The cost of the plastic cover for coverage installed in year 60 and carried through to year 150 for 1 sq. mi. is as follows:

Plastic $140,000 x 9 replacements = $1,260,000

Installation $ 35,000 x 9 replacements = $ 315,000

Monitoring

Labor $ 4,375 x 90 years = $ 393,750

Equipment $ 4,375 x 3 replacements = $ 13,125

Maintenance

Labor $ 30,000 x 0.35 x 90 years = $ 945,000

Equipment $ 30,000 x 0.65 x 3 replacements = $ 58,500

Total $2,985,375

$2,985,375 x 67,000 sq. mi. = $200 billion for all year 60 coverage at the end of year 150. Divided by the tons of carbon equivalent emissions offset of 19.5 billion gives $10.3/ton.

The cost of the plastic cover for coverage installed in year 30 and carried through to year 150 for 1 sq. mi. is as follows:

Plastic $140,000 x 12 replacements = $1,680,000

Installation $ 35,000 x 12 replacements = $ 420,000

Monitoring

Labor $ 4,375 x 120 years = $ 525,500

Equipment $ 4,375 x 12 replacements = $ 52,500

Maintenance

Labor $ 30,000 x 0.35 x 120 years = $1,260,000

Equipment $ 30,000 x 0.65 x 4 replacements = $ 78,000

Total $4,016,000

$4,171,500 x 67,000 sq. mi. = $269 billion for all year 30 coverage at the end of year 150. Divided by the tons of carbon equivalent emissions offset of 19.5 billion gives $13.8/ton.