electricity price policy to expand the peak-valley price difference. For example, in the industrial sector of Shanghai, the electricity price at peak hours in summer and winter will rise by 80% on the basis of the flat price, and the electricity price at peak hours will rise by 25% on the basis of the peak price.
In fact, the core of both ladder and peak electricity prices is to artificially increase the peak-valley price difference. Different electricity consumption, different electricity prices; The electricity price is also different in different power consumption periods; In this way, energy storage that can span time and space and eliminate the difference between supply and demand will have the opportunity to establish an arbitrage mechanism between development and utilization.
The market generally believes that spot trading is conducive to reflecting the changes in market supply and demand, and giving full play to the decisive role of the market in the allocation of power resources. By expanding the proportion range of electricity price that can be floating, we can promote the path of electricity price adjustment.
As the price of green power often refers to the price of thermal power, this may also boost the price of green power.
In a word, the main price feature of the new power system will be the steady increase of the benchmark price and the expansion of the floating price. It can be said that the flexible electricity price mechanism being established provides the necessary market background for the systematic introduction of the fourth element of energy storage.
Mainstream energy storage
According to the capacity of electricity, energy storage can be divided into large-scale energy storage for power stations and power grids (referred to as large storage) and household energy storage for small and household users (referred to as household storage).
In China, large reserves account for more than 95% and play an important role. At present, household storage is mainly for European and American users.
From the perspective of technical route, pumped storage is the most economical and the highest proportion of energy storage technology at present; The battery energy storage represented by lithium-ion battery is growing rapidly and is expected to become the new mainstream.
At the same time, mobile energy storage emerging at the consumer end has gradually become the standard configuration for outdoor people.
In this section, we briefly introduce these three types of energy storage.
Pumped storage
In 2020, the scale of pumped-storage energy will account for 94% of the global energy storage, and the Chinese market will account for 89%.
This high proportion is due to the advantages of lower cost, longer service life and more mature technology compared with other technical routes.
In principle, pumped-storage power stations use the surplus electric energy of other power sources at the time of low power consumption to pump water to the upper reservoir for storage, and then generate electricity when the peak load occurs. That is to say, when pumping, pumped storage is equivalent to a large power user, whose role is to fill the valley of the daily load curve, that is, to achieve the unique "valley filling" function of the pumped storage power station.
Schematic diagram of pumped storage
According to the statistics of the Pumped Storage Industry Branch, by the end of 2021, China's pumped storage power stations have 40 projects in operation with an installed capacity of 36.39GW, 48 projects under construction with an installed capacity of 61.53GW, and more than 200 GW of pumped storage power stations are carrying out preliminary survey and design work.
According to the calculation of Soochow Securities Research Institute, it is estimated that by 2025, the total scale of pumped storage will be more than 62GW; By 2030, the total production scale will reach about 120GW; By 2035, a number of large backbone enterprises of pumped storage will be cultivated. According to the plan, the growth rate of pumped storage energy in China from 2021 to 2025 will reach 70+%, and the CAGR in four years will be 14.25%.
Battery energy storage
Battery energy storage, represented by lithium-ion batteries, is the most important driving force for the development of electric vehicles in recent years.
As a strong advocate of renewable energy, Musk pointed out that its three pillars are electric vehicles, solar/wind energy, and energy storage. The development of battery technology driven by electric vehicles makes battery energy storage become the main external beneficiary. In the latest conference call, Musk predicted that Tesla's battery energy storage business would grow much faster than electric vehicles.
In addition to the update of battery technology and the cost reduction brought by large-scale cell production, battery energy storage also has its own power electronics technology requirements.
Among them, energy storage converter is the key part. In the energy storage system, the energy storage converter is the core equipment to undertake DC/AC conversion, and its cost accounts for about 15-20% of the energy storage system.
At the same time, similar to data centers, large energy storage systems need to be equipped with temperature control and fire safety facilities. The cost of temperature control is about 3-5%, while the cost of fire control is about 3%.
In addition, the high price of lithium resources triggered the recovery of sodium ion battery technology. However, due to the deficiencies in cycle life, energy density, charge-discharge ratio and other aspects, sodium battery looks more like a supplement to lithium battery than a replacement.
In the long run, the consistency of lithium batteries will be better and better, and the cycle life will be longer and longer. Experts predict that by 2030, the battery life of first-tier manufacturers will probably double from 8000 in 2022.
The doubling of service life means that the initial investment cost of lithium battery projects will decrease by about 50% by 2030. That is to say, without considering the price of electricity and only looking at the cost of storing/releasing electric energy in the whole life cycle, the cost per kilowatt-hour of lithium energy storage in the future will probably be less than 0.2 yuan. This price is only slightly more expensive than pumped storage, and lower than all other energy storage technologies. Lithium battery energy storage is better than pumped storage in terms of response speed, charging and discharging speed, active and reactive power support, etc.
From this point of view, the competition time window for other energy storage technologies is about ten years.
Mobile energy storage
In the new energy competition, China has the world's leading scale and innovation environment in the two major fields of photovoltaic power generation and lithium-ion batteries. This provides rich industrial soil for the birth of mobile energy storage applications and brands.
According to consumption scenarios, mobile energy storage is mainly divided into two categories:
Portable energy storage: suitable for outdoor travel, emergency disaster recovery and other scenarios.
The charging of mobile energy storage can be done through both power network and solar panels. For example, a leading brand's 2 degree electricity product can achieve 2 hours of indoor fast charging and 2.5 hours of high-speed optical charging.
There is no clear boundary between portable energy storage and household energy storage. Corresponding to 2B characteristics of large energy storage, mobile energy storage has obvious 2C characteristics. In this field, brand, channel and user experience are as important as the progressiveness of technical indicators.
New energy storage
At the technical level, in addition to pumped storage and lithium-ion batteries, there are many new energy storage technologies. These technologies are at different stages of development. We will briefly introduce them in this section.
It needs to be pointed out that which of these technologies can be industrialized on a large scale will ultimately compete for cost-effective.
Photothermal energy storage
The first time I noticed the solar thermal power station was to take my children along the Qinghai-Gansu Ring Road in the summer vacation of the previous year. When passing through Dunhuang, suddenly two big beams of light appeared in the field of vision, shining on the Gobi Desert in broad daylight.
Later, after checking the information, we learned that it was a solar thermal power generation project of a listed company in Dunhuang. One light pillar is a 10MW pilot project, and the other is a 100MW demonstration project.
The biggest difference between the molten salt photo-thermal power station and the photovoltaic power station is that it does not rely on the photoelectric effect to directly convert the solar energy into electric energy. Instead, it gathers the sunlight through many arc mirrors, melts the molten salt through the generated high temperature, and stores the solar energy first. The heated molten salt is stored in the heat tank, which is equivalent to the coal bunker in the thermal power station.
After that, the hot salt is pumped into the heat exchanger for heat exchange with water, and the steam turbine is driven by the generated high-temperature and high-pressure steam to generate electricity. This includes a series of energy conversion processes including solar energy, thermal energy, kinetic energy and electric energy.
With molten salt as the medium, the diurnal fluctuation of solar energy is effectively buffered, and the stored molten salt can also generate electricity at night. Therefore, photothermal power station is applicable to the field of large-capacity and long-term energy storage.
Molten salt photothermal power generation principle
According to the minutes of an expert exchange held in August 2022, light and heat ranked third after pumped storage (90%) and electrochemistry (9%), accounting for 1.5%. Considering that pumped storage cannot be built in Northwest China due to lack of water, and that there are still problems to be solved in terms of safety, recovery, resources and other aspects of electrochemical energy storage, photothermal energy storage has certain competitiveness.
Generally, solar thermal energy storage can support 6-10 hours of power generation, and the annual utilization hours can reach more than 4000 hours. As the heat energy is stored, it can also be used for heating in winter.
In terms of cost, the accounting cost of the latest 100MW project in Qinghai is about 1.8 billion yuan, and the unit cost of the system is 1800 yuan/kWh. The cost of photo-thermal power generation for new projects has reached about 0.26-0.46 yuan.
compressed air
Schematic diagram of compressed air energy storage
At present, there are four compressed air energy storage projects in China, which are located in Yingcheng, Hubei, Tai'an, Shandong, Chaoyang, Liaoning and Jiuquan, Gansu. The capacity of each project is 300MW, the conversion efficiency of its main charging and discharging system is more than 70%, and the unit cost of the system is not more than 1400 yuan/kWh, which can be compared with pumped storage.
On the whole, compressed air energy storage is still in the transitional stage of demonstration and commercial promotion.
Liquid flow battery
Compared with lithium-ion battery, liquid flow battery represented by all-vanadium liquid flow has the greatest advantages of long life and safety.
Schematic diagram of vanadium liquid flow battery
In terms of cost, the unit cost of all-vanadium liquid-flow battery has decreased from 5000 to 6000 in previous years to less than 3000. In the future, it may be further reduced to about 2000. Considering its ultra-long life, the economy in the whole life cycle is still very advantageous.
In addition, China's vanadium reserves and output are the first in the world and will not be blocked by overseas resources. At the same time, because vanadium can be recycled permanently, as long as the input of electrolyte is maintained for the first 20 years, it can be recycled later.
In general, liquid flow battery has its unique advantages in terms of safety and long life, and is more suitable for large-scale long-term energy storage. On the one hand, the efficiency is not as high as that of lithium battery. At present, the energy efficiency of the demonstration system is about 75%; On the other hand, the current high cost limits its large-scale application.
Scenery hydrogen production Solar hydrogen production is the process of producing hydrogen by electrolysis of water using electricity from solar power stations. At present, there are two technical schemes that have been commercialized, namely alkaline (ALK) water electrolysis for hydrogen production and proton exchange membrane (PEM) water electrolysis for hydrogen production.
Schematic diagram of solar hydrogen production
At present, the biggest bottleneck in the development of solar hydrogen production is the cost. Compared with fossil energy hydrogen production, the current cost of hydrogen production needs to be reduced to less than 20 yuan/kg, and electrolytic water hydrogen production has a certain competitive advantage. At this time, the electricity price of renewable energy should be maintained below 0.3 yuan/kWh.
At present, in the main regions promoting "PV+green hydrogen", such as Xinjiang, the electricity price of renewable energy is basically maintained at about 0.29 yuan/kWh. It is reported that Sinopec Xinjiang Kuqa Photovoltaic Hydrogen Production Project, the largest green hydrogen project in the world, has a hydrogen production scale of 20000 tons per year and a hydrogen production cost of about 18 yuan/kg.
In terms of calorific value, 1 kilogram of hydrogen is equivalent to 4 liters of gasoline. For hydrogen production by electrolysis of water, the cost of electricity accounts for about 70%. With the continuous reduction of the cost of renewable energy, when the cost of power generation falls below 0.15 yuan/kwh, solar hydrogen production will be economical. At this time, the surplus scenic resources in the western region will be converted into hydrogen locally, and then sent to the central and eastern regions through the existing natural gas pipelines.
Forced allocation and storage
From the perspective of investment, energy storage is one of the core growth tracks in the next decade. The certainty of long-term growth is largely related to the policy of mandatory reserve allocation.
|
