Green Alternative to PVC Scott Gibb Advisor: Eric Beckman Department of Chemical and Petroleum Engineering.

Green Alternative to PVC

Scott GibbAdvisor: Eric Beckman

Department of Chemical and Petroleum Engineering

Research Goals

• To design a feasible alternative material for replacing PVC piping systems.

• Develop a process for product design that incorporates a multiple metric system.

• Screen potential alternative materials for product design using life cycle assessment.

• Eventually prepare and test sample of proposed alternative materials.

Current/Previous Replacements

• Polybutylene– PB had problems with oxygen permeation and

deterioration of the acetal fittings resulting in leaks that requires entire homes/building to be replumbed.

• Borealis– They make polypropylene resins for pipe.– The mechanical properties of Borealis’ pipe resins

do not compare to that of PVC.– PP is more expensive than PVC.

• Copper– Copper is expensive and requires a skilled laborer to

install. (Still the standard for water supply piping)

Why Replace PVC?

• Chlorine requires ~3000 kWh/ton to produce.• PVC uses ~1/3 of the world’s chlorine.• Some chlorine production still involves the

use of mercury or asbestos.• PVC’s monomer, vinylchloride monomer

(VCM), and precursor, ethylene dichloride (EDC), are known carcinogens.

• Many environmental pollutants/toxicants are chlorine based.

Chlorine Tree

• ~1/3 of Cl2 goes to PVC.

• ~1/2 of PVC goes to piping/tubing.

Chlorine Production

• Chlorine is produced from a brine solution (salt water) in electrolytic cells.

• NaCl + H2O

• ½Cl2 + NaOH + ½H2

• There are three types of cells:– Mercury Cells– Diaphragms Cells– Membrane Cells

PVC Production

NaCl + H2O Cl2 + NaOH

Cl ClPVC+

HCl

Cl

+ 0.5O2 – H2O

How to Replace PVC for Piping

• For an alternative material to replace PVC piping, the alternative material must have some advantage over PVC.

• Commonly the only advantage consumers care about is upfront cost.

• Using only upfront cost in decision making will not likely result in a better product.

• It is possible to have a product that is better and cheaper if multiple metrics are assessed during the design of the product.

• To achieve this off the shelf alternatives may not work.

Metrics

• Functional metric.– Can the alternative material perform the same

function as PVC piping?– Does the alternative material have similar, higher

or lower values for mechanical strength properties?

• Economic metric.– Is the alternative material similar priced or cheaper

to purchase, install, and maintain than PVC?

• Environmental metric.– Is the alternative material more sustainable and

have a lower environmental impact than PVC?

Alternative Comparison

• Properties of off the shelf alternative materials and two composites.

Cw

($/kg)(MPa)

(g/cm3)

t(in)

m(kg/ft)

Cl,p

($/ft)

PVC 1.1 51.3 1.4 0.034272 0.042935 0.048909

Cw

($/kg)(MPa)

(g/cm3)

t(in)

m(kg/ft)

Cl,p

($/ft)

PVC 1.1 51.3 1.4 0.034272 0.042935 0.048909

ABS 2.2 37.9 1.04 0.04639 0.042815 0.098356

PE 1.72 25.2 0.91 0.069768 0.055437 0.101193

PP 1.54 33.8 0.94 0.052017 0.043224 0.069777

Cw

($/kg)(MPa)

(g/cm3)

t(in)

m(kg/ft)

Cl,p

($/ft)

PVC 1.1 51.3 1.4 0.034272 0.042935 0.048909

ABS 2.2 37.9 1.04 0.04639 0.042815 0.098356

PE 1.72 25.2 0.91 0.069768 0.055437 0.101193

PP 1.54 33.8 0.94 0.052017 0.043224 0.069777

PP-Glass 1.57 60 1.106 0.029303 0.029099 0.04703

PP-CR 1.21 52 1.164 0.033811 0.035228 0.044132

Off the Shelf Comparison

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ABS pipe

HDPE pipe

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Comparison of TRACI Impacts

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Imp

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PP-CR Pipe

PP-Glass Pipe

PP Pipe

PVC Pipe

Life Cycle Assessment

• GaBi LCA software is used to develop LCAs of PVC as well as potential alternatives.

Areas of Overlap with other Disciplines

• Mechanical/Material Engineering– Material properties

• Civil/Environmental Engineering– LCA– Sustainable design

• Industrial Engineering– System design/optimization

Questions?