Sriram Chandrasekhar
30th October 2006
CHBE 301 Project
Is Recycling a Suitable Option for Houston?
Recycling has been debated endlessly for many years now. There are two points of view
regarding this issue. The argument in support of recycling concerns the negative impact of waste
and emissions on our planet. The counter case is that costs undertaken to recycle are larger than
the revenue returns. Houston only recycles 5% of its plastic waste even though it is one of the
largest industrial cities in the country and there is growing concern about its part in the release of
greenhouse gases from industry and the waste system. This is a relevant matter because pollution
is at high levels and there must be efforts from every department to control this. This report aims
to present the current plastic recycling situation in Houston and assess if it is viable or suggest
changes if it is not.
(Superscript refers to calculation reference)
Recycle Rate (%)
0
5
40
(B.3)
(Sup)
(B.3)
Emissions (kg equiv CO2/day)
764.58
Total Cost ($/day)
493.07 (A.3)
472.72 (Sup)
330.24 (A.7)
3.22E+07 (A.2)
3.06E+07 (Sup)
1.95E+07 (A.6)
Total Energy Consumption (kJ/day)
746.49
458.83
(Sup = Supplement)
With a recycle rate of 40% the cost is $330.24/day. Applying this to Houston (recycle rate 5%),
the cost is $472.72. By recycling at 5%, Houston saves 4% in costs1. This is not a substantial
saving, but at 40% recycling, the savings would be 33% (A.7). The emissions and total energy
consumption values are read in the same manner as costs. The required rate of production of
plastic in Houston is 209,708 kg/day while the calculations use a scaled down equivalent of 100
kg/day 2.
1 Refer
to Supplement in calculations; 2 Refer to number 1 on source list page
Total Cost vs. Recycle Ratio
600
493.07
Cost ($/day)
500
472.72
400
330.24
300
200
100
0
0
5
10
15
20
25
30
35
40
45
Recycle Ratio (%)
Figure 1
Emission (kg CO2 /day)
Emissions vs. Recycle Ratio
1000
800
764.58
746.49
600
458.83
400
200
0
0
5
10
15
20
25
30
35
40
45
Recycle Ratio (%)
Figure 2
The general trend of the two figures shows that as the recycle rate increases, the total cost for
daily production decreases and the total emissions also decrease. The gradient of figure 1 shows
the decrease in cost per unit increase of the recycle rate. The gradient of figure 2 is the decrease
in emissions per unit increase of recycle rate. Personally, I agree with this correlation and the
ecologists’ view that recycling is worth its cost and process. The two vital elements of cost and
gas emissions both decrease the more you recycle. Decreasing costs will be favorable for all
parties since they can show higher revenues. Decreasing greenhouse gas emissions is also
favorable to all for environmental reasons.
The trend between the emissions and the cost can be deduced. It will be a strong, positive, linear
correlation. This shows that for Houston, the cost and the emissions can be kept low
simultaneously using an increased recycle rate. It is important to note that several assumptions
were made in the calculations. One assumption made is that only the production Energy
contributes emissions; incineration has not been taken into account. Actually, incineration
contributes largely to the outcome as 30% of waste in Houston is incinerated, emitting large
volumes of gases. The cost of raw material is assumed as the price of crude oil3. Methane, an
emission from landfill plastic waste, has been omitted. Together with other such assumptions,
results can alter greatly.
John Tierney’s article is based on figures that show recycling to be ineffective cost-wise. One
should realize that Tierney has also made assumptions in his work. He may have chosen specific
assumptions to induce his data to imitate his viewpoint. He states that a loss will always be
incurred by the faction attempting to recycle because the cost of plastic production is already at
its cheapest. The results above counter exactly that showing that by recycling, companies can
further reduce these cheap production costs. The main point of difference between the two
articles is that he does not deal with the full life cycle of the materials directly. He mainly looks
at the recycling section and makes his deductions from there. He also talks generally about waste
instead of specifically plastic. He claims that the trivial life cycle is the cheapest method but he
does not show us data that can be compared with the type of data that was collected for this
report.
The recommendation I would make to the City of Houston is to increase its recycle ratio to about
30-40%. By doing so, Houston will see the economic (33% savings A.7) and environmental (less
emissions) benefits. Whether the city is keener to reduce emissions or keener to reduce the costs
of the plastic life cycle, the solution is to recycle at a higher rate as both will be affected by this.
In conclusion, I believe that the current 5% recycle rate is too low a recycle rate as the money
saved is not enough incentive for large-scale process. 4% (2nd paragraph) is saved economically
and emissions are reduced by 2.4%4. These numbers are much too small to have a substantial
current effect. If we take factors such as incineration and methane emission into consideration
then there is a possibility that 5% will not be even a slightly profitable recycle rate. In order for
Houston to see the benefits of recycling on a large scale, the recycle rate must be increased.
3 Refer
to number 6 on the source list page; 4 calculation of this number: (764.58 – 746.49/764.58)x100%
Source List
1) Required Daily Production:
http://www.mindfully.org/Berkeley/Berkeley-Plastics-Task-Force.htm
Population of America and Houston :
https://www.cia.gov/cia/publications/factbook/geos/us.html
2) Production Coefficient :
http://www.mindfully.org/GE/Biotechnology-SustainableJun99.htm
3) Energy for Production from Raw Material
http://www.p2pays.org/ref/20/19893.htm
4) Energy for Disposal : http://www.mindfully.org/Plastic/Incineration-For-Energy.htm
5) Energy for Recycling : http://www.recoup.org/shop/product_documents/33.pdf
6) Cost of Raw material : from Homework 7 : $10.62 per 106 Btu
7) Cost of Collection and Disposal : http://www.p2pays.org/ref/24/23562.pdf
And http://www.mindfully.org/Berkeley/Berkeley-Plastics-Task-Force.htm
8) Cost of Material to be Recycled :
http://www.mindfully.org/Berkeley/Berkeley-Plastics-Task-Force.htm
9) 1 barrel crude oil in Mass: http://128.242.83.179/process/basics/oil_vw.htm
10) Emission information: http://www.eia.doe.gov/cneaf/electricity/epa/epat5p1.html
And : http://www.eia.doe.gov/cneaf/electricity/epa/epat1p1.html