airmosaic-ai

CCS Configuration In Depth

How CCS (Carbon Capture and Storage) is represented in GCAM-China, the relevant configuration files, and common pitfalls when enabling CCS in scenarios.

File	Purpose
`CCS_shrwt_CHINA.xml`	Sets technology share-weights for CCS vs non-CCS technologies at province level
`Cstorage_CHINA.xml`	Defines carbon storage resource supply curves
`no_offshore_ccs.xml`	Sets offshore CCS share weights to zero (effectively disables offshore CCS)
`ccs_supply_lowest.xml`	Sets CCS storage supply to lowest cost tier
`turn_off_ccs.xml`	Broader CCS disabling file that affects all CCS globally

File Relationships

Cstorage_CHINA.xml      -> Defines storage resource AVAILABILITY
CCS_shrwt_CHINA.xml     -> Defines CCS technology SHARE WEIGHTS
no_offshore_ccs.xml     -> Zeroes out offshore storage share weights
ccs_supply_lowest.xml   -> Overrides storage supply curve to lowest cost

CCS_shrwt_CHINA.xml and Cstorage_CHINA.xml serve different purposes and can be loaded independently. CCS_shrwt_CHINA.xml affects which technologies are chosen; Cstorage_CHINA.xml affects the cost of storage once CCS is chosen.

Common Pitfall: CCS_shrwt_CHINA.xml and N Fertilizer

The Problem

Loading CCS_shrwt_CHINA.xml as-is into a GCAM-China DPEC configuration often fails with:

No Discrete Choice function set in AH, N fertilizer

Root Cause

CCS_shrwt_CHINA.xml references N fertilizer as the sector name for fertilizer CCS weights. But GCAM-China v8 uses ammonia as the internal sector name (defined by gcamchina.FERT_NAME <- "ammonia" in constants.R). The generated Fert_CHINA.xml creates provinces with supplysector name="ammonia", not N fertilizer.

The path mismatch means BaseX finds no existing node at AH / N fertilizer, and the model initialization fails because it cannot add share weights to a nonexistent sector.

Resolution Options

Option A: Adapt the CCS XML — Copy CCS_shrwt_CHINA.xml to a new file, replace all N fertilizer with ammonia, and load that instead.

Option B: Remove fertilizer blocks — Remove all N fertilizer blocks from the copied file and test with cement/electricity/liquids CCS only.

Option C: Check GitHub source — The official zgcamchina_L2999.ccs_shrwt_CHINA.R on GitHub may have been updated to use ammonia. Regenerate XML from updated R script.

Loading Order

When adding CCS components, the order in <ScenarioComponents> matters:

<!-- Correct order -->
<ScenarioComponents>
  <Value name="detailed_industry">../input/gcamdata/xml/detailed_industry_CHINA.xml</Value>
  <Value name="cement">../input/gcamdata/xml/cement_CHINA.xml</Value>
  <Value name="fertilizer">../input/gcamdata/xml/Fert_CHINA.xml</Value>
  <!-- CCS can only be added AFTER base sector definitions -->
  <Value name="ccs_shareweights">../input/gcamdata/xml/CCS_shrwt_CHINA_adapted.xml</Value>
  <Value name="no_offshore_ccs">../input/gcamdata/xml/no_offshore_ccs.xml</Value>
</ScenarioComponents>

CCS and Power Sector

In GCAM-China, CCS affects the power sector by splitting coal/gas/liquids/biomass generation into CCS and non-CCS technology variants. This is visible in the output:

subsector=coal with technologies coal and coal CCS
subsector=gas with technologies gas and gas CCS

CCS share weights determine what fraction of generation uses each technology.

CCS in Industrial Sectors

CCS also affects industrial sectors:

cement: cement vs cement CCS
ammonia: coal vs coal CCS, gas vs gas CCS
iron and steel: BLASTFUR vs BLASTFUR CCS

Safe CCS Testing Workflow

Start with a working configuration without CCS
Copy the configuration as a test version
Add only Cstorage_CHINA.xml first — this only defines storage resources, not technology weights
Run a short horizon (e.g., to 2030) and verify no errors
Then add adapted CCS share weights one sector at a time
Check run log for each addition

Key Takeaway

Value name="xxx" in configuration XML is only a label. The actual file path and internal XML structure determine model behavior. Any new component must reference node paths that already exist in the model.

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