Demand chart in steel section should be reconsidered

[mabijkerk]

Background
In the Steel section, the chart "Energy demand of the steel sector" include a series called "Coal (transformation losses)".

Issue
It is very counterintuitive for users what the transformation losses of coal are. The query underlying the series is quite complicated, so the value of the series does not match with a value that users can recognize from the energy balance:

SUM(
    V(
        industry_final_demand_for_metal_steel_coal_gas,
        industry_final_demand_for_metal_steel_cokes,
        energy_chp_coal_gas,
        energy_power_combined_cycle_coal_gas,
        energy_methanol_production_coal_gas,
        "primary_demand - input_of_cokes - input_of_coal_gas"
    )
)

Solution
The original motivation to include the query is to make a fair comparison between the BF BOF route, which includes transformation in addition to final demand, with the other production routes, which only have final demand. If the chart were to show only final demand, the comparison would be unfair.

The question is therefore: what chart can we use that clearly shows the final demand, so that users can recognize those values from the energy balance, while also showing the transformation (which should also match the energy balance) to ensure a fair comparison between production routes.

A Sankey could work, but this might not be easy to read for everyone and it does not show the start and end year in one look, perhaps there are other chart options that are even better? I would be interested to hear your thoughts @kaskranenburgQ @kndehaan.

[kndehaan]

I don't have a better suggestion than agreeing with you that a Sankey might be the best solution to show flows going to transformation in a transparent way. Is the Sankey much more difficult to read / understand you think?

I agree with the downside that you can't see the start year situation. However, we might at some point want to improve our Sankey functionality to allow more flexibility, which could include switching between start year and end year view, and perhaps show values somehow in table or downloadable format.

Alternatively, I'm thinking of correcting the final demand values in the current chart somehow so the transformation losses are implicitly included. But that might worsen comparability with the energy balance...

[kaskranenburgQ]

I also feel that the best way to show the energy transformation and demand flows would be to show them in a Sankey chart.

I think that staying true to the categories in the Energy balance weighs up to the downside of not being able to show the present and future year at the same time.

[mabijkerk]

I had a quick check in with @louispt1 and the button that allows you to switch between hourly and annual views (see example below) could be easily expanded to also allow switching between start and future year - perhaps it even already exists. This would overcome the downside of the Sankey (and we could implement this feature for our current Sankeys as well as the import/export charts).

[kndehaan]

Follow ups from this discussion are:

• Only include final demand in the current "Energy demand of the steel sector" chart, so exclude Coal (transformation losses).
• Create a new chart (probably a Sankey) to show the final demand flows and flows to transformation in the steel sector.