Try to figure out how buying green tags from BEF compares in environmental benefit to doing your own PV system.
BEF Bonneville Environemetal Foundation
https://www.greentagsusa.org/GreenTags/index.cfm
BEF FAQ's:
https://www.greentagsusa.org/GreenTags/faq.cfm
A 500 KWH per month customer is trying to decide whether to build a PV rig to satisfy his full demand, or buy green tags:
CO2 generated by 500KWH per month of Montana mix power is:
(500 KWH/mo)(1.5 lb/KWH) = 750 lb /mo or 9000 lb/yr
PV system:
Per PVWatts it takes a 4.48 KW peak power PV rig to make 6000 KWH/year
This would cost about:
(4480 pkwatts)($9/w) = $40,320 one time cost
Should really include some yearly maintenance, but ignore for now.
--> above ignores the value of the generated electriicty!!
BEF tags:
At $2 per 100 KWH /mo, it takes 5 tags = $10 /mo, or $120 per year
If I were to invest the 40,320 in a 5% CD, I could earn $2016, or enough to offset (2016/120) = 16.8 times as much CO2 using green tags as with doing my own PV rig? Is this true?
Questions:
If I do my own PV rig, I know its going to be built, and that it will be preventing the generation of 9000 lbs of CO2 per year for many years. If I buy an equivalent amount of green tags, how do I know how much CO2 these will actually eliminate?
There calculator gives an answer, but how is it calculated?