This article is full of it. The writer don't understand bitcoin and is writing articles?? Journalism these days
![Undecided](https://bitcointalk.org/Smileys/default/undecided.gif)
Increase in the number of bitcoins and bitcoin transactions is progressively increasing mining difficulty.
Difficulty is based on network hashrate, number of bitcoin and transactions do not affect difficulty.
When it comes to costs, electricity from renewable sources is cheaper compared to other conventional sources.
How about initial upfront investment and maintenance? Electricity from renewable sources are not practical for mining.