[TheAntipodean]

I believe it refers to Estonia selling off excess carbon credits to Mitsubishi under a mid-long term agreement.

Mitsubishi needs to purchase these credits to stay within regulatory requirements pertaining to emittance of CO2 probably in the EU. Given that Mitsubishi is a large manufacturer they probably produce above their alloted quota of CO2 and therefore must purchase credits from someone/some organization (in this case Estonia) that does not use their full quota.

Estonia is using the income from this agreement to fund the fast-charging network.

This is all educated speculation as to its meaning. Apologies for no links to references to back up my understanding. I am sure a quick search will provide more information.