Skip to content

Limitations

PyPSA-AT is a techno-economic optimisation model designed for strategic scenario analysis of the Austrian energy system. Like every model, it is a simplified representation of reality. This page explains in detail what that means for the interpretation of model results: first, why results are indicative rather than technical planning statements, and second, which limitations PyPSA-AT inherits from its upstream model PyPSA-Eur.

Read before drawing conclusions

Model results are indicative and do not replace the detailed hydraulic assessments or power-flow/load-flow calculations that may be required for technical evaluation, validation, or planning purposes.

Indicative Results

PyPSA-AT answers questions about the cost-optimal long-term development of a sector-coupled energy system: which technologies are built where and when, how energy carriers flow between regions, and how policy constraints shape the system. It does not answer questions about the technical feasibility of operating a specific piece of infrastructure. The main reasons are:

Linearised electricity network representation

The electricity grid is modelled with a linearised optimal power flow (DC approximation). This captures active power transfers and congestion between regions, but it ignores:

  • reactive power, voltage levels, and voltage stability,
  • dynamic phenomena such as frequency response, transient stability, and fault behaviour,
  • detailed contingency analysis: security margins are approximated by a uniform reduction of usable line capacity rather than an explicit N-1 (or N-k) calculation.

A grid expansion that appears cost-optimal in PyPSA-AT therefore still requires a dedicated load-flow/power-flow study before any technical conclusion can be drawn.

Capacity-based gas and hydrogen networks

Gas and hydrogen pipelines are modelled as transport capacities between regions: energy can flow up to a technical pipe capacity. The model does not simulate pressures, flow velocities, compressor behaviour, linepack, or gas quality. Statements about whether a pipeline or storage facility can physically deliver a given profile require a dedicated hydraulic assessment, which is outside the scope of this model.

Spatial and temporal aggregation

Each model region (for Austria: NUTS3 zones) is represented by a single node. All demand and generation within a region is aggregated, and grids below the transmission level are only represented by simplified cost and loss assumptions. Time is resolved in steps of one to three hours for a limited set of representative weather years, so extreme events outside those years and sub-hourly dynamics (balancing, ramping within the hour) are not captured.

Idealised optimisation assumptions

The optimisation assumes global perfect foresight (within every planning year in the myopic workflow), perfect competition, and rational cost-minimising behaviour. Real-world market frictions, actor behaviour, financing constraints, permitting timelines, and supply-chain bottlenecks are not modelled. Results also depend strongly on uncertain input assumptions such as technology cost projections, fuel prices, and demand trajectories - they should always be read as scenario outcomes, not forecasts.

Inherited Limitations

PyPSA-AT builds on PyPSA-Eur (via PyPSA-DE) and inherits its documented limitations. Some of them have since been addressed or mitigated in PyPSA-AT for the Austrian model scope — these are marked below — but many still apply, in particular for regions outside Austria.