Waste Stream Diversion Table: Difference between revisions

DRAFT - UNDER CONSTRUCTION Humboldt State University’s Paper Towel Life Cycle Analysis Brief

Executive Summary

Land-filled waste emits Greenhouse Gases (GHG’s) and transporting waste to a landfill consumes considerable energy. In 2000, Humboldt County’s landfill was capped and closed; consequently, landfill-bound waste is trucked an average of 187 miles (374 miles round trip) to either the Dry Creek Landfill in White City, Oregon or the Anderson Landfill outside of Redding, California. If Humboldt State University (HSU) were to divert 37% of our paper towel waste to Humboldt Waste Management Authority’s (HWMA) proposed anaerobic biodigester, the amount of energy generated from that paper towel waste would offset the energy consumed in transporting the remaining paper towel waste to a landfill. This diversion would reduce HSU’s paper towel waste stream carbon footprint by 27% or 9 metric tons of carbon annually.

Background

The waste we produce consumes energy and emits various GHG's after the items are used for their designed purpose. Paper towel waste has been identified as a section of the HSU waste stream that, with minimal effort, can create large reductions in energy and GHG’s. Twice a week HWMA picks up the landfill-bound waste and disposes of it in one of two locations a significant distance away. The landfill waste continues to emit various GHG's as it breaks down. By diverting paper towel waste, HSU can reduce their number of necessary waste shipments and overall landfill waste. Reducing the volume of waste sent to the landfill sites not only reduces the energy and emissions associated with the transportation of waste, but also reduces HSU's GHG emissions at the waste disposal location. Anaerobic digestion of the diverted paper towel waste reduces energy and emissions by significantly lowering the distance the waste travels and results in power generation, offsetting energy and emissions generated by HSU's other landfill waste as well as producing a high quality soil amendment that could be sold for a return.

Methodology

• Landfill emissions were determined for paper towel waste.
• Transportation energy consumption and emissions were calculated from fuel use.
• Number of trips estimated from volume of paper towel waste.
• Calculated power generation based on the energy content of methane captured from anaerobic digestion.
• Determined embedded energy and emissions of additional required materials to divert paper towel waste based on alternatives.�

Transportation The assumption was made that embedded energy from the transportation of waste was contained primarily in the form of fuel, with the other energies being distributed across all HWMA waste and making up a very small amount. Since only the embodied chemical energy and carbon cost of the fuel was used to estimate transportation energy, this value is likely to underestimate the total energy used during the transportation of the estimated 17 tons of annual HSU paper towel waste per year which occupies a space of approximately 9200 cu ft and consume an average of 51 gallons of diesel per round trip#.

Landfill A student analysis determined a paper towel moisture content of 63% and HSU paper towel waste landfill emissions were estimated to be 50 Nm3 methane per dry metric ton#. It is likely to be greater than 50 Nm3, as a result of, the short half life or the quick and complete decomposition experienced by paper towel relative to average landfill waste.

Anaerobic Digester While energy recovery is possible from landfill waste emissions, anaerobic digestion “generates CH4 more quickly and captures it more completely than in a landfill environment, and thus, from a GHG perspective, offers a potentially attractive waste management option (USEPA, 2006).” This increased rate of methane generation and elimination of carbon sequestration results in 200 Nm3 of methane per dry metric ton allowing for power generation and GHG offsets due to the reduced CO2 generation from the production of power than the off gassing of methane in landfills.

Results

Depending on the alternative selected to process and consolidate the paper towel waste, Option B: a mandated 37% diversion, would redirect enough paper towel waste to the anaerobic digester to offset the energy required to transport the remaining 63% to the waste disposal locations. This would make the paper towel waste stream energy neutral, while reducing the amount of CO2e gasses emitted by almost 9 metric tons per year.