Abstract
The development and utilization of biomass energy based on the thermochemical conversion of crop biomass to produce hydrogen are of great significance for promoting China’s ecological civilization construction, energy revolution, and low-carbon economic development. Henan province is one of the largest agricultural and pasturage provinces in China. Based on the analysis of the status and trends of Henan’s biomass energy (BE) development, this paper summarizes the present status of the construction of ecological civilization (CEC) and the factors restricting its development. Challenges in developing biomass energy are analyzed systematically, and strategies and key technical directions for future biomass energy development are discussed. Finally, the paper presents countermeasures and suggestions for CEC based on the development of BE, which will vigorously promote the development and utilization of BE and the process of CEC. This research provides a reference for the further development of BE and CEC in the future.
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Research on the Development Status of Biomass Energy Serving the Construction of Ecological Civilization: A Case Study in Henan Province, China
Xueqin Li,a,b Shuhua Yang,c Zhiwei Wang,d,e Taoli Huhe,b Yantao Yang,b Peng Liu,b Sheng Huang,a Youqing Wu,a,* and Tingzhou Lei b,*
The development and utilization of biomass energy based on the thermochemical conversion of crop biomass to produce hydrogen are of great significance for promoting China’s ecological civilization construction, energy revolution, and low-carbon economic development. Henan province is one of the largest agricultural and pasturage provinces in China. Based on the analysis of the status and trends of Henan’s biomass energy (BE) development, this paper summarizes the present status of the construction of ecological civilization (CEC) and the factors restricting its development. Challenges in developing biomass energy are analyzed systematically, and strategies and key technical directions for future biomass energy development are discussed. Finally, the paper presents countermeasures and suggestions for CEC based on the development of BE, which will vigorously promote the development and utilization of BE and the process of CEC. This research provides a reference for the further development of BE and CEC in the future.
DOI: 10.15376/biores.18.1.465-483
Keywords: Construction of ecological civilization; Biomass energy; Hydrogen production; Low carbon
Contact information: a: Department of Chemical Engineering for Energy Resources, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China; b: National-Local Joint Engineering Research Center of Biomass Refining and High-Quality Utilization, Institute of Urban and Rural Mining, Changzhou University, Jiangsu 213164, China; c: Henan Academy of Science, Zhengzhou, 450008, China; d: School of Environmental Engineering, Henan University of Technology, Zhengzhou, Henan 450001, China; e: Institute for Carbon Neutrality, Henan University of Technology, Zhengzhou, Henan 450001, China;
* Corresponding authors: wyq@ecust.edu.cn (Y. Wu), China_newenergy@163.com (T. Lei)
GRAPHICAL ABSTRACT
INTRODUCTION
Ecological civilization is a Chinese concept also known as eco-civilization (Zhang et al. 2018). It refers to cultural and ethical reform with the basic purpose of harmonious symbiosis, virtuous circles, all-around development, and sustainable prosperity between humans and nature (Zeng and Wu 2013; Yao and Xie 2016). The goal underlying the construction of ecological civilization (CEC) is to raise this form to the height of green development (Magdoff 2011; Wei et al. 2011), and for future generations to “enjoy the cool” and “plant trees” (Liu 2008; Lu et al. 2015), just as “prosperity of ecology leads to the prosperity of civilization, and the decline of ecological leads to the decline of civilization” (Qi et al. 2016). Therefore, the CEC has become a key strategy for addressing China’s resource and environmental issues, which is important to achieve sustainable development (International Paper Board Industry group 2014). As an important part of renewable energy, biomass energy is considered to be an important way to achieve carbon emission reduction (Kaygusuz 2002). China has a vast territory, rich in product resources, and has a rich supply of raw materials for biomass energy (Tian et al. 2021). According to statistics (Ma et al. 2019; Shi 2017), the number of straw resources that may be sourced in China is 1.45 × 108 t, which is equivalent to 7.25 × 107 tce (conversion coefficient is 0.5 kgce/kg). The annual output of available forestry tending and the wood cutting residue is about 1.95 × 108 t, equivalent to 9.75 × 107 tce (conversion coefficient is 0.5 kgce/kg). The annual treatment capacity of municipal solid waste is 1.21 × 108 t, which is equivalent to 1.21 × 108 tce (the conversion coefficient is 0.2714 kgce/kg). Coupled with livestock manure and industrial wastewater, the total amount of biomass resources in China is about 3.26 × 108 tce. If these biomass resources can be maximized for development and utilization, it will effectively solve the current problems such as resource shortage and environmental pollution. At present, the utilization technology of biomass energy has gradually matured, which is mainly divided into four categories (Yang et al. 2019): biomass combustion technology, bioconversion technology, physical and chemical conversion technology, and thermochemical conversion technology (Fig. 1).
Fig. 1. The classification of biomass energy utilization technologies
However, the diversified development and utilization of biomass energy are realized through biomass thermochemical conversion technology. including agricultural and forestry biomass heat-electricity co-production, waste incineration power generation, biomass molding fuel, biological natural gas, biological liquid fuel, biological hydrogen production, biomass carbon-based materials, and other forms of utilization. Take the highly efficient, clean, and widely used pyrolysis/gasification technology as an example, it is the process of transforming biomass into solids, liquids, and gases by increasing temperature under the condition of isolating air or a small amount of air. But biomass tar is produced in this process, and the condensation accumulation of biomass tar at low temperatures will block pipelines and cause energy loss (Zainal 2011). Therefore, how to improve the conversion and utilization efficiency of biomass, especially the yield and quality of gases such as H2 and CH4 produced during pyrolysis/gasification, and how to remove biomass tar have become hot issues in the field of biomass energy.
Henan is one of the main agricultural provinces and food-producing regions in China, where agricultural residue is available in large quantities. With the construction goal of a “prosperous Henan province, beautiful Henan Province, safety Henan Province, and civilized Henan” (Gao 1999; Eryao 2014), the Henan Province has put forward a series of policies to promote the CEC since the 12th five-year Plan period (Ranganathan and Kumar 2014; Xie 2015; Chun 2015), and the construction of beautiful Henan Province is completely in line with the major deployment of the CEC (Yu et al. 2014; Wen et al. 2015).
Kennedy et al. (2016) pointed out that China’s situation, as an ecological civilization country, is based on the infrastructure policy and path study of China’s 2050 high proportion of renewable energy development. Yao et al. (2010) studied aquatic and soil environmental problems associated with the construction of an agricultural ecological civilization in Henan Province and suggested that such problems are key issues impeding sustainable agricultural development. Wang et al. (2015) noted that Henan Province faces severe internal environmental problems and a complex external environment, with limited policy support. Therefore, the CEC must be realized through scientific assessment of the carrying capacity and resources provided by the environment, vigorous promotion of ecological culture, and the CEC performance evaluation index system. Based on the current index system of the CEC in China, a framework CEC index system was released that characterized the economic development and environmental resources of Henan Province (Wu et al. 2015; Bangshan 2016). Li et al. (2018) considered the development of BE in Henan Province from the perspective of CEC and proposed countermeasures and suggestions. Li et al. (2019) analyzed the temporal dynamics and correlates of the ecological civilization level of Henan Province from 2005 to 2015, and showed that the overall level of ecological civilization was gradually improving. However, Henan Province is in the stage of accelerated development of urbanization and industrialization. It is facing the double task of rapid development and environmental protection, the situation of energy structure in which coal is the main source of energy and a large number of pollutants, which are discharged directly, has not been changed fundamentally. Problems such as low utilization efficiency of renewable energy, a large number of waste emissions, serious environmental pollution, and so on are still prominent (Zuo 2015). At the same time, this development path of high carbon and high pollution also violates the basic goal and concept of the CEC (Ma 2013; Jia et al. 2014). Thus, a low-carbon economy is a basic economic condition required for the CEC (Liu and Feng 2011), and its core lies in the saving of energy, the reduction of pollutant emissions, and the innovation of industrial structure (Chen and Wang 2011).
Strategically, traditional energy sources must be replaced by gradually increasing the proportion of alternative energy sources. As a large agricultural province, Henan Province, as one of the largest agricultural provinces in China, is the core area of China’s national grain yield, which accounts for 1/10 of China’s total, and its wheat yield exceeds 1/4 at present. Agriculture, especially grain yield, plays an important role in China. Agricultural residues can be converted to biofuels, which include liquid fuels, briquettes, and gaseous fuels (Wang et al. 2019). However, open burning of agricultural residues has resulted in huge CO2 emissions and large of CO, PM2.5, and black carbon releases in China, especially for three major crops (rice, wheat, corn) (Zhang et al. 2015; Sun et al. 2016). Therefore, China’s low-carbon economic development and the CEC should follow a path based on BE, with Henan Province playing a critical role (Zhang 2017).
Based on the problems described above and the regional characteristics of Henan Province, this paper explores the present situation, existing problems of the CEC and terrestrial environments, and various factors influencing the CEC. The relationship between BE development and CEC is discussed from a dialectical perspective, and a development plan is proposed using low-carbon BE as the major component of CEC, making full use of the development of BE innovation technologies to support the CEC. This plan provides a new path for green low-carbon development.
Current Status and Existing Problems of Ecological Civilization
Henan Province is an important region supporting energy production in China. In 2018, Henan Province produced 108 million tons of raw coal, 1.96 million tons of crude oil, and 200 million m3 of natural gas. The total installed capacity for electric power has reached 86.8 million kW, while biomass power generation has reached 19.2 million kW, accounting for 22.2% of total installed power capacity, which is important for the continued development and utilization of biomass energy (Zhou et al. 2015). Henan Province is an important transportation hub and a center for the flow of people, products, and information. In the process of China’s CEC, Henan Province has the advantage of abundant resources and is in a superior geographical position in the economic and social development of China. It is the key area for the construction and development of ecological civilization. Henan Province is the only province in China that spans the four major basins of the Yangtze, Huaihe, Yellow, and Haihe rivers, so its topography and distribution of water resources are a microcosm of China. The pollution situation of water resources from 2007 to 2018 was reported in the ecological and environmental status bulletin of Henan Province in 2018. In recent years, these basins have maintained a large proportion of class III water resources. Industrial sewage, domestic sewage, and non-point-source pollution from farmland have caused the deterioration of the quality of surface water resources.
According to the GB 3095-2012 (Ke 2012), the factors that influence the quality of urban air environments are particulate matter (PM2.5), respirable particulate matter (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3). The concentrations of various factors of different cities are shown in Fig. 2. The annual average concentrations of PM2.5 and PM10 in 18 cities exceed the second-level standard, and the city has the highest annual average concentration is Anyang. The annual mean concentration of SO2 in Anyang and Jiyuan reach the second-level standard, and the annual mean concentration of SO2 in other cities reached the first-level standard. The annual mean concentration of NO2 is above the second-level standard, and the concentration of O3 and the 95th percentile of CO reached the second-level standard. Throughout the province, the ambient air quality level of Jiaozuo and Anyang is medium pollution; the ambient air quality level of other cities is light pollution. Therefore, the primary pollutant of Henan Province is PM2.5, and the atmospheric quality requires improvement. In addition, with the continuous development of economy, and the improvement of people’s life quality, the quality of the ecological environment has become the focus of people’s attention (An 2016).
Fig. 2. Urban ambient air quality in various regions of Henan Province in 2018
Backward development of renewable energy
Coal is the most important primary energy in China and the largest source of greenhouse gas and air pollutant emissions (Chang et al. 2016). The energy supply is mainly coal in Henan Province, and the proportion of oil, natural gas, and hydropower is small. According to Fig. 3, the total amount of energy production in Henan Province has increased year by year from 1978 to 2013. When the total energy production reached the maximum of 174.4 million tons of standard coal, the total amount of energy production began to decline gradually from 2013 to 2017, and the total amount of energy production was 100.9 million tons of standard coal by 2017. Coal accounts for the largest proportion of total energy production, while the production of natural gas accounts for only 0.38%. Especially, renewable energy accounted for 6.6% of the total, and the consumption of BE only accounted for 1.9% of the consumption of total primary energy and 7.6% of the consumption of renewable energy. The level of development and utilization of biomass energy is extremely backward, and the production of a large amount of coal and crude oil deteriorates the environmental quality. It is urgent to develop the utilization of biomass energy and increase its proportion in the structure of renewable energy is the key to solving environmental problems.
Fig. 4. Proportion of total energy consumption Fig. 3. Proportions of total energy consumption
The energy consumption in Henan Province is shown in Fig. 4. As shown, the total energy consumption has gradually increased, and the structure of energy consumption is dominated by coal, which was over 80% before 2012 and showed a slight decrease in the period 2013 to 2017, mainly due to a shortage of energy resources. In 2017, the consumption of coal, oil, natural gas, and hydropower accounted for 73.3%, 14.1%, 5.9%, and 5.8% of the total energy, respectively, illustrates the irrationality of the energy structure. Coal combustion generates a large amount of pollution. Therefore, it is important to optimize energy structures by utilizing renewable energy represented by BE.
High pollution discharge and serious environmental pollution
The pollution of water resources, the discharges and treatment of wastewater, exhaust gas, and solid waste in different years are shown in Fig. 5. In 2017, the discharge of wastewater was 4.1 billion tons, the discharge of COD was 4.3 million tons for the whole province, the discharge of COD in municipal domestic sewage was 3.9 million tons, and the emission levels of major pollutants based on all indicators decreased, compared with 2015 was not obvious. The pollution problems of surface water and groundwater, and the safety of drinking water safety are becoming increasingly serious.
Fig. 5. Production and utilization of wastewater, toxic Emissions, and industrial solid wastes
Fig. 6. Agricultural energy resources and the consumption of major materials for (a) consumption of chemical fertilizer by 100%, irrigated water supply, diesel oil used for agriculture, and (b) pesticide use, plastic film use for agriculture
As shown in Fig. 6, in 2015, the maximum level of agricultural chemical fertilizer application was 71.6 million tons, and the pesticide application was 1.29 million tons. In 2016, the use maximum amount of agricultural plastic film and agricultural diesel oil was 1.63 and 1.1 million tons. While the use of fertilizers and pesticides can increase grain production, most of them remain in the air, soil, and rivers. Thus, the consumption of energy resources and pollutant emissions continue to increase, and the carrying capacity of the ecosystem faces severe challenges.
Analysis of Causes of the Problem
Guided by the 13th 5-Year Plan of Energy Development, the consumption of non-fossil energy in China will increase to more than 15% by 2020, the consumption of natural gas should reach 10%, and the proportion of coal consumption should be reduced to less than 58% (Ren 2016). Henan Province has changed from a major coal export province to a net coal transfer province, facing a serious gradual depletion of resources and a preliminary crisis of reserve resources. At the same time, it is a province with large agriculture and population, lacks wind energy resources, and cannot have land to develop solar energy resources to ensure food production. Therefore, in the process of CEC, the development of BE will be an inevitable trend.
Low utilization of biomass resources
The total output of grain for Henan Province in 2017 reached 65.3 million tons, the total output of cotton reached 4.4 million tons, and the total output of oil plants reached 5.9 million tons. These crops can produce up to 100 million tons of straw; if the straw which was used as feed is taken out, the remaining straw will reach 50 million tons, which can be used as energy, and the output of forestry waste is more than 10 million tons. Thus, the total amount of rural energy production reaches more than 80 million tons of standard coal equivalent (He 2014). The resource advantages of rural energy remain underdeveloped.
Fig. 7. Total amount of straw burned in some cities
One of the outstanding characteristics of utilization of biomass resources is to adjust measures to local conditions and to carry out efficient development according to the distribution of local renewable resources (Xu et al. 2013). Biomass straw, which constitutes a resource of low energy density and wide dispersion, is not suitable for collection and storage, which increases the collection cost (Wang 2016). With the rapid economic development, the widespread use of commercial energy leads to the direct combustion of a large number of biomasses; which not only causes the loss of a potential energy resource but also seriously pollutes the rural environment. The cities with serious straw burning in Henan Province are shown in Fig. 7. The phenomenon of biomass straw burning is very serious. Therefore, it is urgent to develop and make rational use of agricultural and forestry wastes, which is an important way to solve the ecological environment.
Limited development and utilization of BE
The effective forms of BE utilization mainly include biomass direct combustion power generation, biomass pyrolysis/gasification, and biogas. The unstable supply of biomass straw increases the operating burden of power generation enterprises, which makes most biomass power generation enterprises unreliable. Biomass biogas technology is a complex microbiological process, the goal of which is to obtain clean combustible gas by anaerobic fermentation (Achinas et al. 2017). Due to the limitations of many conditions, projections for the development of biogas technology are not optimistic. Figure 8 shows that the establishment of household biogas digesters and biogas projects is not obvious, and the number of domestic sewage purification biogas digesters is decreasing. Biomass pyrolysis/gasification technology can transform biomass into solid (biochar), liquid (bio-oil), and main gas (H2, CH4), effectively realizing the resource utilization of biomass energy (Hu et al. 2017; Milne et al. 1998). However, tar is a challenge in the application of the technology. Tar produced during pyrolysis and gasification will block pipes after condensation, resulting in equipment damage, energy loss, and environmental problems (Dayton 2002; Park et al. 2018).
Fig. 8. Status of biogas digesters in recent years
Analysis of the Present Situation of BE Development
Henan Province is extremely rich in biomass resources. It is of great significance that abandoned biomass resources can be in full use for effectively alleviating the shortage of energy resources and protecting the ecological environment. This will be conducive to the CEC. Therefore, the analysis of the present situation of BE development is of great significance to exploring a new way for the CEC. Therefore, according to the Statistical Yearbook of Henan Province, the output of agricultural and forestry products in Henan Province from 2010 to 2017 are shown in Figs. 9 and 10. Biomass resource potential can be expressed through the index of biomass resource reserves (Wang et al. 2015). The ratio of grass to grain is the key to estimating the reserves of biomass resources. Because the growth conditions and technical conditions are different in different years, the ratio of grain to grass is constantly changing. Therefore, by referring to the ratio of grain to grass in Henan Province (Table 1) and the conversion coefficient of domestic forestry residues (Table 2), the reserves of biomass resources from 2010 to 2016 in Henan Province were estimated (Fig. 11). The reserves of biomass resource were 171.6 million tons in 2016.
Fig. 9. Outputs of major agricultural products Fig. 10. Major forestry product outputs
Fig. 11. Potential biomass energy resources (10,000 tons)
Table 1. Grain-to-Grass Ratios of Major Crops
Table 2. Conversion Coefficients of Forestry Residues
Analysis of the Present Situation of Development and Utilization of BE
The technologies for the development and utilization of BE in Henan Province include biomass briquetting fuel, liquid fuel, gas fuel, and biomass power generation.
Technology of biomass power generation
At present, the scale power generation technology of biomass in Henan Province is basically at the forefront, and the common scales of generator sets are 12, 15, and 25 MW (Zaitao et al. 2011). An example is shown in Fig. 12. The project utilized 35 million tons of agricultural and forestry waste such as crop straws, peanut shells, and bark from the surrounding area. The project invested 220 million, which generates more than 80 million of income for farmers, and an average annual power generation of 210 million kWh. This design involves a rural industrial chain employing 1060 people and would reduce carbon emissions by 22 million tons of CO2. Therefore, biomass power generation promotes renewable energy and has benefits for people’s livelihood.
Fig. 12. A biomass power plant in Henan Province for (a) Biomass collection, (b) Biomass power generation (outside view), and (c) Biomass power generation(inside view)
Technology of biomass liquid fuel
Henan Province is the leading producer of cellulosic ethanol in China (Fig. 13). Henan Province has filled the gap in the straw ethanol industry and created a new system of straw ethanol production in accordance with national conditions. Dong et al. (2008) analyzed the energy and energy budgets of a typical wheat plantation/alcohol distillery system in Henan Province, showing that bioethanol from food crops is not a sustainable source of fuel. The industrialization of cellulosic ethanol has been developed to provide a new method of producing biological liquid fuel from non-food raw materials, which is an important method for the replacement of fossil fuels.
Fig. 13. Process of ethanol production from biomass fuel in Henan Tianguan Company
Technology of biomass briquetting fuel
An enterprise in Henan Province has designed four pilot briquetting fuel plants using corn stalks as the main raw material, and has reached a stable annual production base of 50,000 tons of briquetting fuel from crop straw. The production line is shown in Fig. 14. The development of this project provides a net income of more than 4 million per year and an income of more than 10 million for local farmers and provides employment for more than 300 people. This facility can replace 25,000 tons of standard coal per year, reduce greenhouse gas emissions by 55,000 tons, and sulfur dioxide emissions by 500 tons. It strongly promotes the large-scale utilization of BE and is of great significance for CEC. In summary, the development prospect of BE industrial of Henan Province has broad development prospects and obvious economic, social, and environmental benefits, which can improve the quality of the water environment, atmospheric environment, and ecological environment, promote regional development and increase farmers’ income. the improvement of these aspects will be conducive to the CEC.