Dude...

Depreciation is capital rotting away without use. Which happens, in relative terms if it takes longer to get an energy source up and running. So it means co2 being spent on capital that cannot be fully used.

This is your comment.

Depreciation is a term used in accounting, economics and finance to spread the cost of an asset over the span of several years. In simple terms, it can be said that depreciati on is the reduction in the value of an asset or good due to usage, passage of time, wear and tear, technological outdating or obsolescence, depletion, inadequacy, rot, rust, decay or other such factors.

This is what this source says about depreciation.

Both of them are about money. Answer about money is in my 2nd comment.

But you also said depreciation is the environmental cost. If you are trying to say "How much carbon emission goes to waste" or "how much CO2 per kWh should be spent", then read this. Combined cycle gas turbines using natural gas has footprint of 488 gCO2eq/kWh while wind turbines have less than 100 gCO2eq/kWh at worst and around 10 gCO2eq/kWh at best. If this isn't what you are talking about, then what is?

So far you haven't shown us any documents about what you are talking about. Care to share any so we can understand better?