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Where is the way out for 886 million tons of straw wastes?

2019-03-28 09:45:00 460

The term “straw” refers to the residues of crops discarded after harvesting the seeds, like stems, leaves, stalks, shells, alfalfa and ear. Rich in nitrogen, phosphorus, potassium, calcium, magnesium and organic matters, straw is a kind of multi-purpose renewable biological resource and a kind of new energy with the highest potential of development and utilization and has good economic, ecological and social benefits.

Current Status of Straw Waste Utilization

High Theoretical Resources and Low Utilization Rate of Energy in Power Generation

In recent years, with the increase of China's support for modern agriculture, the crop planting area has been increasing, and the number of straw has also been rising sharply. According to relevant survey data, the theoretical resource of straw in 2018 was expected to reach 886 million tons. Insufficient comprehensive utilization of such huge straw resource wastes will not only cause a series of environmental problems but also waste valuable biological resources.

 

12010-2018年中國稭稈理論資源量測算(單位:億噸)

Figure 1: Estimation of Theoretical Quantity of Straws Resources in China 2010-2018 (unit: 100 million tons)

 

To this end, in October 2018, the Ministry of Agriculture proposed at the Northeast Straw Treatment Action Field Exchange and Results Exhibition Meeting, “By 2020, the comprehensive utilization rate of straw in the country will reach more than 85% and issued the Action Plan for Agricultural and Rural Pollution Control War jointly with the Ministry of Ecology and Environment. According to data, at present, the comprehensive utilization rate of crop straw in China is close to 82%, 47.2% for fertilizer utilization, 17.99% for feeds and only 17.99% for power generation. It can be seen that the comprehensive utilization rate of crop straw in China is close to the national planning target, but the utilization rate of power generation is relatively low.

 

圖2:我國稭稈綜合利用情況(單位:%)

Figure 2: Comprehensive Utilization of Straws in China (unit: %)

未利用

Unutilized

原料化

Used as raw material

基料化

Used as base stock

能源化

Used as energy

飼料化

Used as feeds

肥料化

Used as fertilizer

Straw waste treatment market

Rapid Increase in Scale and Revenue Scale

Straw is an ideal green renewable resource. It was only used as a kind of rural living energy and livestock feed in the past. Now, it has entered into the modern industry and the energy field to rapidly improve comprehensive benefits. In 2017, the market size of China's straw waste treatment industry has reached RMB 331.7 billion, an increase of 3.5% compared with RMB 320.5 billion in 2011; The industry income reached RMB 188.40 billion, an increase of 0.8% year-on-year, and the industry's rate of return reached 56.8%; It is expected that the market size of straw waste treatment industry is to reach RMB 332.9 billion in 2018, and the scale of industry income is expected to continue to grow to RMB 189.09 billion.

 

3:2011-2018年中國稭稈垃圾處理行業受益規模(單位:億元)

Figure 3: Profits of China's Straw Waste Treatment Industry 2011-2018 (Unit: RMB 100 million)

4:2011-2018年中國稭稈垃圾處理市場規模(單位:億元)

Figure 4: Market Sizes of China's Straw Waste Treatment 2011-2018 (Unit: RMB 100 million)

The utilization rate of straw waste treatment in China has been continuously improved, and the relevant technical level has been continuously improved. In the future, the market scale and the industry income scale of the straw waste treatment industry are expected to achieve sustained growth in the scale of the industry market under the huge straw output.

Straw Comprehensive Utilization Experiences Tortuous Development Yingherui SAHP Technology Boosts Industrialization Process

 

Among various utilization methods of straw, straw feed has the highest income with net benefit reaches RMB 717 / ton; followed by straw power generation with net benefit of RMB 173 / ton; The net benefit of the straw biogas also exceeds RMB 100 / ton, RMB 125 / ton.

 

1:中國稭稈垃圾處理行業經濟效益分析(單位:元,元/噸)

Table 1: Analysis of Economic Benefits of China's Straw Waste Treatment Industry (unit: RMB, RMB / ton)

用途

Purpose

稭稈還田

Straw turnover

稭稈飼料

Straw feed

稭稈沼氣

Straw biogas

稭稈發電

Straw power generation

經濟效益分析(每噸)

Economic Benefit Analysis (Ton)

頓稭稈還田成本120元;收益110

Cost of per ton of straw turnover: RMB 120; income: RMB 110

收儲及後續加工等費用313元;飼料收益1030

The cost of storage and subsequent processing: RMB 313; feed income: RMB 1,030.

沼氣化過程成本245元;收益370

Cost of biogasification process: RMB 245; income: RMB 370.

發電過程成本307元;收益480

Cost of the power generation process: RMB 307; income: RMB 480.

-10/

RMB -10 / ton

717/

RMB 717 / ton

125/

RMB 125 / ton

173/

RMB 173 / ton

 

However, as an important means of clean utilization of straw and an important part of biomass power generation, the development of straw power generation industry in China is tortuous. From the perspective of variety distribution, China's straw varieties mainly include rice, wheat and corn. Among them, the proportion of corn stalks is the highest, reaching 32.5%, followed by straw and wheat straw.

 

5:中國農作物稭稈品種結構(單位:%

Figure 5: Chinese Crop Straw Variety Structure (unit: %)

其他稭稈

Other straw

薯類稭稈

Potato straw

豆類稭稈

Bean straw

油料作物稭稈

Oil crop straw

棉杆

Cotton rod

玉米稭稈

Corn straw

稻草

Rice straw

麥稭

Wheat straw

These raw materials all have problems of high dry matter content and low moisture content, resulting in fiber shrinkage and outstanding hydrophobicity of the crystal structure. This makes the technical difficulty of anaerobic degradation increase, thus the whole industry is limited by the high cost and slow progress. 

原料

Raw material

稻草

Rice straw

玉米杆

Corn rod

水分

Moisture

灰分

Ash

冷水抽出物

Cold water extract

熱水抽出物

Hot water extract

1%NaOH溶液抽出物

1% NaOH solution extract

蠟質

Waxiness

果膠質

Pectin

聚戎糖

Polysaccharide

纖維素

Cellulose

木質素

Lignin

水稻稭稈相對于玉米稭稈厭氧降解難度更高,主要原因:

It is more difficult for rice straw to have anaerobic degradation relative to corn straw. The main reasons are: 

1. 灰分含量高,主要為二氧化矽

1. High ash content, mainly silica;

2. 高蠟質含量,形成降解屏障

2. High wax content, forming a degradation barrier;

3. 纖維分子聚合度高、結晶度高

3. High degree of fiber molecules polymerization and high degree of crystallinity;

此外,CN比過高,極度缺乏微量元素

In addition, the C:N ratio is too high and trace elements are extremely deficient.

Under the impetus of national policies, specific to the characteristics of Chinese raw materials, Yingherui has cooperated with German advanced laboratories to complete a lot of experiments and researches and made constant improvements and perfection. It has developed the SAHP technology suitable for Chinese raw materials. The technology can obviously improve the hydrolytic acidification rate of raw materials to rapid the degradation rate of raw materials and boost the further improvement of the comprehensive utilization rate of the straw.