Life-cycle analysis of fuels from post-use non-recycled plastics

- NRP-derived ULSD fuel is less GHG-intensive on a life-cycle basis than petroleum fuel.
- NRP-derived ULSD fuel is less Water-intensive on a life-cycle basis than petroleum fuel.
- Fuel gas treatment is the key factor that influences LCA results for NRP-derived ULSD.
- GHG reduction depends on the efficiency of the fuel gas combustion technology.
- GHG emissions results vary by region, depending on the electricity grid generation mix.
- PTF technology is a viable waste management option that can reduce GHG emissions and landfill waste.

Plastic-to-fuel (PTF) technology uses pyrolysis to convert plastic waste-especially non-recycled plastics (NRP)-into ultra-low sulfur diesel (ULSD) fuel. To assess the potential energy and environmental benefits associated with PTF technology, we calculated the energy, water consumption, and greenhouse gas emissions of NRP-derived ULSD and compared the results to those metrics for conventional ULSD fuel. For these analyses, we used the Greenhouse gases, Regulated Emissions and Energy use in Transportation (GREET®) model. Five companies provided pyrolysis process product yields and material and energy consumption data. Co-products of the process included char and fuel gas. Char can be landfilled, which, per the company responses, is the most common practice for this co-product, or it may be sold as an energy product. Fuel gas can be combusted to internally generate process heat and electricity. Sensitivity analyses investigated the influence of co-product handling methodology, product yield, electric grid composition, and assumed efficiency of char combustion technology on life-cycle greenhouse gas emissions. The sensitivity analysis indicates that the GHG emissions would likely be reduced up to 14% when it is compared to conventional ULSD, depending on the co-product treatment method used. NRP-derived ULSD fuel could therefore be considered at a minimum carbon neutral with the potential to offer a modest GHG reduction. Furthermore, this waste-derived fuel had 58% lower water consumption and up to 96% lower fossil fuel consumption than conventional ULSD fuel in the base case. In addition to the comparison of PTF fuels with conventional transportation fuels, we also compare the results with alternative scenarios for managing NRP including power generation and landfilling in the United States.