How to formulate a combined farming and breeding energy-saving solution?
With the continuous improvement of people’s living standards, the diet structure has been greatly adjusted, the demand for meat is increasing, and the pig farming industry has a good market prospect.
The huge demand for pig meat drives people to constantly rebuild and expand pig farms. A large number of pig farms are accompanied by a large amount of waste gas, waste water and feces, which has caused a certain degree of pollution to the environment. Therefore, the construction of standardized pig factories and the treatment and utilization of waste generated by pig factories can protect the environment and save energy. Improving the economic benefits of pig plants has become an urgent need for people.
1、The circular economy principle of combined farming and breeding
The technical solution of planting and breeding combined with economical and efficient biogas internal combustion cogeneration has been widely used in farms, and is a mature engineering solution. This program organically combines the crops, farms and the nearby energy supply stations. The waste and agricultural and forestry waste generated by the farm can be fermented to produce biogas, waste residue and waste liquid. The biogas generator set can burn the biogas to provide electricity and valuable hot water (or steam), and the electricity can illuminate the pig farm. This not only solves the problem of environmental pollution in pig farms, but also uses resources to achieve energy regeneration, saves energy, and improves the economic benefits and efficiency of pig farms.
FIG. 1. Schematic diagram of breeding and breeding combined with circular economy in typical pig plants
2、1000 pig breeding ,farming combined with heat and power generation soulution demonstration
The project is located in Songjiang District, Shanghai. The scale of the pig plant is 1000 pigs. The pig plant and the surrounding farming industry are organically integrated to create an ecological recycling system. Biogas is used for cooking , power generation, lighting; Biogas residue and biogas liquid as fertilizer. This can not only save fertilizer and water, but also reduce environmental pollution, and solve the problem of livestock manure and urine treatment .
Considering the actual situation and energy consumption of the end user, the project is planned to be divided into two parts: livestock and biomass waste treatment system and biogas cogeneration system. The core power equipment is selected as PowerLink brand ACG30S-BG biogas generator set, and biogas pretreatment equipment is selected as CDB50-BG. Figure 2 is the main equipment diagram of the project site.
Figure 2. ACG30S-BG biogas generator set
- Project system process flow
FIG. 3 shows the process flow chart of the project combining planting and breeding. Organic waste such as pig manure and straw from surrounding pig farms and plantations are sent to anaerobic fermentation equipment to ferment and produce biogas, biogas residue and biogas liquid. After the biogas is treated by pretreatment equipment, it is sent to biogas generator set for combustion, which can generate electricity and heat. The heat energy generated can be used to keep the anaerobic tank warm and can also be used as domestic hot water, and the biogas residue produced is used to make organic fertilizer for sale, and the biogas liquid can be used directly to fertilize crops around, which is a complete efficient recycling of organic matter, reflecting the perfect harmony between man and nature.
FIG. 3. Circular economy process flow chart of planting and breeding combined
- Analysis of economy,energy saving and emission reduction
Economic society, every activity of human beings pay attention to economic benefits, for the cogeneration part of this case, we also do an economic analysis. See Table 1.
Table 1. Economic benefit analysis of an ACG30S-BG unit
|Actual output power
|Annual running time
|Equipment maintenance cost
|Total hourly revenue of
|Economic and benefit analysis
|Gross annual income
|Ten thousand yuan/year
|Annual net income
|Ten thousand yuan/year
The total annual power generation income of a single ACG30S-BG unit is 135,000 yuan, and the annual net income is 126,000 yuan after deducting equipment maintenance costs. Considering the requirements of project working conditions, thermal income is not calculated here.
Similarly, let’s simply calculate the energy saving and emission reduction benefits of using biogas cogeneration technology in pig farms. Table 2 shows the annual power generation and annual emission reduction values calculated according to the matching cogeneration units of pig plants of different sizes. The data show that the adoption of planting and breeding combined with cogeneration has certain emission reduction and environmental protection effects.
Table 2. Calculation table of energy saving and emission reduction benefits of pig plants of different sizes.
|Calculation table of gas production and energy saving and emission reduction benefit of waste material in pig farm
|According to the calculation, each pig can produce 0.2m³ biogas per day, the low calorific value is 5.5kW/m³, the CHP electrical efficiency is 38%, and the annual operating time is 6000h
|Number of pigs kept (Unit)
|Daily gas capacity
|Annual energy output（MWe）
|Annual saving of standard coal
|Annual CO2 reduction (tons)
3、Significant advantages of combining planting and breeding
The model of planting and breeding combined obviously has certain economic benefits and energy-saving and emission-reduction effects, and matching cogeneration technology has more significant advantages in efficiency.
- Economic value
The farm of 1000 pigs and the nearby plantation, the waste such as manure and agricultural straw are fermented to produce usable biogas, generate electricity to obtain electricity, and the annual net income of power generation can reach 126,000 yuan; The remaining biogas residue is fermented to produce organic fertilizer, which can be sold with a certain income, and the biogas liquid can be used to fertilize nearby planting parks and return fields, reducing the production cost of fertilizers and other agricultural materials.
- Energy conservation and emission reduction
The pig farm of 1000 pigs is measured by 6,000 hours per year, and the biogas cogeneration technology is used to save 40 tons of standard coal and reduce 100 tons of carbon dioxide per year.
- Environmental protection
Plantation waste and pig farm water flushing manure and other odors, occupy a lot of land and pollute the environment, planting and breeding combined with a circular economy cogeneration model can ensure that residents’ living environment is improved, and air quality is guaranteed.