The direction of the energy transition is to shift the energy structure based on fossil energy to renewable energy. This is the cornerstone of achieving carbon neutrality and the engine of the green transformation of the global economy.
However, the new energy technologies that support the energy transition are still not fully prepared. The current main new energy products need to be further reduced in cost and efficiency; new energy products with greater development potential and not yet commercialized development need to break through the barriers of technology and cost.
At present, the large-scale commercial development of renewable energy is mainly solar and wind energy. The main product of the former is PERC (emitter and back passivation cell) monocrystalline silicon battery, and the latter is onshore wind turbine. The energy efficiency of these two main products is close to the bottleneck, and more efficient photovoltaic cells and higher-power offshore wind turbines are gradually rising to a new generation of energy products that can be developed commercially.
The shortcomings of solar and wind energy are intermittent and fluctuating. Therefore, while reducing costs and increasing efficiency, it is necessary to develop energy storage facilities that can be used for peak shaving. On the other hand, hydrogen produced by wind power and solar power has zero carbon emissions and is stable, and can be used as a peak-shaving medium. It is considered to be the main energy source in the carbon neutral era, second only to wind power.
In addition, mankind is still exploring more efficient and cleaner new energy sources, such as tidal energy, nuclear fusion power generation and so on. Although the dawn of the commercial development of these more advanced new energy sources has not yet been seen, new energy technologies, like stars, illuminate a better direction for the earth.
The potential of existing new energy
The fastest-growing renewable energy is solar power generation, which is divided into two technology paths: solar thermal and photovoltaic. The current mainstream is photovoltaic power generation. The core of photovoltaic power generation is to use batteries to convert solar energy into electricity. Therefore, photovoltaic cells are the key to improving the efficiency of photovoltaic power generation.
The competitiveness of Chinese photovoltaic companies ranks in the forefront of the world, and the Chinese photovoltaic market represents the most advanced level of the photovoltaic industry today. The current mainstream photovoltaic cells are monocrystalline silicon cells, which can be divided into N-type cells and P-type cells according to the silicon wafer model. The ultimate of the latter is the PERC battery, whose photoelectric conversion efficiency has exceeded 23%, which is close to the theoretical maximum value of the battery. The more efficient N-type monocrystalline silicon cell currently only accounts for a very small market share.
Two types of N-type batteries with great commercial potential are TOPCon (tunneling oxide passivation contact) batteries and HJT (heterojunction) batteries. The industry believes that the theoretical efficiency of the photoelectric conversion limit of these two batteries is about 28.7%. All major photovoltaic leading companies have now deployed.
The “China Photovoltaic Industry Development Roadmap (2020 Edition)” issued by the China Photovoltaic Industry Association stated that in 2020, China’s new mass-produced photovoltaic cell production lines will be dominated by PERC cells, accounting for 86.4% of the market, and N-type cells will account for approximately 3.5%. As the efficiency and cost advantages of N-type batteries continue to improve, the market share of N-type batteries will gradually increase.
Amorphous silicon photovoltaic cells can also achieve commercial mass production in the foreseeable future. At present, the most promising amorphous silicon photovoltaic cell is the perovskite cell, which has a theoretical limit of 33% conversion efficiency, and the theoretical limit of the tandem cell composed of perovskite cell and crystalline silicon can reach 43%.
The large-scale development of wind energy is earlier than that of photovoltaics, but the industry generally believes that the development potential of wind energy is slightly less than that of photovoltaics. At present, onshore wind power technology in major countries is basically mature and is in a stage of rapid growth in installed capacity. Offshore wind power is still in the period of technological improvement, and more powerful and more economical offshore wind turbines are the direction pursued by the industry.
Offshore wind turbines are more technically difficult than onshore wind turbines, and face technical challenges in aerodynamics, shipbuilding, and fluid mechanics. According to statistics from the Global Wind Energy Council (GWEC), last year’s global offshore wind power capital expenditure exceeded offshore oil and natural gas investment for the first time.
Once the technical difficulties are overcome, offshore wind power will have the same potential as thermal power and nuclear power. GWEC predicts that the annual installed capacity of global offshore wind power will quadruple within five years; its share of global new wind power installed capacity will increase from the current 6.5% to 21% in 2025.
At present, offshore wind power is moving towards COSCO waters. The industry believes that floating wind turbines will be more suitable for COSCO waters than current fixed offshore wind turbines. The governments of the United States, Europe, and China are all actively promoting the technological progress of floating wind turbines, and they have all developed relevant experimental units.
According to the prediction of the National Renewable Energy Laboratory (NREL), floating offshore wind turbines can expand the potential of the United States’ offshore wind resources to more than 7000 terawatt hours (TWh) per year, which is almost twice the total annual energy consumption of the United States.
Photovoltaic cells are the key to improving the efficiency of photovoltaic power generation. Figure/IC
For solar and wind energy, its development potential depends not only on its own technological progress, but also on the development of energy storage technology.
As the proportion of photovoltaic and wind power in the power supply structure continues to increase, the scale of energy storage on the grid side is rapidly expanding. At the end of 2019, the cumulative installed power scale of China’s electrochemical energy storage has increased by nearly ten times compared with 2015.
Pumped storage is the most mature and lowest-cost energy storage technology, but its development space is limited. Chemical energy storage, including lead-acid batteries, lithium-ion batteries, flow batteries, sodium-sulfur batteries, etc., is the focus of current technological research. The industry hopes to find new batteries with longer life, safer and lower cost.
Flywheel energy storage technology, which is the same physical energy storage as pumped storage, has developed rapidly recently. Demonstration projects have been established in multiple wind farms, and some projects have also adopted a hybrid energy storage mode of flywheel and battery.
Flywheel energy storage refers to the storage of kinetic energy through the rotation of a high-speed rotating body, and the conversion between kinetic energy and electrical energy at the same time. It has the advantages of long service life, greater power density, and rapid charging and discharging. At present, the technology is becoming mature and in the early stage of commercial development.
The embryonic form of new energy in the future
Hydrogen is an ancient gas, and the use of fossil energy to produce hydrogen is also a mature technology. It was not until the large-scale development of wind power and photovoltaics that hydrogen was renamed hydrogen energy. Because only hydrogen produced by renewable energy (called green hydrogen in the industry) is a renewable energy with zero carbon emissions. It is considered to be the ultimate energy source in the era of carbon neutrality, in areas that cannot be electrified.
Renewable energy hydrogen production generally refers to hydrogen production by electrolysis of water, that is, hydrogen is produced after passing an electric current in an aqueous electrolyte solution. There are three main technical routes: hydrogen production by alkaline water electrolysis cell, hydrogen production by proton exchange membrane water electrolysis cell and Hydrogen production by solid oxide water electrolyzer.
The commercial development of green hydrogen requires two factors: the cost of renewable energy power generation is reduced, and the technology of electrolysis water hydrogen production equipment is advanced.
At present, the trend of reducing the cost of renewable energy power generation is very clear, and the technical development of electrolyzed water hydrogen production equipment is still facing challenges. European countries have mastered the world’s most advanced electrolysis water hydrogen production equipment technology, and Europe is also the most active region in promoting green hydrogen. The European Union plans to rapidly expand the market size of electrolyzers in the next ten years to reduce costs.
However, within ten years, blue hydrogen should be a more viable transitional energy than green hydrogen. Blue hydrogen refers to the production of hydrogen from fossil energy, plus CCUS (capture, utilization and storage of carbon dioxide). Because of the low cost of mature hydrogen production technology from fossil energy, CCUS is also developing rapidly.
The British government previously announced that it will invest 220 million pounds to promote the clean and low-carbon transformation of carbon-intensive industries, including CCUS technology. At the same time, the UK also plans to increase the supply of blue hydrogen through new mechanisms such as CFDs in the next ten years. It plans to vigorously develop green hydrogen with reduced costs after 2030.
The “World Energy Outlook 2021” issued by the International Energy Agency (IEA) stated that by 2050, the successful realization of net zero emissions will create more than 1 trillion yuan per year for wind turbines, solar panels, lithium ion batteries, green hydrogen and other industries. The dollar market is comparable in size to the current oil market.
In addition to the above-mentioned renewable energy that has been or will be commercialized, mankind is still exploring many cleaner and more efficient new energy products.
The most abundant resource on earth is the ocean, and the energy in the ocean is a huge treasure to be developed. According to data from the International Renewable Energy Agency (IRENA), the total power generation potential of all ocean energy technologies is 45,000-130,000 TWh per year, which is more than twice the current annual global electricity demand. People are optimistic about its prospects for cost reduction. It is expected that after ten years, ocean energy will enter the stage of large-scale development like mature renewable energy.
At present, ocean energy is still in its early stages of development, but tidal energy and wave energy have become viable alternative energy sources on remote islands with high electricity costs. 55% of tidal currents and wave projects under construction worldwide are in Europe. In the offshore energy strategy issued by the European Union, in addition to vigorously developing offshore wind power, other forms of ocean energy such as tidal energy and wave energy are also included. The EU believes that compared to wind and solar, wave and tidal power generation is more stable and can play a vital role in decarbonizing the EU and stabilizing the power grid.
The sun that illuminates everything has also given people the inspiration to develop energy. Create an internal condition similar to the sun, produce a nuclear fusion reaction, and then use its heat to generate electricity, then humans will have almost endless clean energy.
Nuclear fusion is a process in which light nuclei (mainly hydrogen isotopes deuterium and tritium) aggregate into heavier atomic nuclei and release huge energy at the same time. This is the principle of the sun’s glow and the explosion of hydrogen bombs. The energy released by the fusion reaction is huge. The deuterium in 1 liter of seawater can release the energy equivalent to the combustion of 300 liters of gasoline through the fusion reaction, and the reaction product of the fusion is relatively stable helium.
Controlled thermonuclear fusion has always been the dream of scientists. Although it has not yet been realized, many official institutions and private enterprises in the United States, China and other countries are actively exploring this ultimate energy source.