Split CCS policy lever into two sector-specific, subscripted CCS levers

[jrissman]

Currently, the CCS policy is in the "Cross-Sector" category and is subscripted by sector, with only Industry Sector and Electricity Sector available. The lever is specified as a percentage of the CO2 capture potential achieved, with that capture potential specified (as a share of CO2 emissions) for each industry and each power plant type in ccs/CPPbES and css/CPPbI.

The problem with this approach is: suppose you want to use a 100% clean energy standard to retire all the non-peaker fossil plants, and use CCS to capture the CO2 from the peaker plants. When building a wedge diagram, the model will test the clean energy standard disabled. The CCS lever setting is specified as a percentage of potential achieved, and that potential is now much higher, because the clean energy standard is not retiring the fossil plants. So the CCS policy will ratchet up and capture all the CO2 from all the fossil plants. This is wrong - we want the CCS to remain at essentially the same level when testing disabled policy groups for the wedge diagram.

We must not change the CCS lever to specifying a quantity of CCS achieved (like a share of potential amount specified in input data). This is how it used to work, and it caused problems. This was fixed in issue #52. Read that issue description for more details on why that approach does not work.

Instead, the new, desired approach is to break the CCS policy into two levers: Industry Sector CCS and Electricity Sector CCS. Each of these levers is moved to its respective sector, leaving the Cross-Sector section. The Electricity Sector CCS lever is subscripted by plant type, so that CCS can be applied only to peaker plants, not to all plant types, as part of the decarbonization scenario described above. The Industry Sector CCS lever is subscripted by industry, which avoids a similar problem that can arise when building a wedge diagram for the industry sector (for example, if you are shifting industry to 100% clean energy and trying to use the CCS policy to sequester the process CO2 emissions from the cement sector).

[jrissman]

Completed in f2f8307

[jrissman]

Though this feature works, it doesn't solve the wedge diagram issue for industry, because now all the industry categories have non-trivial CO2 process emissions. Therefore, we cannot simply target the industries that have CO2 process emissions with this lever. We'll need to further subscript the industry version of this policy lever by "energy-related emissions" and "process emissions"

[jrissman]

Completed