Introduction - Mathematics and Statistics for the Environment - page 37

1.7.14 t ons oF W aste r eCyCled i nstead oF l andFilled
To develop the conversion factor for recycling rather than landfilling waste, emission factors from
the USEPA's Waste Reduction Model (WARM) were used (USEPA, 2013a). These emission factors
were developed following a life-cycle assessment methodology using estimation techniques devel-
oped for national inventories of greenhouse gas emissions. According to WARM, the net emission
reduction from recycling mixed recyclables (e.g., paper, metals, plastics), compared with a baseline
in which the materials are landfilled, is 0.73 metric tons of carbon equivalent per short ton. This
factor was then converted to metric tons of carbon dioxide equivalent by multiplying by 44/12, the
molecular weight ratio of carbon dioxide to carbon.

1.7.14.1 Calculation
Due to rounding, performing the calculation given in the equation below may not return the exact
results show.

(0.73 metric tons of carbon equivalent per ton) × (44 g CO 2 per 12 g C) = 2.67 metric tons
CO 2 equivalent per ton of waste recycled instead of landfilled.

1.7.15 C oal -F ired p oWer p lant e missions For 1 y ear
In 2009, a total of 457 power plants used coal to generate at least 95% of their electricity (USEPA,
2012a). These plants emitted 1,614,625,638.1 metric tons of CO 2 in 2009. Carbon dioxide emissions
per power plant were calculated by dividing the total emissions from power plants whose primary
source of fuel was coal by the number of power plants.

1.7.15.1 Calculation
Due to rounding, performing the calculations given in the equations below may not return the
exact results shown.

(1,614,625,638.1 metric tons of CO 2 ) × (1/457 power plants) = 3,533,098 metric tons CO 2 /
power plant.

1.8 UNITS OF DERIVATIVES AND INTEGRALS
If x = meters and t = seconds, the units of these quantities.

2

2

dx
dt

dx
dt

dx
dt

t

= ∫

2

; ; ; y x dt

2

t 1

are m s -1 , m s -2 , m 2 s -2 , and m 2 s, resp e ct ively.

REFERENCES AND RECOMMENDED READING
FHWA (2010). Highway Statistics 2010 . Office of Highway Policy Information, Federal Highway
Administration, U.S. Department of Transportation, Washington, DC (http://www.fhwa.dot.gov/policy-
information/statistics/2010/index.cfm).
Hancock, K. and Sreekanth, A. (2001). Conversion of weight of freight to number of railcars. Transportation
Research Record , 1768, 1-10.
IPCC. (2006). 2006 IPCC Guidelines for National Green House Gas Inventories . Intergovernmental Panel on
Climate Change, Geneva, Switzerland.
Smith, J.L., Heath, L., and Nichols, M. (2010). U.S. Forest Carbon Calculation Tool User's Guide: Forestland
Carbon Stocks and Net Annual Stock Change , General Technical Report NRS-13 revised. U.S. Department
of Agriculture Forest Service, Northern Research Station, St. Paul, MN.