China should directly develop renewable energy by cornering overtaking

The Paris Agreement The Chinese government has officially ratified and its core content is to ensure that climate change is controlled to no more than 2 °C. According to this plan, by 2050, the total amount of carbon dioxide emissions worldwide will not exceed 15 billion tons.

This is a serious challenge because China's total carbon emissions now exceed 10 billion tons per year. According to the total carbon emissions of 15 billion tons, China's carbon credits can be up to 3.5 billion tons by 2050, only one-third of the current 100 tons. Now there are still 33 years and two months from 2050. During this time, how can we reduce the total carbon emissions in China by 2/3? This is a serious challenge. Therefore, there should be planning and action now. In fact, developed countries, especially Europe, have already begun to take action. For example, developing renewable energy, improving energy efficiency, adjusting energy mix, developing nuclear energy, and even CCS (CO2 capture and storage) to achieve this goal.

Throughout the history of human energy use, we have gone through several times.

Before the Second World War, except for the US coal ratio fluctuating between 50% and 60%, other countries basically used coal as the leading energy source. After the end of World War II, from 1950 to 1975, 25 years from the coal era to the oil and gas era. At that time, from coal to oil, coal consumption fell from more than 90% to less than 30% to 40%, or lower. From the 1970s, it basically entered the oil and gas era. It started with oil and was later dominated by gas. The total amount of coal reaches 20%, 30% and 40%. This is the process by which humans use energy structure to adjust and change.

China's current coal consumption is still on the 65%, 70% figure, or it can be considered still in the coal era. Nowadays, due to the problem of climate change, developed countries have begun to change from the oil and gas era to the low-carbon era dominated by renewable energy. For example, the European Union, Denmark, Finland, Germany, Sweden and other countries all plan to achieve zero carbon or low carbon by 2050, and renewable energy will become energy-led. China also plans to reach a peak before 2030, and the peak will fall. In 2030, renewable energy accounts for more than 20% of total energy.

The question we are facing now is: Is China going to take the old road that the developed countries have gone through, that is, from the coal era to the oil and gas era? China's natural gas now accounts for less than 5% of total energy, while 30% to 40% of developed countries' total energy is natural gas. Although China's natural gas only accounts for 5%, its dependence on foreign countries has reached 30%. To further increase the proportion of natural gas, it can only increase imports. From the current coal energy to natural gas energy, huge infrastructure investment is needed. But in turn, China's coal-fired technology is in a leading position in the world, both in terms of cleanliness and efficiency.

Therefore, should China take such a path: first use 10 to 15 years to change coal into oil and gas, and then spend 10 to 15 years to replace oil and gas to achieve low-carbon renewable energy-based transfer? Or choose another road: focus on the existing manpower and material resources, overtake the curve, directly develop to the low-carbon structure of renewable energy, and enter the low-carbon or zero-carbon energy era simultaneously with developed countries?

The answer is obvious. Only by choosing the second road can we change the unfavorable conditions of China's current lack of gas and oil, and become a favorable condition for promoting the development of renewable energy.

China's current energy consumption is high, and the total amount of carbon emissions is also the highest in the world. One of the most important reasons is the rapid urbanization. The Luqiao Dam Building includes energy systems, which require a large amount of steel, cement, and building materials, all of which are high-energy industries. Strong market demand has caused China's carbon emissions to remain high or continue to grow, resulting in huge energy consumption. At this time, China's economic development model should be transformed, and it should be changed from investment-driven to high-value-added innovation. As infrastructure development and construction demand diminishes, the coal energy era will end and move directly to the era of renewable energy. This is a viable option because it can avoid duplication of construction and repetitive investment in oil and gas energy infrastructure.

So, can China achieve a low-carbon energy structure in the future? The answer is yes. In the future, China's annual electricity consumption is about 8.5 trillion to 9 trillion kWh, which is used for construction of 2.5 trillion kWh, transportation of 1.5 trillion kWh, and industry of 4.5 trillion kWh. Where does this electricity come from? Hydropower now grows to 1 trillion kWh per year by 1 trillion kWh; nuclear power can now grow to 1 trillion kWh at 0.15 trillion kWh; wind power can reach 1 trillion kWh by 0.2 trillion kWh; Optoelectronics can grow to 1 trillion kWh. These add up to provide about 50% of the electricity used. Then, another 50% of the gas and coal-fired power plants are provided. However, while providing electricity, it is also responsible for power peaking. In this way, carbon emissions will reach 2.2 billion tons. In terms of fuel supply, an additional 1.7 billion tons of standard coal is needed. Among them, 850 million tons of standard coal can be provided by biomass, including agricultural straw, animal waste, and kitchen waste . The forestry straw can be made into biomass gas of 180 billion cubic meters per year, compressed pellets of 400 million tons, and carbon dioxide can be derived to form negative carbon. The remaining material of biofuels can also be returned to the farmland to become a good fertilizer, and the energy crop can have a capacity of 200 million tons of standard coal per year. Then, coal, gas, and fuel oil will provide another 850 million tons of standard coal fossil energy, which will form 1.5 billion tons of carbon emissions, which will add up to the target.

There are several key technologies to achieve this low-carbon energy structure: First, we must solve the problem of power peak shaving and ensure the effective use of photovoltaic wind power. It is necessary to turn CSP (Photothermal Power Generation) into a power peaking power station through cogeneration and energy storage. The second is to develop DC power supply for buildings to achieve distributed energy storage. Stabilize the electricity at the end and solve the power fluctuations by itself. The third is to use the low-temperature waste heat of the current thermal power plants and industrial production, such as steel, non-ferrous, chemical, building materials, information industry, low-temperature heat rejection to solve building heating.

The author is an academician of the Chinese Academy of Engineering and chairman of the China Energy Conservation Association. This article is taken from its speech at the 2016 International Symposium on China's Total Coal Consumption Control and Energy Transformation. The title is added by the editor. (Jiangyi)

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