Ask HN: How to model numerical energy data in Wolfram Alpha -style?

I'm working on a dataset that contains energy supply and consumption data. This is just a hobby and idea is to do visualizations and simple moodelling based on this data.

Are there good material how to model relationship and units in this kind of data in database level. A bit in a similar vein as Wolfram Alpha structures data?

For example, I'm collecting data like Total Primary Energy Supply (TPES), Electricity Generation and structuring it by year, by country, by source (Coal, Oil, ...), by sector etc.

Also, in different information sources, units might differ. I'd like to input data to database in the original units (with a link to the information source) and be able to automatically convert them when doing queries.

There is a probably name and terminology for this kind of databases, but as I'm not familiar with the field, I have hard time finding good material by googling.