Sources of emissions
Waste disposal
Waste from DUSP emits 32 MTCDE as a result of recycling, landfill and incineration. This figure was scaled from Institute-wide data. Waste leaving MIT is either recycled or disposed of as Municipal Solid Waste. Several assumptions are made about the relative proportions of waste that are incinerated or landfilled, and the impact of methane capture and energy recovery.
The waste stream is not broken down into food, packaging or other waste types. Data on waste and recycling should be recorded at the level of individual buildings to make it easier to quantify the total originating from DUSP, and to monitor progress. MIT's recycling program could restart composting of food wastes. A waste audit of DUSP's trash could identify potential locations for more recycling or minimization of waste entering the department.
Methodology for quantifying waste GHG emissions
No data are available on the waste streams emerging from individual departments or buildings. The most up to date information on trash is available from MIT Facilities for 2005, which identifies total institute wide output as 5,800 tons, of which 3,288 tons (61%) were recycled 1. 1. The MIT Recycling Facts page reports that 324 tons is equivalent to 6% of all Institute waste, so this number has been scaled accordingly. Assuming that the production of waste is evenly distributed between all MIT staff, students and faculty, DUSP's waste output is proportional to its relative size, 1.26%. Therefore, the total waste output from DUSP is 67.8 tons, of which 41.3 tons were recycled 2. 2. DUSP has 263 members, using staff and faculty data from the department website, and a count of student from the 2006 handbook. The MIT Facts handbook lists a total headcount of 20,953 people in the Institute. This is equivalent to a quarter ton per person in the department.
The non-recycled waste becomes Municipal Solid Waste (MSW) and is either landfilled or incinerated. Assuming the New England distribution of MSW 3. 3. EPA Waste Facts Report, 2005, 20% is incinerated and the rest sent to landfill . For DUSP, this means 5.3 tons are incinerated and 21.2 landfilled. As identified by Groodie4 4. Groodie, T A, A methodology for assessing MIT's energy used and greenhouse gas emissions. ME SM thesis 2004. Available via DSpace., there are differences in emissions resulting from the different disposal methods. Incineration with energy recovery will result in low emissions since the energy produced is used to create electricity, thereby offsetting addition generation requirements. For landfill, the options are unmitigated landfill with high emissions (comparison index value: 100), landfill with methane recovery (index: 28), or landfill with methane recovery used for electricity generation (index: 12). The transport, storage and treatment of recycled waste will also result in emissions.
For this audit, the following emissions scenario for recycled and MSW is assumed5 5. Figures in this paragraph are derived from 2003 data provided by Groodie and scaled to 2005 DUSP waste volume. The emissions from recycling are not covered by Groodie so equivalent emissions to landfil with methane recovery are assumed.:
- 67.8 tons of waste produced, 41.3 tons recycled, 26.5 treated as MSW.
- Dealing with 41.3 tons of recycled waste produces an equivalent amount of greenhouse gas as if the waste had been landfilled with methane recovery: 11.56 MTCDE
- Incinerating 20% of MSW (5.3 tons) with energy recovery: 0.42 MTCDE
- Landfilling 80% of MSW (21.2 tons) with no methane recovery: 21.63 MTCDE
- Total: 32 MTCDE emitted
Limitations
No information was readily available on waste volume by building. The current data includes all waste MIT-wide, including dining waste and construction debris, so the per capita estimate used to generate DUSP's own waste footprint is probably high. DUSP might also be better or worse at recycling than the institute average.
The estimates for how MSW is treated are probably inaccurate. It should be possible to establish the type of landfill treatment given to MIT waste, and the resulting emissions that occur.
The emissions resulting from or avoided by recycling should be quantified, this information could be broken down by material type (paper, glass, plastics etc)
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