Different CH4 pipeline costs that are not 'guesstimates'

Currently, the CH4 pipeline value comes from a wikipedia article.
It could be updated to the estimates given in this paper https://doi.org/10.1016/j.isci.2021.103495 for different pipeline parameters.

Proposed entries (by @euronion)

- CH4 (g) pipeline mini -> 12 in
- CH4 (g) pipeline small -> 20 in
- CH4 (g) pipeline medium -> 36 in
- CH4 (g) pipeline large -> 48 in