生物乙烯生产技术简介（英文版）_24页

Summary of Bio-Ethylene Production

Core Content

Bio-ethylene is a renewable alternative to petrochemical ethylene, chemically identical and capable of using existing production infrastructure. It is primarily produced from bio-ethanol derived from biomass, which can be classified into three categories: sucrose, starchy, and ligno-cellulosic feedstocks. The potential for bio-ethylene is significant, but its widespread adoption depends on several factors, including biomass availability, production costs, and policy support.

Main Advantages of Bio-Ethylene

• Environmental benefits: Bio-ethylene can reduce greenhouse gas (GHG) emissions by up to 40% and save fossil energy by up to 60% compared to petrochemical ethylene.
• Energy security: It can reduce dependence on fossil fuel imports, especially in countries with abundant biomass resources.
• Local economic development: Bio-ethylene production stimulates local economies and creates employment opportunities.

Key Production Routes and Feedstocks

1. Sucrose-based bio-ethanol

• Feedstocks: Sugarcane, sugar beets, sweet sorghum.
• Production: Direct fermentation of sucrose by yeast.
• Current leaders: Brazil (sugarcane), India (sugarcane), China (sweet sorghum).
• Production costs: Around USD 1,200/t in Brazil and India, USD 1,650/t in China, and USD 2,000/t in the U.S. and EU.

2. Starchy-based bio-ethanol

• Feedstocks: Corn, wheat, barley.
• Production: Hydrolysis of starch to glucose, followed by fermentation.
• Current leader: United States (corn).
• Production costs: Higher than sucrose-based, with USD 2,000/t in the U.S. and USD 2,500/t in the EU.

3. Ligno-cellulosic bio-ethanol

• Feedstocks: Wood, straw, grasses.
• Production: More complex due to the chemical structure of lignocellulosic biomass; involves hydrolysis and fermentation or thermo-chemical processes.
• Potential: Offers no competition with food production and requires less arable land and water.
• Production costs: Estimated at USD 1,900-2,000/t in the U.S., and is expected to become more cost-effective in the future.

Conversion Process

• Bio-ethanol is converted to bio-ethylene using alumina or silica-alumina catalysts.
• One tonne of bio-ethylene requires 1.74 tonnes of bio-ethanol.
• Conversion yields of 99% with 97% selectivity to ethylene have been achieved.
• The process is endothermic, requiring 1.6 GJ per tonne of bio-ethylene.

Environmental Performance

• GHG emissions reduction:
  • Sugarcane-based bio-ethylene: Up to 120% reduction (including co-products like electricity and heat).
  • Corn-based bio-ethylene: Up to 45% reduction.
  • Ligno-cellulosic bio-ethylene: Up to 90% reduction.
• Land use: Sugarcane and corn require 0.48–0.47 ha/t, while ligno-cellulosic feedstocks need only 0.19 ha/t.
• Land use change (LUC): Can significantly increase GHG emissions if pristine land is converted for biomass cultivation. This highlights the importance of sustainable land use practices.

Market and Cost Analysis

• Current production capacity: Around 375 kt/yr, with 200 kt/yr used for bio-PE and the rest for bio-ethylene glycol (EG).
• Future projections: By 2035, bio-ethylene could meet 40–125% of global demand, depending on scenarios and co-products.
• Cost comparison:
  • Bio-ethylene costs: 1.1–2.3 times higher than petrochemical ethylene globally.
  • Petrochemical ethylene: Global average cost of USD 1,100/t, with some regions producing at USD 600/t.
• Ligno-cellulosic bio-ethylene: Expected to reduce the cost gap in the near future due to the use of 100% of biomass material.

Policy and Market Considerations

• Policy support is essential for bio-ethylene deployment, including incentives, carbon tax schemes, eco-labeling, and removal of import tariffs on bio-ethanol.
• Import duties in the EU (up to USD 310/t) act as a barrier to imported bio-ethanol for bio-ethylene production.
• Future oil prices will influence the competitiveness of bio-ethylene. The IEA projects oil prices in 2035 to be between USD 90–135 per barrel.
• Removing fossil fuel subsidies can help close the price gap between bio-ethylene and petrochemical ethylene.

Challenges and Barriers

• Competition for biomass: Industrial sectors like transportation, power generation, and chemicals may compete for biomass feedstock.
• Food vs. fuel: Using starchy or sucrose feedstocks for bio-ethylene may conflict with food production, leading to increased food prices.
• Technological challenges: Ligno-cellulosic biomass conversion is more complex and costly, requiring advanced hydrolysis and fermentation technologies.
• Uncertainty in feedstock prices: Linked to food demand and biofuel use, which can fluctuate significantly.

Conclusion

Bio-ethylene offers environmental and economic benefits, especially in regions with abundant and cheap biomass resources like Brazil and India. However, its widespread adoption depends on policy support, technological advancements, and stable feedstock prices. The future of bio-ethylene is promising, but overcoming barriers related to land use, costs, and market competition will be critical for its growth.