unit conversion from mass/volume to standard energy

[RLiNREL]

This issue is to implement the unit conversion from unconventional energy units (kg, lb, kgal, etc.) to standard energy units (kwh, mmbtu, etc.)

[RLiNREL]

Move the comment from #211 to here. Need help from @koay9f

1. Could you provide some guidance on the energy conversion from mass (kg, lb), volume liquid (kgal), volume gas (kscf) to common energy unit (kwh/MMBtu/J)?
2. Also, should we consider using different notations to distinguish these units from standard mass and volume measurements? e.g. kg-energy, kgal-energy?

[RLiNREL]

Move Kristina's comment from #211

If the "collection" or price unit is in mass or volume, then you need to ask users for the "Higher Heating Value". For Natural Gas we can provide this 0.001029 MMBTU/scf and do conversions for any other gas volume or energy unit.
We can also probably have a list of common materials in a dropdown for other fuels with HHV. VERIFI has all this. but for now, a field with HHV should be enough.