Glossary

Key terms and acronyms used in VerveStacks

Technical Terms

Bus (grid node)

A clustered high-voltage substation that serves as an injection point for generation and demand in the transmission representation. Naming convention in the TIMES model: e_<bus_id> for the electricity commodity at that node.

Clustering

Spatial aggregation of geographic points into regions using algorithms like Voronoi tessellation or DBSCAN.

Composite score

The ranking metric used by the sparsification step to decide which buses to retain as demand nodes. Defined per bus as load_share × voltage_weight ^ voltage_priority_factor × connectivity_weight ^ connectivity_priority_factor. Biases selection toward electrically meshed, high-voltage substations rather than purely toward population weight.

Coverage target

The fraction of national electricity demand that the sparsification step is required to retain on kept buses (default 0.80). Buses are accepted in descending composite-score order until the cumulative raw load share of kept buses crosses this threshold, subject to min_nodes and max_nodes guardrails. See the sparsification step.

FLO_MARK

A VEDA/TIMES parameter that bounds the share of a commodity’s flow that a given process must supply. VerveStacks uses FLO_MARK~lo = load_share × 0.98 on demand-technology processes to force each kept bus to serve its designated fraction of the end-use electricity demands; see Translation into the TIMES Model.

LCOE

Levelized Cost of Electricity - the average cost per unit of electricity generated over the lifetime of a technology.

Load share

The fraction of national electricity demand attributed to a single transmission bus. Produced by Allocation Pipeline, stored in {ISO}_bus_load_share_voronoi.csv (or its distance-weighted / synthetic variants), and consumed by grid_modeling.py to generate TIMES demand artefacts. After sparsification, load shares across kept buses always sum to 1.

NTC

Net Transfer Capacity - the maximum transmission capacity between regions.

REZ

Renewable Energy Zone - areas with high renewable resource potential.

Sparsification

The step that compresses the dense bus-level load-share distribution onto a small, electrically meaningful subset of transmission nodes. Combines a composite importance score (ranking) with a raw demand coverage target (stopping rule), then zeros the dropped buses and renormalises the survivors. See the sparsification step.

Stress Period

Time periods when the energy system experiences operational challenges due to supply-demand imbalances.

Timeslice

Representative time periods used to aggregate 8760 hourly data into manageable segments for optimization.

VerveStacks

Verve (vigor, energy, passion) + Stacks (the layered scenario-assumption sets that an analysis explores — data, technology, policy, demand, grid, and temporal layers). The name came first; the backronym below was fitted afterward. The intent: a stack-based environment that preserves the energy and momentum of modeling while hiding unnecessary complexity — closer in spirit to creative tools than to a solver. See also the FAQ: Where does the name “VerveStacks” come from?.

Voltage weight

A capacity-based multiplier assigned to each transmission bus from its voltage level (e.g. 380 kV → 10.0, 220 kV → 5.0, 110 kV → 1.0). Used both to weight population during Voronoi allocation and as a factor in the composite score. See the table in Allocation Pipeline.

Acronyms

AR6

IPCC Sixth Assessment Report climate scenarios

DBSCAN

Density-Based Spatial Clustering of Applications with Noise

EMBER

Energy and climate think tank providing electricity data

GEM

Global Energy Monitor - power plant database

IRENA

International Renewable Energy Agency

TIMES

The Integrated MARKAL-EFOM System energy modeling framework

VEDA

Versatile Energy Data Analyst - interface for TIMES models

VerveStacks (backronym)

Versatile Engine for Regional and Varied Energy scenarios - a post-hoc expansion of “Verve.” The acronym explains the letters; the name conveys the philosophy.

Note

Additional terms and definitions to be added as needed.