Do we need so many waste-to-energy plants?
According to CCTV News on June 6, garbage incineration power plants in developed cities along the eastern coast and in central and western regions are suffering from varying degrees of "underfeeding".
Since July 1, 2019, the Regulations of Shanghai Municipal Household Waste Management have been officially implemented, and compulsory waste classification has been generally implemented. According to the Implementation Plan of the Household Waste Classification System issued by the National Development and Reform Commission and the Ministry of Housing and Urban-Rural Development in March 2017, 46 cities in China have implemented compulsory household waste classification by the end of 2020. China's garbage sorting has entered a "mandatory era".
Waste classification and waste incineration power generation are both waste disposal means. The former extracts the "resource" value of garbage and reduces the amount of garbage disposal; The latter extracts the "energy" value of waste and reduces the cost of waste disposal. So, is the main reason for the "lack of food" of waste in waste incineration power plants the reduction of waste caused by waste classification? How to "eat full"?
What is the main cause of garbage and not enough to eat?
In the latest report of CCTV news, a waste incineration plant in Pucheng County, Weinan, Shaanxi province, is planned to centrally dispose household waste in the county, 15 towns and 2 subdistrict offices. At full capacity, it can burn more than 182,500 tons of waste per year and generate more than 78 million kilowatt-hours of electricity. But the plant will handle 133,000 tons of waste in 2023, at only about 70% of capacity; Fushan Circular Economy Industrial Park is responsible for about 35% of Guangzhou's daily garbage disposal tasks. Garbage sorting significantly reduces the amount of garbage at the source, and the park is not operating at full capacity.
In exchanges with industry insiders, researchers from the Paper Research Institute found that the phenomenon of "insufficient food" from waste incineration power plants lasted for two to three years, and almost became a common problem in many provinces in China. The main reason for "not enough to eat" is not the reduction of waste caused by waste sorting, but the overcapacity of waste incineration power plants.
According to the Ministry of Ecology and Environment, the number of waste incineration plants in China increased from 278 in 2017 to 925 in August 2023, with a disposal capacity of 1.035 million tons per day, fulfilling the target of the 14th Five-Year Plan ahead of schedule, that is, by the end of 2025, the national urban household waste incineration capacity will reach about 800,000 tons per day. According to E20 Research Institute, the current average load rate of waste incineration plants in China is about 60%, and a large part of household waste incineration plants are not operating at full capacity.
"Not eating enough" waste is equivalent to insufficient "fuel" for waste incineration power plants. Wang Weiquan, deputy secretary general of the Renewable Energy Committee of the China Energy Research Society, pointed out that the excessive construction of waste incineration power plants in recent years has led to disorderly competition, from first-tier cities to second - and third-tier cities, and eventually even every county. This waste diversion is the main reason for the "underfeeding" of waste incineration power plants. On the other hand, the amount of waste is related to the local economic development, urbanization level and people's living habits. The growth rate of waste is much lower than the expansion rate of waste incineration power plants. Coupled with the reduction effect of waste classification, under the action of multiple factors, it is difficult to "feed" the waste incineration power plants that expand too fast.
The phenomenon of "not enough to eat" garbage is first caused by the lack of overall local planning. Due to the lack of overall planning for the construction of waste incineration power plants by local governments, new projects are constantly put into operation, which diverts waste and ultimately leads to "insufficient food" for waste incineration power plants. Second, it is also related to the lack of unified coordination among localities. For local county-level governments, they will consider the construction of local waste incineration power plants from the perspective of local financial expenditure. For example, if the county has a waste incineration power plant but does not have it, it will need to spend transportation fees to remove the waste, if the transportation distance is far, it will increase transportation costs. Building your own factory, you only need to pay for garbage disposal, which not only reduces expenses, but also is not controlled by others. This has led each county to want to build its own waste-to-energy plant, with capacity far exceeding the amount of waste to be disposed of.
How to solve the problem of garbage and "not enough to eat"
In order to solve the problem of "insufficient food" of waste, the key is to increase the amount of waste treatment under the premise of surplus capacity of waste incineration power plants. It is understood that there are two main solutions at present: one is to use domestic waste incineration facilities to coordinate the disposal of domestic waste and industrial solid waste; The second is to dig out the stale garbage that has been buried deep underground in the landfill for many years and treat it for use in the waste incineration power plant. In practice, it is necessary to improve the technology to ensure the efficiency of waste incineration power generation, and pay more attention to environmental protection and safety.
First of all, national standards on collaborative disposal of industrial solid waste have long been issued, which has high requirements on the equipment of waste incineration power plants. According to the 2014 Pollution Control Standards for Household Waste Incineration issued by the Ministry of Ecology and Environmental Protection of the People's Republic of China, the sludge and general industrial solid waste generated by domestic sewage treatment facilities can enter household waste incinerators for incineration and disposal on the premise that the discharge standards of pollutants from household waste incinerators and the normal operation of the incinerators are not affected. As waste is a kind of "fuel" with complex components and different calorage values, waste incineration power plants need to achieve complete incineration of waste by improving technology and process, and ensure that it meets environmental protection standards and does not cause secondary pollution to the environment.
Second, dispose of stale waste in landfills, which is more suitable for waste-to-energy plants that lack incinerable industrial solid waste but are located next to landfills. It is understood that the original intention of incinerating the stale garbage in the landfill is not to solve the problem of "not enough to eat", but for environmental protection considerations. After the ecological restoration of landfill waste, the land originally occupied can be used for other purposes to alleviate the shortage of land resources, and the excavation of stale waste before restoration can reduce land pollution. Landfill sites are generally operated by governments rather than enterprises. Although the cost of digging out stales for incineration is low, the cost of ecological restoration of landfill sites is high, so it is necessary to ensure the environmental protection and safety of the process.
At the same time, garbage "not enough to eat" has become an established fact. Waste classification can improve the efficiency of waste incineration power generation and make up for the loss of economic benefits caused by waste reduction to a certain extent.
First of all, after garbage classification, the content of kitchen waste in dry garbage is greatly reduced, which makes the calorification value of garbage into the furnace significantly increased; Secondly, due to the separation of kitchen waste wet waste, the moisture content of waste is reduced, which also reduces the generation of leachate, thus reducing the cost and environmental risk of leachate treatment; Finally, the air distribution required for the operation and combustion adjustment of boiler equipment is relatively reduced, thus reducing the power consumption rate of the factory and improving the online power consumption of waste incineration power generation.
Take Suzhou as an example. Since June 2020, Suzhou has officially implemented waste classification. Except for Wujiang District, domestic waste in Suzhou urban area is fully incinerated in Everbright Environmental Protection Energy (Suzhou) Co., LTD. (hereinafter referred to as "Suzhou Energy"). Since the waste sorting, Suzhou Energy has reduced the amount of household waste to be incinerated by about 3%, but the water content of the waste has decreased by more than 10%.
Liu Dapeng, general manager of Suzhou Energy, believes that although waste classification reduces the amount of waste, it improves the calorification value of waste and power generation efficiency. In general, the reduction of waste classification has not had a great impact on waste incineration power plants. Even if the amount of waste is reduced by 20%, the calorage value increases, and the economic benefits of waste incineration power plants will not be greatly affected.
In short, in the case of overcapacity of waste incineration power plants, in order to solve the problem of "insufficient food" of waste, it is necessary to increase the amount of waste treatment through coordinated disposal of industrial solid waste and incineration of obsolete waste in landfills. Waste classification can make waste "eat well", improve the efficiency of waste incineration power generation, bring economic benefits, and make up for the impact of waste reduction. At the same time, relevant departments should strengthen the orderly construction and operation of waste incineration power plants, reduce the diversion of waste volume, and achieve healthy and sustainable development of the industry.
Source: https://mp.weixin.qq.com/s/VRGhgoaNs32BwQE-ck0p_g