What can biomass materials do for "carbon peak and carbon neutrality"?

How to fight the battle to achieve "carbon peak and carbon neutrality"? Expanding renewable energy on a large scale is a breakthrough point.

As the most potential renewable energy, biomass energy has become the fourth largest energy after coal, oil and natural gas in China. Promoting the resource utilization of abundant reserves and green environmental protection biomass materials is an effective technical way to achieve "double carbon", and is also an important task of energy conservation, emission reduction and environmental protection in China, in line with the current needs of environmental protection, energy saving and low-carbon economy.

The field of application is constantly expanding

The biomass materials that can be used as resources mainly include plants that directly use photosynthesis to synthesize organic matter, such as crop straw, rice husk, corncob, waste wood and municipal waste. It also includes organic matter formed by indirect use of photosynthesis products, such as animal manure, crab shells, shrimp skins and shells, as well as photoautotrophic prokaryotic algae.

At present, the field of efficient comprehensive utilization of biomass is distributed in energy, ecological agriculture, environmental restoration, building materials and so on. Take applications in the energy sector, including biomass to ethanol and biomass power generation. The former is the most traditional way of efficient and comprehensive utilization of biomass. In 2018, the output of biomass fuel ethanol in China was about 3.4 million tons, which gradually became an important part of liquid fuel. With the strong support of state financial subsidies, the scale of power generation has grown rapidly, and biomass power generation has reached 111.1 billion KWH in 2019.

Taking the field of ecological agriculture as an example, straw returning to the field is an important link, and the focus is on the collection of straw and the nearby return to the field. Organic fertilizer prepared by composting and other fermentation methods can effectively improve the content of organic matter and soil fertility in farmland, improve the ecosystem function of crop roots, and achieve high-quality crop yield increase.

The future application fields of biomass materials are expanding in the direction of high-value utilization, such as modular building materials, biomass carbon fiber, biomass energy storage materials, biomass environmental remediation materials, etc.

In terms of modular building materials, several major molding industries involving biomass building materials, such as straw composite wallboard, restructured wood, new fiberboard, wood-plastic composite materials and bio-steel, will make important contributions to the modularization, environmental protection and energy saving of prefabricated passive houses in the construction industry.

In the field of biomass material return, some new application technologies are approaching practical application, such as biomass degradable mulching film, biochar direct return to field, etc., are being promoted on a small scale.

In terms of biomass carbon fiber, high-quality biomass based carbon fiber precursors are an important direction. The carbon content of lignin is higher than that of cellulose. It is a future research trend to prepare lignin carbon fiber by dry spray wet spinning carbonization and melt spinning to improve the hot melt and spinnability of lignin.

In terms of biomass energy storage, the use of biomass materials to prepare carbon materials, as a substitute for graphite in batteries, to improve the energy storage performance of lithium-ion batteries. In terms of biomass environmental remediation, biochar materials have the largest application prospects.

There is still a long way to go before it can be fully applied

However, there are still some problems in the full application of biomass materials. What kinds of biomass materials to develop, how to collect these biomass raw materials, how to use biomass materials on a large scale and in multiple ways, and how to find new methods for the preparation of biomass materials are all problems that need to be solved urgently.

There are many kinds of raw materials that can prepare biomass materials, and multiple factors such as reserves, cost, performance and process should be considered in screening. At present, the biomass widely used is straw, straw, sawdust, waste wood, manure, kitchen waste, waste packaging boxes and so on. Most of these raw materials have the characteristics of abundant reserves, high carbon content and simple preparation process.

Although the sources of biomass materials in China are extensive, the cultivated land is more dispersed and the degree of agricultural mechanization is low. Taking the large-scale straw development as an example, the straw production distribution is uneven across the country, and the collection of straw needs to consume a lot of manpower and material resources, and the resulting logistics cost is an important factor to be considered in the utilization of straw. Therefore, it is an inevitable trend for straw to be used in a large scale.