Introduction
Data centers are among the most energy-intensive facilities globally, with energy consumption increasing as digital infrastructure expands. In North America, data centers account for a significant portion of electricity usage, contributing to environmental concerns. At the same time, non-recyclable plastic waste is a growing challenge, with millions of tons generated annually. Innovative technologies like pyrolysis and gasification offer promising solutions to convert this waste into valuable energy, potentially powering data centers while addressing plastic pollution.
Non-Recyclable Plastic Waste: Energy Potential
Non-recyclable plastics—including mixed plastics, multilayer packaging, and contaminated plastics—contain a high calorific value, making them attractive as an energy source. Typical calorific values for municipal non-recyclable plastics are approximately:
- 35–42 MJ/kg (~35,000–42,000 MJ/ton)
- Equivalent to 9,700–11,700 kWh per ton of plastic waste
This energy content is comparable to or even higher than coal (~24 MJ/kg) and makes plastic waste suitable for conversion into electricity or liquid fuels through thermal processes.
Canada generates roughly 3.3 million metric tons of plastic waste annually, with a large fraction being non-recyclable. In the United States, annual plastic waste exceeds 35 million tons, with a significant portion unsuitable for mechanical recycling. Capturing the energy from these plastics could supply substantial amounts of electricity to high-demand facilities such as data centers.
Pyrolysis: Converting Plastic Waste into Liquid Fuel and Energy
Pyrolysis is a thermal decomposition process that breaks down plastics in the absence of oxygen, producing pyrolysis oil, gas, and char. The calorific content of non-recyclable plastic directly impacts the energy yield:
- Energy yield: ~70–80% of plastic calorific value can be converted into pyrolysis oil
- For 1 ton of plastic waste (~40,000 MJ), this produces roughly 28,000–32,000 MJ of usable energy
- Equivalent to ~7,800–8,900 kWh per ton of plastic waste
The resulting pyrolysis oil can be used in combined heat and power (CHP) systems to generate electricity for data centers. This process also significantly reduces landfill dependence and greenhouse gas emissions compared to conventional disposal.
Advantages of Pyrolysis:
- High energy recovery efficiency
- Carbon footprint reduction (approximately 50% lower CO₂ than incineration)
- Converts non-recyclable plastics into liquid fuels suitable for electricity generation
Gasification: Transforming Plastic Waste into Syngas
Gasification partially combusts plastic waste at high temperatures to produce syngas—a mixture of hydrogen (H₂), carbon monoxide (CO), and methane (CH₄). The energy yield is directly related to the calorific value of the feedstock:
- 1 ton of plastic waste (~40,000 MJ) can produce syngas with ~25,000–30,000 MJ usable energy
- Equivalent to 6,900–8,300 kWh per ton
- Syngas can be fed into gas turbines or engines to generate electricity continuously for data centers
Gasification offers several advantages:
- High conversion efficiency
- Versatile output: electricity, synthetic fuels, or chemical feedstocks
- Reduced emissions relative to direct combustion
Carbon Intensity and Environmental Benefits
Using non-recyclable plastic waste as an energy source also offers significant carbon intensity advantages compared to conventional electricity generation. When plastics are sent to landfills, they slowly degrade, emitting methane (CH₄)—a greenhouse gas roughly 28–34 times more potent than CO₂ over 100 years—contributing substantially to climate change. Converting these plastics into energy via pyrolysis or gasification avoids these methane emissions and recovers the embedded chemical energy.
On a lifecycle basis, generating electricity from plastic waste typically produces 0.4–0.6 kg CO₂-equivalent per kWh, depending on technology and feedstock treatment, which is lower than coal-fired electricity (~0.9–1.0 kg CO₂/kWh) and comparable to natural gas (~0.45 kg CO₂/kWh). Moreover, pyrolysis and gasification can be coupled with carbon capture or energy efficiency measures to further reduce net carbon emissions. Thus, using non-recyclable plastics for energy not only provides a renewable electricity source for data centers but also substantially mitigates greenhouse gas emissions relative to landfilling and fossil-fuel-based power generation.