2/ Determining H, E and R

Obtaining data for hash and revenue is straightforward. I downloaded it from http://blockchain.com. The data for efficiency was more tricky to derive.  I was only able to find efficiency data in terms of energy i.e. TH/J, from https://ccaf.io/cbnsi/cbeci.  Converting from TH/J to TH/$ requires an assumption on the electricity costs of mining.

Fortunately, electricity price does not scale as much as energy efficiency of the mining rigs themselves, so it is not too critical a parameter for modeling the overall trend. Only a small correction is needed to account for the improved price of electricity secured by the miners over time. 

To this end, I propose two heuristic models for electricity price:

Model 1: Electricity price is fixed at 0.1 dollar per kWhr
Model 2: Electricity price is modeled as 0.24/sqrt(year-2009) dollars/kWhr*

*This model is only applicable for years >2010.

https://m.primal.net/KQfc.png  

 3/ Results and Discussion

The chart with the two models is shown below. It can be seen that even when assuming constant electricity price, the CoP price strongly correlates to the actual price over a long time period. However, at 10 cents per kWhr, it ends up sightly overestimating the absolute breakeven price (given by the price floor) during the more recent period. The varying price model corrects for this aspect. I used the later model in all the other charts in this post.

https://m.primal.net/KQfj.png