Plastics : Energy Consumption in the Plastic Industry

Energy consumption in the plastic industry refers to the total amount of power used throughout the entire lifecycle of plastic products, from raw material extraction and processing to manufacturing, transportation, use, and disposal or recycling. This includes electricity, natural gas, petroleum, and other energy sources used to power machinery, heat processes, and transport materials.

Raw material extraction and production:

• Converting fossil fuels (primarily petroleum and natural gas) into plastic resins requires significant energy
• Approximately 4-8% of global oil production goes toward plastics manufacturing
• Petrochemical cracking and polymerization processes are particularly energy-intensive

Petrochemical cracking is a process that breaks down large, complex hydrocarbon molecules from crude oil or natural gas into smaller, more useful molecules by applying high heat and pressure.
Polymerization is the opposite process where small molecules (monomers) are chemically joined together to form long chains or networks called polymers. This is like connecting many small building blocks to create a long chain or network structure.

Manufacturing processes:

• Extrusion: melting plastic pellets and forcing them through dies to create shapes (4-7 kWh/kg)
• Injection molding: injecting molten plastic into molds (3-6 kWh/kg)
• Blow molding: creating hollow objects like bottles (4-8 kWh/kg)
• Thermoforming: heating plastic sheets and forming them over molds (2-5 kWh/kg)
• Compression molding: pressing heated material in open molds (3-5 kWh/kg)

Operational energy requirements:

• Process heating: 45-60% of energy consumption
• Motor drives for machinery: 20-30% of energy consumption
• Facility operations (HVAC, lighting): 10-15% of energy consumption
• Compressed air systems: 5-10% of energy consumption

Transportation energy:

• Moving raw materials to manufacturing facilities
• Distributing finished products to markets
• Collecting waste and recycling materials

End-of-life processing:

• Recycling: mechanical (1-3 kWh/kg) versus chemical recycling (varies widely)
• Incineration for energy recovery: can offset some energy usage
• Embodied energy loss: plastics in landfills represent lost energy that could be recovered through recycling or waste-to-energy processes
• Potential energy recovery from landfills: some modern landfills capture methane for electricity generation

The plastics industry's total energy footprint accounts for approximately 4-8% of global annual oil and gas production when factoring in both feedstock (raw input materials used to produce plastic resins. These are primarily petroleum-based chemicals) and energy requirements. Efforts to reduce this energy consumption include improved process efficiency, increased use of recycled materials (which typically require 40-70% less energy than virgin materials), adoption of renewable energy sources, and development of bioplastics derived from plant-based sources rather than fossil fuels.