  Macro-energy system modelling is used by decision-makers to steer the global
energy transition toward an affordable, sustainable and reliable future.
Closed-source models are the current standard for most policy and industry
decisions. However, open models have proven to be competitive alternatives that
promote science, robust technical analysis, collaboration and transparent
policy decision-making. Yet, two issues slow the adoption: open models are
often designed with limited geographic scope, hindering synergies from
collaboration, or are based on low spatially resolved data, limiting their use.
Here we introduce PyPSA-Earth, the first open-source global energy system model
with data in high spatial and temporal resolution. It enables large-scale
collaboration by providing a tool that can model the world energy system or any
subset of it. This work is derived from the European PyPSA-Eur model using new
data and functions. It is suitable for operational as well as combined
generation, storage and transmission expansion studies. The model provides two
main features: (1) customizable data extraction and preparation scripts with
global coverage and (2) a PyPSA energy modelling framework integration. The
data includes electricity demand, generation and medium to high-voltage
networks from open sources, yet additional data can be further integrated. A
broad range of clustering and grid meshing strategies help adapt the model to
computational and practical needs. A data validation for the entire African
continent is performed and the optimization features are tested with a 2060
net-zero planning study for Nigeria. The demonstration shows that the presented
developments can build a highly detailed energy system model for energy
planning studies to support policy and technical decision-making. We welcome
joining forces to address the challenges of the energy transition together.
