Focus on the Chicken Manure Power Generation in China: How to Promote the Biomass Waste Industry?

With the vigorous growth of animal husbandry, animal feces in the agriculture sector gradually deteriorate the environment. The chicken manure power generation is becoming viable and useful for energy conversion to comply with the context of environmental protection in China. Based on resource endowments and technical conditions, this paper studies the current situation of chicken manure power generation in China. Combined with the policy environment, the research conducts a PEST-SWOT matrix analysis to thoroughly look into the strengths and weaknesses, the opportunities and challenges. Then, the paper analyzes the distribution of chicken manure and gives some solutions from respects of government regulatory behavior, industrial-organizational behavior and corporation strategic behavior. Finally, it is concluded that: 1) the government should strengthen policy support by actively improving the subsidy mechanism and lowering the threshold of financing and credit; 2) enterprises should focus on improving power generation technology and boiler treatment technology.


Introduction
At present, China is striving to reach the peak of carbon dioxide emissions by 2030, and to achieve carbon neutrality by 2060. China is less than 10 years away from achieving the peak carbon goal, and only 30 years from the peak carbon goal to the carbon neutral goal, compared with developed countries, China has an extremely difficult task to achieve the peak carbon and carbon neutral goals. The demand for energy growth for economic development and the pressure for carbon reduction coexist, and the development of clean energy is indispensable in improving the energy supply structure and building a national ecological security barrier. Biomass energy, the only renewable energy source, that can be transported, has received extensive attention because of the rich resources and wide geographical distribution [1]. It is reported by the China National Renewable Energy Centre that in 2015, China's biomass power installed capacity reached 10.6 million kilowatts, second only to that of the United States (15.9 million kilowatts) and Brazil (11 million kilowatts) [2]. China's biomass power generation grid-connected capacity reached 29.52 million kilowatts at the end of 2020, up 22.6% year-on-year; the annual installed capacity was 5.43 million kilowatts, ranking the first in the world. Meanwhile, due to the development of the chicken industry, the environmental problems caused by chicken manure have become serious increasingly [3]. The excrement of the chicken farm cannot be managed effectively, which causes a series of problems to the surroundings. More importantly, the improper disposal of chicken manure on farms can cause pollution to the ground, groundwater and soil, which would damage the ecological environment at last.
Chicken manure is a high-quality raw material for power generation and its production in China is huge. However, the history of chicken manure power generation in China is relatively short. Noted that the first combustion power plant and biogas power plant using chicken manure as raw materials were put into operation in April 2009 [4]. So far, the installed capacity of China's grid-connected power plant using chicken manure has been less than 100 MW. The handling capacity of chicken manure per year is less than 1% of its total excretion. It can be seen that the utilization rate of chicken manure is at a superficial level, which means chicken manure power generation has much more potential for development.
In order to promote the rapid development of clean energy, the Chinese government has issued many policies since 2013. The National Development and Reform Commission issued the "Revolution Strategy for Energy Production and Consumption" (2016-2030) in 2016, and clarified that from 2021-2030, new energy demand will be met mainly by clean energy. Total energy consumption will be controlled within 6 billion tons of standard coal. The proportion of non-fossil energy in total energy consumption will reach about 20%, and carbon dioxide emissions per unit of GDP will drop by 60% -65% compared to 2005. Therefore, the clean energy industry will face major challenges. Although solar energy and wind energy are mainstream clean energy, wind curtailment and solar curtailment have frequently occurred in China for more than ten years [5]. In contrast, chicken manure is not only inexhaustible but also stable to provide electrical energy [6]. The development of chicken manure power generation can bring considerable effective environmental benefits as well as economic benefits because of its obvious role in pollution abatement. For all that, as an emerging in-dustry, chicken manure power generation sector still faces lots of problems to be solved, such as technology innovation and acquisition of raw material and so on [7].
In the PEST-SWOT matrix, strengths, weaknesses, opportunities and threats of chicken manure power generation are analyzed from four aspects: policy, economy, society and technology. According to the requirements of clean energy, it is necessary to consider the factors of supply and demand, technology and environment to make a judgment on the development direction of chicken manure power generation. Through the analysis, this paper puts forward some solutions on government regulatory behavior and industrial-organizational behavior. In the end, combining the comparison of two kinds of power generation technologies and the distribution of chicken manure in various regions of China, the corporation strategic solutions are given.

Characteristics of Chicken Manure
The test of the combustion characteristic shows that the mixture of chicken manure and rice husks can produce 10.45 MJ/kg lower heating value, half of the raw coal [8]. And the carbon-nitrogen ratio of chicken manure is 15.6 to 1, which is very high. The calorific value of biogas is 23 -24.3 MJ/m 3 so that 1 m 3 of biogas is equivalent to 3.3 kg of raw coal [9].

Production and Distribution of Chicken Manure
The chicken manure emission factors are from First National Survey of Pollution Sources of Livestock and Poultry Livestock Production Sewage Coefficient Manual, in which layers are 0.12 kg/day and broilers are 0.14 kg/day. Based on the number of layers and broilers in the China Agricultural Statistics 2018, it can be calculated that chicken manure production reached 287.31 million tons in the country. Chicken manure volume and distribution density in each province (municipal city, autonomous region) are displayed in Figure 1.
Chicken manure volume is calculated according to the following formula [10]: W F : chicken manure annual emission (million tons); H L : the number of layer stock and broiler stock (ten thousand); F D : the chicken manure emission factor (kg/day/per capita); T D : feeding days.
In the last decade, China's chicken industry has developed rapidly from the scale of farming to the level of production.   Compared to 2006, the total number of farms and large-scale farms increased significantly in 2017, as can be seen in Figure 2. This shows that the chicken industry has an increasingly high degree of intensification. The number of large-scale farms with an annual chicken slaughter above 500,000 in each province (municipal city, autonomous region) is displayed in Figure 3.

Combustion Power Generation Using Chicken Manure
The boiler uses the combustion technology of circulating fluidized bed and adopts low-temperature combustion and segmented air supply to effectively reduce the NO x and SO 2 generated during combustion, which has gained a great advantage in environmental protection [4]. In addition, the combustion by-product of the boiler contains high organic substances such as phosphorus and potassium, which can be used as high-quality compound fertilizer [11]. The value chain of combustion power generation using chicken manure is displayed in Figure 4.

Biogas Power Generation Using Chicken Manure
Biogas power generation uses methane produced by mixing chicken manure with farm sewage and crop straw as fuel. And per kilogram of chicken manure can produce 0.37 m 3 biogas [12]. The electricity can be used in farms and can be delivered to the grid. At the same time, the thermal energy generated during the electricity generation process will be used for the fermentation system to keep warm and provide heat to the chicken farm in winter [13]. The value chain of chicken manure biogas power generation is displayed in Figure 5.

Installed Capacity
According to the data released by the National Energy Administration, in 2020, China's biomass power generation grid-connected installed capacity reached 29.52 million kilowatts, an increase of 22.6% [14]. However, the installed capacity of chicken manure power generation is very small, and the current chicken  manure combustion power generation and chicken manure biogas power generation is only tens of thousands of kilowatts, and chicken manure is a kind of manure that produces less gas than other livestock manure [14]. At present, there are three main ways to recycle chicken manure in the world: energy, fertilizer and feed. In western developed countries, power generation is an important way of using chicken manure. In China, however, it is fertilizer, and the proportion of power generation is very small. It can be learnt in Figure 6 [15].

Methodology: PEST-SWOT Analysis
Combining the industry status of chicken manure power generation, this article analyzes the strengths, weaknesses, opportunities and threats of the industry from the four aspects of policy (P), economy (E), society (S) and technology (T). The analysis matrix is displayed in Figure 7.

Policy Opportunities
In the "13th Five-Year Plan for Renewable Energy Development", it was proposed that "improve the price, taxation and other preferential policies to support the development of biomass energy". Also, since 2010, the government has successively issued the "National Development and Reform Commission Circular on the Management of Biomass Power Generation Project Construction", "Guidance on Promoting the Development of Biomass Energy Heating" (2017) and so on. All of these policies can clarify the status of the biomass power generation industry and promote the development of chicken manure power generation enterprises directly [16] [17] [18].   Firstly, China has not yet set emission standards specifically for the biomass power generation industry. The current standards for the emissions from agricultural and forestry biomass power generation are implemented according to that of the coal-fired power generation, which is unfair for environmentally significant biomass power generation. Secondly, the biomass power companies have invested significant amounts of capital to achieve ultra-low emissions, but they are unable to enjoy electricity price subsidies in time [19]. Moreover, biomass power generation is plagued by technological lags, and many companies are unable to reach the continuously updated ultra-low emission level, which makes them unable to obtain subsidies for reducing emissions [20].

Policy Threats 1) Emission standards are not clear
2) Loan discount policy is not perfect At present, fewer projects can enjoy the benefits of the loan interest subsidy policy. Chicken manure power generation is an emerging industry encouraged by the government and requires a large amount of capital. However, commercial banks cannot provide lower loan rates than conventional ones, which makes the financial situation of chicken manure power generation projects more dangerous [21].

Economic Strengths
Chicken manure is abundant and inexpensive, which can achieve higher economic benefits than itself when it is energized [22]. Biogas power generation is the most common method of converting manure into energy. The "chicken-fertilizer-methane-electricity" recycling industry chain can achieve excellent economic benefits, and it can also save a large number of sewage charges [23]. In another way, the ash left by combustion power generation is high-quality potassium and phosphate fertilizer that can be used directly, which eliminates the costs of ash delivery and storage [24].

Economic Weaknesses
Although the chicken manure production is massive in China, the distribution is not concentrated. The high transportation cost of chicken manure is an essential factor that restricts the power generation [25]. Chicken manure power generation needs enormous investment, and capital recovery is slow. Moreover, investment in emission reduction is huge [26].

Economic Opportunities
1) Industrial economy upgrade At present, the environmental carrying capacity of China has approached the upper limit, and new ways are urgently needed to promote low-carbon development. The "Revolution Strategy for Energy Production and Consumption" (2016-2030) clear that, in combination with new-type urbanization and agricultural modernization, China will expand the scope of electricity use, give priority to the use of renewable energy power, simultaneously promote electrification and information technology construction, and open up a new era of future-oriented energy consumption [27]. As an important project for capacity reduction, chicken manure power generation can promote the sound development of circular economy.
2) Carbon emission trading The greenhouse gas produced by burning chicken manure is about 25% of it produced by burning coal [4]. Moreover, greenhouse gas emissions from biogas power generation are close to zero. Most importantly, the project can also obtain the Clean Development Mechanism (CDM) income. For example, Sunner Company obtains 100 million yuan by processing 700,000 tons of chicken manure annually [28]; Shandong Minhe Stock Co., Ltd. also obtained CDM transaction benefit from biogas power generation [29]. Chicken manure power generation is less capital intensive than traditional power generation projects so that investors are more cautious about investing in the project. In particular, it is often located in rural areas or suburbs, where financing is difficult [30].

Economic Threats 1) Investment and financing difficulties
2) Transportation and supply bottlenecks Compared with coal-fired power generation, biomass power generation projects are environmentally friendly and renewable, but the collection costs are huge [31]. Besides, the quality and supply efficiency of raw materials have restricted the development of China's biomass energy industry to some extent [32].

Social-Natural Opportunities 1) Better environmental awareness
With the advancement of society, citizens' awareness of emission reduction has gradually increased. Besides, enterprises have begun to use energy-saving equipment to reduce electricity consumption, and the government has also adopted restrictions on high-energy-consuming projects, which has contributed to the promotion of chicken manure power generation with low-carbon [33].

2) Providing employment opportunity
In recent years, the trend of rural migrant workers returning home for employment or entrepreneurship is noticeable. The development of the chicken manure power generation industry is conducive to promoting the development of the chicken industry, which can provide more employment opportunities for farmers [34].

Social-Natural Threats 1) Low cognition degree of society
Since chicken manure power generation has just emerged in China, and the media has reported very little on it. People are surprised by this type of power generation, and few investors have noticed it, which is an important reason why it has not been widely promoted [35].

2) Secondary pollution
At present, there is no standardized system for the operation of chicken manure power generation project in China, and secondary pollution exists in the production process. On the one hand, pollutants may leak during transportation. On the other hand, how to make full use of the large amount of biogas and ash produced by combustion is a problem to be solved [36].

Technological Strengths 1) Combustion power generation technology
Compared to conventional coal power, combustion power generation does not require a crushing and milling system. It only requires some conventional system, such as the combustion system, circulating cooling water system and thermal system. However, fuel delivery and ash collection are the main concerns that need attention. It is worth mentioning that the ash collection adopts two-stage dust removal technology, which can collect nearly 99% of the dust [37].
2) Chicken manure fermentation technology A mixture per kilogram of chicken manure and straw produces 0.37 m 3 of biogas with a methane content of 54%, and raw material digestibility is about 65%. It can achieve higher natural gas production than other biomass fermentation materials [38].

Technological Weaknesses
At present, there are certain technical defects in the boilers developed in China. The slag tends to block the discharge port, and the fluidization boiler sometimes fails to cause coking, resulting in insufficient output. Moreover, the accumulation of ash on the surface of the back-end flue is severe, considering the special fuel characteristics and smoke composition of chicken manure [39].
Due to seasonal changes and weather changes, the water content of chicken manure is variable, and this change reduces the efficiency of starter culture. Besides, biogas fermentation temperature is mainly at medium-temperature (about 37˚C). However, the temperature in the north of China is generally low in winter and spring, which significantly limits the gas production rate of biogas [40].

Results and Discussion
Based on the introduction of the industry's status and the PEST-SWOT matrix analysis, in the chicken manure power generation sector, it is demonstrated that some practical problems need us to solve. In order to promote the positive development of the sector, this section gives some solutions in three aspects: government regulatory behavior, industrial-organizational behavior and corporation strategic behavior. As displayed in Figure 8.

Reduction of the Financing Credit Threshold
Government agencies should lower the threshold for financing credit and establish a complete competition mechanism between the same industry, which can implement a differentiated credit system. In order to make direct financing become the main channel for chicken manure power generation companies, a comprehensive diversified and multi-level capital market system should be established. Also, it is proposed to form a new policy financial organization to provide financing services for strategic emerging sectors.

Establishment of the Power Generation Demonstration Site
The demonstration and promotion of this power generation technology have the nature of quasi-public products. Therefore, it is advisable to establish chicken manure power generation demonstration sites in provinces with a well-developed poultry industry, in order to solve the difficulty of technology promotion and the high cost of operation. It also helps promote the vigorous development of farming entities and other investment entities in the vicinity of power generation projects.

Setting of the Emission Standards
It is recommended to issue environmental emission standards for the chicken manure power generation sector. Due to the specificity of the components contained in chicken manure, it should not be measured by coal-fired emission standards. For the long-term development of the sector, appropriate emission standards should be formulated according to the level of development. Such an approach can avoid unreasonable losses caused by policies and taxes. In addition, due to seasonal changes, some characteristics of chicken manure composition and gas emissions may be slightly different. To reduce the tax pressure of those companies, it is suggested that punishment for environmental pollution should be decoupled from the Value Added Tax (VAT) rebate.

Construction of Raw Material Recovery System
The problem of a raw material bottleneck in the development of chicken manure power generation sector can be solved through supply chain optimization.
The main purpose of supply chain optimization is to reduce the cost of raw material supply and improve the quality of raw material supply. For the first model described in 3.2.4, e-commerce could be introduced. Farmers can share chicken manure quality standards and prices and other information through the Internet platform to reduce the benefits for brokers. For the second model, it is possible to learn from the practice of Kaidi Eco and establish a storage station in cooperation with the village committee to reduce the construction and operation costs of the storage station. For the third mode, farmers can be encouraged to collect and transport chicken manure to enterprises by appropriately increasing the price of chicken manure. In a word, the key to supply chain path optimiza-tion is that enterprises should master the dominance of the supply chain and can enhance the enthusiasm of all parties involved in the storage and transportation of raw materials.

Construction of Distributed Generation System
With the advancement of urbanization and distributed energy technology, distributed power generation based on biomass power has great potential. Most chicken farms are built in rural areas or around towns near the countryside, where per capita resource occupation and energy demand have increased significantly. Chicken manure power generation is in line with the characteristics of integrated generation and utilization of distributed power generation. Based on the comprehensive utilization of chicken manure biomass, it can constitute a distributed renewable energy system combining multiple uses such as gas production, power generation, and heating. Due to sufficient raw materials, the system is stable enough to support the electricity demand of residents in rural or small-medium cities, which also can reduce environmental protection pressure.

Strategic Options
This section compares the characteristics of the two types of power generation, especially the raw material consumption and emission levels. According to the distribution of raw materials in the country, the most efficient power generation modes in each region are given.
1) Comparison of two types of power generation Based on the industry status and PEST-SWOT matrix analysis, the characteristics of the two types of power generation modes can be derived, as displayed in Table 1.
2) Selection of strategic scheme The grading standard for the total amount and distribution density of chicken manure are displayed in Table 2, which was determined by using the "three-equidistant intervals method" [10]. High cost for emission reduction; Poor fuel adaptability; Large initial investment.

Gas power generation
The fuel is fermented to produce biogas, which is purified and burned, and then drives an internal combustion engine or a gas turbine.  The total amount of chicken manure (Ten thousand tons) ≥1400 320 -1400 ≤320 The distribution density of chicken manure (kg/hm 2 ) ≥800 300 -800 ≤300 Taking the total amount of chicken manure as the abscissa and the distribution density of chicken manure as the ordinate to make the matrix diagram displayed in Figure 9. The total amount of chicken manure and its distribution density is displayed in Figure 1. According to the grading standard given in Table 2, 31 provinces (municipal cities, autonomous regions) in the country are divided into 9 parts and are listed in Figure 9.
According to the matrix, this study divides the distribution of chicken manure in 31 provinces (municipal cities, autonomous regions) into three major types. And the strategic choice of the enterprise is displayed in Figure 10.
The first category is the areas with a high abundance of chicken manure, including high quantity-high density areas, high quantity-medium density areas and medium quantity-high density areas, totaling ten provinces, as displayed in Figure 9. In these ten provinces, the total chicken manure was 202 million tons in 2017, accounting for 70.30% of the national total, and the chicken manure distribution density was 1047.42 kg/hm 2 in 2017, which is 2.48 times higher than the national average density. This type of area can be used as a critical development area for chicken manure power generation throughout the country, where high-density areas are suitable for the development of combustion power generation or large-scale biogas power plants.
The second category is the areas with a generally available abundance of chicken manure, including high quantity-low density areas, medium quantity-middle density areas, and low quantity-high density areas with a total of eight provinces. In these eight provinces, the total amount was 83.72 million tons in 2017, accounting for 29.14% of the national total, and the chicken manure availability distribution density was 148.27 kg/hm 2 , which was 49.3% of the national average density. High density areas in this type of category, such as Tianjin, have higher requirements for environmental protection. The biogas power generation project is carried out in the area, which is conducive to improving the environmental management of the farm. Moreover, other provinces in this category can be developed as biogas power generation projects. Coupled power generation can also be considered if boiler conditions permit.
The third category is the areas with a low abundance of chicken manure, including medium quantity-low density areas, low quantity-middle density areas, with a total of thirteen provinces. In these thirteen provinces, the total amount of chicken manure obtained was 42.11million tons in 2017, accounting for 14.66% of the national total, and the chicken manure distribution density was 61. 28    density. Considering the development of new energy sources, this type of area must fully consider the availability of chicken manure. When conditions permit, coupled power generation of chicken manure can be developed [41].

Technological Innovation 1) Increase of the boiler output
Due to the melting characteristics of chicken manure fuel ash, the combustion temperature in the furnace is from 100˚C to 150˚C, which is lower than that of conventional coal-fired boilers [42]. Therefore, if the chicken-combustion boiler has the same heating area as the coal-fired boiler, it will inevitably lead to the insufficient output. Comparing the state before and after the transformation of the boilers, the removal of the local castable in the furnace can significantly increase the heating area of the furnace. Therefore, the furnace evaporating heat Energy and Power Engineering receiving area of the chicken manure boiler is designed more than the conventional coal-fired circulating fluidized bed boiler, so that the design output can be achieved.
2) Fermenter thermostatic system design In order to ensure that the biogas fermenter can maintain a constant temperature and produce a sufficient amount of gas in winter, it is necessary to design a constant temperature system. Installation of the biogas fermenter in a sealed building with an air interlayer. Due to the relatively small thermal conductivity of air, it is suitable for heat preservation. The "gas-heat-constant temperature-gas" process is displayed in Figure 11. The waste heat generated by the biogas power generation heats the CSTR reactor and the secondary fermentation reactor through an external heat exchanger, thereby maintaining a high level of medium temperature gas production efficiency.

Conclusions
Chicken manure power generation is a vital renewable energy resource, featuring in green, low-carbon, clean and renewable. The development of chicken manure power generation is a crucial measure to improve environmental quality and develop a circular economy, which is of great significance for achieving the goal of low carbon development and energy transformation. Based on the analysis of this paper, the following main conclusions are drawn: Firstly, in China, chicken manure power generation sector is still in its early stages of development, but related power generation technologies are almost mature. At present, many chicken manure generators are in operation and have excellent economic and environmental benefits. With the rapid expansion of the scale of chicken industry and the continuous reduction of the cost of collecting chicken manure, the promotion of the chicken manure power generation industry will be successful. Through the PEST-SWOT matrix, this paper conducts a comprehensive analysis of combustion power generation and biogas power generation industry in terms of policies, economy, society and technology. China has paid more and more attention to the chicken manure power generation in-dustry, especially in terms of electricity price subsidies and external construction environment optimization. Moreover, China is in the stage of optimization and upgrading of industrial structure. The green power generation industry has a good opportunity for development, and CDM transaction revenue also provides important economic benefits.
Secondly, this article provides some solutions which are suitable for China. To begin with, the government should strengthen policy support by actively improving the subsidy mechanism and lowering the threshold of financing and credit. Through the establishment of targeted discharge standards of chicken manure power generation and the construction of raw material recovery systems and demonstration base, the standard of the industry can be achieved. Then, professionals are trained through school-enterprise cooperation. Also, to achieve the purpose of improving power generation efficiency, enterprises should focus on improving power generation technology and boiler treatment technology, such as the design of fermentation tank thermostatic system. Finally, according to the distribution of chicken manure resources in China, a reasonable enterprise strategy selection scheme is developed. These methods enable us to achieve the highest economic, social and environmental benefits.
Lastly, there are still some problems with chicken manure power generation. The problem of severe dust accumulation in the flue and short operating cycle has not been resolved. It is necessary to analyze the crystallization temperature of chicken manure in light of its chemical characteristics and to design-related technologies. In addition, the standards for the catalyst of chicken manure fermentation have not yet formed. Thus, it is urgent to make improvement in relevant technologies.