1. 1 Basic overview of straw power generation
Straw is a good clean and renewable energy. The calorific value of every two tons of straw is equivalent to one ton of standard coal, and its average sulfur content is only 3.8‰, while the average sulfur content of coal is about 1%. In the process of biomass recovery, CO2 emitted and CO2 absorbed in the process of biomass regeneration reach carbon balance, which has the function of zero CO2 emission and has a very broad market prospect.
Straw power generation is one of the most important forms of optimal utilization of straw. With the promulgation of "Renewable Energy Law" and "Trial Measures for the Management of Price and Cost Allocation of Renewable Energy Power Generation", straw power generation has attracted much attention, and the current straw power generation shows a rapid growth trend. Governments at all levels also regard straw power generation as a bright spot in attracting investment, and the concept of straw power generation has also begun to be active in the capital market. Straw power generation is beneficial to the country and the people, and people pay more and more attention to it.
On June 5438+February 10, 2007, the first self-developed soft straw power generation project in China was completed and put into operation in Huai 'an, Jiangsu. The project was successfully put into production, which initiated the soft straw power generation in China.
People who have been to the countryside in autumn must have seen the scene of burning waste straw all over the mountain. Although the choking smell reveals the harvest information, it is more about air pollution.
It is understood that China's annual crop straw output is about 700 million tons. At present, except some of these crop straws are used for cooking and heating in rural areas, feed processing, straw returning to fields and paper making, about half of them are abandoned and burned, and the combustion efficiency is only 15%, which has become the chief culprit of air pollution in rural areas.
Using straw to generate electricity not only improves the comprehensive utilization rate of straw and provides a lot of clean energy, but also reduces air pollution and increases farmers' income. How does straw generate electricity? How to change from pollution source to new energy source? In this regard, the reporter interviewed Professor Li Shujun, the chief Chinese expert in the field of agricultural products processing in Sino-US agricultural science and technology cooperation.
How to generate electricity from straw?
Straw power generation is a form of biomass power generation. The pretreated straw is directly burned in a high-temperature and high-pressure boiler to generate heat energy, which is then further converted into electric energy. Straw is a good clean and renewable energy. The calorific value of every two tons of straw is equivalent to one ton of standard coal, and its average sulfur content is only 3.8‰, while the average sulfur content of coal is about 1%.
Biomass energy refers to the energy that plant chlorophyll converts solar energy into chemical energy and stores it in biomass. Biomass power generation is a technology to generate electricity by burning biomass or converting biomass into combustible gas. There are mainly three ways of direct combustion power generation, mixed combustion power generation and gasification power generation.
Can straw generate electricity?
According to reports, there are currently three main types of straw used for direct-fired power generation. The first kind is yellow straw, mainly corn straw, wheat straw, rice straw and other vegetation crop straws. It has the characteristics of large volume, light weight and low density. In order to meet the heating value of boiler combustion and ensure the feeding amount in unit time, it is necessary to bundle it into a specified volume and weight and then transport it to the furnace for combustion; There is also a kind of gray straw, which is mainly woody plants with high density such as cotton straw, soybean straw, branches and sawdust. It needs to be crushed and treated before being transported to the furnace for combustion; The third type is to compress the straw into a certain volume of particles to improve the combustion value. In processing, the operation of yellow grass is the most difficult.
"On the one hand, 5 1% of agricultural output is waste, which is what we usually call straw, which has not been fully utilized for a long time; On the other hand, China still needs to import major grains such as soybeans, corn, rice and wheat, and the National Development and Reform Commission has explicitly banned the use of grain as biomass raw materials. In this way, we began to think on straw. If it can be fully utilized, it is almost equivalent to creating another agriculture. " Professor Li Shujun's high evaluation made the reporter re-understand the straw that has been classified as "waste".
Where is the difficulty of straw power generation?
Professor Li Shujun told reporters that straw power generation is an emerging industry that has just started in the past year or two. At present, the best straw power generation in the world is the Nordic countries lacking coal resources, especially Finland. China is also in the world's leading level, surpassing Northern Europe, but the Nordic countries mainly use fast-growing forests to cut into sawdust to generate electricity, which is far from the national conditions of China, which mainly uses agricultural wastes. Therefore, it is very difficult for China to engage in independent research and development in completely unfamiliar fields, both in terms of biological chain and technology chain.
"As long as the straw can be sent to the boiler, the technology of complete combustion and waste treatment is relatively mature, but how to transport the straw from the field to the factory workshop seems easy to store, transport, package and pretreat, but it puts high demands on agricultural machinery. Working in rugged field, forklift trucks not only need large lifting force, but also adapt to various working conditions caused by different soils. In addition, the original harvester directly crushed straw and covered it on the land, but now it is necessary to collect straw, so that not only the harvester but also the seeder will be changed accordingly, and the' no-tillage mulching seeder' widely used in the past should also be adjusted appropriately. It can be said that the use of straw to generate electricity has brought about major changes in the field of machinery and even agricultural production methods. "
The reporter also learned that different regions and crops have different requirements for machinery, and the horsepower of tractors needs to change accordingly. For example, corn baler, which is a blank and difficult, has been basically developed in China.
"The logistics system designed by the Electric Power Design Institute and the requirements of straw transportation pretreatment still need to be run-in." Professor Li Shujun added.
What is the value of straw power generation?
According to the relevant person in charge of Guoneng Biological Co., Ltd., the first straw power plant in China, the current purchase price of about 1 kg straw can generate electricity 1 kWh and 1 ton straw is around 200 yuan, and the price of "straw electricity" is 0.25 yuan higher than the standard price of coal-fired electricity. As a green environmental protection project, this achievement is gratifying.
Professor Li Shujun also said that the highest price of straw can reach about half of the price of grain. If all the straws can be purchased, farmers can increase their income by about 50%. "Many local farmers spontaneously organized farmers' associations and cooperative groups. Even some simple manipulators are used to tie straws. As long as there is a market, the enthusiasm of farmers is still very high. "
How does straw power generation affect the environment?
As the daily energy consumption of farmers, the combustion efficiency of straw is only about 15%, while the direct-fired biomass power generation boiler can improve the thermal efficiency to over 90%, greatly reducing the waste discharge. Because the fuel is crop straw, biomass power generation can not only provide clean energy, but also turn waste into treasure.
It is understood that the total amount of biomass energy resources that can be developed in China is about 500 million tons of standard coal every year in the near future, and about 654.38 billion tons of standard coal every year in the long term. If all kinds of energy forests are planted in barren hills and slopes, the long-term biomass energy resources can approach 65.438+0.5 billion tons of standard coal every year. If China's biomass energy utilization reaches 500 million tons of standard coal, it can solve about 20% of the current national energy consumption every year, reduce carbon dioxide emissions by nearly 350 million tons, and reduce sulfur dioxide, nitrogen oxides and soot emissions by nearly 25 million tons.
The straw is full of treasures?
In addition to direct-fired power generation, the comprehensive utilization of straw has also extended to an infinitely broad field. According to reports, straw can be fermented alone or mixed with livestock manure to produce biogas, which can be directly gasified into combustible "straw gas" through a gasifier, or mixed with coal and compressed into granular fuel "green coal". Recently, straw and additives are mixed to make bio-based materials, which can be used to make non-toxic furniture, decorative boards, flower pots, fully degradable disposable tableware, fully degradable plastic films and so on. Professor Li Shujun also specifically mentioned the importance of making liquid fuel from straw. "This technology has just matured at home and abroad, and the United States has entered the' pilot' stage, which means that it can basically be used, but it has not yet been promoted. Our country has also invested a lot of energy, which can be said to be the strategic focus we pursue in straw utilization. "