Error in calculation of line lengths

[bobbyxng]

Checklist

• [X] I am using the current main branch or the latest release. Please indicate.
• [x] I am running on an up-to-date pypsa-earth environment. Update via conda env update -f envs/environment.yaml.

Describe the Bug

• The calculated line lengths from build_osm_network.py seem largely overestimated (depending on the region of interest, size of region and used projection --> In config distance_crs: EPSG:3857 should not be used as a default/general --> dictionary depending on the focus region?).
• This can distort subsequent processes like the calculation of electrical parameters and the quality of the underlying data.
• In my checks, I choose the regions ["FR", "GB"], e.g. looking at the interconnector IFA2 for quick validation (link index: 1897) ~ 205 km (https://en.wikipedia.org/wiki/IFA-2)

Error Message

• No error messages

# %%
import geopandas as gpd
import shapely
import pypsa
import pandas as pd

# %%
# Load data
# Lengths are provided in km
n = pypsa.Network("base.nc")
link_lengths = n.links.loc[n.links.tag_type == "cable",  ["v_nom", "geometry", "length"]].copy()
link_lengths = link_lengths[link_lengths.v_nom == 320]
link_lengths = gpd.GeoDataFrame(link_lengths, geometry = link_lengths.geometry.apply(shapely.wkt.loads), crs = "EPSG:4326")
link_lengths["length"] = round(link_lengths["length"], 1)
# %%
utm = link_lengths.estimate_utm_crs(datum_name = "WGS 84")
link_lengths["length_wgs84"] = round(link_lengths.to_crs(utm).length / 1000, 1)

# %%
distance_crs = "EPSG:3035"
link_lengths["length_epsg3035"] = round(link_lengths.to_crs(distance_crs).geometry.length / 1000, 1)

# %%
distance_crs = "EPSG:3857"
link_lengths["length_epsg3857"] = round(link_lengths.to_crs(distance_crs).geometry.length / 1000, 1)